2. Stellar evolution – a crash course

2. Stellar evolution – a crash course Rolf Kudritzki SS 2015

1

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

Rolf Kudritzki SS 2015

2

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


3

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

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

He-flash after flash stars on HB with central He burning and H burning shell


5

Maeder, 2009

interior structure during evolution

the nuclear H-burning shell moves outwards until He-burning ignites in the degenerate He-core

He-flash hydro-dynamic

Con

cepc

ion

2007

NGC 300 Cycle 11 HST/ACS imaging

Distance from TRGB Rizzi, Bresolin, Kudritzki et al., 2005, ApJ agrees with Cepheids

Con

cepc

ion

2007

NGC 300 Cycle 11 HST/ACS imaging

Distance from TRGB Rizzi, Bresolin, Kudritzki et al., 2005, ApJ agrees with Cepheids your name

Mager et al. (2008)

TRGB

TRGB distance (theory new) (m-M)0=29.51 0.05 0.05 MASER distance (Humphreys et al. 2013) (m-M)0=29.40 0.06 0.06

Comparison with MASER distance to NGC4258 M. Salaris, MIAPP 2014


8 your name Makarov et al. 2006

TRGB detection (maximum likelihood methods)

The fitted parameters are

mTRGB = 21.79 [21.76, 21.83], RGB slope a = 0.36 [0.30, 0.43] RGB jump b = 0.44 [0.38, 0.50] AGB slope c = 0.13 [0.03, 0.24]

‘noisy’ edge detection response

LF parametrised as

M. Salaris, MIAPP 2014


9

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


10 your name

HORIZONTAL BRANCH MORPHOLOGY



11

globular cluster CMD

Hansen & Kawaler, 1994


12

globular cluster CMD

RR Lyrae pulsators in HB

Hansen & Kawaler, 1994


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RR Lyrae stars as distance indicators and stellar tracers

RR Lyrae variables

 Initial mass (MS): ~0.8-0.9 Msun

 Mass (HB): ~0.6-0.8 Msun

 Core He + Shell H burning

 [Fe/H] ~ -2.5 – 0.0 (Smith, 2005)

 Old: >10 Gyr (GCs, halo, bulge) Main Sequence (MS)

Horizontal Branch (HB)

Stetson, VFB et al. (2014)

M4

HB Maruzio’s talk

Guiseppe Bono, MIAPP 2014


14

Vittorio Francesco Braga

M4 CMDsDistance determination to M4 with optical, NIR and MIR photometry of RR Lyrae

Garching, MIAPP, 11/6/2014


15

HB evolution

Maeder, 2009


16 your name

HORIZONTAL BRANCH Core He-burning phase in old stellar populations

Ingredients: He-core mass at He-ignition Convective-core mixing Bolometric corrections Star Formation histories/RGB mass loss



17

internal structure of AGB star

Maeder, 2009


18

AGB and post-AGB evolution

CSPN

WD


19

Evolution of intermediate mass stars

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

2.5M� M 8.0M�


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evolution of a 7 Msun star

Maeder, 2009


21

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

pAGB core mass – luminosity relationship simple fit formula by Paczynski, 1970 L

L�= 5.29 104

✓M

M�� 0.52

◆

Maeder, 2009


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Maeder, 2009


23


Maeder, 2009

Cepheid instability strip


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instability strip

main sequence

Hayashi limit of low mass fully convective stars


25

Evolution of massive stars

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

M � 8.0M�

Ath

ens

2013

Blue supergiants – objects in transition

B1–A4

Brightest normal stars at visual light: 105..106 Lsun -7 ≥ MV ≥ -10 mag tev ~ 103 yrs L, M ~ const. ideal to determine

•  chemical compos. •  abundance grad. •  SF history •  extinction •  extinction laws •  distances

of galaxies

MIA

PP 2

014

IR beacons in universe: red supergiants

B1–A4

Brightest stars at infrared light: -8 ≥ MJ ≥ -11 mag

K–M

medium resolution J-band spectroscopy: atomic lines dominate à medium res. spectra ok

à  enormous potential with Keck/VLT, TMT/E-ELT beyond Local Group out to Coma cluster

