a galaxy party in paris
DESCRIPTION
Je cherche fortune Tout autour du Chat Noir Au clair de la lune A Montmartre le soir bfdbf. Black cat Black hole Black matter (or Dark matter) Black energy (or Dark energy). A galaxy party in Paris. Suzanne et Michel FAYE, Paris, France [email protected] ; [email protected]. - PowerPoint PPT PresentationTRANSCRIPT
Black cat
Black hole
Black matter (or Dark matter)
Black energy (or Dark energy)
Black cat
Black hole
Black matter (or Dark matter)
Black energy (or Dark energy)
Je cherche fortune
Tout autour du Chat Noir
Au clair de la lune
A Montmartre le soir
Suzanne et Michel FAYE, Paris, France [email protected]; [email protected]
Part one
Angular measurements with Google Earth or / and Stellarium
Let us begin with a starry night, by Van Gogh, fond of nocturnal skies;
he used to read much about astronomical observations at his time
Whirlpool galaxy
M51 = NGC 5195
Credit Nasa
Let us compare to a whole night exposure around the Northern Pole
Van Gogh’s skies
And then, astronomy for kids, starry lines around Northen Pole, starry curtain, colouing Van Gogh’s starry night.
About Whirlpool Galaxy
Where? In the constellation Canes Venatici
1774 : Discovered by Charles Messier (M 51 A = NGC 5194)
1781: Companion discovered by Pierre Méchain (M51 B = NGC 5195)
1845: Sketched by Lord Rosse
XXth century: Radio astronomy and subsequent radio images of M51 unequivocally demonstrated the reality of the interaction.
Blue knots = Starbirth regionsLord Rosse drawing
Check Whirlpool Galaxy with Google Earth
Explore Sky
Canes VenaticiCanes Venatici
Big Bear
Slowly scroll around Canes Venatici
Ask for to get angular information directly on the screen
Enlarge and click on the red central point of the galaxy;
click on NED to learn more
Check many informations, such as velocity, redshift, H0.
and …
1pc = 3.26 ly; 1Mpc = 3.26 Mly; H0 = 73 to 75 km/s/Mpc
Down: you will find Distance, various measurement methods, from 21 to 30 Mly
The cross within the nucleus of M51
indicates two dust rings around the
black hole at the center of the nebula
Galaxies also have a heart:
…and the heart of a galaxy can
split bubbles of gamma rays
(Nasa, center of our Galaxy)
sings BOUM
Part two
Measuring the black hole in the center of our galaxy
A slice of the Milky Way, on a nice summer night
March planet, and the Milky Way, seen from Hawaïi
Our galaxy, the Milky Way, is a merry-go-round of 200 to 400 billion stars
turning roung a central black hole; it has 2 smaller companions, Magellanic
clouds; our solar system is in one of the arms, as drawn by an artist.
Artistic view, from side Artistic view, from above
Diameter: 80 000 ly Diameter: 80 000 ly
The heart of our galaxy, down below; the image combines:
a near-infrared view from the Hubble Space Telescope,
an infrared view from the Spitzer Space Telescope
an X-ray view from the Chandra X-ray Observatory
The heart of our galaxy, down below; the image combines:
a near-infrared view from the Hubble Space Telescope,
an infrared view from the Spitzer Space Telescope
an X-ray view from the Chandra X-ray Observatory
What do we know about the center of our Galaxy?
Illustrating the 3 Kepler’s laws
2 a
Kepler’s 1st law:
A star orbits along an ellipse around the attractive center
Kepler’s 2nd law:
Equal areas during equal intervals of time:
Closer = faster
Duration several years
Duration less than one year
Kepler’s 3rd law: T² / a3 = 4 ²/ GM
What can we check about the black hole in the center of our Galaxy?
