introduction to astronomy march 2019 journal march 2019.pdfintroduction to astronomy march 2019...

SOCIETY JOURNALMARCH 2019

Introduction to Astronomy March 2019MONDAY 4 MARCH 2019 AT 8.00PMWITH CHRIS BENTONHow do astronomers measure how bright stars are and the distances to them?

Tonight we will discuss the techniques used to determine these and many other properties of stars including their temperatures and size.

Discover how observations of starlight split into its various wavelengths through spectroscopes and colour filters enable astronomers to do this, and then use simple formulas to deduce further properties. Find out with a simple experiment yourself illustrates how the parallax method of determining distances to the stars works.

Sirius A: Surface Temperature 10,000 K; Radius 1.19 million km; Distance to Earth 8.61 light years

Betelgeuse: Surface Temperature 3500 K; Radius 617 million km; Distance to Earth 700 light years

Examples of well-known stars in the southern night sky will allow you to relate to these methods and the results at your next star-gazing session!

I look forward to seeing you all there, where you will receive a three-page hand out explaining these principles further.

The talk will also be complemented by a video lecture with Professor Alex Fillippenko from the University of California reviewing how the luminosity, or power output, from stars is quantified.

2 SOCIETY JOURNAL, MARCH 2019

Big, Bigger, Biggest – Telescope (Film Night Feb)By Gavin Logan

February’s Film Night was exceptionally well attended and featured film about building very large telescopes. It covered the history of the development of the reflecting telescope and how larger and larger ones were built. Its particular focus was on the large binocular telescope in Arizona and the logistical and political problems with building it and in particular getting the very large mirrors to the top of the mountain. It also covered how adaptive optics worked and how this process could remove some of the problems of observing through the Earth’s atmosphere.

It was followed by a Sky at Night show on the rate of expansion of the universe and how many of the measurements of the speed of expansion differed. Another interesting piece in the show covered the Baker Street Irregular Astronomy Group and how they managed to photograph and also show the public deep sky objects from light polluted Central London.

Next month’s Film Night is on Monday 25th March at 8pm at Stardome. It features a film entitled “17th Century British Scientists that changed the World.” This is a documentary about Christopher Wren, Robert Hooke, Robert Boyle, Isaac Newton and Edmond Halley and how their work changed world thinking about biology and astronomy. This fascinating documentary includes some little known facts about these men, their work and relationships.

A large audience for the first Film Night of 2019

2019 NZ Astronomical YearbookThe 2019 Yearbook is now available. This is a must-have as-tronomy almanac for what’s happening in the New Zealand skies for 2019, plus current highlights in astronomy. Full of spectacular images from New Zealand astrophotographers.

This year’s issue features Information for beginners as well as veterans:

• Gaia’s Outrageous Mission – Learn about the mission that’s creating the greatest catalogue of our galaxy to date. The statistics of this mission are mind blowing!

• Not that long ago on a Moon far away – The coming year marks the 50th anniversary since humankind first set foot on the Moon. David Britten reflects on this giant leap that changed the course of history forever.

• A Centennial Celebration – The International Astronomical Union, founded in Paris in 1919, celebrates its 100th We re-flect on the pivotal role it has played in spreading astronomy education far and wide over the past century.

• Chasing the Lights – Dr Ian Griffin, Otago Museum, tells the story of how he took his passion for chasing aurora to new heights.

• Sky guides and star charts for the year

• Monthly guide to celestial events

• Contact information for NZ Astronomical Societies

The Yearbook also tells the success story of two astro-tour-ism pioneers at Lake Tekapo, pays a special tribute to the late Graeme Kershaw who contributed so much to the develop-ment of Mt John Observatory, and profiles friends, Phil Yock and Bill Allen, who have been two key contributors to New Zealand astronomy and astrophysics.

The 2019 Yearbook will be available at AAS meetings or can be ordered from Astronz on phone 09 473 5877 or on the website at www.astronz.nz.

Special AAS member price is $15.00 (+$4.00 postage). On the Astronz website use the discount code ‘AAS’.

3WWW.ASTRONOMY.ORG.NZ

Royal Astronomical Society of New Zealand

SWAPAStudents with a Passion

for Astronomy

RASNZ offers 10 top secondary students who are NZ citizens and at secondary school anywhere in New Zealand scholarships to enable them to attend the RASNZ annual astronomy conference, which will take place this year in New Plymouth, Friday 17 (evening) to Sunday 19 May (about 4 pm).

The scholarships comprise free registration for the conference (normallyabout $200), free travel from their home to New Plymouth, free backpacker accommodation in New Plymouth for 17 and 18 May, and a free banquetticket for the conference banquet on 18 May.

To be considered, students should email a short statement of no more than300 words explaining why they would like to attend the conference and whythey are interested in astronomy. This statement should be sent to RASNZ Immediate-Past President, John Drummond ([email protected] ) by Friday 15th March 2019, 5 pm. Include your name, gender, age, school, year of study at school in 2019, city, email address, telephone contact and science teacher’s name, phone and email.

left: M51 pinwheel spiral galaxy; centre: SWAPA students with astronomers at RASNZ conference in Dunedin 2017right: Kepler 186f, an Earth-like planet discovered by the Kepler spacecraft.


The society has a wide variety of equipment available to rent to members. The range of scopes go from the beginner Dobsonian telescopes through to the advanced computerised GOTO systems. All rental equipment is of high quality and regularly maintained. Rental periods are typically in 4-week blocks, but other arrangements may be available if you have a specific requirement. Full training and support is given for all equipment, including advice if equipment is suitable for your needs, or experience level.

8” Astronz Dobsonian Telescope $10/week Celestron Nexstar 5 127mm SCT Alt/Az Goto Telescope $12.5/week

iOptron Minitower Alt/Az with Celestron C5 OTA $12.50/week iOptron ZEQ25 GOTO Equatorial Mount with Celestron C8 $15/week

Meade LX-10 200mm Schmidt Cassegrain $10/week Coronado PST 40mm Hydrogen-Alpha Solar Telescope $10/week

iOptron Skytracker $10/week 20x80 Binocular $7.50/week

We are often adding items to our rental equipment, and we are really keen to hear what other items may be useful to members. Any ideas of for any information regarding availability or how to rent equipment, please contact:

Curator of Instruments -Steve Hennerley on 027 2456441 orDarren Woodley on 021 776481 [email protected]


MARCH PROGRAMME

Fri 1 7:00 pm Young Astronomers with Margaret Arthur

Mon 4 8:00pm Intro to Astronomy with Chris Benton

Mon 11 8:00pm Monthly Meeting March: Kumeu Observatory – Astro-nomy & Science “Out West” with Steve Hennerley

Mon 18 7:00pm Astrophotography Group - Deep Sky Image Processing with Shaun Fletcher followed byPractical Astronomy March - A Planetarium session looking at the Autumn night sky.

Mon 25 8:00pm Film Night March, 17th Century British Scientists that changed the World with Gavin Logan

APRIL PROGRAMME

Mon 1 8:00pm Intro to Astronomy with Chris Benton

Fri 5 7:00 pm Young Astronomers with Margaret Arthur

Mon 8 8:00pm Monthly Meeting April: TBA

Mon 15 7:00pm Astrophotography Group - Pixinsight with Liam Murphy followed byPractical Astronomy

Mon 22 8:00pm Film Night April with Gavin Logan

Calendar and Events

WAHARAU DARK SKY WEEKEND - APRIL 2019 FRIDAY 05 APR, 2019 AT 16:00HRS VENUE: WAHARAU REGIONAL PARK SPEAKER/HOST: GAVIN LOGAN

The Waharau Dark Sky Weekend is from Friday 5th April to Sunday 7th April at Waharau Regional Park, 1748 E Coast Rd, Orere Point, Whakatiwai 2473.

