Transcript Identifications of modes in the upper MS pulsators by

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
DIVERSITY OF STELLAR PULSATION
J. Christensen-Dalsgaard
Amplitude
frequency [c/d]
mode identification: osc →(n,,m)
ASTEROSEISMOLOGY
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
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, 1992
Christensen-Dalsgaard 1993
Mass discrepancy remains
ML relation dependence
Keller 2008
Z dependence
mass loss ?
internal mixing ?
Keller, Wood 2006
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 !
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
Period–luminosity diagrams
for Classical Cepheids in the LMC
OGLE Data
Soszyński 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
sdO PULSATORS
Woudt, Kilkenny, Zietsman et al. 2006
SDSS object: 13 independent frequencies (P=60-120 s)
Rodriguez-Lopez, Ulla, Garrido, 2007
two pulsating candidates in their search (P=500s and 100 s)
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
Origin and connection (if any) between
normal and the He-rich stars
helium-rich sdB star
Pulsation in high order g-modes
such 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, 522
White dwarf stars with carbon atmospheres
Six hot DQ White Dwarfs
Montgomery et al. 2008, ApJ 678, L51
SDSS J142625.71575218.3: 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
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
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
Dufour, Fontaine et al. 2008, ApJ 683, L167
SDSS J142625.71575218.3: The first pulsating
white dwarf with a large detectable magnetic field
EVOLUTION OF PLANETARY SYSTEMS
Planets around oscillating solar type stars
e.g.  Ara
Planets around compact pulsators
V391 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)
C/O bump
Pamyatnykh 1999, AcA 49, 119
CONESQUENCES OF Z-BUMP
 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
NEW SOLAR CHEMICAL COMPOSITION
Asplund, Grevesse, Sauval 2004, 2005
Comparison of the old and new solar composition
A. A. Pamyatnykh
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
Conspiracy at work: better is worse
Basu & Antia, 2007, astro-ph0711.4590
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
Evolutionary tracks for non–rotating and rotating models
Maynet, Maeder, 2000
The evolution of (r) during the MS evolution of a 20M star
Maynet, Maeder, 2000
Stars can reach the break-up velocity
M=20
Z=0.004
Maynet, Maeder, 2000
EFFECTS OF ROTATION ON PULSATION
The third order expression for a rotationally split frequency
Goupil et al. 2000
Dziembowski, Goode 1992
Soufi, Goupil, Dziembowski 1998
Mathis
M=1.8 M, Teff=7515 K, Vrot=92 km/s.
Pamyatnykh 2003
EFFECTS OF ROTATION ON PULSATION
j - k   ; j = k 2 ; mj = mk ( >> )
rotational mode coupling

perturbation approach fails
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
Description of slow modes ( ~ )
 the traditional approximation
Townsend(2003)
 Expansion in Legendre function series
Lee, Saio (1997)
 2D code (Savonije 2007)
2.5
2.5
Rotation
confines pulsation towards
the stellar equator
Vrot= 0 km/s
2.0
Vrot= 150 km/s
=1, m=0
Vrot= 50 km/s
2.0
Vrot= 150 km/s
Vrot= 250 km/s
r, m=-1
Vrot= 250 km/s

1.5
1.5
1.0
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
-1.0
0
10
20
30
2.5
2.5
=1, m=0
=1, m= +1


Vrot= 250 km/s
Vrot= 150 km/s
2.0
2.0
1.5
1.5
0.5
0.5
0.5
0.5
0.0
0.0
0.0
0.0
-0.5
-0.5
-0.5
-0.5
-1.0
-1.0
-1.0
-1.0
2.5
20
20
30
30
40
40
50
50

30
40
50

60
70
80
90
60
60
50 km/s
Vrot= 250
km/s
70
70
80
80
90
90
r
, =1,
m=-1
m= -1
Vrot= 150 km/s
Vrot= 250 km/s
1.0
1.0
10
10
20
0 km/s
Vrot= 150
km/s
1.0
1.0
00
10
2.5
2.5
Vrot= 50 km/s
Vrot= 50 km/s
Vrot= 150 km/s
1.5
1.5
50
60
70
80
90
0
Hough
functions

