CHALLENGES FOR STELLAR EVOLUTION

AND PULSATION THEORY

Jadwiga Daszyńska-Daszkiewicz Instytut Astronomiczny, Uniwersytet Wrocławski, POLAND

JENAM Symposium "Asteroseismology and stellar evolution" September 8, 2008, Vienna

DDIVERSITY IVERSITY OOFF SSTETELLAR PULSATIONLLAR PULSATION

J. Christensen-Dalsgaard

AAm

plit

ud

em

plit

ud

e

frequency [c/d]frequency [c/d]

mode identification: osc →(n,,m)

AASTEROSEISMOLOGYSTEROSEISMOLOGY

PS -- parameters of the model: the initial values of M0, X0, Z0, the angular momentum (or Vrot,0 ),

age (or logTeff )

SEISMIC MODELSEISMIC MODEL

j,obsj,obs==j,calj,cal((nnj j , , j j , m, mj j , , PPS S ,,PPTT))

PT -- free parameters of the theory:convection, overshooting distance,parameters describing mass loss,

angular momentum evolution,magnetic field

SOME OBSERVATIONAL

KEY PROBLEMS

CLASSICAL CEPHEIDS

primary distance indicators

Mass discrepancy problem for double mode Cepheids

pulsational masses evolutionary masses

Petersen Diagram (P1/P0 vs logP0 ) for Scuti stars and double mode Cepheids LAOL & OPAL tables

Moskalik i in, 1992Christensen-Dalsgaard

1993

Mass discrepancy remains

Keller 2008

mass loss ?internal mixing ?

ML relation dependence

Z dependence

Keller, Wood 2006

double mode Cepheids modelsresult from ignoring bouyancy in convectively stable layers ! Smolec R., Moskalik P., 2008

double mode solution is not found !

Growth rates: 0,1- for the fundamental mode with respect to the first overton, 1,0- for the first overton

another interesting facts (OGLE):

nonradial modes in Classical Cepheids Blazhko Cepheids

1O/3O double-mode Cepheids

single mode 2O Cepheids

triple-mode Cepheids

eclipsing binary systems containing Cepheids

Udalski, SoszyńskiKołaczkowski, Moskalik,

Mizerski

Period–luminosity diagrams for Classical Cepheids in the LMC

OGLE DataSoszyński et al. 2008

B type main sequence pulsators

M>8M - progenitors of Type II Supernova (most Cep’s)

M<8M – form CNO elements (most SPB stars)

Cep and SBB stars in Magellanic Clouds

Pigulski, Kołaczkowski (2002)

Kołaczkowski, 2004, PhD

Kołaczkowski et al. (2006)

Karoff et al. (2008)

LMC Z=0.008

SMC Z=0.004

Pamyatnykh, Ziomek

Miglio, Montalban, Dupret

problem of mode excitation

uncertainties in opacity and element distribution

extent of overshooting distance

estimate of the interior rotation rate

Dziembowski, Pamyatnykh 2008

sdB stars

core helium burning phase

thin hydrogen envelope

final stage before white dwarfs

sdB PULSATORS

Charpinet et al. 1996 – theoretical predication

Kilkenny et al. 1997 – observational evidence

Green et al. 2003 – long period oscillations

Fontaine et al. 2003 – iron accumulation in Z-bump

Fontaine et al. 2006 – including radiative levitation

Inner structure and origin ?

single star evolution

binary star evolution -- common envelope evolution -- stable Roche-lobe overflow -- the merge of two He WD stars

sdO stars

C/O core

helium burning shell phase

Woudt, Kilkenny, Zietsman et al. 2006SDSS object: 13 independent frequencies (P=60-120 s)

Rodriguez-Lopez, Ulla, Garrido, 2007two pulsating candidates in their search (P=500s and 100 s)

sdO PULSATORS

Rodriguez-Lopez, Ulla, Garrido, 2007

Iron levitation in the pure hydrogen medium

Mode excited in the range P105-120 s

inner structure and origin ?

„luminous” sdO post-AGB stars

„compact” sdO post-EHB objects, descendants of sdBs He-sdOs – the merger of two He WDs or deleyed core He flash scenario

sdOB pulsators – perfect object for testing diffusion processes

hybrid sdOB pulsators - Schuh et al. 2006

Extreme helium stars

Detection of variability in hydrogen deficient Bp supergiants:V652 Her (P=0.108d), V2076 Oph (P=0.7-1.1d)– Landlot 1975

Jeffery 2008

strange-mode instabilit

y – high L/M ra

tio

Z-bump instability

Origin and connection (if any) between normal and the He-rich stars

helium-rich sdB star

Pulsation in high order g-modessuch modes should be stable Ahmad, Jeffery 2005

Hot DQ White Dwarf stars

Carbon atmospheres with little or no trace of H and He

new sequence of post-AGB evolution

Dufour, Liebert, Fontaine, Behara, 2007, Nature 450, 522White dwarf stars with carbon atmospheres

