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Home , Stellar wind

Stellar and Hydrodynamic Atmospheres of

Rolf Kudritzki Spring Semester 2016 I. Introduction First suspicion of existence 1929 C. Beals of continuous stellar winds: MNRAS 90, 202 91, 966 (1931) 1934 S. Chandrasekhar MNRAS 94, 522 Optical spectrum of broad H, HeI, metal lines with B2 and LBV : blue-shifted absorption red-shifted emission Optical spectrum of broad He, C, N emission lines Wolf-Rayet stars : no hydrogen lines widths of lines Doppler-shifts of out-flowing atmospheres

Vexpansion ≈ 200 km/s to 3000 km/s H and HeI lines of P Cygni

Note different y-scale of plots

Emission in Hα is huge Hδ is much weaker

Najarro, Kudritzki et al. 1997 Same Fig. as before, but now replaced by

estimate of outflow velocities P Cygni - B2 hypergiant and LBV: Model atmosphere fit - optical lines

Najarro, Kudritzki et al. 1997 Concepcion 2007 Wolf-Rayet in NGC 300 at 2 Mpc distance Mpcdistance 2 at NGC300 in star Wolf-Rayet 2002, 2002, L107 ApJ Letters 577, et al. Najarro Kudritzki, Bresolin, pattern pattern outside Local Group first detailed abundance emission line diagnostics: WN11 star

I. Introduction First suspicion of existence 1929 C. Beals of continuous stellar winds: MNRAS 90, 202 91, 966 (1931) 1934 S. Chandrasekhar MNRAS 94, 522 Optical spectrum of P Cygni broad H, HeI, metal lines with B2 hypergiant and LBV : blue-shifted absorption red-shifted emission Optical spectrum of broad He, C, N emission lines Wolf-Rayet stars : no hydrogen lines widths of lines Doppler-shifts of out-flowing atmospheres

Vexpansion ≈ 200 km/s to 3000 km/s 1934 Adams and McCormack ApJ 81, 119 optical spectra of M supergiants α Ori M2 Ib α1 Sco M1 Ib α1 Her M5 II blue-shifted absorption cores of groundstate lines of MnI, CaI, CrI etc. (“0.00 eV lines”) modern spectra (high res. & S/N) narrow P Cygni profile superimposed to photospheric line core (Bernat & Lambert, 1976, ApJ 204, 830)

1/2 vexp ≈ 10 to 20 km/s but vesc = [2GM/R] escape velocity is of same order!

Is the flow able to escape the gravitational potential ????

Bernat & Lambert, 1976 ApJ α Ori 204, 830

MnI λ 4030.8 Å λ 4033.1 Å

tiny P Cygni profile superimposed to photosperic line core 1934 Adams and McCormack ApJ 81, 119 optical spectra of M supergiants α Ori M2 Ib α1 Sco M1 Ib α1 Her M5 II blue-shifted absorption cores of groundstate lines of MnI, CaI, CrI etc. (“0.00 eV lines”) modern spectra (high res. & S/N) narrow P Cygni profile superimposed to photospheric line core (Bernat & Lambert, 1976, ApJ 204, 830)

1/2 vexp ≈ 10 to 20 km/s but vesc = [2GM/R] escape velocity is of same order!

Is the flow able to escape the gravitational potential ????

1956 Armin J. Deutsch ApJ 123, 210 Mt. Palomar 5m Coude spectra with very high resolution of M supergiants with earlier spectral-type companions

α1 Sco M1 Ib α2 Sco B2 V CaII, TiII etc. lines very unsual for B2

α1 Her M5 II α1 Her G0 III MNI, CrI etc. very unusual for G0

circumstellar lines produced by of M supergiant Maniakalani – the Maui fish hook southern cross

Antares

Keawaula Beach (Yokohama Bay), June 24, 2012

Model by Kudritzki & Reimers, 1978, A&A 70, 227

wind envelope extension ≈ 1000 Rstar 1/2 vexp ≈ 20 km/s >> vesc = [2GM/r] ≈ 1/30 vesc- Vexp >> Vesc (r) M supergiants have winds !!!