Vrot= 0 km/s
Vrot= 0 km/s
2.0
2.0
40
Townsend 1997
70
70
80
80
90
90
2.5
00
Vrot= 250 km/s
10
10
20
20
30
30
40
40
50
50

60
60
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 rotation
J. Christensen-Dalsgaard
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. 2003 (V836 Cen)
Pamyatnykh, Handler, Dziembowski, 2004 ( Eri)
Dziembowski, Pamyatnykh 2008 ( Eri,12 Lac)
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
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
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 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
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
3D versus 1D
H+HeI convection zone
HeII convection zone
vertical velocity [km/s]
main-sequence A-type star (Teff =8000 K, log g =4.00, [M/H]=0)
Radiative layer between two convection zones is mixed
Steffen M. 2007 IAUS 239, 36
Pulsating stars with „convection problem”
 Scuti
 Doradus
Classical Cepheids
RR Lyrae
Red giants
White dwarfs (V777Her, 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
M =1.6 M, Teff = 6665 K,  = 1.8, mode =0, p1
Dupret et al. 2004
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
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
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. 2004
Townsend 2007
GW Vir stars
Constraints on mass loss from the red-edge position
different mass loss laws
Quirion, Fontaine, Brassard 2007
not only pulsation frequencies
can probe stellar interior
photometric and spectroscopic observables
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)
The flux derivatives over Teff and log g depend on:
 microturbulence velocity, t
 metallicity, [m/H]
 models of stellar atmospheres, NLTE effects
The f parameter is very sensitive to:
 global stellar parameters
 chemical composition
 element mixture, mixing processes
 opacity
 subphotospheric convection
multicolor photometry + radial velocity data
simultaneous determination
of  and f from observations
Comparison of theoretical and empirical
f values yields constraints on
MEAN STELLAR PARAMETERS
STELLAR ATMOSPHERES
INPUT PHYSICS
f - a new asteroseismic probe
sensitive to subphotospheric layers
and
complementary to pulsation frequency
Ocillation spectrum of FG Vir
0.1
5
10
15
20
25
30
35
40
45
frequency [c/d]
| only photometry
| photometry + Vrad
Ay [mmag]
10
1
0.1
5
10
15
20
25
30
35
40
45
frequency [c/d]
67 independent frequencies !
Breger et al. 2005
Empirical and theoretical f values.
Model: MLT, convective flux freezing approximation
10
10
 = 0.0
fR
5
5
0
0
-5
fI
-10
 = 0.5
 = 1.0
 = 1.5
-5
-10
-15
-15
 = 0.0
 = 0.5
-20
-20
 = 1.0
 = 1.5
-25
-25
8
10
12
14
16 18
 [c/d]
20
22
24
26
8
10
12
14
16 18
 [c/d]
20
22
24
26
Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653
Empirical and theoretical f values.
Model: non-local, time-dependent formulation of MLT
10
=
=
=
=
5
10
0.25
0.50
1.00
1.50
5
0
0
fR-5
fI -5
-10
-10
-15
-15
-20
-20
-25
-25
8
10
12
14
16 18
 [c/d]
20
=
=
=
=
22
24
26
8
10
12
14
16 18
 [c/d]
0.25
0.50
1.00
1.50
20
22
24
26
due to Guenter Houdek
Daszyńska-Daszkiewicz et al. 2005, A&A 438, 653
OSCILLATION SPECTRUM OF  ERI
12 independent frequencies
Jerzykiewicz i in., 2005, MNRAS 360, 619
Comparison of the empirical and theoretical f values
for the dominant frequency (=0 mode) of  Eri
2.0
OP S92
1.5
OP A04
1.0
fI
ov=0.0
0.5
ov=0.1
0.0
OPAL GN93
-0.5
-1.0
-10.0
-9.5
-9.0
-8.5
fR
-8.0
-7.5
-7.0
Daszyńska-Daszkiewicz et al. 2005, A&A 441, 641
Seismic model with the new solar composition added
2.0
OP S92
1.5
OP A04
1.0
fI
ov=0.0
0.5
ov=0.1
0.0
OPAL GN93
-0.5
-1.0
-10.0
-9.5
-9.0
-8.5
fR
-8.0
DIFFUSION ???
-7.5
-7.0
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