Kepler’s third law: T² / a3 = 4 ²/ GPeriod power 2 / Half main axis power 3 M mass of the central black hole
Infrared image of the center of our galaxyStudent work in lycée Louis-le-Grand and lycée Chaptal / Image VLT
2 a
Animate with Salsa J software and 12 « Black Hole Sgr A » Images1 - Open the file
Black Hole SgrA Images
2 - Open alltogether
the 12 images.fts
3 – Go to
Images/Piles/
Transférer images dans pile
= Transfer Images into piles
4 – You can enlarge with the « Magnifying glass » of Salsa J
5– Go to Images/Piles/
Démarrer animation
= Start animation
In Piles, you can slower the speed of the film at Piles/ Options des animations
Enjoy merry-go-round in Paris, and in our Galaxy
Merry_go_round: a star revolving around the black hole
Date
X
Y
Draw the ellipse by hand or with a software (Excel, Regressi)
To get a quick table of measurements, click on
Plugins/Macros/Installer
Look at the software list of plugins
Macros/Tools/PixelPicker Tool/ Open
Or read X,Y on the tool bar
1 – Stop the animation then
Image/Piles/Convertir pile vers images
Or Open again alltogether
the 12 images.fts
2 – Click on Fenêtre/ Séparer
3 – Choose a star that you can follow from picture to picture
(we advise the one inside the red circle, it is called S2 )
4 – Enlarge an image with the « Magnifying glass » of Salsa J
5– Quick step: click on S0 ; read X, Y
6 – Prepare an (X,Y) table
S2
X
Y
22 pixels = 10 light days
ZOOM on the scale:
enlarge and count pixels
Calculate merry-go-round in Paris, and in our Galaxy
22 pixels = 10 light days
2 * a = 19,5 pixels
a = 4,4 light days
T = 18 years
M = 3.1036 kg
= 1,5 . 106 Msun1992
1993
1995
1997
1997,6
2000
2000,6
2001
2001,5
20022002,2
2002,9
Calculate merry-go-round axis and Black Hole Mass
Dancing in Moulin Rouge
Part three
Measuring the distance of a galaxy with Hubble’s law
Measuring the redshift of a galaxy.
Absorption lines in the optical
spectrum of a distant galaxies
(right), as compared to
absorption lines in the optical
spectrum of the Sun (left).
Arrows indicate redshift.
Wavelength increases up
towards the red and beyond
(frequency decreases).See Doppler-Fizeau effect v /c
Sun GalaxyEdwin Hubble
Measuring a galaxy – Example: NGC 7083
Where? in Indus Constellation (Southern hemisphere)
Why Southern hemisphere? Because of very performant telescope ESO – VLT (Chili)
Google Earth/ Sky : Ask NGC 7083
Right Ascension: 21 hours 35 minutes 45 s
Declination: -63 degrees, 54 minutes 15s
Apparent Magnitude: 12
Apparent Diameters: 3.5’ long; 2,0’ wide (slide 5)
About Indus Constellationsouthern hemisphere (visible with VLT, Chili)
http://www.starrynightphotos.com/constellations/indus.htm
The constellation was one of twelve constellations created by
Pieter DirkszoonKeyser and Frederick de
Houtman between 1595 and 1597, and it
first appeared in Johann Bayer's Uranometria of 1603.
Since Indus was introduced in the 17th century, and lies in the
south, it was notknown to classical or early
cultures thus they produced no mythology concerning it.
NGC
7083
Answer for the angular sizes of the galaxy: 3,5’ long; 2,0’ wide
Angular dimensions of galaxy NGC 70831 - Open Google Earth 2 - Affichage/ Explorer / Ciel (Sky)3 – Look for : NGC 7083: we obtain Right Ascension and Declinaison4 – Zoom to have full galaxy 5 – Outils (Tools) / Regle (secondes d’arc)6 – Make measures (in two perpendicular directions)
What is the orientation of the galaxy disc plane; angle i ?