It will be a weekend of practical astronomy and dark sky observing.

It is great opportunity to spend a weekend viewing the sky from a dark site on Moonless nights through a range of different telescopes. Bring your telescope or binoculars, but if you dont have any there will be plenty there for you to look through.

During the day on Saturday there will be a full programme of practical astronomy – how to use equipment and various types of telescopes, new equipment demonstrations and an astrophotography workshop.

Films will be shown in the early evening on Friday and Saturday.

Price:

AAS Member earlybird $20.00 Payment by Friday 15th March.

AAS Member standard $30.00

Non-member earlybird $40.00 Payment by Friday 15th March.

Non-member standard $50.00

This price includes bunk bed type accommodation.

To book please email Gavin Logan: [email protected] giving the names of the people attending. Phone 021 144 1055.

INTRODUCTION TO ASTRONOMY MARCH 2019Monday 04 Mar, 2019 at 20:00Hrs Venue: Stardome Observatory Speaker/Host: Chris Benton

How do astronomers measure how bright stars are and the distances to them?

Tonight we will discuss the techniques used to determine these and many other properties of stars including their temperatures and size.

Discover how observations of starlight split into its various wavelengths through spectroscopes and colour filters enable astronomers to do this, and then use simple formulas to deduce further properties. Find out with a simple experiment yourself illustrates how the parallax method of determining distances to the stars works.

Examples of well-known stars in the southern night sky will allow you to relate to these methods and the results at your next star-gazing session!

I look forward to seeing you all there, where you will receive a three-page hand out explaining these principles further.

WELCOME NEW MEMBERS

Rigel Chiu OrdinaryLogan Carpenter FamilySteve Foster OrdinaryJoseph Ward FamilyBryan Whitlock FamilyAkbota Altynbekova FamilySasha Green OrdinaryChin Abeywickrama FamilySasha Todd Youth Brent Sykes OrdinarySarah Poulter Youth Membership

ASTROPHOTOGRAPHY GROUP MARCH 2019Monday 18 Mar, 2019 at 19:00Hrs Venue: Stardome Observatory Speaker/Host: Shaun Fletcher

Deep Sky Image Processing March‘s meeting will be a workshop on processing stacked deep sky images in Photoshop (or equivalent editor). I will provide a couple of DSS stacked images, and both demo and help people work through trying to process them into something respectable, and give/receive useful tips and tools for your image processing software.Please feel free to bring your laptop, your problems and your ideas.


OUTREACH TEAM – EVENTS

The Society is very active in public outreach. There are a growing number of events, particularly around the Matariki Festival, where the Society can fulfil its aim of taking astronomy to the public. This summer, the Society will be actively supporting the Auckland Botanic Gardens with their space-themed event running from December 2018 through to March 2019. There will be solar viewing days as well as night viewing – even though night comes late over summer.

Being part of the Outreach Team entails attending public events where members and the Society provide telescopes for viewing, discussing the night sky and the importance of dark skies and light pollution. This is a very satisfying team to be a part of as you really get to experience the wonder of astronomy over and over again. Even if you don’t have your own telescope, you’re very welcome to join the team and get involved.

Please contact Niven at [email protected] or on 021 935 261.

SOCIETY COUNCIL AND OFFICERS

President Bill Thomas (09) 478 4874 [email protected]

Vice-President Grant Christie (021) 0240 4992 [email protected]

Treasurer/ Outreach Niven Brown (021) 935 261 [email protected]

Secretary Gavin Logan (021) 144 1055 [email protected]

Membership Chris Benton (09) 424-4278 [email protected]

Curator of Instruments Steve Hennerley (027) 245 6441 [email protected]

Darren Woodley 021776481

Librarian Jerina Grewar (09) 444 5086 [email protected]

Journal Milina Ristić (029) 912 4748 [email protected]

Shaun Fletcher (09) 557 8686

Meetings Coordinator David Britten (09) 846 3657 [email protected]

Social Media Jonathan Green (09) 415 7284 [email protected]

Events [email protected]

Councillor Carolle Varughese 022 488 1906 [email protected]

SOCIETY CONTACTS

Auckland Astronomical Society Inc.PO Box 24187, Royal OakAuckland 1345, New Zealand

Website: www.astronomy.org.nzFacebook www.facebook.com/AuckAstroSocYoutube: www.youtube.com/channel/UC4W5_RJtWZBceOteC-8PTIAEmail: [email protected]

Meeting BroadcastsThe Society is now broadcasting many of its meetings online through our YouTube channel. You can watch the meetings live or at a later time. Perfect if you are unable to make it to the meeting or would just like to see the

talk again.

You can subscribe to our YouTube channel at:

https://www.youtube.com/channel/UC4W5_RJtWZBceOteC-8PTIA


Waharau Dark Sky Weekend 2019 by Gavin Logan, AAS

The Auckland Astronomical Society’s Waharau Dark Sky Weekend is from Friday 5th April to Sunday 7th April at Waharau Regional Park, 1748 E Coast Rd, Orere Point, Whakatiwai 2473 (about 1 hour drive from central Auckland).

It will be a weekend of practical astronomy and dark sky observing.

It is great opportunity to spend a weekend viewing the sky from a dark site on Moonless nights through a range of different telescopes. Bring your telescope or

binoculars, but if you don’t have any there will be plenty there for you to look through.

During the day on Saturday there will be a full programme of practical astronomy – how to use equipment and various types of telescopes, new equipment demonstrations and an astrophotography workshop.

Films will be shown in the early evening on Friday and Saturday.

Price:

AAS Member earlybird $20.00. Payment by Friday 15th March.

AAS Member standard $30.00

Non-member earlybird $40.00. Payment by Friday 15th March.

Non-member standard $50.00

This price includes bunk bed type accommodation.

To book please email Gavin Logan: [email protected] giving the names of the people attending. Phone 021 144 1055.


Notice of Annual General Meeting

The Annual General Meeting of the Auckland Astronomical Society Inc. will be held at the Stardome Observatory, One Tree Hill Domain on Monday 29th April 2019 starting at 8:00pm. All society members are encouraged to attend and help with the future of the Society. The agenda and a copy of the reports will be posted on the member’s area of the society website (www.astronomy.org.nz) prior to the meeting. Printed copies will also be distributed at the meeting. Nominations are open for all council positions; President, Vice President, Treasurer, Secretary, Librarian, Curator of Instruments, Editor and three to five council members. Nominations must be received by the Secretary by Monday 8th April 2019 and made using the form below. Note nominees, nominators and seconders must be current financial members.

Any questions or enquires can be directed to Bill Thomas (President) by email to [email protected] or phone 09 478 4874.

NOMINATION FOR AUCKLAND ASTRONOMICAL SOCIETY COUNCIL

To be completed by the nominator & a seconder. Both must be a current financial member.

I .................................................................... nominate .............................................................................

for the position of ................................................................................

signed: ...................................................... .........dated:

I .................................................................... second the nomination of .............................................................

for the position of ................................................................................

signed: ...................................................... .........dated:

To be completed by the nominee. The nominee must be a current financial member and have been so for at least one year.

I .................................................................... accept nomination for ........................................................

signed: ...................................................... .........dated:

SEND FORM TO: The Secretary, Auckland Astronomical Society email: [email protected] post: PO Box 24187, Royal Oak, Auckland 1345

Must be received by 8th April 2019.


Help Wanted

The Society continues to grow. To maintain our level of programmes and member services it takes a lot of work to organise, so the more people than can help with the various tasks will spread the load and makes it an easier job for everybody.

