1. in the Local Group and beyond
Hot Massive Stars
in the Local Group and beyond
Rolf Kudritzki
In collaboration with
Fabio Bresolin, Miguel Urbaneja, Norbert Przybilla, Paco Najarro, Don Figer, Sungsoo Kim, Joachim Puls, Adi Pauldrach, Wolfgang Gieren, Gregorsz Pietrzynski and many others …

2. Because they are the ones, which make the universe interesting!!!!
Initial Mass Function (IMF), Scalo (1986)
Why massive stars?
Log dN(M)
Only a tiny fraction (a few ‰) of the stars in a spiral or irregular or starburst galaxy are massive with masses ≥ 10 Msun.
Why bother???
Because they are the ones, which make the universe interesting!!!!
massive
stars
M/Msun

3. A galaxy without massive stars is dull !!!

4. Extragalactic stellar astronomy
A galaxy with massive stars is interesting !!!

5. massive stars
provide the light
make the spiral arms visible
ionize the HII regions
energy & momentum to ISM (winds, SN)
trigger star formation
crucial for chemical evolution (winds, SN)
allow you to do something!!!

6. Bresolin & Kennicutt 2002, ApJ, 572, 838
HII regions in M83
disk
element abundances
stellar content
ionizing flux, stellar atmospheres
Hot spot

7. Metal line diagnostics

8. Massive stars and star formation (SF)
Massive stars perfect tracer of SF
young
luminous
strong UV sources
 directly visible in UV (GALEX)
 heat ISM dust
 strong mid & far IR (Spitzer)
 ionize ISM gas
 strong recombination lines (10m, Spitzer)
!!! Diagnostics of SF physics !!!
The following slides are from
Rob Kennicutt (2005)
Workshop on “Extreme Starbursts”
Lijiang, Cina, August 2005

9. 11 Mpc Ha and Ultraviolet Survey (11HUGS)
Kennicutt (2005)
Ha imaging for 400 spiral-irregular galaxies within 11 Mpc of Milky Way (complete for b > 20o, B < 15)
GALEX UV imaging (Cycle 1 Legacy project + archival data) for 284/400 galaxies
drift-scan integrated spectra for ~200 galaxies
Science goals
SFR statistics, demographics for a volume-limited sample
the SFR burst duty cycle in dwarf galaxies (Janice Lee)
evolution/migration of star formation within galaxies
SFR metrics, reference for cluster, lookback studies
HII region/cluster statistics, atlas
an archival resource for the astronomical community

10. Spitzer Infrared Nearby Galaxies Survey (SINGS)
Kennicutt (2005)
complete IRAC, MIPS imaging of 75 nearby galaxies (3.5 – 160 mm)
IRS, MIPS radial strip maps (10 – 100 mm)
IRS maps of centers, 75 extranuclear sources (5–37 mm)
ancillary dataset covering UV to radio

11. M81 CFHT

12. Kennicutt (2005)
Ha + R
GALEX FUV + NUV (1500/2500 A)
IRAC mm
MIPS 24 mm

13. Kennicutt (2005)

14. (P region, d~6 kpc
Scoville et al. 2001)
Kennicutt (2005)

15. Kennicutt (2005) 0.15 mm 0.4-0.8 mm 1.2-2.2 mm 3.6 mm

16. Kennicutt (2005)

17. Concentration of SF vs. Total SFR for a variety of galaxy types.
area
SCUBA
sources
BCDs
LBGs
SFR
Kennicutt (2005)

18. SFR vs Gas Density (Schmidt Law) ρgas
area
disk-averaged star SFR vs mean gas density of the disk
a single power law of slope N ~ 1.4 fits the full range of galaxy types, from normal disks to ultraluminous infrared starburst galaxies
does this global relation also apply locally within galaxies?
ρgas
Kennicutt et al. (2005)
Kennicutt (2005)

19. Kennicutt, Calzetti, Walter, et al. 2005, in prep.
Local Schmidt Law
slope= 1.41
Kennicutt, Calzetti, Walter, et al. 2005, in prep.
Kennicutt (2005)

20. Schmidt Law… Kennicutt (2005) Whole galaxies
Kennicutt et al. 2005, in prep.
Kennicutt (2005)

21. Star Formation Rate versus Redshift
Sanders
(2005)

22. Massive stars and star formation (SF)
Results depend fundamentally on our
knowledge of massive stars
massive stars only ‰ of integrated IMF, but we
extrapolate SF down to 0.2 Msun
every mistake enormously amplified
stellar mass and ionization?
stellar mass and dust heating?
stellar mass and UV radiation?
!!! Knowledge of massive stars crucial !!!

