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2. Stellar Evolution – a Crash Course

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2. Stellar Evolution – a Crash Course Rolf Kudritzki SS 2015 2. Stellar evolution – a crash course Extragalactic stellar distance indicators need to be bright advanced stages of stellar evolution • Red Giant Star (SFB) • Tip of Red Giant Branch (TRGB) • Horizontal Branch – RR Lyrae • post-AGB stars, Planetary Nebulae • Cepheid Stars • Blue Supergiant Stars 1 Rolf Kudritzki SS 2015 Evolution of low mass stars 0.5M M 2.5M main sequence (MS): H core burning à Red Giant Branch (RGB): H shell burning à He-flash: ignition of He core burning à Tip of RGB (TRGB) à Horizontal Branch (HB): He core burning H burning shell RR Lyrae pulsators à Asymptotic Giant Branch (AGB): He burning shell H burning shell àpost-AGB (pAGB): hot Central Stars of PN (CSPN) à White Dwarfs (WD): no energy sources, cooling supernovae in binaries 2 Rolf Kudritzki SS 2015 Maeder, 2009 all low mass stars ignite He-flash at almost the same luminosity à tip of red giant branch but there is a metallicity dependence 3 Rolf Kudritzki SS 2015 He-flash after flash stars on HB with central He burning and H burning shell Maeder, 2009 all low mass stars ignite He-flash at almost the same luminosity à tip of red giant branch but there is a metallicity dependence 4 Rolf Kudritzki SS 2015 interior structure during evolution He-flash hydro- dynamic Maeder, 2009 the nuclear H-burning shell moves outwards until He-burning ignites in the degenerate He-core 5 NGC 300 Cycle 11 HST/ACS imaging Concepcion 2007 Distance from TRGB Rizzi, Bresolin, Kudritzki et al., 2005, ApJ agrees with Cepheids Mager et al. (2008) TRGB distance NGC 300 Cycle 11 HST/ACS imaging(theory new) (m-M)0=29.51 0.05 0.05 MASER distance Concepcion 2007 (Humphreys et al. 2013) TRGB (m-M)0=29.40 0.06 0.06 Distance from TRGB Rizzi, Bresolin, Kudritzki et al., 2005, ApJ Comparison with MASER distance to agrees with Cepheidsyour name NGC4258 M. Salaris, MIAPP 2014 TRGBRolf Kudritzki detection SS 2015 (maximum likelihood methods) LF parametrised as ‘noisy’ edge detection response The fitted parameters are mTRGB = 21.79 [21.76, 21.83], RGB slope a = 0.36 [0.30, 0.43] RGB jumpb = 0.44 [0.38,0.50] Makarov et al. 2006 your name AGB slope c = 0.13 [0.03, 0.24] M. Salaris, MIAPP 2014 8 Rolf Kudritzki SS 2015 after the hydrodynamic He-flash stars with central He-burning and a H-burning shell assemble on the Horizontal Branch (HB) HB stars have roughly the same He-core mass but different envelope masses à Teff sequence 9 Rolf Kudritzki SS 2015 HORIZONTAL BRANCH MORPHOLOGY your name M. Salaris, MIAPP 2014 10 Rolf Kudritzki SS 2015 globular cluster CMD Hansen & Kawaler, 1994 11 Rolf Kudritzki SS 2015 globular cluster CMD RR Lyrae pulsators in HB Hansen & Kawaler, 1994 12 RolfRR Kudritzki Lyrae starsSS 2015 as distance indicators and stellar tracers RR Lyrae variables M4 Initial mass (MS): ~0.8-0.9 Msun Mass (HB): ~0.6-0.8 Msun Horizontal Branch Core He + Shell H burning (HB) [Fe/H] ~ -2.5 – 0.0 (Smith, 2005) Old: >10 Gyr (GCs, halo, bulge) Main Sequence (MS) HB Maruzio’s talk Stetson, VFB et al. (2014) Guiseppe Bono, MIAPP 132014 DistanceRolf Kudritzki determination SS 2015 to M4 with optical, NIR and MIR photometry of RR Lyrae M4 CMDs 14 Vittorio Francesco Braga Garching, MIAPP, 11/6/2014 Rolf Kudritzki SS 2015 HB evolution Maeder, 2009 15 Rolf Kudritzki SS 2015 HORIZONTAL BRANCH Core He-burning Ingredients: phase in old He-core mass at He-ignition Convective-core mixing stellar populations Bolometric corrections Star Formation histories/RGB mass loss your name16 M. Salaris, MIAPP 2014 Rolf Kudritzki SS 2015 internal structure of AGB star Maeder, 2009 17 Rolf Kudritzki SS 2015 AGB and post-AGB evolution CSPN WD 18 Rolf Kudritzki SS 2015 Evolution of intermediate mass stars 2.5M M 8.0M main sequence (MS): H core burning à Red Giant Branch (RGB): H shell burning à no He-flash: normal ignition of He core burning on RGB à blue loops during He core burning Cepheid pulsators à Asymptotic Giant Branch (AGB): He burning shell H burning shell àpost-AGB (pAGB): hot Central Stars of PN (CSPN) à WD cooling sequence supernova in binaries 19 Rolf Kudritzki SS 2015 evolution of a 7 Msun star Maeder, 2009 20 Rolf Kudritzki SS 2015 pAGB evolution note: heavy influence of mass-loss, for instance, 7 Msun star has only 1 Msun left evolution time much faster for luminous objects Maeder, 2009 pAGB core mass – luminosity relationship simple fit formula by Paczynski, 1970 L M =5.29 104 0.52 L M − ✓ ◆ 21 Rolf Kudritzki SS 2015 evolution of a 7 Msun star Maeder, 2009 22 Rolf Kudritzki SS 2015 evolution of a 7 Msun star Cepheid instability strip Maeder, 2009 23 Rolf Kudritzki SS 2015 