The Society Council recently identified various jobs that we need help with and we are looking for volunteers to join the small teams than run these functions. Please note, none of these jobs are positions on Council

If you are interested in helping out with one of the below jobs please contact Bill Thomas at [email protected] or phone 09 478 4874 or 021 225 8175 to discuss further. He will also be available at AAS meetings.

SPECIAL EVENTS COORDINATOR

This role is primarily to organise the Burbidge Dinner and also any other special events that the Society may hold. The role receives a lot of support from Council in terms of inviting speakers, venue hire etc. The Coordinator liaises with the coordinators of the astrophotography competition and writing prize but is not required to organise the judging for these awards.

OUTREACH TEAM

The Society is very active in public outreach. There are a growing number of events, particularly around the Matariki Festival, where the Society can fulfil its aim of taking astronomy to the public. Being part of the Outreach Team entails attending public events where members and the Society provide telescopes for viewing, discussing the night sky and the importance of dark skies and light pollution. This is a very satisfying team to be a part of as you really get to experience the wonder of astronomy over and over again.

SECRETARY

This role includes the recording and preparation of minutes of Council meetings.

The secretary is also responsible for the archival of Society records and documents

ASSISTANT EDITOR

We urgently need volunteers to be part of the team that prepares the Society Journal.

You will need to have access to and experience in using publishing tools such as Adobe InDesign or Microsoft Publisher


Solving The Solar Neutrino ProblemChris Benton - AAS

1. Introduction

Motivation and Scope: The Nobel Prize committee has recognised and awarded no fewer than four solar neutrino scientists involved with discovering and solving what is known as The Solar Neutrino Problem. The achievements of these recipients are the motivation for this paper to outline the research experiments and results these, and other physicists directed, with special attention to the Sudbury Neutrino Observatory (SNO) which ultimately solved this scientific enigma. With regards to the SNO, the focus is on the unique nuclear reactions they utilised, key methodology procedures undertaken ensuring accurate data, and a summary of their results. Brief comments on the Standard Solar Model (SSM) historical background and internal solar processes will precede this discussion, followed by essential and relevant information on solar neutrinos including mechanisms of production, as well as their behavioural and energy properties.

Introductory Comments: The Sun is the ultimate source of power and vital to most of life on Earth. It is paramount to science that we fully understand internal solar processes generating this energy which, according to twentieth-century thermonuclear physics, is nuclear fusion of hydrogen (H) into helium (He) at the Sun’s core.

As a by-product of this process, trillions of elusive particles known as neutrinos should be emanating from the Sun to the Earth every second. Detecting and quantifying neutrinos is hence crucial to confirm such internal solar reactions.

The quest to find these particles, however, is extremely challenging and for which scientists have devised Nobel Prize-winning bold and ingenious experiments. The Homestake Experiment was the first successful neutrino detector but discovered neutrino counts were surprisingly only a fraction of those expected from predictions. This result gave rise to The Solar Neutrino Problem, inspiring other scientists to develop new technology and techniques to confirm and build on these findings, in turn advancing knowledge and understanding of this field of astrophysics.

On the foundations of these more advanced experiments, and through solid methodology with carefully calibrated

and analysed data, the Sudbury Neutrino Observatory (SNO) solved this problem, validating the SSM and the associated principles of particle theory. The SNO continues to do more science, correlating data with the KamLAND anti-neutrino detector, and the next generation neutrino experiment BOREXINO.

2. The Standard Solar Model

Building on Einstein’s 1905 Special Theory of Relativity paper demonstrating that mass and energy were interchangeable, and nuclear astrophysics from 1930 onwards, came the theory that thermonuclear fusion of H into He occurs in the Sun’s core. The small net loss in mass from this reaction would release sufficient energy to account for the Sun’s age of approximately 4.6 billion years, and current luminosity of 3.828 x 1026 W (Mamajek et al. 2015).

The theory involving internal solar nuclear reactions leads to the development of the Standard Solar Model (SSM), describing predictions of the Sun’s internal structure and processes. According to the SSM, various pathways of nuclear fusion chain reactions produce small electrically neutral particles of differing energy levels. Known as solar neutrinos, trillions of these elusive particles should be travelling unimpeded through the Sun and towards Earth possibly at the speed of light every second. If detected and quantified, these sub-atomic particles could confirm the proposed thermonuclear reactions and their rates, providing an invaluable method to validate the SSM.

The SSM is the theory of the Sun’s internal structure, conditions and processes to explain its observed luminosity, size, mass and composition.

According to the SSM, due to gravitational forces from the Sun’s large mass, the Sun’s core experiences temperatures up to 15.7 million degrees Kelvin (Fiorentini & Ricci, 2002), sufficient to allow thermonuclear fusion of H into He. The energy released from H fusion is predominantly in the form of high-energy gamma-ray photons. These photons are randomly absorbed and scattered by free electrons in the Sun’s dense interior, such that it may take up to a million years for them to appear at the solar surface as lower energy photons of optical wavelength. In contrast, the extreme


numbers of neutrinos, each of which removes small amounts of energy, have an unimpeded estimated two-second transit.

Standard Solar Model of Thermonuclear Fusion in the Sun’s Core

The SSM proposes two main forms of thermonuclear fusion of H into He and subsequent production of neutrinos occur at the Sun’s core. These are the more dominant Proton-Proton (P-P) chain, and to a much lesser extent, the CNO cycle, each of which has many reaction pathways producing neutrinos of different energy levels. All neutrinos produced during both these reactions are associated with electrons, and hence known as electron neutrinos, annotated as νe.

The Proton-Proton Chain

The P-P chain, accounting for approximately 98.2 % of solar He production, is a sequence of five pathways divided into three branches abbreviated as PPI, PPII, and PPIII, as well as the pep and hep pathways (Lang, 2006). Each of the five pathways produces a solar electron neutrino, but as Figure 1 indicates, each pathway contributes a different percentage of He production to the chain. Irrespective of the total contribution of energy from each PP branch, all three generates the same 26 million electron volts (MeV) of energy for every helium-4 (4He) nucleus formed.

Figure 1: Summary of the five pathways of the proton-proton chain sequence. 1H is denoted with a p+, referring to it as essentially being a proton. Each solar electron neutrino is highlighted in red and presented as νe. The superscript preceding each element corresponds with the number of protons and neutrons making up the atomic nuclei. Credit: Creativecommon.org

The PPI branch, significantly the most dominant, accounting for almost 85% of helium production, occurs with the following three steps, as displayed in figure two:

Step 1: Two hydrogen nuclei (1H or p+), which are one positively charged proton each, collide to produce a proton and a neutral neutron, together forming the nucleus of the hydrogen isotope deuterium (2H). This conversion of a proton into a neutron produces two byproducts: a positively charged electron, known as a positron (e+); and the neutral neutrino particle (νe). The positron then encounters a negatively charged electron, the both of which are annihilated to form a high-energy gamma-ray photon, abbreviated as ɣ.

Step 2: The 2H nucleus then collides with a third 1H nucleus to form a helium isotope, 3He, with two protons and one neutron. This step produces another gamma-ray photon.

84.92 % of the 3He then proceeds with step 3, while 15.08 % leads to the PPII chain and an extremely small amount goes on to the hep pathway.

Step 3: Two 3He nuclei collide to produce a 4He nucleus with two protons and two neutrons, releasing two protons to continue this ongoing process.

The net result of the PPI branch is four 1H nuclei are converting into a 4He nucleus, two neutrinos, and two high-energy gamma-ray photons. These electron neutrinos, produced in Step 1, are also known as proton-proton (or pp) neutrinos.

The PPII branch, as indicated above, involves approximately 15 % of the 3He fusing to form a beryllium-7 (7Be) nucleus and a gamma ray, before 99.9% of the 7Be then transforms into Lithium-7 (7Li) with the creation of an electron neutrino (νe) as a neutron converts to a proton. From there, the 7Li captures a proton to form 4He. The neutrino in this pathway is known as the 7Be neutrino.