Six hot DQ White Dwarfs

Montgomery et al. 2008, ApJ 678, L51SDSS J142625.71575218.3: A Prototype for a new class variable white dwarfs

P=417.7 [s] from time-series potometry

new class of pulsating carbon-atmosphere WDs (DQVs) or first cataclysmic variable with a carbon-dominated spectrum

Period [s]

417 208 83

Fontaine, Brassard, Dufour, 2008, A&A 483, L1Might carbon-atmosphere white dwarfs harboura new type of pulsating star?

Dufour, Fontaine et al. 2008, ApJ 683, L167SDSS J142625.71575218.3: The first pulsating white dwarf with a large detectable magnetic field

Unstable low-order g-modes for models with Teff

from 18 400 K to 12 600 K, log g = 8.0, X(C) = X(He) = 0.5

Pulsation in hotter models can be excited if surface gravity is increased or if convective is more efficient

EVOLUTION OF PLANETARY SYSTEMS

Planets around oscillating solar type starse.g. Ara

Planets around compact pulsatorsV391 Peg, Silvotti et al. 2007

SOME THEORETICAL

KEY PROBLEMS

OPACITIES

determine the transport of radiation through matter (T,, Xi)

LAOL (Los Alamos Opacity Library) till ~1990

Simon (1982) suggestion that the opacity were at fault OPAL (OPAcity Library)F.J. Rogers, C.A. Iglesias i in. 1990 ApJ 360, 221 1992 ApJ 397, 717; ApJS 79, 507 1994 Science 263, 50 1996 ApJ 456, 902

OP (Opacity Project) International team led by M.J. Seatona 1993 MNRAS 265, L25 1996 MNRAS 279, 95 2005 MNRAS 360, 458, MNRAS 362, L1

Opacity in the Cephei model (M=12 M, X=0.70, Z=0.02):OP (Seaton et al.) vs. OPAL (Livermore) vs. LAOL (Los Alamos)

(< 1991)

A. A. Pamyatnykh

(OPAL) as a function of logT and log/T63 (T6

=T/106)

Pamyatnykh 1999, AcA 49, 119

C/O bump

CONESQUENCES OF Z-BUMP

Seismic model of the Sun improved

Cepheids mass discrepancy Cepheids mass discrepancy solved

pulsation of B type MS stars explained

sdB and sdO pulsation

pulsation of some extreme He stars

OSCILLATION FREQUENCIES TEST OF STELLAR OPACITY

NEW SOLAR CHEMICAL COMPOSITION

Asplund, Grevesse, Sauval 2004, Asplund, Grevesse, Sauval 2004, 20052005

Comparison of the old and new solar composition

A. A. Pamyatnykh

better agreement of solar metallicity better agreement of solar metallicity with its neighbourhoodwith its neighbourhood

No problem with B main sequence pulsatorsNo problem with B main sequence pulsatorsPamyatnykh (2007): more Fe relative to CNOPamyatnykh (2007): more Fe relative to CNO

For AGS04 galactic beat Cepheid modelsFor AGS04 galactic beat Cepheid modelsare in better agreement with observations are in better agreement with observations

Buchler, Szabo 2007Buchler, Szabo 2007

Reduction of the lithium depletion in pre-main

sequence stellar models gives better agreement

with observations, Montalban,D’Antona 2006

Basu & Antia, 2007, astro-Basu & Antia, 2007, astro-phph0711.45900711.4590

Conspiracy at work: better is worseConspiracy at work: better is worse

ROTATION

Achernar: the ratio of the axes is 1.56 ± 0.05

1. Structure (spherical symetry broken)

2. mixing (meridional circulation, shear instabilities,

diffusion, transport, horizontal turbulence) distribution of internal angular momentum (the rotation velocity at different depths)

3. mass loss from the surface enhanced by the rapid rotation (the centrifugal effect)

Laplace, Jacobi, Lioville, Riemann, Poincare, Kelvin, Jeans,Eddington, von Zeipel, Lebovitz, Lyttleton, Schwarzachild, Chandrasekhar, Kippenhahn, Weigert, Sweet, Öpik, Tassoul, Roxgurgh, Zahn, Spruit, Deupree,Talon, Maynet, Maeder,