1951 Ludwig Biermann Zeitschrift fuer Astrophysik 29, 274 all comet plasma tails point away from solar wind with v ≈ 400 km/s

1962 Marcia Neugebauer & C.W. Snyder Science,138, 1169 Mariner 2 probe to Venus finds fast solar wind present all times

v ≈ 500 ± 300 km/s at -3 nwind = 5 cm highly variable -13 = some 10 Msun/yr

1958 Eugene Parker ApJ 128, 664 first hydrodynamic theory of solar wind II. Spectroscopic evidence for stellar winds

1. Spectral lines in hydrostatic atmospheres

Hydrostatic à barometric formula

thin, plane-parallel atmosphere with gradient symmetric absorption line around central wavelength

λ0

Width of line determined by a) thermal motion of gas b) c) Pressure broadening, stellar 1. Line scattering in expanding atmospheres

in front of stellar remaining envelope: disk: blue-shifted red- & blue-shifted scattering by gas scattering by gas moving towards moving towards and observer away from observer

P Cygni profile

width determined

by vmax Note: “line scattering” is special re-emission process

photon is absorbed and re-emitted by spontaneous emission in same line transition

de facto scattering

number of photons is conserved

Nabs = Nem

typical process for resonance lines 2. Thermal or recombination emission in expanding atmospheres

If τspont > τcoll absorbed photon not re-emitted and destroyed by collisional level excitation or de-excitation re-emission coupled to local T(r) since wind envelope can a huge volume, an emission line might occur

pure emission profile

width determined by vmax If ionization of the atoms with subsequent recombination dominates, then the population of the upper level is controlled from transitions cascading from above

ionization from ground cascade of subsequent or excited level spontaneous emissions

pure emission line 3. Other signatures of stellar winds

Stellar winds are ubiquitous in all wavelength domains !!!

Radio: hot stars: free-free emission of winds “ radio- excess” cool stars: maser emission of winds

OH, H2O, SiO, NH3

IR: ground-based & satellite telescope (IRAS, ISO, Spitzer, Herschel) hot stars: free-free emission of winds weaker than “ radio- excess” rich emission line spectra H, He, metals cool stars: dust emission in winds, PAHs stellar winds are ionized plasma ff/bf radiation of extended stellar wind envelope additional contribution to photospheric SED photosperic SED

excess from wind

IR/radio from cool wind

(T=Teff)

X-rays from very hot (T ~ 106 … 107 K) shocks in wind P Cygni - B2 hypergiant and LBV: Model atmosphere fit – IR (ISO)

Najarro & Kudritzki, 1997 P Cygni

mid IR (ISO)

Najarro, 2005 Optical: line diagnostics of mass-loss rates wind velocities chemical composition A-supergiant in M31 – stellar wind

Model calculation

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 M˙ by ± 20%

Kudritzki & Puls, 2000, AARA 38, 613

Concepcion 2007 Wolf-Rayet star in NGC 300 at 2 Mpc distance Mpcdistance 2 at NGC300 in star Wolf-Rayet 2002, 2002, L107 ApJ Letters 577, et al. Najarro Kudritzki, Bresolin, pattern pattern outside Local Group first detailed abundance emission line diagnostics: WN11 star

Concepcion 2007 NGC 300 WN11 star WN11star NGC 300 hydrodynamic model atmospheres atmospheres model hydrodynamic 2002, 2002, L107 ApJ Letters 577, et al. Najarro Kudritzki, Bresolin, non-LTE line-blanketed H, He, CNO, Al, Si, Fe with stellar winds winds stellar with stellar parameters parameters stellar wind parameters parameters wind abundances abundances

Concepcion 2007 NGC 300 NGC WN11 star 300 Concepcion 2007 T Fe 1.510 Mg 1.5 10 He 0.3011.06 H 0.6880.97 eff = 10000K, L = 10000K, = 3.1 10 Najarro, Urbaneja, Kudritzki, Bresolin Bresolin Kudritzki, Urbaneja, Najarro, LBV mass fraction mass X/X

-4 -3 7 Mpc 7 NGC 3621 0.22 1.08 2005 5 L sun sun

UV: satellite telescopes: Copernicus, IUE, HST, ORFEUS, EUVE, FUSE

very rich stellar wind spectra of hot and cool stars

OVI, OV, OIV, OIII, NV, NIV, NIII, CIV, CIII, CII, SiIV, SiIII, SVI, SV, MgII, FeII …..