The PPIII branch: Just 0.1% of the above 7Be may capture a proton to transform into boron-8 (8B), and then transforming to 8Be producing 8B neutrinos, then forming two 4He nuclei.

The hep pathway: As illustrated in figure two, an extremely small amount (10-5 %) of 3He produced from step two of the PPI branch captures a proton to form the isotope 4He, an electron and a helium-proton (hep) neutrino.

The pep pathway: A small number of neutrinos are also by the proton-electron-proton (pep) reaction.

The CNO cycle

Figure 2: Summary of equations involved in the CNO-I cycle of fusing hydrogen into helium. Credit: Swinburne Astronomy Online.

While the P-P chain accounts for 98.2% of the Sun’s fusion of protons into helium, and subsequent gamma-ray and neutrino production, 1.8% involves carbon, nitrogen, and oxygen as catalysts in what is known as the CNO cycle (Lang, 2006). Two branches of the CNO cycle occur in the Sun, CNO-I and CNO-II. Figure 2 summarises these equations in the dominant CNO-I branch, showing two solar electron neutrinos for each cycle known as 13N and 15O neutrinos for their parent nuclei. The minor CNO-II branch involves fluoride as 17F and no carbon, resulting in 17F neutrinos.

Solar Neutrino Properties and Energy Spectrum


The solar electron neutrinos created as by-products from the P-P and CNO chains are elementary particles of nature and have several interesting properties.

Being extremely small, having at least six times less mass than that of an electron (Mertens, 2016), and electrically neutral, the only fundamental force they effectively act with is the weak nuclear force. Because the nuclei of atoms that make up matter are proportionally negligible in size relative to their electron fields, neutrinos only experience forces and interact with material on the rare occasion of a direct hit with an atomic nucleus. As a result, they can travel through matter relatively unimpeded at velocities close to the speed of light. The favourable aspect of this is that they arrive at Earth unaltered by subsequent interactions in just over eight minutes following their creation. The downside, however, is that these same properties make then elusive to detection by scientific instruments in the search for evidence of the thermonuclear reactions proposed by the SSM.

Furthermore, while the Sun produces large quantities of electron neutrinos, particle physics models predict two further neutrino types, also known as flavours, that are created by weak force interactions in other nuclear processes. These non-solar related reactions involve short-lived muon (µ), and tau (τ) charged particles decaying to produce their respective muon and tau neutrinos. Highly relevant to the solar neutrino problem, to be discussed, neutrinos have been discovered to oscillate between different flavours, providing the evidence for their, albeit near-zero, mass and extending the standard model of particle physics (Bilenky, 2016).

Of interest to physicists, the SSM predicts the total numbers, known as the flux, of solar electron neutrinos arriving at Earth, plus also the flux and different energy levels of the various sub-types from the individual P-P and CNO chain pathways. Figure 3 shows this energy spectrum with the expected flux of each sub-type, along with the degree of uncertainty, as a function of the neutrino energy levels.

Figure 3: The flux of neutrino sub-types reaching Earth, originating from different pathways, as a function of their energy. Credit: Bahcall & Serenelli, 2005.

Relevant to designing solar neutrino experiments, the diagram indicates that while the largest flux comes from the PPI branch of the Proton-Proton chain, they have the lowest energy levels, and hence the hardest to detect. The highest energy neutrinos, however, needing relatively less sensitive instruments to identify, originate from hep sub-branch and the PPIII branch of the proton-proton chain, but both of which have smaller fluxes.

Further complicating matters, “sterile” neutrinos that do not interact through the weak nuclear force are hypothesised to exist and may account for 3 to 4 % of total solar neutrinos (Lopes, 2018). These sterile solar neutrinos will be extremely difficult to detect, assuming they exist. For the rest of this paper, unless otherwise specified, all neutrinos will be considered as being of the “active” variant that does interact through the weak force.

3. The Search for Solar Neutrinos

While helioseismology studies and computer modelling provide indirect evidence of solar core thermonuclear

reactions, detecting the sub-atomic by-products, solar neutrinos, would be direct and superior.

Numerous complex and expensive neutrino detectors have hence been built over recent decades to achieve this, each with important sets of results and scientific implications. These observatories are designed to detect and record the rare occasions when a neutrino travelling through the Earth directly collides with an atomic nucleus of a specific material in a tank.

It follows they must be deep underground and large. The detectors are built at considerable depth underground to avoid undesired signals or “noise” from high energy sub-atomic particles, known as cosmic rays, and muons secondary to cosmic rays interacting with atmospheric particles, which are unable to penetrate the overlying rock. Furthermore, since both the neutrinos and the target nuclei are small, large numbers of target particles increase the desired “hit rate”. The sensors used to detect the signals must also be sensitive enough to record such events.

Due to this relative rarity of neutrino interaction, despite the Sun producing in the order of 1038 neutrinos per second, such that approximately 1014 reach every square metre of Earth each second, the rate of detection is frustratingly low. To record data on these low rates, physicists devised the Solar Neutrino Unit (SNU), each unit being equal to one neutrino interaction per second for every 1036 target atoms in the experiment.

A discussion of key solar neutrino observatories, with their results and scientific implications leading up to solving the solar neutrino problem, and their results follow.

3.1. The Homestake Experiment

In the late 1960s, a team headed by astrophysicists Ray Davis, Jr. and John Bahcall, built a 380,000-litre tank of the readily available dry-cleaning fluid perchloroethylene (C2Cl4) 1.5 kilometres underground in the Homestake Gold Mine in South Dakota, USA.

The purpose of this set-up was for any solar electron neutrinos with energy levels above the required 0.814 MeV that by chance directly hit a chlorine (Cl) atom, one of the atoms neutrons would transform into a proton, thus creating radioactive argon (Ar) and an electron (e-) as outlined in equation 1 (Bahcall, 1969).

Equation 1: νe + 37Cl => 37Ar + e-.

The energised argon rebounds from this encounter to break free and separate itself from the original molecule, to then enter the liquid solution. After several months, the chemically inert argon is removed by bubbling helium gas through the tank and then separated from the helium by a charcoal trap cooled by liquid nitrogen (Bahcall & Davis, 1976). The total amount of accumulated 37Ar essentially reflects the total flux of high-energy neutrinos from the isotope 8B PPIII branch of the proton-proton chain, indicated in Figures 1 and 3, as the “hep” neutrino flux is one thousand times smaller (Aharmin et al. 2013).

The Solar Neutrino Problem

After 108 meticulous and efficient extractions over 25 years, the combined result was 2.56 +/- 0.32 SNU, the +/- value


representing the level of uncertainty (Cleveland et al. 1998; Davis et al. 1968). This result, however, was one-third of the expected neutrino flux of 7.7 +/- 1.2 as predicted by the standard solar model at that time (Bahcall, 2001; Bahcall et al. 1968). This discrepancy became known as the Solar Neutrino Problem and sparked debate within the scientific community.

Some scientists suggested the SSM might be wrong concerning interior temperatures and pressures, with subsequent different nuclear reaction rates than those theorised based on the Sun’s luminosity (Friedlander, 1978). However, Bahcall (1976) points out high precision helioseismology observations provide strong evidence for predicted internal solar conditions. Other scientists argued the particle physics was not complete, in that neutrinos might undergo undiscovered processes and behaviours.

Another possibility was there being an unknown experimental problem, which inspired other teams to build solar neutrino detectors.

3.2 The Kamiokande Experiment

From 1987, in Kamioka, Japan, another large underground detector began operations under the leadership of Masatoshi Koshiba. Known as the Kamiokande Experiment, a 4.5 million litre tank of purified water surrounded by 948 50-cm diameter photomultiplier tubes (PMTs), designed to amplify light signals, was engineered to detect signals from incoming solar neutrinos, through a process known as elastic scattering (ES) of electrons.