Mathis

and many others

Maynet, Maeder, 2000

Evolutionary tracks for non–rotating and rotating models

Maynet, Maeder, 2000

The evolution of (r) during the MS evolution of a 20M star

Stars can reach the break-up velocity

Maynet, Maeder, 2000

M=20

Z=0.004

The third order expression for a rotationally split frequency

Dziembowski, Goode 1992Soufi, Goupil, Dziembowski 1998

Mathis

Goupil et al. 2000

EFFECTS OF ROTATION ON PULSATION

Pamyatnykh 2003

M=1.8 MM=1.8 M, T, Teffeff=7515 K, Vrot=92 km/s.=7515 K, Vrot=92 km/s.

j - k ; j = k 2 ; mj = mk ( >> )

rotational mode coupling

perturbation approach fails

EFFECTS OF ROTATION ON PULSATION

rotational mode coupling

Daszyńska-Daszkiewicz et al. 2002

ak - contributions of the k-modes to the coupled mode

eigenfunction of an individual mode is a linear combination

complex amplitude of the flux variation

Soufi, Goupil, Dziembowski 1998

Description of slow modes (Description of slow modes ( ~ ~ ) )

the traditional approximationthe traditional approximation Townsend(2003)Townsend(2003)

Expansion in Expansion in Legendre function series Lee,Lee, Saio (1997)Saio (1997)

2D code (Savonije 2007)2D code (Savonije 2007)

Rotation confines pulsation towards the stellar equator

Townsend 1997Townsend 1997

Hough functionsHough functions

Rotation complicates identification of pulsational modes

diagnostic diagrams become dependent on (i,m,Vrot)

Coupled modes: Daszyńska-Daszkiewicz et al. 2002

Slow modes: Townsend 2003, Daszyńska-Daszkiewicz et al. 2007

Solar rotationSolar rotation

J. Christensen-J. Christensen-DalsgaardDalsgaard

The rotational splitting kernel, K the ==(r)(r) profileprofile

The rotation rate increases inward, e.g.Goupil, Michel, Lebreton, Baglin 1993 (GX Peg)

Dziembowski, Jerzykiewicz 1996 (16 Lac)Aerts, Toul, Daszynska et al. 2003 (V836 Cen)

Pamyatnykh, Handler, DziembowskiPamyatnykh, Handler, Dziembowski,, 2004 2004 ( ( Eri) Eri)Dziembowski, Pamyatnykh 2008 ( Eri Eri,12 Lac)

For the For the Eri model from Eri model from Pamyatnykh, Handler, Pamyatnykh, Handler,

DziembowskiDziembowski,, 2004 2004

Dziembowski & Pamyatnykh 1991, A&A 248, L11Dziembowski & Pamyatnykh 1991, A&A 248, L11

Modes which are largely trapped in the region Modes which are largely trapped in the region surrounding the convective core boundary surrounding the convective core boundary

can measure the extend of the overshooting.can measure the extend of the overshooting.

EEkk==22 22

V836 CenV836 Cen – first evidence – first evidence ofof the core overshooting the core overshooting in in Cep Cep starstar

Aerts, Toul, DaszyAerts, Toul, Daszyńńska et al., 2003 , Science 300, 1926ska et al., 2003 , Science 300, 1926

Miglio, Montalban, Noels, Eggenberger 2008Miglio, Montalban, Noels, Eggenberger 2008

Properties of high order g-modes in SPB and Properties of high order g-modes in SPB and Dor Dor starsstars

Effects of mEffects of mixing processes on ixing processes on PP

models of 1.6M with Xc=0.3, =1

IMPACT OF PULSATION ON ROTATIONAL EVOLUTION

Talon, Charbonnel 2005 Internal gravity waves contribute to braking the rotation in the inner regions of low mass stars

Townsend, MacDonald 2008Pulsation modes can redistribute angular momentum and trigger shear-instability mixing in the zone

The evolution of in the gradient zone transport by (,m)=(4,-4) g-modes

COVECTION

Convection transports energy

Mixing and overshooting convective flows

convection affects stellar spectra

stochastic convective motions excite stellar oscillation

role of convection in heating of stellar chromospheres

Convection + differential rotation stellar activity

MLT theory of stellar convection

Böhm-Vitense 1958

full-spectrum turbulence theory of convection

Canuto, Goldman, Mazzitelli 1996 (CGM)

Fractional heat flux carried by covection in the local MLT and in the Gough’s nonlocal, time-dependent convection formalisms, M=1.8 M, log Teff = 3.860, log L = 1.170

main-sequence A-type star (Teff =8000 K, log g =4.00, [M/H]=0)

Steffen M. 2007 IAUS 239, 36

3D versus 1D

vert

ical velo

cit

y [

km

/s]

H+

HeI co

nvect

ion z

one

HeII c

onvect

ion z

one

Radiative layer between two convection zones is mixed

Pulsating stars with „convection problem”

Scuti

Doradus

Classical Cepheids

RR Lyrae

Red giants

White dwarfs (V777Her, ZZ CetV777Her, ZZ Cet)

