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Presentation on theme: "CHALLENGES FOR STELLAR EVOLUTION"— Presentation transcript:

AND PULSATION THEORY Jadwiga Daszyńska-Daszkiewicz Instytut Astronomiczny, Uniwersytet Wrocławski, POLAND JENAM Symposium "Asteroseismology and stellar evolution" September 8, 2008, Vienna

J. Christensen-Dalsgaard

3 ASTEROSEISMOLOGY mode identification: osc →(n,,m) Amplitude
frequency [c/d] mode identification: osc →(n,,m) ASTEROSEISMOLOGY

4 SEISMIC MODEL j,obs=j,cal(nj , j , mj , PS ,PT)
PS -- parameters of the model: the initial values of M0, X0, Z0, the angular momentum (or Vrot,0 ), age (or logTeff ) PT -- free parameters of the theory: convection, overshooting distance, parameters describing mass loss, angular momentum evolution, magnetic field


6 CLASSICAL CEPHEIDS primary distance indicators

7 Mass discrepancy problem for double mode Cepheids
pulsational masses  evolutionary masses

8 Petersen Diagram (P1/P0 vs logP0 ) for  Scuti stars
and double mode Cepheids LAOL & OPAL tables Moskalik i in, 1992 Christensen-Dalsgaard 1993

9 Mass discrepancy remains
ML relation dependence Keller 2008 Z dependence mass loss ? internal mixing ? Keller, Wood 2006

10 double mode Cepheids models
result from ignoring bouyancy in convectively stable layers ! Smolec R., Moskalik P., 2008 Growth rates: 0,1- for the fundamental mode with respect to the first overton, 1,0- for the first overton double mode solution is not found !

11 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, Soszyński Kołaczkowski, Moskalik, Mizerski

12 Period–luminosity diagrams
for Classical Cepheids in the LMC OGLE Data Soszyński et al. 2008

13 B type main sequence pulsators
M>8M - progenitors of Type II Supernova (most  Cep’s) M<8M – form CNO elements (most SPB stars)

14  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

15 Pamyatnykh, Ziomek

16 Miglio, Montalban, Dupret

17  problem of mode excitation
 uncertainties in opacity and element distribution  extent of overshooting distance  estimate of the interior rotation rate

18 Dziembowski, Pamyatnykh 2008

19 sdB stars  core helium burning phase  thin hydrogen envelope
 final stage before white dwarfs

20 sdB PULSATORS Charpinet et al – theoretical predication Kilkenny et al – observational evidence Green et al – long period oscillations Fontaine et al – iron accumulation in Z-bump Fontaine et al – including radiative levitation

21 Inner structure and origin ?  single star evolution
 binary star evolution -- common envelope evolution -- stable Roche-lobe overflow -- the merge of two He WD stars

22 sdO stars  C/O core  helium burning shell phase

23 sdO PULSATORS Woudt, Kilkenny, Zietsman et al. 2006
SDSS object: 13 independent frequencies (P= s) Rodriguez-Lopez, Ulla, Garrido, 2007 two pulsating candidates in their search (P=500s and 100 s) Rodriguez-Lopez, Ulla, Garrido, 2007

24 Iron levitation in the pure hydrogen medium
Mode excited in the range P s

25 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

26 sdOB pulsators – perfect object
for testing diffusion processes hybrid sdOB pulsators - Schuh et al. 2006

27 Extreme helium stars

28 strange-mode instability – high L/M ratio
Detection of variability in hydrogen deficient Bp supergiants: V652 Her (P=0.108d), V2076 Oph (P= d)– Landlot 1975 strange-mode instability – high L/M ratio Z-bump instability Jeffery 2008

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

30 helium-rich sdB star Pulsation in high order g-modes
such modes should be stable Ahmad, Jeffery 2005

31 Hot DQ White Dwarf stars
Carbon atmospheres with little or no trace of H and He new sequence of post-AGB evolution

32 Dufour, Liebert, Fontaine, Behara, 2007, Nature 450, 522
White dwarf stars with carbon atmospheres Six hot DQ White Dwarfs