Elastic scattering involves an incident neutrino striking an electron in the water, knocking it out of its atomic energy level, with the electron then accelerating to velocities greater than that of light in that medium. The result is a cone-shaped pulse of blue light, known as Cherenkov radiation, in the direction of the electron’s path, which the PMTs can detect.

Moreover, since the electron’s path aligns with that of the incident neutrino, the resultant light signal indicates the direction from which the neutrino came, extra information the Homestead Experiment could not provide. Knowing the neutrino direction not only confirms the Sun is the prime source of these by-products of thermonuclear fusion, but also assists in differentiating solar from other neutrino sources, allowing more accurate data.

The energy required of a solar neutrino to initiate such an event would need to be at least 7.5 MeV, a higher threshold that of the Homestead chlorine reaction, but still sufficient to detect the same 8B neutrinos.

Data from January 1987 to February 1995 recorded a neutrino flux of 2.82 +/- 0.38 SNU, a 55% deficit in the expected numbers from solar models (Fukuda et al. 1996), supporting the validity of the Homestake outcome. Furthermore, this period covered an entire solar activity period, concluding there was no correlation with changing flux; as well as noting no differences in data between day and night.

Serendipitously, in February 1987, the Kamiokande experiment detected a brief burst of 11 neutrinos from supernova SN1987 in the nearby Large Magellanic Cloud galaxy. Also by chance, the Irvine-Michigan-Brookhaven (IMB) detector in the United States, designed as a proton decay experiment, detected these non-solar neutrinos. The

small difference in arrival time of SN1987’s neutrinos to these observatories at different locations suggested these particles were travelling at a velocity less than that of light, implying they may have mass (Arnett & Rosner, 1987). However, neither Kamiokande or IMB had high-precision timing instruments to be more definite.

Both Ray Davis Jr. and Masatoshi Koshiba shared the Nobel Prize in Physics 2002, for their pioneering work in this difficult but extremely important field of astrophysics.

Large Uncertainly of High-Energy Neutrino Flux

As informative as this new data for the Kamiokande Experiment was, the PP-III chain from which the 8B neutrinos arise, however, is highly dependant on the Sun’s core temperature, creating a high percentage of flux uncertainty. Experiment sensors capable of detecting the more numerous low-energy pp neutrinos would thus give more reliable results.

3.3 GALLEX & SAGE Experiments

To achieve this capability, two international collaborations, the Soviet-American Gallium Experiment (SAGE), and combined GALLium EXperiment (GALLEX) plus Gallium Neutrino (GNO) constructed large detectors under mountains in Russia and Italy respectively. Their tanks contained the rare and expensive metal gallium-71 (71Ga), kept molten over 300 K. When struck head-on by a solar neutrino with 0.23 or more MeV energy, a gallium-71 nucleus would transform into a germanium-71 (71Ge) isotope through the conversion of a neutron into a proton.

Figure 4: Energy thresholds of Homestake, Kamiokands, GALLEX and SAGE Experiments with their respective chlorine, water and gallium detectors, compared with energies and flux spectra of solar neutrinos.Credit: Bahcall & Serenelli, 2005

This lower detection threshold, as can be seen in Figure 4, not only enables more 8B to be identified but also a large number of proton-proton neutrinos. The latter has a stronger correlation with the well-defined solar luminosity, thus significantly producing superior results reflecting reactions inside the Sun (Altmann et al. 2001).

Results are achieved after runs of four to six weeks when a series of chemical processes are undertaken to separate the 71Ge, which is then quantified by its radioactive decay back to 71Ga (Altmann et al. 2000). SAGE, from 1990 to 2001, measured 70.8 +/- 5.3 SNU (Abdurashitov et al. 2002); while combined GALLEX/GNO data from 1991 to 2003 gave a value of 69.3 +/- 5.5 (Altmann et al. 2005). Both results were


just above half of the predicted range of 120 to 140 SNU from various models (ibid), further highlighting the solar neutrino problem.

Neutrino Flavour Oscillations

To further address this problem, detailed helioseismic observations from the SOlar and Heliospheric Observatory (SOHO) spacecraft were used to build an advanced model of the solar interior structure and conditions. The authors, Turch-Chièze et al. (2001), confirmed the expected solar neutrino flux was flavour transitions.

The idea of other flavours of neutrinos, as well as their ability to oscillate between types, developed during the 1960s (Gribov & Pontecorvo, 1969). While it is possible for neutrinos to oscillate in a vacuum en-route from the Sun to Earth (Upadhyay & Batra, 2012), it became apparent that neutrinos readily oscillate within matter such as the Sun’s interior (Wolfenstein, 1978). Known as the MSW (Mikheyev, Smirnov, Wolfenstein) effect, neutrinos transform from one flavour to another while travelling in a medium of varying density, due to combining and mixing the three small quantum mass units that they are composed of (Smirnov, 2005), as illustrated in Figure 5.

Figure 5: Each neutrino flavour has a unique mass fraction. Credit: A McDonald 2015 Nobel Lecture

3.4 The Super-Kamiokande Experiment

In the late 1990’s, the Super-Kamiokande Experiment (Super-K), a 40-meter high stainless steel tank with 50,000 tons of ultrapure water one kilometre deep in a Japanese zinc mine, effectively demonstrated this MSW effect.

This involved Super-K’s 13,000 PMTs mounted on the tanks inner walls (Figure 6), designed to detect Cherenkov light emitted by electrons recoiling from a colliding neutrino, similar in concept to the Kamiokande Experiment. The difference, however, is now being able to observe both solar 8B electron neutrinos and muon neutrinos. The muon neutrinos, arising from high-energy cosmic rays colliding with atomic nuclei in Earth’s upper atmosphere, are distinguished from solar neutrinos by a tighter cone of signal light, reflecting their higher energy.

Figure 6: Configuration of the Super-K Experiment tank and 13,000 PMTs of Credit: ScienceDaily.com

Interestingly, observations from a 535-day exposure recorded

a significantly higher atmospheric muon neutrinos flux from directly overhead the observatory during the daytime, compared with that from the other side of the Earth during nighttime (Fukuda et al. 1998). Further analysis and calculations, proved the data to be consistent with some of the muon neutrinos having transformed into undetectable tau neutrinos while travelling through the Earth. Further experiments involving sending intense fluxes of muons to the Super-K detector from particle accelerators on the far side of the Earth confirmed this phenomenon (Suzuki et al. 2014).

This first demonstration of neutrino flavour transformation was an important step towards solving the solar neutrino problem and earned the experiment team leader, Takaaki Kajita, a share in the Nobel Prize for Physics 2015. While the results did not specifically involve solar neutrinos they did, however, provide the foundations for the SNO to ultimately solve the solar neutrino problem.

Solving The Solar Neutrino Problem

The final phase in solving the solar neutrino problem would be to detect and accurately quantify all three neutrino types. All the experiments up until this point had been detecting only the electron neutrinos which are from the charged-current (CC) reaction, the weak force interaction mediated by exchange particles known as W bosons, and involves changing electrically charged particles.

An experiment to detect all three neutrino flavours with equal sensitivity was required and would involve neutral-current (NC) weak force interactions mediated by the Z boson exchange particle. This reaction involves no transfer of electrical charge and would be key to the success of the SNO.

3.5 Sudbury Neutrino Observatory (SNO)

To achieve the detection of all three flavours, a collaboration of Canadian, American and British scientists constructed the SNO using heavy water (D2O) as their reaction medium. D2O has two deuterium (D) atoms, which are isotopes of H containing a neutron, with the deuterium neutrons uniquely enabling both the CC and NC reactions to occur and thus detect the solar electron neutrinos alone, and then all three flavours together (Chen, 1985).

