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A galaxy party in Paris

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 mfaye2@wanadoo.fr ; mme.faye@yahoo.fr.

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A galaxy party in Paris

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  1. Je cherche fortune Tout autour du Chat Noir Au clair de la lune A Montmartre le soirbfdbf 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 mfaye2@wanadoo.fr; mme.faye@yahoo.fr

  2. Partone Measuring a galaxy Angular measurements with Google Earth or / and Stellarium

  3. 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 VINCENT VAN GOGH Whirlpool galaxy M51 = NGC 5195 Credit Nasa

  4. Let us compare to a whole night exposure around the Northern Pole

  5. And then, astronomy for kids, starry lines around Northen Pole, starry curtain, colouing Van Gogh’s starry night. Van Gogh’s skies

  6. 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. Lord Rosse drawing Blue knots = Starbirth regions

  7. Explore Sky Check Whirlpool Galaxy with Google Earth Big Bear Canes Venatici

  8. Slowly scroll around Canes Venatici Ask for to get angular information directly on the screen

  9. Enlarge and click on the red central point of the galaxy; click on NED to learn more

  10. Check many informations, such as velocity, redshift, H0. and …

  11. 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

  12. Galaxies also have a heart: sings BOUM …and the heart of a galaxy can split bubbles of gamma rays (Nasa, center of our Galaxy) The cross within the nucleus of M51 indicates two dust rings around the black hole at the center of the nebula

  13. Parttwo Sagittarius and the black hole Measuring the black hole in the center of our galaxy

  14. Our Galaxy, the Milky Way A slice of the Milky Way, on a nice summer night March planet, and the Milky Way, seen from Hawaïi

  15. Artistic view, from side Artistic view, from above Diameter: 80 000 ly Diameter: 80 000 ly 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.

  16. What do we know about the center of our Galaxy? 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

  17. 2 a Illustrating the 3 Kepler’s laws Kepler’s 2nd law: Equal areas during equal intervals of time: Closer = faster Duration several years Kepler’s 3rd law: T² / a3 = 4 p²/ GM Kepler’s 1st law: A star orbits along an ellipse around the attractive center Duration less than one year

  18. 2 a What can we check about the black hole in the center of our Galaxy?

  19. Animate with Salsa J software and 12 « Black Hole Sgr A » Images 1 - 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

  20. Enjoy merry-go-round in Paris, and in our Galaxy

  21. To get a quick table of measurements, click on Plugins/Macros/Installer Look at the software list of plugins Macros/Tools/PixelPicker Tool/ Open Merry_go_round: a star revolving around the black hole Or read X,Y on the tool bar Draw the ellipse by hand or with a software (Excel, Regressi)

  22. 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

  23. 22 pixels = 10 light days ZOOM on the scale: enlarge and count pixels

  24. Calculate merry-go-round in Paris, and in our Galaxy 22 pixels = 10 light days

  25. Calculate merry-go-round axis and Black Hole Mass 2002,2 2002 2001,5 Dancing in Moulin Rouge 2001 2002,9 2000,6 • 2 * a = 19,5 pixels • a = 4,4 light days T = 18 years M = 3.1036 kg = 1,5 . 106 Msun 2000 1997,6 1997 1992 1995 1993

  26. Partthree Edwin Hubble's redshift Measuring the distance of a galaxy with Hubble’s law

  27. Measuring the redshift of a galaxy. Sun Galaxy Edwin Hubble 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 Dl / l = v /c

  28. 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

  29. NGC 7083 About Indus Constellation southern 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 itfirst 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.

