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.
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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 … Concepcion 2007 Log Why dN(M) Initial Mass Function (IMF), Scalo (1986) massive stars? Only a tiny fraction (a few ‰) of the stars in a spiral or irregular or starburst galaxy aremassive massive with masses ≥ 10 Msun. stars Why bother??? Because they are the ones, which make the universe interesting!!!! M/Msun Concepcion 2007 A galaxy without massive stars is dull !!! Concepcion 2007 A galaxy with massive stars is interesting !!! Extragalactic stellar astronomy Concepcion 2007 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!!! Concepcion 2007 Bresolin & Kennicutt 2002, ApJ, 572, 838 HII regions in M83 disk element abundances stellar content ionizing flux, stellar atmospheres Hot spot Concepcion 2007 Metal line diagnostics Concepcion 2007 Massive stars and star formation (SF) Massive stars perfect tracer of SF • young The following slides are from • strong UV sources Rob Kennicutt (2005) directly visible in UV (GALEX) Workshop on dust “Extreme Starbursts” heat ISM Lijiang, Cina, 2005 strong mid & August far IR (Spitzer) • luminous ionize ISM gas strong recombination lines (10m, Spitzer) !!! Diagnostics of SF physics !!! 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 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 http://sings.stsci.edu http://irsa.ipac.caltech.edu/data/SPITZER/SINGS/ http://data.spitzer.caltech.edu/popular/sings/ NRAO 2006 M81 CFHT Kennicutt (2005) GALEX FUV + NUV (1500/2500 A) IRAC 8.0 mm Ha + R MIPS 24 mm Kennicutt (2005) (Pa region, d~6 kpc Scoville et al. 2001) Kennicutt (2005) 0.15 mm 8.0 mm 0.4-0.8 mm 24 mm 1.2-2.2 mm 70 mm 3.6 mm 160 mm Kennicutt (2005) Kennicutt (2005) Concentration of SF vs. Total SFR for a variety of galaxy types. SFR area SCUBA sources BCDs LBGs Kennicutt (2005) SFR SFR vs Gas Density (Schmidt Law) SFR 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 (2005) Kennicutt et al. (2005) Local Schmidt Law slope= 1.41 Kennicutt (2005) Kennicutt, Calzetti, Walter, et al. 2005, in prep. Schmidt Law… Whole galaxies Kennicutt et al. 2005, in prep. Kennicutt (2005) Star Formation Rate versus Redshift Sanders (2005) Concepcion 2007 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 !!! evolution of galaxies in early universe heavily influenced by first generations of very massive stars cosmic web@ z=3.5 Springel & Hernquist, 2003 WMAP very massive stars 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 Stars forming at z=10! Observable with a 30m telescope! 1 Mpc (comoving) GSMT Science Working Group Report, 2003, Kudritzki et al. http://www.aura-nio.noao.edu/gsmt_swg/SWG_Report/SWG_Report_7.2.03.pdf Simulation As observed through 30-meter telescope R=3000, 105 seconds, Barton et al., 2004, ApJ 604, L1 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) TMT: A partnership of CELT, AURA & ACURA GMT 7-Mirror Concept Carnegie, Harvard/Smiths., Arizona, MIT, Michigan, Texas SubaruGalaxy survey@ z =6.96 Adaptive Optics The most Iyedistant et al., 2006, galaxies Nature 443, 1861 @ z =7 Lα @ z =6.96 Ionization by Massive stars Mauna Kea View MK Haleakala 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 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 Spectral diagnostics of high-z starbursts cB58 @ z=2.7 fully synthetic spectra vs. observation Rix, Pettini, Leitherer, Bresolin, Kudritzki, Steidel 2004, ApJ, 615, 98 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, Rome 