Figure 7: Scale diagram of SNO general structure, as discussed above. Note the depth of the cavity in comparison to a person. Credit: Boger et al. 2000.


Situated two kilometres underground in a working nickel mine in Ontario, Canada, the SNO consists of a 12-meter diameter transparent acrylic sphere filled with one million litres the heavy water, which they borrowed from Atomic Energy of Canada (Boger et al. 2000). Struts supporting 9438 PMTs surround the sphere in a geodesic arrangement as illustrated in Figure 7, all of which are in a much larger cavity containing 7.8 million litres of purified normal “light H2O” water. The surrounding normal water importantly provides shielding against background natural radioactivity of the surrounding rock uranium and thorium producing gamma rays and neutrons. Furthermore, cosmic-ray muon interactions with the light water, distinguishable from solar neutrino events, were quantified identifying potential false counts and thus providing more accurate data.

With this design, the advanced SNO was now able to commence its research programme using three principal neutrino reactions: The CC, NC and the ES reactions as discussed below.

I. Charged Current (CC) Reaction

Figure 8: Charged-Current Reaction. Credit: Carleton University

Equation 3-1: νe + D => p + p + e-

Where νe is an electron neutrino, D is deuterium, p is a proton, e- is an electron.

As summarised in Equation 3-1 and Figure 8, the CC reaction involves an electron neutrino striking a deuterium nucleus, with the neutron converting into a proton with the production of a high-speed electron. The accelerating electron produces Cherenkov light to be detected by the photomultiplier tubes. The threshold energy for this reaction is 1.4 MeV, implying this is measuring the 8B electron neutrino flux (McDonald, 2005). Also of note, the electron energy is strongly correlated with the neutrino energy, thus providing any distortions of the expected 8B flux energy spectrum to be noted.

II. Neutral Current (NC) Reaction

Figure 9: Neutral-Current Reaction. Credit: Carleton University

Equation 3-2: νx + D => p + n + νx

Where νx is any one of the three neutrino flavours.

In the NC reaction (Figure 9 and Equation 3-2), a neutrino of any flavour with a threshold energy of 2.2 MeV, collides with and splits a deuterium nucleus into its proton and neutron, with the neutrino travelling on, but with less energy. Two methods over three phases of the research were then used to detect the neutrons (McDonald, 2005).

Phase one, running from November 1999 to May 2001, involved deuterium capturing neutrons to form 3H with the emission of 6.25 MeV gamma-ray photons. These photons subsequently Compton scatter, whereby they impart energy to electrons, which then accelerate to emit detectable Cherenkov light (Boger et al. 2000).

Phase two, from July 2001 to September 2003, involved the same process but adding in two tonnes of sodium chloride. The 35Cl nuclei increase the available neutron reaction cross-section, improving the capture rate by approximately 40%, producing a cascade of higher energy gamma-rays up to 8.6 MeV and subsequently more Cherenkov light providing a significant improvement in the accuracy of measurements (ibid).

For phase three, November 2004 to December 2006, the salt was removed and an array of 3He-filled proportional counters installed (McDonald, 2005). 3He provides a large cross-section to capture thermal neutrons in equilibrium with the heavy water, the reaction resulting in an electrical pulse, and thus detection independent of the photomultiplier tubes.

III. Elastic Scattering (ES) Reaction

Figure 10: Electron Scattering Reaction. Credit: Carleton University

Equation 3-3: νx + e- => νx + e-

The ES reaction (Figure 10 and Equation 3-3) occurs when a neutrino of any flavour collides with an atomic electron, accelerating to produce Cherenkov light, as occurs in the Kamiokande and Super-K detectors. The difference with the SNO detector, however, is a sensitivity to all neutrino flavours, albeit less sensitive to the muon and tau flavours than the electron neutrino, due to six times larger cross-section for the latter (Aharmim et al. 2013). The directional nature of elastic scattering is also useful in confirming which of the detected neutrinos are solar in origin, and which are from deuterium breakup from radioactive contaminants.

Instrument Calibrations

Using three different reactions and phases as described allowed results from detectors with different systematic uncertainties which, with blind analysis of each separate set of data, gave confidence in the experimental accuracy.

Further to this, as well as stricture procedures to minimise potentially radioactive contaminating body and clothing material, special techniques were employed to measure and calibrate the sensitivity of the detectors reducing system errors. These involved a laser source of variable wavelengths measuring optical properties of detectors, the beta decay of the unstable isotope of nitrogen 16N, and radioactivity of natural uranium (U) and thorium (Th), the latter two methods


providing events and associated particles with different but known energy levels.

SNO produced 16N and transferred it to a decay chamber inside both the heavy and light water cavities. While the chamber blocked the high-energy electrons produced, the gamma-rays of 6.13 MeV exited with the resultant Cherenkov light to be recorded by the observatory detectors, enabling calibration (Dragowsky et al. 2002).

Encapsulated sources of U and Th moved strategically about inside the experiment provided Cherenkov light for PMT calibration (Jonkmans et al. 1999). Furthermore, measurements of U and Th decay chain elements allowed calculations of the expected numbers of free neutrons produced from associated gamma-rays splitting deuterium nuclei.

Summary of SNO Results

SNO data analysis involves using various statistical methods. The process includes Monte Carlo-based computer simulations of distributions from the expected variable signals which are then used as probability density functions (PDFs) to fit SNO’s experimental data. For example, to overcome the challenges in separating signals from the CC, NC and ES reactions in phase one, PDFs to fit the SNO data are constructed for (a) the kinetic energy of gamma-rays associated with NC reaction neutron capture, plus the CC and ES recoiling electrons; (b) the radial position of interactions; and (c) the direction of incident neutrinos (Bellerive et al. 2016).

Results from phase one showed the flux (ϕ) of νe’s from 8B decay during the CC reaction as 1.75 +/- 0.07 (statistical error) +0.12/-0.11 (system error) x 106 cm-2s-1 (Ahmad et al. 2001). The comparison of this number with the ES reaction results, sensitive to all neutrino types (νx), could potentially give evidence of flavour changes. The SNO ES ϕ (νx) value of 2.39 x 106 cm-2s-1 had a large margin of error, however, of +/- 0.34 (stat.) and +0.16/-0.11 (sys.), but comparison of SNO’s CC ϕ (νe) value with that of Super-K’s high-precision value of 2.32 +/- 0.03 (stat.) +0.08/-0.07 (sys.) x 106 cm-

2s-1 for ES ϕ (νx) provided the first evidence of solar electron neutrino transformations (ibid).

After completion of all three phases of the project, combined data analysis showed the total flux of all 8B neutrinos from the Sun was 5.25 +/- 0.16 (stat.) +0.11/-0.13 (syst.) x 106 cm-2s-1 (Aharmin et al. 2013), closely matching those of the BP2000 Solar Standard Model (Bahcall et al. 2001), and thus finally solving the solar neutrino problem!

Figure 11: Results of SNO data for total and electron solar neutrino fluxes from 8B decay. Note the excellent agreement with SSM calculations. Credit: Cerncourier.com

Moreover, since CC and NC reactions use different detectors, a total count of just the electron neutrino flux could be determined from the CC numbers, without dependency on figures from other experiments or theory. This value of 1.76

+/- 0.05 (stat.) +/-0.09 (syst.) cm-2s-1 (Bellerive et al. 2016) equals approximately one-third of the total flux recorded. These results, highlighted in Figure 11, provide clear evidence for electron neutrinos having changed to τ and µ neutrinos en route to Earth and thus having accounted for the “missing” neutrinos in prior observatories. Interestingly, the SNO data showed no evidence of, or the need for, sterile neutrinos to match the SSM.

