Sept. 18, 2007 1

Science A-36 Overview and Intro

Welcome to A-36!

Course Staff:Professor Jonathan (“Josh”) Grindlay

Jaimie Pineda (TF)

Josh Younger (TF)

Sam Quinn (Clay Telescope & Astro. Lab mgr.)

Sept. 18, 2007 2

What’s A-36 all about?

Seeing Stars!

Observing, and actually measuring

the building blocks of the Universe

From the closest, the Sun

To the nearby young stellar cluster, the Pleiades

To star birth in Orion

And death in the Crab nebula and neutron star

Sept. 18, 2007 3Dense star field in Milky Way

Sept. 18, 2007 4

What’s A-36 all about?

Seeing Stars!

Observing, and actually measuring

the building blocks of the Universe

From the closest, the Sun

To the nearby young stellar cluster, the Pleiades

To star birth in Orion

And death in the Crab nebula and neutron star

Sept. 18, 2007 5Telescope image of Sun, with sunspots

Sept. 18, 2007 6

What’s A-36 all about?

Seeing Stars!

Observing, and actually measuring

the building blocks of the Universe

From the closest, the Sun

To the nearby young stellar cluster, the Pleiades

To star birth in Orion

And death in the Crab nebula and neutron star

Sept. 18, 2007 7

Sept. 18, 2007 8

What’s A-36 all about?

Seeing Stars!

Observing, and actually measuring

the building blocks of the Universe

From the closest, the Sun

To the nearby young stellar cluster, the Pleiades

To star birth in Orion

And death in the Crab nebula and neutron star

Sept. 18, 2007 9Orion nebula: stellar nursery…

Sept. 18, 2007 10

What’s A-36 all about?

Seeing Stars!

Observing, and actually measuring

the building blocks of the Universe

From the closest, the Sun

To the nearby young stellar cluster, the Pleiades

To star birth in Orion

And death in the Crab nebula and neutron star

Sept. 18, 2007 11Crab Nebula: remnant of Supernova in 1054AD

Sept. 18, 2007 12

And… some simple experiments (Daylab)

• Using a sun dial to measure the march of the seasons and the actual radius of the Sun

• Measure Sun’s diameter in red vs. blue filters and deduce temperature structure of solar atmosphere

• Measure Sun’s rotation velocity and period and deduce the size of our Solar system, and so distance yardstick to the stars

Sept. 18, 2007 13

How is A-36 “run”?

• Two class meetings/week (lecture and discussions) to understand the stars and the readings

• Readings typically 1 chapter/week in assigned textbook Universe: Stars and Galaxies (Freedman and Kaufmann; 3rd ed.)

• Two lab meetings/week (DayLab and Evelab), ea. 1h, for hands-on actual observations. “Sections” if cloudy

What background/skills required?None! Course will use simple algebra, and explain all…

Sept. 18, 2007 14

See Syllabus for A-36 details…

• Learning style – hands on (unique in Core…)• Workload – not bad; 1 “extra” hour/week of lab…• Grading – Labs, final, midterm, participation, quizes

• Labs (Evelab and Daylab): section signup in Thursday class this week; announced on class website by next MONDAY when labs begin

• OPEN HOUSE for Daylab (right after class today, SC804) and for Evelab (TONIGHT, and Thurs.) 730-9pm on Science Ctr. roof top (8th floor; then 2 flights up stairs) to Clay Teles.

Sept. 18, 2007 15

Distance to Sun and Stars: Large…

• Astronomy is a “remote” observation and measurement science; can’t “go there” and study stars up close.

• But… we can measure (even precisely) physical distances, sizes, masses and composition of stars: the parsec (pc) is distance at which star’s parallax moves it by 1arcsec as viewed over 3months. See Fig.: Definition: 1pc = 1AU/1” = 3 x 1018cm

• Closest star (Proxima Cen) is at distance d = 1.3pc = 4.3lightyears = distance light travels at 186,000miles/sec over 4.3 years, given that 1 year = 3 x 107sec:d = 1.86 x 105 x 4.3 x 3 x 107 = 2.40 x 1013 miles = 3.93 x 1013 km = 3.93 x 1018cm