33 a new class variable white dwarfs
Montgomery et al. 2008, ApJ 678, L51 SDSS J : A Prototype for a new class variable white dwarfs P=417.7 [s] from time-series potometry Period [s] 417 208 83 new class of pulsating carbon-atmosphere WDs (DQVs) or first cataclysmic variable with a carbon-dominated spectrum

34 Fontaine, Brassard, Dufour, 2008, A&A 483, L1
Might carbon-atmosphere white dwarfs harbour a new type of pulsating star? Unstable low-order g-modes for models with Teff from K to 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 Dufour, Fontaine et al. 2008, ApJ 683, L167 SDSS J : The first pulsating white dwarf with a large detectable magnetic field

Planets around oscillating solar type stars e.g.  Ara Planets around compact pulsators V391 Peg, Silvotti et al. 2007


37 OPACITIES determine the transport of radiation through matter
(T,, Xi)

38 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. ApJ 360, 221 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

39 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

40  (OPAL) as a function of logT and log/T63 (T6 =T/106)
C/O bump Pamyatnykh 1999, AcA 49, 119

 Seismic model of the Sun improved  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

42 Asplund, Grevesse, Sauval 2004, 2005
NEW SOLAR CHEMICAL COMPOSITION Asplund, Grevesse, Sauval 2004, 2005

43 Comparison of the old and new solar composition
A. A. Pamyatnykh

44 better agreement of solar metallicity with its neighbourhood
No problem with B main sequence pulsators Pamyatnykh (2007): more Fe relative to CNO For AGS04 galactic beat Cepheid models are in better agreement with observations Buchler, Szabo 2007 Reduction of the lithium depletion in pre-main sequence stellar models gives better agreement with observations, Montalban,D’Antona 2006

45 Conspiracy at work: better is worse
Basu & Antia, 2007, astro-ph


47 Achernar: the ratio of the axes is 1.56 ± 0.05

48 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

49 Evolutionary tracks for non–rotating and rotating models
Maynet, Maeder, 2000

50 The evolution of (r) during the MS evolution of a 20M star
Maynet, Maeder, 2000

51 Stars can reach the break-up velocity
M=20 Z=0.004 Maynet, Maeder, 2000

52 Soufi, Goupil, Dziembowski 1998
EFFECTS OF ROTATION ON PULSATION The third order expression for a rotationally split frequency Goupil et al Dziembowski, Goode 1992 Soufi, Goupil, Dziembowski 1998 Mathis

53 M=1.8 M, Teff=7515 K, Vrot=92 km/s. Pamyatnykh 2003

j - k   ; j = k 2 ; mj = mk ( >> ) rotational mode coupling    perturbation approach fails

55 rotational mode coupling
eigenfunction of an individual mode is a linear combination ak - contributions of the k-modes to the coupled mode Soufi, Goupil, Dziembowski 1998 complex amplitude of the flux variation Daszyńska-Daszkiewicz et al. 2002

56 Description of slow modes ( ~ )
 the traditional approximation Townsend(2003)  Expansion in Legendre function series Lee, Saio (1997)  2D code (Savonije 2007)

57 Rotation confines pulsation towards the stellar equator
Townsend 1997 Hough functions

58 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

59 J. Christensen-Dalsgaard
Solar rotation J. Christensen-Dalsgaard

60 The rotational splitting kernel, K  the =(r) profile
For the  Eri model from Pamyatnykh, Handler, Dziembowski, 2004 The rotation rate increases inward, e.g. Goupil, Michel, Lebreton, Baglin 1993 (GX Peg) Dziembowski, Jerzykiewicz 1996 (16 Lac) Aerts, Toul, Daszynska et al (V836 Cen) Pamyatnykh, Handler, Dziembowski, 2004 ( Eri) Dziembowski, Pamyatnykh 2008 ( Eri,12 Lac)