Concepcion 2007 supergiant z supergiant Puppis UV spectrum of O4 Pauldrach, Puls,et al. Kudritzki 1994, SSRev, 66, 105 Concepcion 2007 HD 93129AO3Ia 321, 531 et al. 1997, A&A, Taresch, Kudritzki X-ray: hot stars: emit X-rays through shocks in their winds strong X-ray emitters

cool stars: have coronae, except M supergiants/giants Concepcion 2007 et (Owocki al., 1997) Feldmeier, 1988; time dependent stellar wind radiation-hydro à

shocks Concepcion 2007

Feldmeier, Kudritzki et al., Kudritzki Feldmeier, 1997 Calculated spectraobservations ROSAT and

● ROSAT ζ Pup, If O4 ι Ori O9 III 15 Mon O7 V O7 Mon 15 III O9 Ori ROSAT FWHM with convolved theory III. Stellar winds and Astronomy

1. Stellar winds and

Massive stars dominate light of star forming galaxies Strong and broad stellar wind lines easily detectable in spectra of integrated stellar populations Example: starburst galaxies at high z UV shifted to optical/IR

population synthesis, , Energy and momentum input à galactic winds, Nuclear burned material input à chemical evolution of galaxies P Cygni profiles and

Galaxy LMC SMC

Kudritzki, 1998 cB58 @ z=2.7 Population synthesis of high-z galaxies

Stellar spectra

Stellar Population Initial Mass Function Star Formation History Metallicity

Galaxy spectra

non-LTE atmospheres with winds plus stellar evolution models à Synthetic spectra of galxies at high z à as a function of Z, IMF, SFR Starburst99 population synthesis models + UV stellar libraries at ~solar and ~0.25 solar (LMC, SMC) abundance

NGC 5253 Leitherer et al. 2001, ApJ, 550, 724 ofstarbursts diagnostics high-z Spectral

Rix, Pettini, Leitherer, Bresolin, Kudritzki, Steidel, 2004, 615, 98 ApJ Rome 2005 Starburst models - fully synthetic spectra based on model models-fullyon atmospheres syntheticspectraStarburst based Spectral diagnostics of high-z starbursts ofstarbursts diagnostics high-z Spectral Rome 2005 2004, 615, 98 ApJ Bresolin, Kudritzki, Steidel Rix, Pettini, Leitherer, vs. observation vs. fully syntheticspectra cB58

@ z=2.7@ 2. Winds and stellar evolution Winds affect stellar evolution significantly

winds mass-loss

mass M is decisive parameter for /evolution

crucial in certain phases, because it changes stars with significant during stage

good approximation Reimers – formula Reimers, 1975; Kudritzki & Reimers, 1978, A&A 70, 227

Note: tremendous mass-loss in RGS and AGB – phase star with 8 Msun on ends up with 1 Msun

7 Msun re-cycled to ISM ejection of at tip of AGB

Late stages of low-mass stellar evolution: CSPN

depends on L

small, but ≈ mass of hydrogen burning shell

tevol strongly modified by winds

for review of CSPN winds see Kudritzki, Mendez et al., 1997, Proc. IAU Symp. 180, 64 Kudritzki et al., 2006, Proc. IAU Symp. 234, 119 White Dwarfs: extremely narrow mass distribution

without mass-loss stars with such masses cannot have evolved from the main sequence within Hubble time

from the HRDs of open clusters we know that all stars with

have formed WDs

The mass spectrum observed can be explained by IMF and stellar evolution with mass-loss applying Reimers - formula stars with Stellar winds observable during whole evolution

Kudritzki & Puls, 2000, AARA 38, 683 Kudritzki & Urbaneja, 2009 strong for no evolution towards red supergiants stars can lose up to 90% of their mass until He-ZAMS Wolf-Rayet stars: massive stars on He-ZAMS with no H very strong winds !!! 3. Winds and galaxy evolution stellar winds Energy and momentum input into ISM affects star formation causes “galactic winds” recycles nuclear burned matter into ISM affects chemical evolution