23. WMAP evolution of galaxies in early universe heavily influenced by
first generations of very massive stars
cosmic z=3.5
Springel & Hernquist, 2003
very
massive
stars
WMAP

24. First stars are very massive hydrodynamic simulations
Hydrodynamic simulations by Davé, Katz, & Weinberg
Ly-α cooling radiation (green)
Light in Ly-α from forming stars (red, yellow)
z=10
z=8
z=6

25. Stars forming at z=10! Observable with a 30m telescope!
1 Mpc (comoving)
GSMT Science Working Group Report, 2003, Kudritzki et al.
As observed through 30-meter telescope R=3000, 105 seconds,
Barton et al., 2004, ApJ 604, L1
Simulation

26. A possible IMF diagnostic at z=10
HeII (1640 Å)
Standard IMF
HeII (1640 Å)
Top-Heavy IMF, zero metallicity
(IMF + stellar model fluxes from
Bromm, Kudritzki, & Loeb 2001, ApJ 552,464
see also Schaerer, 2003, A&A 397, 527)

27. TMT: A partnership of CELT, AURA & ACURA

28. GMT 7-Mirror Concept Carnegie, Harvard/Smiths., Arizona, MIT,
Michigan,
Texas

29. Adaptive Optics Subaru survey The most distant galaxies @ z =7
z =6.96
Iye et al., 2006, Nature 443, 1861
Adaptive Optics
z =6.96
Ionization by
Massive stars

30. Mauna Kea

31. View MK  Haleakala

32. Population synthesis of high-z galaxies
Stellar spectra
Stellar Population
Initial Mass Function
Star Formation History
Metallicity
Stellar Evolution
Galaxy spectra
non-LTE atmospheres with winds
plus stellar evolution models
 Synthetic spectra of galxies at high z
 as a function of Z, IMF, SFR

33. Spectral diagnostics of high-redshift starbursts
Starburst models - fully synthetic spectra based on model atmospheres
Rix, Pettini, Leitherer, Bresolin, Kudritzki, Steidel, 2004, ApJ, 615,98

34. Spectral diagnostics of high-z starbursts
z=2.7
fully synthetic spectra
vs. observation
Rix, Pettini, Leitherer,
Bresolin, Kudritzki, Steidel
2004, ApJ, 615, 98

35. Ionizing flux of high-z starburst galaxies ionization of IGM
Lyman continuum of high-z starbursts
fully synthetic spectra vs. observation
Haehnelt, Madau, Kudritzki, Steidel 2001, ApJ,

36. Massive stars die as SN or GRB
Massive stars form iron cores during evolution
 core collapse SN
GRB
Tracks by
Maeder & Meynet
(with and without
rotational mixing)

37. The Nearest Galaxies
LMC
February 22, 1987
SMC

38. Supernova!
SN 1987A

41. M74 red supergiant progenitor
Smartt et al., 2004, Science 303, 499

42. Progenitor HRD
Smartt et al. 2004

43. SN2005cs in M51 Discovered by Wolfgang Kloehr in June 2005
German Amateur astronomer
20cm reflector + CCD

44. SN2005cs in M51
normal SN type II-P

45. SN2005cs in M51 - Hubble images

46. GRBs and massive stars
Chandra
GRB = SN1998bw
@ z=0.0085
HST

47. GRB 050904 @ z=6.29 4' position from Swift
Optical observations at 3h didn't see anything
Bright NIR afterglow
MAGNUM observations at 12h
Flat spectrum over JHK, no detection in RI
z=6.29 from Subaru

48. Massive stars Extremely luminous  ideal as individual targets
to study
chem. evolution
of galaxies
distances
Tracks by
Maeder & Meynet
(with and without
rotational mixing)

49. Extragalactic stellar astronomy
Quantitative stellar spectroscopy of individual stars
in galaxies beyond the Local Group
Extragalactic stellar astronomy
Properties of stellar populations
Evolution of galaxies
Chemical abundance and abundance pattern gradients
Interstellar extinction
Distances
Dark matter content

50. NGC 300
2 Mpc

51. Cycle 11 HST/ACS imaging blue supergiants Bresolin et al. 2005

52. FORS/VLT spectra
Bresolin, Gieren,
Kudritzki et al. 2002
ApJ 567, 277

53. Bresolin, Kudritzki, Mendez, Przybilla 2001, ApJ Letters 548, L159
NGC 7Mpc
HST/ACS
0.2 & 0.5 solar metallicity models
A0 Ia star
V = MV = -9
NGC 7 Mpc
FORS/VLT
multi-object spectroscopy
NGC 3621 FORS/VLT
@ 7 Mpc
Bresolin, Kudritzki, Mendez, Przybilla 2001, ApJ Letters 548, L159