instability strip Hayashi limit of low mass fully convective stars main sequence 24 Rolf Kudritzki SS 2015 Evolution of massive stars M 8.0M ≥ main sequence (MS): H core burning à blue supergiants (BSG): H shell burning à red supergiants (RSG): normal ignition of He core burning à M < 15 Msun blue loops during He core burning Cepheid pulsators à post RSG evolution leads to à iron core collapse supernovae 25 Blue supergiants – objects in transition 5 6 Brightest normal stars at visual light: 10 ..10 Lsun -7 ≥ MV ≥ -10 mag Athens 2013 3 tev ~ 10 yrs L, M ~ const. B1–A4 ideal to determine • chemical compos. • abundance grad. • SF history • extinction • extinction laws • distances of galaxies IR beacons in universe: red supergiants Brightest stars at infrared light: -8 ≥ MJ ≥ -11 mag Advantage: AO supported MIAPP 2014 MOS possible B1–A4 medium resolution J-band spectroscopy: atomic lines dominate àmedium res. spectra ok à enormous potential with Keck/VLT, TMT/E-ELT beyond Local Group out to K–M Coma cluster Rolf Kudritzki SS 2015 structure of a massive star shortly before iron core SN collapse Maeder, 2009 28 Rolf Kudritzki SS 2015 The bright and beautiful death of many stars: Supernovae Maeder, 2009 29 Rolf Kudritzki SS 2015 light curves of supernova types and peak magnitudes Maeder, 2009 30 Rolf Kudritzki SS 2015 The bright and beautiful death of many stars: Supernovae Maeder, 2009 31 Rolf Kudritzki SS 2015 structure of a massive star shortly before iron core SN collapse Maeder, 2009 32 Introduction Rolf Kudritzki SS 2015 Type IIP supernovae - progenitors Several direct detections of progenitors (e.g. Smartt et al. 2009): mostly red supergiants Mass range ~9 to ~18 M⊙ Core-collapse explosions of massive, H-rich stars Image: Mattila et al. 2010 33 Stefan Taubenberger (MPA) Distance measurements with Type IIP supernovae Observational data II: SNe IIP at intermediate redshift Rolf Kudritzki SS 2015 SNe IIP at the GTC 34 Stefan Taubenberger (MPA) Distance measurements with Type IIP supernovae Rolf Kudritzki SS 2015 Phenomenology ● Strong Hydrogen lines --> Type II classification ● A long Plateau in their lightcurve ● A sharp fall ● A radioactive tail 35 Rolf Kudritzki SS 2015 Phenomenology ● Strong Hydrogen lines --> Type II classification ● A long Plateau in their lightcurve ● A sharp fall ● A radioactive tail Olivares et al. 2010 36 Rolf Kudritzki SS 2015 SNe IIP in a nutshell ● The duration of the plateau is ● The SN event is generated usually of the order of ~100 by the core-collapse of a days, ranging between 80 massive star and 120 days ● Progenitors are usually Red ● The initial velocity of the Supergiants (RSG, in some ejecta is of the order of 1-2 x cases we have a BSG, such 10^4 km/s as SN 1987A) ● The initial temperature is of ● Their masses are expected the order of 1-2 x 10^4 K to be up to 25-30 M , but on ● Peak luminosities commonly the basis of the progenitors range between Mv = -15.5 analysis, the accepted limit is and Mv = -18.5 mag --> how of the order of 15-18 M ... can we use them as distance indicators? ...Until now... 37 Rolf Kudritzki SS 2015 The bright and beautiful death of many stars: Supernovae Maeder, 2009 38 Rolf Kudritzki SS 2015 SNe Ia: Far-Reaching Candles • CO White Dwarf in binary pushed to Chandrasekhar limit (fundamental physics) Mass transfer, companion, time scales not well understood. Most uniform standard candle at this luminosity scale • Empirical and theoretical calibrations give MV=-19 mag, explain yield of IME • Identified by strong Si II, absence of H in spectra, come in late/early type hosts 39 A. Riess, 2012, Naples WS Rolf Kudritzki SS 2015 Surveying the Universe with Type Ia Supernovae NOAO 4m image of SN 2011fe in M101 (T.A. Rector, SN 2014J in M82 (Marco Burali, Osservatorio MTM Pistoia) H. Schweiker & S. Pakzad NOAO/AURA/NSF) Saurabh W. Jha MIAPP The Extragalactic Distance Scale May 28, 2014 40 Rolf Kudritzki SS 2015 SNIa background physics all stars with CSPN M 8M evolve into the cooling sequence of White Dwarfs WD 41 Rolf Kudritzki SS 2015 cooling sequence of WDs V.Weidemann and collaborators 42 White Dwarfs: extremely narrow mass distribution MWD 0.6M h i⇡ 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 0 . 8 M M 8 M have formed WDs The mass spectrum observed can be roughly explained by IMF and stellar evolution with mass-loss applying Reimers – formula Note: no WD with masses M 1 . 4 M !!! ≥ Rolf Kudritzki SS 2015 The Physics of White Dwarfs the equation of state (EOS) of WDs is different from normal stars because of their much higher densities: 0.6 solar masses confined within earth-like radius mean particle distance << de Broglie wavelength quantum nature (fermions!) of matter important: 1.
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