Convective–flux freezing approximation

Fconv=const during pulsation cycle

pulsation-convection interactions

Unno 1967 Gough 1977

Solar-like stars – Houdek, Goupil, Samadi

Scuti, Doradus -Xiong, Houdek, Dupret, Grigahcène, Moya

Classical Cepheids, RR Lyr – Feuchtinger, Stellingwerf, Buchler, Kollath, Smolec

Pulsating Red Giants – Xiong, Deng, Cheng

DB (V777 Her) white dwarfs – Quirion, Dupret

Dupret et al. 2004

M =1.6 M, Teff = 6665 K, = 1.8, mode =0, p1

MASS LOSS

Important for late evolutionary phases and for massive stars

mostly empirical mass-loss formulae are used

Hot stars Radiation-driven wind

Cool and luminous stars Dust-driven wind

pulsation and mass loss coupling

Red giants (Mira and SR) – Wood 1979, Castor 1981mass loss: stellar pulsation & radiation pressure on dust grainsdM/dt - P relation

Knapp et al. 1998

pulsation and mass loss coupling

Massive stars (OB MS, W-R stars), LBV

Howarth et al. 1993 – wind variability in Oph

Kaufer 2006 – B0 supergiant (HD 64760)pulsation beat period observed in H

Owocki et al. 2004Townsend 2007

GW Vir starsConstraints on mass loss from the red-edge position

different mass loss laws

Quirion, Fontaine, Brassard 2007

not only pulsation frequencies not only pulsation frequencies can probe stellar interiorcan probe stellar interior

photometric and spectroscopic photometric and spectroscopic observablesobservables

iinput from pulsation calculation:nput from pulsation calculation:

linear nonadiabatic theorylinear nonadiabatic theory: the : the ff parameter parameter the ratio of the bolometric flux variation to the radial displacement at the photosphere level

Theoretical photometric amplitudes and Theoretical photometric amplitudes and phases:phases:

iinput from atmosphere models:nput from atmosphere models:

derivatives of the monochromatic flux over Tderivatives of the monochromatic flux over Teffeff andand gg

limb darkening coefficients: hlimb darkening coefficients: h(T(Teff eff , g) , g)

TThe flux derivatives over The flux derivatives over Teffeff and log g depend and log g depend on:on:

microturbulence velocity, t

metallicity, [m/H]

models of stellar atmospheres, NLTE effects

The The ff parameter is very sensitive parameter is very sensitive to:to:

global stellar parameters

chemical composition

element mixture, mixing processes

opacity

subphotospheric convection

multicolormulticolor photometry + photometry + radial velocity radial velocity datadata

simultaneous determination simultaneous determination of of and and ff from from observationsobservations

Comparison of theoretical and Comparison of theoretical and empirical empirical

ff values yields constraints onvalues yields constraints on

MEAN STELLAR PARAMETERSMEAN STELLAR PARAMETERS

STELLAR ATMOSPHERESSTELLAR ATMOSPHERES

INPUT PHYSICSINPUT PHYSICS

ff - - a new a new asteroseismic probeasteroseismic probe

sensitive tosensitive to subphotospheric layers subphotospheric layers and and

complementary to pulsation frequency complementary to pulsation frequency

Ocillation spectrum of FG Ocillation spectrum of FG VirVir

67 independent frequencies !

Breger et al. 2005

Empirical and theoretical Empirical and theoretical ff values. values.Model: MLT, Model: MLT, convective flux freezing approximation

Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653

Empirical and theoretical Empirical and theoretical ff values values..Model: non-local, time-dependent formulation of Model: non-local, time-dependent formulation of MLTMLT

due to Guenter Houdekdue to Guenter Houdek Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653

OSCILLATION SPECTRUM OF OSCILLATION SPECTRUM OF ERIERI

Jerzykiewicz i in., Jerzykiewicz i in., 20020055, MNRAS 3, MNRAS 3660, 0, 619619

12 independent frequencies

Comparison of the empirical and theoretical Comparison of the empirical and theoretical ff values values

for the dominant frequency (for the dominant frequency (=0 mode) of =0 mode) of Eri Eri

Daszyńska-Daszkiewicz et al. 2005, A&A 441, 641Daszyńska-Daszkiewicz et al. 2005, A&A 441, 641

Seismic model with the new solar composition Seismic model with the new solar composition added added

DIFFUSION ???DIFFUSION ???

CONCLUSIONS more realistic treatment of macro- and

microphysics in stellar modelling

more parallel photometric and spectroscopic observations

Ideal seismic stellar models should account not only for all measured frequencies but also for associated pulsation characteristics Asteroseismology helps:Asteroseismology helps:

-- to solve the equation to solve the equation observation observation =theory=theory-- to avoid to avoid more date=less understanding