Towards observation i
i
Answer for angle i : cos(i) = width/length = 2,0 / 3, 5 => i = 55°; sin(i) = 0,82
length width
.
i
i
We see as an ellipse what is in fact a circle
Part of NGC 7083 spectrum, by VLT - ESO
Continuum emitted by the
core of the galaxy
Lines emitted by atoms from the disk of the galaxy
Have a look at Image/ Informations
Which lines did VLT astronomers have sent to us?
N nitrogen
H hydrogen
S sulfur
Image Information:
CRPIX1 = - 1559. / Reference pixelCRVAL1 = 4937. / Coordinate at reference pixel CDELT1 = 0.986999988556 / Coordinate increment per pixel CTYPE1 = 'Angstrom ' / Units of coordinate
pixel) = a*(pixel-reference) + b
=
CDELT1 * (pixel+ 1559) + 4937 (Å)
Core of the galaxy
lines
Be careful:
1 Å = 0.1 nm
How can we get the exact number of pixels? « Plot Profile! » or ZOOM and count pixels
Raie N II a : X = 140, So λ (nm) = (140 + 1559) x 0,09870 + 493,7 → λ = 661,39 nm
HN IIa
Calculate redshift of the core for each line
LineSpectrum on Earth
λ1 (nm)Spectrum of NGC 7083
X (pixel) => λ2 (nm) Redshift
∆λ/λ = (-
Vgalaxie= c. ∆λ/λ(km/s)
c = 3.105 km/s
NIIa 654.80 X=140 661.39 0.0101 3030
Hα 656.28 X=156 =662.97 0.0102 3060
NIIb 658.35 X=178 665.14 0.0103 3090
SIIa 671.60 X=313 678.47 0.0102 3060
SIIb 673.10 X=328 679,95 0.0102 3060
Let us keep VNGC7083 = 3.06*103 km/s
pixel) = CDELT1*(pixel-reference) + b = 0,09870 * (pixel+ 1559) + 493,7 (nm)
Good measurement!
What is the distance D of galaxy NGC 7083?
Let us use Hubble law : Vgalaxie = H * D ,
with H ≈ 73 km.s-1.Mpc-1
1pc = 3,26 a.l. et 1a.l. ≈ 9,47.1015 m
D = VNGC7083 /H = 3060/73
= 42 Mpc = 4,2 x107 pc
D = 1.4 x108 a.l.
D = 1,3 x1024 m
Measuring the size dNGC7083 of the galaxy
Our Galaxy, Milky Way : dMilky Way = 25 000 pc
NGC 7083: dNGC7083 = 4,2 . 104 pc = 1,7 * dMilky Way
dgalaxy = α(en radians) * D
αNGC 7083 ≈ 3,5’= 1,02. 10-3 rad
D = 4,23 x107 pc
Have sizes of the galaxy with Image/ Informations and apparent diameters
core ≈ 16 pixels = 13’’
Width of the picture ≈ 289 pixels = 237’’
αNGC 7083 ≈ 3,5’ = 210’’= 256 pixels
Another way to measure the size dcore of the core of the galaxy : Plot « vertical »profile.
Let us evaluate: dcore = 16 pixels; dNGC7083 ≈ 256 pixels
=> dcore / dgalaxy = 16/256 et dNGC7083 = 4,3. 104 pc ; so dcore ≈ 2,7.103pc= 8,3.1019 m
Part four
Measuring dark matter in a galaxy
Dancing with galaxy NGC 7083
RedshiftRedshift of the core
+
« Relative » Doppler shift by rotating around
the core
Why is the shift of the spectrum constant for r > R ?
Dar
k m
atte
r bou
nded
?
Turning around the core
2 R
Dar
k m
atte
r bou
nded
?
Vera Rubin (born 1928) is an astronomer who has done pioneering work on galaxy rotation
rates. Her discovery of what is known as "flat rotation curves" is the most direct and robust
evidence of dark matter.
Wavelength
What is a flat rotation curve? Let us watch Doppler shift !