Figure 12 also shows the SNO data, but with bands, the width of which at the x- and y-axis’ reflect +/- 1 standard deviation (σ) error of the CC, NC and ES reactions. Note the total 8B neutrino flux (ϕ), as measured by the NC reaction fits well inside the predicted BP2000 SSM parameters shown by the dashed lines, indicating experimental values of more accuracy than those with solar model uncertainties. The bands from the combined sets of results intersect at model fit values of ϕe and ϕµτ as would be expected with no distortion of the 8B energy spectrum, with the error ellipses representing the 68%, 95% and 99% probabilities. Though not able to show the fractions of ϕ (ντ) and ϕ (νµ) individually, the certainty of these results was such that there was a 5σ probability, or less than one chance in 10 million, for solar neutrinos not changing flavour.

Figure 12: SNO results showing flux (ϕ) values and error margins for ES, CC and NC reactions, with SSM prediction range inside the dashed lines. Credit: Bellerive et al. 2016.

This ingenious study with attention to experimental detail and its ground-breaking results confirmed not only that the total solar electron neutrino flux from 8B decay matched models of nuclear fusion rates in the Sun’s interior, but also that the SSM was incomplete with evidence of solar neutrino flavour oscillations, and thus neutrinos having mass. Deservingly, the SNO’s director, Arthur McDonald, was awarded a share in the Nobel Prize in Physics 2015 award with Takaaki Kajita from the Super-K experiment.

Further to these and future experiments, the SNO data when combined with that from two more recent detectors continues to advance solar neutrino physics. KamLAND, although an anti-neutrino detector, enhances understanding of solar neutrino science; as does the newest and most sensitive Borexino detector.

3.6 Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND)

Constructed at the site of the older Kamiokande detector, KamLAND detects electron anti-neutrinos, products of nuclear fission from nuclear power plants travelling through the Earth. Measurements of anti-neutrino rates reflect neutrino transformations, providing constraints to neutrino mass and oscillation values, as well as supporting evidence that most neutrino flavour alteration occurs in the Sun’s interior (Gando et al. 2011).

3.7. The Borexino Experiment


The Borexino Experiment, operating since 2007 by international collaboration in Italy, works whereby PMTs detect signals from neutrino-induced electron elastic scattering in a purified liquid scintillator (Alimonti et al. 2009). This highly sensitive detector detects low energy neutrinos from the pp, 7Be, pep, 8B, and CNO cycles with results in good agreement with the SSM predictions, as well providing the first evidence of neutrino oscillation in a vacuum (Bellini, 2016).

4. Summary

According to nuclear physics theory, it is the fusion of H into He in the solar core that powers our Sun and supports life on Earth. This thermonuclear process involves multiple pathways of the proton-proton chain and CNO cycle reactions, producing gamma-ray photons and extreme numbers of small and electrically neutral electron neutrino particles of differing flux and energy levels.

The search to detect and quantify these elusive solar neutrinos has been central to confirming the modern theory of SSM, and for which require large deep underground specialised observatories.

The first to achieve this was the Homestake Experiment, measuring argon from rare neutrino reactions with chlorine atoms, to detect high-energy 8B solar neutrinos. The flux of these neutrinos, however, measured only one-third of the amount predicted by the SSM, with this discrepancy to become known as The Solar Neutrino Problem. Further research programmes included the Kamiokande Experiment which used PMTs to detect Cherenkov radiation from the elastic scattering of electrons by 8B neutrinos in purified water. A similar neutrino flux deficiency was noted thus confirming the problem. The directors of both organisations won Nobel prizes recognising their contribution to this important area of solar particle physics.

Further highlighting this conundrum, the Gallex and Sage Experiments used gallium nuclei as targets to successfully detect low-energy pp neutrinos produced inside the Sun in larger numbers, but also discovered much less of these than expected.

A solution to the Solar Neutrino Problem was the idea that solar electron neutrinos oscillate between all three flavours, including tau and muon neutrinos, particularly while traversing the Sun’s interior. The observation of muon and electron neutrinos by the Super-K demonstrated this idea resulting in a Nobel prize and importantly setting up the SNO to ultimately validate the SSM.

Using large quantities of heavy water, the SNO ran a series of highly calibrated experiments involving CC, NC and ES reactions to detect all three neutrino flavours and independently quantify the electron neutrino flux with a high level of certainty. The total detected flux of all solar 8B neutrinos was 5.25 +/- 0.16 (stat.) +0.11/-0.13 (syst.) x 106 cm-2s-1, matching those of SSM figures and validating theories of solar nuclear fusion rates. Furthermore, the electron flavour neutrino count of 1.75 +/- 0.07 (stat.) +0.12/-0.11 (syst.) x 106 cm-2s-1 was approximately one-third of all solar 8B neutrinos, providing clear evidence for neutrino oscillation en route from the core of the Sun to the Earth, and consequently, the SSM is incomplete.

The fourth Nobel prize in this field of physics awarded to the SNO director, Arthur McDonald, exemplifies not only the importance of supporting the scientific theory with sound experimental observations and methods but also how each scientist builds on the achievements of those before. In this case, it was the progressive work of many observatories and associated teams that lead to solving The Solar Neutrino

Problem.

Continuing with solar neutrino science, the KamLAND electron anti-neutrino detector and the highly sensitive Borexino neutrino detector are both using these results to further advance understanding of solar neutrino masses and behaviour, thus refining the SSM. Possibly, the search for sterile solar neutrinos may lead to The Solar Neutrino Problem II with even more Nobel Prizes!

5. References

Abdurashitov, J.N. et al. 2002, J.Exp.Theor.Phys, 95, 181

Ahmad, Q.R. et al. 2001, Phys. Rev. Lett, 87, 071301

Aharmim, B. et al. 2013, Phys.Rev, C88, 025501

Alimonti, G. et al. 2009, Nucl. Instrum. Methods Phys. Res, Sect. A, 600, 568

Altmann, M.F., Mößbauer, R.L. & Oberauer, L.J.N. 2001, Rep. Prog. Phys, 64, 97

Altmann, M. et al. 2000, Phys. Lett. B, 490, 16

Altmann, M. et al. 2005, Phys. Lett. B, 616, 174

Arnett, W.D. & Rosner, J.L. 1987, Phys. Rev. Lett, 58, 1906

Bahcall, J.N. 1969, Sci. Am, 221, 28

Bahcall, J.N. 2001, Nucl. Phys. B Proc. Suppl, 91, 9

Bahcall, J.N., Bahcall, N.A. & Shaviv, G. 1968, Phys. Rev. Lett, 20, 1209

Bahcall, J.N. & Davis, R. Jr. 1976, Sci, 191, 264

Bahcall, J.N., Pinsonneault, M.H. & Basu, S. 2001, ApJ, 555, 990

Bahcall, J.N., Serenelli, A.M. & Basu, S. 2005, ApJ L, 621, L87

Bellerive, A., Klein, J.R., McDonald, A.B., Noble, A.J. & Poon, A.W.P., 2016, Nucl. Phys. B, 908, 30

Bellini, G. 2016, Nucl. Phys. B, 908, 178

Bilenky, S. 2016, Nucl. Phys. B, 908, 2

Boger, J. et al. 2000, Nucl. Instrum. Methods Phys. Res, Sect. A, 449, 172

Chen, H.H. 1985, Phys. Rev. Lett, 55, 1534

Cleveland, B.T., Daily, T., Davis, R, Jr., Distel, J.R., Lande, K., Lee, C.K., Wildenhain, P.S. & Ullman, J. 1999, ApJ, 496, 505