Advantage: AO supported MOS possible


28

Maeder, 2009

structure of a massive star shortly before iron core SN collapse


29

The bright and beautiful death of many stars: Supernovae

Maeder, 2009


30

Maeder, 2009

light curves of supernova types and peak magnitudes


31


Maeder, 2009


32

Maeder, 2009

structure of a massive star shortly before iron core SN collapse


33 Stefan Taubenberger (MPA) Distance measurements with Type IIP supernovae

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

Introduction

Image: Mattila et al. 2010


34 Stefan Taubenberger (MPA) Distance measurements with Type IIP supernovae

SNe IIP at the GTC

Observational data II: SNe IIP at intermediate redshift


35

Phenomenology

● Strong Hydrogen lines --> Type II classification

● A long Plateau in their lightcurve

● A sharp fall

● A radioactive tail


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Phenomenology

● Strong Hydrogen lines --> Type II classification

● A long Plateau in their lightcurve

● A sharp fall

● A radioactive tail

Olivares et al. 2010


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SNe IIP in a nutshell

● The duration of the plateau is usually of the order of ~100 days, ranging between 80 and 120 days

● The initial velocity of the ejecta is of the order of 1-2 x 10^4 km/s

● The initial temperature is of the order of 1-2 x 10^4 K

● Peak luminosities commonly range between Mv = -15.5 and Mv = -18.5 mag --> how can we use them as distance indicators?

● The SN event is generated by the core-collapse of a massive star

● Progenitors are usually Red Supergiants (RSG, in some cases we have a BSG, such as SN 1987A)

● Their masses are expected

to be up to 25-30 M

, but on

the basis of the progenitors analysis, the accepted limit is

of the order of 15-18 M

...

...Until now...


38


Maeder, 2009


39

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

A. Riess, 2012, Naples WS


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NOAO 4m image of SN 2011fe in M101 (T.A. Rector, H. Schweiker & S. Pakzad NOAO/AURA/NSF)

Saurabh W. Jha MIAPP The Extragalactic Distance Scale May 28, 2014

Surveying the Universe with Type Ia Supernovae

SN 2014J in M82 (Marco Burali, Osservatorio MTM Pistoia)


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SNIa background physics

all stars with evolve into the cooling sequence of White Dwarfs

M 8M� CSPN

WD


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cooling sequence of WDs

V.Weidemann and collaborators

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 roughly explained by IMF and stellar evolution with mass-loss applying Reimers – formula Note: no WD with masses !!!

hMWDi ⇡ 0.6M�

0.8M� M 8M�

M� � 1.4M�


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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.  Pauli principle: only one particle per quantum state 2.  Fermi distribution of energies instead Maxwell/

Boltzmann 3.  different EOS


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�B =hp

2⇡mkT

r0 = n� 13n =

N

V=

1

r30

f(✏) =1

e(�⌘+ ✏kt ) + 1

↵ = 2

de Broglie wavelength

particle separation

energy distribution

degeneracy parameter for �B � r0

spin degeneracy of electrons

⌘ =1.21

↵

✓�B

r0

◆2

/ n23


46

strong degeneracy of free electrons in WD electrons provide pressure acting against gravity different EOS


47

f(✏) =1

e(�⌘+ ✏kt ) + 1

✏/kT

Fermi energy

P ⇠ n53

eWD EOS: degenerate matter pressure de-coupled from temperature

✏f ⇠ n23

e


48

Mass – radius relationship of WDs dP

dr= �G

Mr

r2⇢

dP

dr⇠ P0 � Pc

R� 0= �Pc

R⇠ �M

R2⇢̄

⇢̄ ⇠ M

R3

Pc ⇠M2

R4

Pc ⇠ ⇢̄53 ⇠ M

53

R5

R ⇠ M� 13

hydrostatic equilibrium

on the other hand: EOS

(1)

(2)

combine (1) and (2)

WD radii shrink with increasing mass!!!!


49

with higher mass Fermi energy increases and particles become relativistic

R ⇠ M� 13 ⇢̄ ⇠ M2

✏f � mec2

✏f ⇠ ⇢23

✏ = m0c2(1 +

p2

m0c2)

12 p = m0v(1�

v2

c2)�

12

relationship between energy and momentum p changes

P = A2⇢43 (1�B2⇢

� 23 )

relativistic EOS at higher mass

The Chandrasekhar limit of WDs


50

P = A0M2

R4⇢ = B0

M

R3combining eq (1) and

with relativistic EOS yields

R =B

130

B122

M13

r1� M

MCh

MCh =

✓A2

A0

◆ 32

B20 ⇡ 1.4M�

at the Chandrasekhar mass MCh the radius is zero

no higher masses than MCh possible !!!

The Chandrasekhar limit of WDs


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relativistic degeneracy

WD Mass radius relationship

Close to the Chandreasekhar limit: We will show in the next chapter that such configurations are unstable collaps and explosive carbon burning Supernova explosion

P ⇠ ⇢43


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Scenario for SNIa supernova explosions

WD in binary system is accreting mass approaching Chandrasekhar limit and explodes as SNIa Since explosion happens always at same mass, released energy (luminosity) should be the same Bright standard candle !! ??