2005 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) The Nearest Galaxies LMC February 22, 1987 SMC SN 1987A M74 red supergiant progenitor Smartt et al., 2004, Science 303, 499 Progenitor HRD Smartt et al. 2004 SN2005cs in M51 Discovered by Wolfgang Kloehr in June 2005 German Amateur astronomer 20cm reflector + CCD SN2005cs in M51 normal SN type II-P SN2005cs in M51 - Hubble images GRBs and massive stars Chandra GRB 980425 = SN1998bw @ z=0.0085 HST 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 Rome 2005 Massive stars Extremely luminous ideal as individual targets to study • chem. evolution of galaxies • distances Tracks by Maeder & Meynet (with and without rotational mixing) Quantitative stellar spectroscopy of individual stars Rome 2005 in astronomy galaxies beyond the Local Group Extragalactic stellar Properties of stellar populations Evolution of galaxies Chemical abundance and abundance pattern gradients Interstellar extinction Distances Dark matter content Rome 2005 NGC 300 2 Mpc Rome 2005 Cycle 11 HST/ACS imaging blue supergiants Bresolin et al. 2005 NRAO 2006 FORS/VLT spectra Bresolin, Gieren, Kudritzki et al. 2002 ApJ 567, 277 NGC 3621 @ 7Mpc NRAO 2006 HST/ACS 0.2 & 0.5 solar metallicity models A0 Ia star V = 20.5 NGC 3621 @ 7 Mpc NGC 3621 FORS/VLT FORS/VLT @ 7 Mpc multi-object spectroscopy MV = -9 Bresolin, Kudritzki, Mendez, Przybilla 2001, ApJ Letters 548, L159 Rome 2005 Massive stars O I -V B0-3 I B4-A3 I Tracks by Maeder & Meynet (with and without rotational mixing) Concepcion 2007 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 Concepcion 2007 2. Diagnostics of massive stars • effects of stellar winds on spectra and SEDs • effects of NLTE • basic concept of hot star model atmospheres 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 Concepcion 2007 UV spectrum of O4 supergiant z Puppis Pauldrach, Puls, Kudritzki et al. 1994, SSRev, 66, 105 P Cygni profiles and stellar winds Wind in front of star Scattered photons from envelope Total line profile λ P Cygni profiles and vinfinity fit of v∞ ± 5% accuracy Kudritzki & Puls, 2000, AARA 38, 613 P Cygni profiles and mass-loss Kudritzki & Puls, 2000, AARA 38, 613 P Cygni profiles and metallicity Galaxy LMC SMC Kudritzki, 1998 A-supergiant in M31 – stellar wind McCarthy, Kudritzki, Venn, Lennon,Puls 1997, ApJ 482, 757 Keck, Hires Hα emission B superrgiant – stellar wind Model calculation Kudritzki et al. 1999, A&A 350, 970 Hα emission O-star Model calculation Variation of by ± 20% M_ Kudritzki & Puls, 2000, AARA 38, 613 atmospheric velocity field log vwind M_ high , vwind > vth M_ low , vwind < vth log τ Kudritzki 1998 atmospheric density structure log ρ M_ low M_ high log τ Kudritzki 1998 FUV- and IR- excess through winds winds effects on ionization! Gabler, Gabler, Kudritzki, Puls, Pauldrach, 1989, A&A 226, 162 Lyman continuum of B-stars effects of winds on ionization !! Najarro, Kudritzki, Cassinelli, Stahl, Hillier 1996, A&A 306, 892 Hα and M_ Hγ and M_ HeI 4471 and M_ HeII 4542 and M_ Concepcion 2007 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 Concepcion 2007 time dependent stellar wind radiation-hydro shocks (Owocki et al., 1988; Feldmeier, 1997) Concepcion 2007 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 Concepcion 2007 Calculated spectra and ROSAT observations Feldmeier, Kudritzki et al., 1997 ζ Pup, O4 If ι Ori O9 III 15 Mon O7 V theory convolved with ROSAT FWHM ● ROSAT Concepcion 2007 X-ray Luminosity of O-stars Correlated with log L and cooling length Kudritzki et al., 1998