* Doppler shift is constant for r > R,
which means that the relative speed is
then constant
* Because of the inclination i of the
galaxy plane, = Vrelative * sin(i)
/c )
Let us imagine
that the arms of
the dancer are
blocked by ???
Dark Matter!!!
V rotation
How can we measure ?
pixels ≈ 8 Å or 0,8 nm
core = 16 pixels
You can either use quotient in pixel, or use CDELT1: 1 pixel ≈ 1 Å or 0,1 nm; remember sin(i); i = 55 degrees
Vrotation =
[c / sin (55)
We use line H ,
with rotation shift
/ core≈ 6630Å
So:
Vrotation ≈ (4/6630)* c/0.82
Vrotation ≈ 2,21. 105 m/s
Around the core of the galaxy:
mV² / r = G m M/ r²
so Mcore= V² R / G
G=6,67. 10-11 SI
R= dcore/2 ≈ (see slide16) 4,15.1019 m
Mcore = 3. 1040 kg
galaxy = 256 pixels
Hthe brightestline
For the core of the galaxy:
mV² / R = G m Mcore / R²
so Mcore= V² R / G
G = 6,67. 10-11 SI R = dcore/2 ≈ 4,15.1019 m
Mcore = 3. 1040 kg
For the whole galaxy:
mV² / rwhole = G m Mwhole / rwhole ²
so Mwhole= V² rwhole / G
G = 6,67. 10-11 SI rwhole = dgalaxy/2 ≈ 6,65.1020 m
Mwhole = 4,8. 1041 kg
Mwhole = 16*Mcore > Brighting mass
Here is dark matter, a challenge for researchers !!:::!!
Bright galaxies, dark matters, by Vera Rubin
Part five
Supernovae, abnormal redshift and black energy
The cosmological constant
The observation: light curve of a supernova . Photometrie avec SalsaJ
Supernova = a single exploding star gives, during one year, as
much light as the core of a galaxy
Supernova
1-Open 12 images SUPERNOVA_LIGHT_CURVES (12 images/ Read dates in Image Info) 2 – Automatic photometry is not precise enough; open and enlarge every image(zoom) 3-Analyse /Plot Profile, follow the line with the mouse, read intensities
Date (Image Info) 0 5 9 11 12 19 20 21 25 26 31 34
Core of the galaxy (Brightness)
393 561 1457 686 765 1117 1116 1181 1237 1060 916 1115
Supernova(Brightness) 217 819 2103 923 823 665 913 883 658 576 349 407
Supernova/Core 0.552 1.460 1.443 1.345 1.076 0.595 0.818 0.748 0.532 0.543 0.381 0.365
Core of galaxy
Supernova
12
Draw the light curve of a supernova according to date (making reference to the core of the galaxy)
Date
Supernovae SN1a are standard candles to measure distances of galaxies
=> We receive Light emitted/ (4 d²)=> we can calculate the distance d of the galaxy
Ordinate = Brightness of the supernova/ Brightness of the core of the galaxy
Was Xmas star a supernova?
The Puzzle: Supernovae SN1a, give abnormal redshifts
The clue: 2 potential energies
Normal gravity : for a spherical homogenous Universe,
EP1 = - 16 G R5/15
Dark energy, looking like anti-gravitation
dEP2 = c²r² dm et dm = 4r² dm => EP2= 4 c² R5/15
Total potential energy is null if G/3 c², which is the cosmologic
constant that Einstein had imagined (his was G/c²) and said it
nonsense!
Hooked galaxy, a young galaxy , at the Universe borders
Abnormal redshift, irregular shapes.
Far away
Dark matter: 25%
Dark energy: 70 %
Known matter: 5%:
Hydrogen and Helium: 4%
Stars : 0,5 %
Neutrinos: 0,3 %
Heavy atoms: 0,03 %
Merry go round
Merry Astronomy
Merry teaching
Thank you