  30. Angular dimensions of galaxy NGC 7083 1 - Open Google Earth 2 - Affichage/ Explorer / Ciel (Sky) 3 – Look for : NGC 7083: we obtain Right Ascension and Declinaison 4 – Zoom to have full galaxy 5 – Outils (Tools) / Regle (secondes d’arc) 6 – Make measures (in two perpendicular directions) Answer for the angular sizes of the galaxy: 3,5’ long; 2,0’ wide

  31. Towards observation (p/ 2) - i What is the orientation of the galaxy disc plane; angle i ? . We see as an ellipse what is in fact a circle i length i width i Answer for angle i : cos(i) = width/length = 2,0 / 3, 5 => i = 55°; sin(i) = 0,82

  32. Part of NGC 7083 spectrum, by VLT - ESO Lines emitted by atoms from the disk of the galaxy Continuum emitted by the core of the galaxy

  33. Have a look at Image/ Informations

  34. lines Core of the galaxy Ha Which lines did VLT astronomers have sent to us? N nitrogen H hydrogen S sulfur • (pixel) = a*(pixel-reference) + b = CDELT1 * (pixel+ 1559) + 4937 (Å) Image Information: CRPIX1 = - 1559. / Reference pixel CRVAL1 = 4937. / Coordinate at reference pixel CDELT1 = 0.986999988556 / Coordinate increment per pixel CTYPE1 = 'Angstrom ' / Units of coordinate Be careful: 1 Å = 0.1 nm

  35. How can we get the exact number of pixels? « Plot Profile! » or ZOOM and count pixels N IIa Ha Raie N II a : X = 140, So λ (nm) = (140 + 1559) x 0,09870 + 493,7 → λ = 661,39 nm

  36. Calculate redshift of the core for each line • (pixel) = CDELT1*(pixel-reference) + b = 0,09870 * (pixel+ 1559) + 493,7 (nm) Let us keep VNGC7083 = 3.06*103 km/s Good measurement!

  37. 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

  38. Measuring the size dNGC7083 of the galaxy dgalaxy = α(en radians) * D αNGC 7083 ≈ 3,5’= 1,02. 10-3 rad D = 4,23 x107 pc Our Galaxy, Milky Way : dMilky Way = 25 000 pc NGC 7083: dNGC7083 = 4,2 . 104 pc = 1,7 * dMilky Way

  39. Have sizes of the galaxy with Image/ Informations and apparent diameters acore≈ 16 pixels = 13’’ Width of the picture ≈289 pixels = 237’’ αNGC 7083 ≈ 3,5’ = 210’’= 256 pixels

  40. Another way to measure the size dcore of the core of the galaxy : Plot « vertical »profile. The core ! 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

  41. Partfour Vera Rubin's dark matter Measuring dark matter in a galaxy

  42. Redshift Dancing with galaxy NGC 7083 Redshift of the core + « Relative » Doppler shift by rotating around the core

  43. Dark matter bounded? 2 R Dark matter bounded? Turning around the core Why is the shift of the spectrum constant for r > R ? 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 l

  44. What is a flat rotation curve? Let us watch Doppler shift ! * Doppler shift Dl is constant for r > R, which means that the relative speed is then constant * Because of the inclination i of the galaxy plane, Dl / l = Vrelative * sin(i) /c ) Let us imagine that the arms of the dancer are blocked by ???Dark Matter!!! V rotation Solid Dark Matter Gauss-Kepler

  45. How can we measure Dl / l ? 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 = [Dl/l] * c / sin (55) We use line Ha , with rotation shift l (Ha /core)≈ 6630Å So: Vrotation ≈ (4/6630)* c/0.82 Vrotation≈ 2,21. 105m/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 agalaxy = 256 pixels Ha : the brightestline acore = 16 pixels 2 Dl = 8 pixels ≈ 8 Å or 0,8 nm

  46. Bright galaxies, dark matters, by Vera Rubin

  47. Partfive When Einstein thought he was wrong... Supernovae, abnormal redshift and black energy The cosmological constant

  48. The observation: light curve of a supernova . Photometrie avec SalsaJSupernova = a single exploding star gives, during one year, as much light as the core of a galaxy Supernova

  49. 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 Core of galaxy Supernova 12

  50. Draw the light curve of a supernova according to date (making reference to the core of the galaxy) Ordinate = Brightness of the supernova/ Brightness of the core of the galaxy Was Xmas star a supernova? Date Supernovae SN1a are standard candles to measure distances of galaxies => We receive Light emitted/ (4 p d²)=> we can calculate the distance d of the galaxy

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