61 Dziembowski & Pamyatnykh 1991, A&A 248, L11
Modes which are largely trapped in the region surrounding the convective core boundary can measure the extend of the overshooting. Ek=2 2 V836 Cen – first evidence of the core overshooting in  Cep star Aerts, Toul, Daszyńska et al., 2003 , Science 300, 1926

62 Miglio, Montalban, Noels, Eggenberger 2008
Properties of high order g-modes in SPB and  Dor stars Effects of mixing processes on P models of 1.6M with Xc=0.3, =1

Talon, Charbonnel 2005 Internal gravity waves contribute to braking the rotation in the inner regions of low mass stars Townsend, MacDonald 2008 Pulsation 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

64 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

65 MLT theory of stellar convection
Böhm-Vitense 1958 full-spectrum turbulence theory of convection Canuto, Goldman, Mazzitelli 1996 (CGM)

66 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

67 3D versus 1D Radiative layer between two convection zones is mixed
main-sequence A-type star (Teff =8000 K, log g =4.00, [M/H]=0) H+HeI convection zone vertical velocity [km/s] HeII convection zone Radiative layer between two convection zones is mixed Steffen M IAUS 239, 36

68 Pulsating stars with „convection problem”
 Scuti  Doradus Classical Cepheids RR Lyrae Red giants White dwarfs (V777Her, ZZ Cet)

69 Convective–flux freezing approximation
Fconv=const during pulsation cycle

70 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

71 M =1.6 M, Teff = 6665 K,  = 1.8, mode =0, p1 Dupret et al. 2004

72 MASS LOSS Important for late evolutionary phases and for massive stars
Hot stars  Radiation-driven wind Cool and luminous stars Dust-driven wind mostly empirical mass-loss formulae are used

73 pulsation and mass loss coupling
Red giants (Mira and SR) – Wood 1979, Castor 1981 mass loss: stellar pulsation & radiation pressure on dust grains dM/dt - P relation Knapp et al. 1998

74 pulsation and mass loss coupling
Massive stars (OB MS, W-R stars), LBV Howarth et al – wind variability in  Oph Kaufer 2006 – B0 supergiant (HD 64760) pulsation beat period observed in H Owocki et al. 2004 Townsend 2007

75 GW Vir stars Constraints on mass loss from the red-edge position
different mass loss laws Quirion, Fontaine, Brassard 2007

76 not only pulsation frequencies
can probe stellar interior photometric and spectroscopic observables

77 input from pulsation calculation:
Theoretical photometric amplitudes and phases: input from pulsation calculation: linear nonadiabatic theory: the f parameter the ratio of the bolometric flux variation to the radial displacement at the photosphere level input from atmosphere models: derivatives of the monochromatic flux over Teff and g limb darkening coefficients: h(Teff , g)

78 The flux derivatives over Teff and log g depend on:
 microturbulence velocity, t  metallicity, [m/H]  models of stellar atmospheres, NLTE effects

79 The f parameter is very sensitive to:
 global stellar parameters  chemical composition  element mixture, mixing processes  opacity  subphotospheric convection

80 simultaneous determination of  and f from observations
multicolor photometry + radial velocity data simultaneous determination of  and f from observations

81 Comparison of theoretical and empirical f values yields constraints on

82 f - a new asteroseismic probe sensitive to subphotospheric layers and
complementary to pulsation frequency

83 Ocillation spectrum of FG Vir
67 independent frequencies ! Breger et al. 2005

84 Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653
Empirical and theoretical f values. Model: MLT, convective flux freezing approximation Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653

85 Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653
Empirical and theoretical f values. Model: non-local, time-dependent formulation of MLT due to Guenter Houdek Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653

86 OSCILLATION SPECTRUM OF  ERI Jerzykiewicz i in., 2005, MNRAS 360, 619
12 independent frequencies Jerzykiewicz i in., 2005, MNRAS 360, 619

87 Comparison of the empirical and theoretical f values
for the dominant frequency (=0 mode) of  Eri Daszyńska-Daszkiewicz et al. 2005, A&A 441, 641

88 Seismic model with the new solar composition added

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


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