54. Massive stars O B0-3 B4-A3 I -V I I (with and without Tracks by
Maeder & Meynet
(with and without
rotational mixing)

55. outline stellar atmospheres and diagnostic methods
parameters and winds of hot massive stars
the first stars
population synthesis at high redshift
IR spectroscopy of massive stars in the GC
a new distance to M33 from eclipsing binaries
the B supergiant companion to SN 1993J in M81
eclipsing binaries, SN, LBVs, Miras in the local
universe and Pan-STARRS
stellar abundances: from the Local Group to 7 Mpc
new spectroscopic distance determination method

56. 2. Diagnostics of massive stars
effects of stellar winds on spectra and SEDs
effects of NLTE
basic concept of hot star model atmospheres

57. Spectral diagnostics of massive stars
diagnostic problem:
high luminosity  enormous energy and momentum
density of radiation field
NLTE
stellar winds
Model atmospheres and radiative transfer
detailed NLTE treatment
radiation-hydrodynamics of line-driven winds
spherical extension

58. Pauldrach, Puls, Kudritzki et al. 1994,
UV spectrum of O4 supergiant z Puppis
Pauldrach, Puls, Kudritzki et al. 1994,
SSRev, 66, 105

59. P Cygni profiles and stellar winds
Wind in front of star
Scattered photons from envelope
Total line profile λ

60. P Cygni profiles and vinfinity
fit of v∞
± 5% accuracy
Kudritzki & Puls, 2000, AARA 38, 613

61. P Cygni profiles and mass-loss
Kudritzki & Puls, 2000, AARA 38, 613

62. P Cygni profiles and metallicity
Galaxy
LMC
SMC
Kudritzki, 1998

63. A-supergiant in M31 – stellar wind
McCarthy, Kudritzki,
Venn, Lennon,Puls
1997, ApJ 482, 757
Keck, Hires

64. Hα emission B superrgiant – stellar wind
Model calculation
Kudritzki et al. 1999,
A&A 350, 970

65. Hα emission O-star _ M Model calculation Variation of by ± 20%
Kudritzki & Puls, 2000, AARA 38, 613

66. atmospheric velocity field
log vwind
high , vwind > vth _ M
low , vwind < vth _ M
log τ
Kudritzki 1998

67. atmospheric density structure
log ρ
low _ M
high _ M
log τ
Kudritzki 1998

68. FUV- and IR- excess through winds
effects on
ionization!
Gabler, Gabler, Kudritzki, Puls, Pauldrach, 1989, A&A 226, 162

69. Lyman continuum of B-stars
effects of winds
on ionization !!
Najarro, Kudritzki, Cassinelli, Stahl, Hillier 1996, A&A 306, 892

70. Hα and _ M

71. Hγ and _ M

72. HeI 4471 and _ M

73. HeII 4542 and _ M

74. X-ray emission of hot, massive stars
all O- stars show X-ray emission
LX/LBol ≈ 10-7, but large scatter
hypothesis: hot shocks in stellar wind emit X-rays
X-rays affect stellar wind ionization  OVI, SVI, NV
wind models need to include X-rays
study of X-ray emission (Kudritzki et al., 98)
ROSAT X-ray SEDS and radiative transfer model
randomly distributed shocks imbedded into winds

75. time dependent stellar wind radiation-hydro  shocks (Owocki et al
time dependent stellar wind radiation-hydro  shocks (Owocki et al., 1988; Feldmeier, 1997)

76. X-ray emission of hot, massive stars
all O- stars show X-ray emission
LX/LBol ≈ 10-7, but large scatter
hypothesis: hot shocks in stellar wind emit X-rays
X-rays affect stellar wind ionization  OVI, SVI, NV
wind models need to include X-rays
study of X-ray emission (Kudritzki et al., 98)
ROSAT X-ray SEDS and radiative transfer model
randomly distributed shocks imbedded into winds

77. Calculated spectra and ROSAT observations
Feldmeier, Kudritzki et al., 1997
ζ Pup, O4 If ι Ori O9 III Mon O7 V
theory
convolved with
ROSAT FWHM
● ROSAT

78. X-ray Luminosity of O-stars
Correlated with log L
and cooling length
Kudritzki et al., 1998