The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA

Size: px

Start display at page:

Download "The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA"

Susan Walters
6 years ago
Views:

1 Hello!

2 The Universe of Galaxies The Universe o Galaxies Ajit Kembhavi IUCAA

3 Galaxies: Stars: ~10 11 Mass: ~10 11 M Sun Contain stars, gas and dust, possibly a supermassive black hole at the centre. Much of the mass is in the form of dark matter.

4 The Milky Way Galaxy

5 Spitzer Near-IR Central 900 light years

6 The Milky Way Galaxy COBE-DIRBE composite near-ir image, 1.25, 2.2 and 3.5 m. Emission is dominated by relatively cool giant K stars in the disk and bulge. Dust obscuration is weak in the near-ir. Cosmic Background Explorer-Diffuse IR Background Experiment

7 The Milky Way Galaxy

The halo is thought to be spherical in shape and consists of metal poor (old) globular clusters and filed stars. The stars have high proper motion. The mass of the halo is ~10 9 M Sun.

9 The halo is thought to be spherical in shape and consists of metal poor (old) globular clusters and filed stars. The stars have high proper motion. The mass of the halo is ~10 9 M Sun. In addition there is a The disk dark consists matter of halo flattened which system could contain of stars, as gas much as and dust 90 with percent a variety of the of mass structures of the galaxy. like spiral arms and bars. There is substantial star formation and a mix of old and new stars. The Classically disk is supported a bulge consists by of old rotation. About 95 percent of stars the stars and is are supported in a thin by random disk with scale height of ~300 motions pc, the of other stars 5 rather percent than rotation. are in a thick disk with scale But height there ~1000 are pseudobulges pc. The in some stellar mass of the disk is ~6x10 galaxies 10 M Sun which and the are more disk like in luminosity is ~2x10 10 L Sun. The nature. Sun The completes bulge of one the Galaxy has orbit in ~250x10 6 yr. a mass of ~2x10 10 M Sun and the luminosity is ~5x10 9 M Sun. Spark & Gallagher Galaxies in the Universe

10 illustration October GeV map from Fermi Gamma Ray Space Observatory all sky data

11 The Content of the Milky Way Galaxy

12 Stars and masses Radius Radius 700, ,000 km km R SUN R SUN ~1000 R SUN Planet and White Dwarf

Swan Nebula Omega Nebula, M 17, NGC 6618 in Lyra 5000-6000 light years away, ~15 light years diameter,

13 Swan Nebula Omega Nebula, M 17, NGC 6618 in Lyra light years away, ~15 light years diameter, HII region Embedded open cluster of 35 stars ionizes surrounding gas due to radiation from hot young stars.

14 Bok Globule B68 Distance 125 pc Size ~10 4 AU ~ Oort cloud size Close to collapse, Mass ~2M Sun

15 Planetary Nebula Ring Nebula, M57, NGC 6720 in Lyra 8.8 mag, ~2300 light years away Torus of light emitting material, surrounding a central star, which is a white dwarf Ring expands at ~1 arcsec/century, so age is ~ years.

16 Supernova Remnant Crab Nebula in Taurus, M1, NGC 1952 First Observed April 4, 1054 AD 8.4 mag, distance 6300 light years Diametre 10 light years Expansion velocity 1800 km/s Radio pulsar at the centre

17 The Crab Pulsar

19 ISM Phases Gas and dust are generally well mixed in the ISM.

20 Globular Cluster 47 Tuc NGC 104, massive globular cluster containing millions of stars, 20 light years across and at a distance of 13.4 thousand light years. Contains many exotic pulsars.

21 The Galactic Centre

22 VLA 1m radio image

23 Galactic Centre Chandra X-ray Images [B] 10 light years

24 SgrA* Keck 2 micron HKL Composite

25 Star Closest to Galactic Centre NTT, Gemini, VLT Schodel et.al 2003 Bound, highly eccentric (0.87) orbit, period 15.2yr, pericentre distance 17 light hours (0.5mpc), semi-major axis 4.54mpc Best fit central point mass 3.7x10 6 M Sun

26 The Shape of the Milky Way Galaxy

27 Herschel s Milky Way A model of the Milky Way Galaxy by William Herschel based on his own observations in the 19 th century

28 Jan Oort

29 Spiral structure of the Milky War from HI observations

30 External Galaxies

31 Andromeda Galaxy M31, NGC million light years M32 M 101

32 M 51 Distance ~31 Mly First object to be recognized as a spiral, by Lord Ross 1845.

33 Elliptical Galaxy M 87 Largest and brightest galaxy in the Virgo Cluster, distance 55 Mlyr

34 Ellipsoidal Galaxies

35 Niel Brandt Hubble s Tuning Fork

36 Sudhanshu Barway 2007

37 Surface Brightness Distribution

38 NGC 661 V

39 Surface Brightness Profile

41 Bulge Disk Decomposition 2 = (O i -m i ) 2 / i 2 UGC 1250

42 Bulge-Disk Decomposition

43 The Fundamental Plane

44 Log r e = A*log + B*log I e + const

45 Photometric Plane Ellipticals and Early Type Bulges

46 Hubble Deep Field Deep exposure of a region in Ursa major 7 sq arcmin in four filters hr at 606 nm. Most of the ~3000 objects in the field are galaxies.

47 Coma Cluster NGC 4889 NGC 4874 Rich cluster containing ~1000 identified galaxies. Distance 99 Mpc

48 Large Scale Structure 2DF Galaxy Redshift Survey

49 Centaurus A Lenticular galaxy, closest radio galaxy to Earth, distance ~11 Mly

50 Radio Galaxy Cen A VLA 6 cm A

51 M87

53 Radio Galaxy M87 One-sided jet. Bulk relativistic motion. Superluminal motion.

54 The Jet in M87

55 Quasars

56 Emission Lines, Rapid Variability

57 Quasar Host Galaxies

58 Unification

59 Supermassive Black Hole

60 Thank You!

61 Coma Cluster

62 Black Hole Mass

63 Gravitational Lens

65 Butterfly Nebula

66 Horsehead Nebula

72 Structures in the Universe

74 The Milky Way Galaxy

75 No foreground stars because cloud is a short distance away. Alves, Lada & Lada, Nature 2001

76 Four Component ISM Gas Phase Temp T(K) Density nt Covering n cm -3 factor Cold H 2 ~15 > x10 3 <0.01 Molecular The covering factors sum to unity, if Cool atomic H I all phases ~18 are known. ~30 5.4x10 3 ~0.03 The volume of the ISM is mostly Warm H I, filled by ~8000 tenuous ~0.3 hot plasma, 2.4x10 but 3 ~ H II the mass is dominated by the Hot ionized H II cooler atomic ~5x10 5 and ~5x10 molecular x10 3 ~ clouds.

View of the Galaxy from within. Lecture 12: Galaxies. Comparison to an external disk galaxy. Where do we lie in our Galaxy?

Lecture 12: Galaxies View of the Galaxy from within The Milky Way galaxy Rotation curves and dark matter External galaxies and the Hubble classification scheme Plotting the sky brightness in galactic coordinates,