53

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



54

NOAO 4m image of SN 2011fe in M101 (T.A. Rector, H. Schweiker & S. Pakzad NOAO/AURA/NSF)

Saurabh W. Jha MIAPP The Extragalactic Distance Scale May 28, 2014

Surveying the Universe with Type Ia Supernovae

SN 2014J in M82 (Marco Burali, Osservatorio MTM Pistoia)


55

May 18, 1998

Ca

Fe

S

Si

Si

Fe

intermediate mass elements are fused from C and O during the explosion

ejecta travels at ~10,000 km/s

March 14, 1997

What is a Type Ia Supernova?

May 18, 1998

strong evidence that SN Ia are explosionsof carbon-oxygen white dwarfs

but big questions about companion star, white dwarf mass and explosion process SN 1998bu in M96

S.W. Jha, 2014, MIAPP WS


56

The Groundbreaking Work: Calán/Tololo

Hamuy et al. (1996a,b)

1996AJ....112.2391H

1996AJ....112.2398H



57 Krisciunas et al. (2006)

SN Ia are standardizable candles,with emprically derived corrections:

light curve-shape correction(aka the Phillips 1993 relation)

color-correction(including dust reddening/extinction,

e.g. Riess et al. 1996, 1999)

light curve fitters (in use today):MLCS2k2 (Jha, Riess, & Kirshner 2007)

SALT2 (Guy et al. 2007)SiFTO (Conley et al. 2008)

BayeSN (Mandel et al. 2009, 2011)SNooPy (Burns et al. 2011)

Gaussian Process (Kim et al. 2013, 2014)...

Standardizing the Candles



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MLCS2k2 light-curve fitsJha, Riess, & Kirshner (2007)

6

0

1000

2000

-20 -10 0 10 20 30 40 50 60

0

1000

2000

-20 -10 0 10 20 30 40 50 60

SN 2005ff z=0.09

g

r

i

Tobs - 53634.7

Flu

x

0

1000

2000

-20 -10 0 10 20 30 40 50 60

0

200

400

600

-20 -10 0 10 20 30 40 50 60

0

200

400

600

800

-20 -10 0 10 20 30 40 50 60

SN 2005fb z=0.18

g

r

i

Tobs - 53632.8

Flu

x

0

200

400

600

-20 -10 0 10 20 30 40 50 60

0

100

200

-20 -10 0 10 20 30 40 50 60

0

100

200

300

-20 -10 0 10 20 30 40 50 60

SN 2005fr z=0.29

g

r

i

Tobs - 53633.4

Flu

x

0

100

200

-20 -10 0 10 20 30 40 50 60

0

25

50

75

-20 -10 0 10 20 30 40 50 60

0

50

100

150

-20 -10 0 10 20 30 40 50 60

SN 2005gq z=0.39

g

r

i

Tobs - 53646

Flu

x

0

100

200

-20 -10 0 10 20 30 40 50 60

Fig. 1.— Light curves for four SDSS-II SNe Ia at different redshifts: SN 2005ff at z = 0.09, SN 2005fb at z = 0.18, SN 2005fr atz = 0.29, and SN 2005gq at z = 0.39. The passbands are SDSS g (top), r (middle), and i (bottom). Points are the SMP flux measurements(flux = 10(11−0.4m), where m is the SN magnitude) with ±1 σ photometric errors indicated. Solid curves show the best-fit mlcs2k2 modelfits (see §5.1), and dashed curves give the ±1 σ error bands on the model fits. The Modified Julian Date (MJD) under each set of lightcurves is the fitted time of peak brightness for rest-frame B-band.

SNANA: Kessler et al. (2009b)“scene-modeled” multi-color light curves, with fits for light curve shape and dust extinction

Holtzman et al. (2008)

Si

MLCS2k2 light curve fits

SN 1999cp and SN 2002cr, both in NGC 5468μ = 33.46 ± 0.07 mag μ = 33.49 ± 0.10 mag

KAIT BVRI photometry Ganeshalingam et al. (2010)



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Si

~6 to 10% distance precision per object -- average this down with pN

Standardizing the Candles

Jha, Riess, & Kirshner (2007)



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q0, 1998: High-z SNe Ia; Acceleration (q0<0), Dark Energy!

Riess et al. 2007

Not just supernovae require “dark energy”…



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2. Stellar evolution – a crash course