Davis, R. Jr., Harmer, D.S. & Hoffman, K.C. 1968, Phys. Rev. Lett, 20, 1205

Dragowsky, M.R. et al.2002, Nucl. Instrum. Methods, Sect. A, 481, 284

Fiorentini, G. & Ricci, B. 2002, Phys. Lett. B, 526, 186

Friedlander, G. 1978, ComAp, 8, 47

Fukuda, Y. et al. 1996, Phys. Rev. Lett, 77, 1683

Fukuda, Y. et al. 1998, Phys. Rev. Lett, 81, 1562

Gando, A. et al. 2011, Phys. Rev. D, 83, 052002

Gribov, V. & Pontecorvo, B. 1969, Phys. Lett. B, 28, 463

Jonkmans, G. et al. 1999, Nucl. Phys. B, 70, 329

Lang, K.R. 2006, Sun, Earth and Sky, 2nd edition (Singapore: Springer Science and Business Media)

Lopes, I. 2018, EPJC, 78, 327

McDonald, A. B. 2005, Phys. Scr. T, 121, 29

Mamajek, E.E. et al. 2015, arXiv:1510.07674

Mertens, S. 2016, JPhCS, 718, 022013

Smirnov, A.Y. 2005, Phys. Scr. T, 121, 57

Suzuki, K. et al. 2015, Prog. Theor. Exp. Phys, 2015, 053C01

Turck-Chièze, S. et al. 2001, ApJ, 555, L69

Upadhyay, A. & Batra, M. 2013, ISRN High Energy Phys, 2013, ID 206516

Wolfenstein, L. 1978, Phys. Rev. D, 17, 2369


The Evening Sky in March 2019By Alan Gilmore, University of Canterbury‘s Mt John Observatory, www.canterbury.ac.nz


Bright stars are overhead in the early evening. Northwest of the zenith is Sirius the brightest star in the sky (but

out-shone by star-like Venus and Jupiter when they are around). Southwest of the zenith is Canopus, the second brightest star. Below Sirius are Rigel and Betelgeuse, the brightest stars in Orion. Between them is a line of three stars: Orion’s belt. To southern hemisphere star watchers, the line of three makes the bottom of ‘The Pot’. Orion’s belt points down and left to a V-shaped pattern of stars. These make the face of Taurus the Bull. The orange star is Aldebaran making one eye of the bull. Continuing the line from Orion down and left finds the Pleiades or Matariki star cluster.

Mars is the only naked-eye planet in the evening sky. It appears as a lone reddish star setting two hours after the sun. At 280 million km from us it appears too small in a telescope to be of much interest.

Sirius is the brightest star in the sky both because it is relatively close, nine light years* away, and 23 times brighter than the sun. Rigel, above and left of Orion’s belt, is a bluish supergiant star, 40 000 times brighter than the sun and much hotter. It is 800 light years away. Orange Betelgeuse, below and right of the line of three, is a red-giant star, cooler than the sun but much bigger and 9000 times brighter. It is 400 light years from us. The handle of “The Pot”, or Orion’s sword, has the Orion Nebula at its centre; a glowing gas cloud many light-years across

and 1300 light years away.

Near the north skyline are Pollux and Castor marking the heads of Gemini the twins. Low in the north is the star cluster Praesepe, marking the shell of Cancer the crab. Praesepe is also called the Beehive cluster, the reason obvious when it is viewed in binoculars. The cluster is some 500 light years from us.

Crux, the Southern Cross, is in the southeast. Below it are Beta and Alpha Centauri, often called ‘The Pointers’. Alpha Centauri is the closest naked-eye star, 4.3 light years away. Beta Centauri, like most of the stars in Crux, is a blue-giant star hundreds of light years away. Canopus is also a very luminous distant star; 13 000 times brighter than the sun and 300 light years away.

The Milky Way is brightest in the southeast toward Crux. It becomes broader lower in the southeast toward Scorpius. Above Crux the Milky Way can be traced to nearly overhead where it fades. It becomes very faint in the north, right of Orion. The Milky Way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one. We are 30,000 light years from the galaxy’s centre, below Scorpius.

The Clouds of Magellan, LMC and SMC are high in the south sky, easily seen by eye on a dark moonless night. They are two small galaxies about 160 000 and 200 000 light years away.

The bright planets appear in the late night sky (so don’t appear on the chart). Jupiter rises in the southeast around 1 a.m. at the beginning of the month. It is the brightest ‘star’ in the late night sky and shines with a steady golden light. By the end of the month it is up soon after 11. Saturn rises below and right of Jupiter around 3 a.m. at the beginning of the month and 1 a.m. at the end. Though much fainter than Jupiter it is still the brightest ‘star’ in that part of the sky. Both planets are good sights in a telescope but blurry when low in the sky. Jupiter is 780 million km away mid-month; Saturn 1560 million km. We are catching up these planets so they rise earlier each night. The moon will be close to Saturn on the morning of the 2nd. It passes by Jupiter on the 26th and 27th and past Saturn on the mornings of the 29th and 30th.

Brilliant Venus appears around 4 a.m. at the beginning of the month. Venus is leaving us behind and moving to the far side of the sun. As it does so it sinks lower in the dawn sky. By the end of the month it is rising around 5 a.m. Venus is 175 million km away mid-month. It appears as a small featureless disc in a telescope. The thin crescent moon will be above Venus on the morning of the 3rd and again on April 2nd.Mercury begins its best morning sky appearance of the year in the second half of March. At the end of the month it will be a bright ‘star’ below and right of Venus, rising before 6 a.m.

Diary of events in March by RASNZ

March 1 Moon southern most declination (-21.6 degrees)

March 1 Saturn 0.3 degrees south of the Moon Occn

March 2 Pluto 0.5 degrees south of the Moon Occn

March 2 Venus 1.2 degrees north of the Moon

March 4 Moon at apogee

March 5 Mercury stationary

March 6 Neptune 3.0 degrees north of the Moon

March 6 Moon new

March 7 Neptune at conjunction

March 10 Uranus 4.6 degrees north of the Moon

March 11 Mars 5.5 degrees north of the Moon

March 13 Aldebaran 1.9 degrees south of the Moon

March 14 Moon first quarter

March 15 Mercury inferior conjunction

March 15 Moon northern most declination (21.8 degrees)

March 19 Regulus 2.5 degrees south of the Moon

March 19 Moon at perigee

March 20 Equinox

March 21 Moon full

March 25 Mercury 2.4 degrees north of Neptune

March 27 Jupiter 1.9 degrees south of the Moon

March 27 Mercury stationary

March 28 Moon last quarter

March 28 Moon southern most declination (-21.9 degrees)

March 29 Saturn 0.1 degrees north of the Moon Occn

March 29 Pluto 0.3 degrees south of the Moon Occn

DATE (NZDT) DIARY OF SOLAR SYSTEM EVENTS IN MARCH 2019 FOR NEW ZEALAND

T E L E S C O P E S

Astronz only stock high quality telescopes that are suitable for real astronomy, whether you are a beginner or an expert.

Our range includes Newtonian and Ritchey-Chretien type telescopes with apertures from 153mm (6”) to 406mm (16”).

people who love the night sky

A B O U T U S

Our goal is to promote astronomy in New Zealand by providing quality equipment at a reasonable price. We are owned by Auckland Astronomical Society and run by volunteers.

Astronz is unique in reinvesting everything we make back into astronomy and science education in New Zealand.

A S T R O P H O T O G R A P H Y

Get started or extend your hobby or research with our range of CCD and CMOS cameras that attach to your telescope.

We stock computerised astrophotography telescope mounts or you can even use a DSLR camera with one of our camera mounts and take great wide field astrophotographs with no telescope at all.

www.astronz.nz

[email protected]

09 473 5877

introduction to astronomy march 2019 journal march 2019.pdfintroduction to astronomy march 2019...

Documents