Josefina Montalbán Université de Liège · Eggenberger et al. 2010; Mazumdar et al. 2010; Montalban et al. 2010 Number of modes by Tassoul 80 Interaction between p and g modes increases

Asteroseismology of Red Giants

Josefina Montalbán

Université de Liège

Oscillation mode

Variations of vr : spectroscopy

Variations of luminosity: photometry

Stellar oscillations

Basic properties

Lamb Frequency:

Brunt-Väisälä Frequency:

oscillatory if:

If not, evanescent

or

g mode

p mode

Mixed mode

pressure modes

gravity modes

Periods: minutes to hours

Intrinsically damped but externally forced byturbulent convection

Amplitudes ~ ppm/ tens of ppm

Solar like oscillations

G-K red giants

BISON data

Sun

Ulrich 1986;Brown 1991Kjeldsen & Bedding 1995Belkacem 2011

Comb-like spectrum

Solar-like oscillations

Solar-like oscillationsSolar like star

1.5 M

in He burning phase

L l

g cavity < N < L

S2S1N

max

p cavity > N > L

evanescent zone N < < L

log

N, L

(

Hz)

r/R

mixed modes

more interactions forl=1 modes than for l=2

Propagation diagram

Pressure-gravity mixed character

Dziembowski et al. 2001; Christensen-Dalsgaard, 2004; Dupert et al. 2009Eggenberger et al. 2010; Mazumdar et al. 2010; Montalban et al. 2010

Modes trapped in the

envelope: low E

acoustic dominant character

Modes trapped in the center: high E

g dominant character

Pressure dominated non-radial modes between two consecutiveradial ones, separated by Δν

l=2 modes better trapped in the acoustic cavity. Low degree of gravity-acoustic coupling.

l=1 modes: more significantcoupling of gravity and acousticcavities.

Spectrum properties

PopI RGB

Dziembowski et al. 2001; Christensen-Dalsgaard, 2004; Dupret et al. 2009;Eggenberger et al. 2010; Mazumdar et al. 2010; Montalban et al. 2010




Spectrum properties

Δν

PopI RGB


Outline

A. From acoustic modes

Global parameters

He abundance

B. From mixed modes

Evolutionary state

Near core mixing processes

Internal rotation and AM transport

Ensemble asteroseismology

average seismic parameters:

Stello et al. 2009, Miglio et al. 2009, Mosser et al. 2010,2011, Hekker et al. 2010, Chaplin et al. 2011, Kallinger et al. 2010 …

Ensemble asteroseismology

Study of stellar populations (Miglio et al. 2009, 13, Hekker et

al 2009, Mosser et al.2010, Chaplin et al. 2011, Corsaro et al. 2012, Basu et al. 2011…)

Mass loss from clusters (Miglio et al. 2012)

Cluster membership (Stello et al 2010, 11)

Determination of log g spectroscopy (Morel & Miglio 2012; Creevey et al. 2013)

R (Miglio 2012, Huber et al . 2012, White et al. 2012)

M Age (but model dependent)

Population study of CoRoT RedG

Sample dominated byRed Clump stars!

CoRoTCoRoT

Model Model

max~35HzD ~ 4 Hz

Miglio et al. 2009Hekker et al. 2009Mosser et al. 2010

Ensemble seismology of G-K giants

•Radius + Teff

•apparent mag + BC

L

ld2 ∝L/l

• max and D with 2.4% and 0.6% (Mosser et al. 2010)

• Teff from 2MASS J and Ks photometry in EXODAT ( ~0.02 mag) + colour-Teff calibration (Alonso et al. 1999) (Teff

)~ 190K• Ks BC (Girardi et al. 2005)• Galactic extinction (Drimmel et al. 2003)

((Av) ~0.3)

DISTANCE10-15% uncertainty

Miglio et al. 2013 EDJ-Proc

3D map of G-K giants

CoRoT LRs: ~ 3000 stars Mosser

et al. 2010

Kepler data: ~ 12000 stars Hekker

et al. 2011, Stello et al.

LRa01

LRc01

CoRoT LRa01+LRc01 => 2000 RGs with average seismic parameters

9/25/2013 SF2A - Montpellier 2013

Early results: differential

population studies

Different distribution of M in the center and anticenter

directions

Different agesLRc01 sample older thanLRa01

ZLRa01 ZLRc01<

Miglio et al. 2013 MNRAS9/25/2013 SF2A - Montpellier 2013

Constraining RGB mass loss

Outline


Global parameters

He abundance

B. From mixed modes

Evolutionary state



Signatures of local features

quasi-discontinuity in the distribution of an equilibrium variable inside the star

Deviations from constant Δνas oscillatory components in the frequencies of oscillation

sharp variations of due to helium ionization

transition from convective to radiativetransport at the base of the convective envelope

e.g. p-modes, helioseismology

envelope Helium abundance

depth of the convective envelope

Periodic components in ν

Signature of an acoustic glitch in the star!!

e.g. Gough 1990

acoustic depth acoustic radius

Period acoustic depth ()

Acoustic glitches

• The solar case

6 years GOLF observations

Houdek & Gough, 2007 Ballot et al. 2004

Acoustic radius of

base of the CZ2nd He ionization region

e.g.Perez Hernandez & Christensen-Dalsgaard 1998Roxburgh&Vorontsov, 1998Monteiro et al. 1998, 2000Mazumdar&Antia 2001Ballot et al. 2004Basu et al. 2004Verner et al. 2006 Houdek & Gough 2007Mazumdar & Michel this conference

Possible for other stars?

He burning 1.5Msun

1.5Msun in Ascending Red Giant Branch

Acoustic glitches

Cov Env.

He II

HR 7349 : acoustic glitches

Model 1.2 Msun

Miglio et al. 2010 A&A

Amplitude of the oscillatory signal vs. He abundance

Broomhall et al. in preparation

Amplitude of the oscillatory signal vs. He abundance

Initial helium mass fraction

Y=0.40

Y=0.25

M=1.5M

Initial helium mass fraction

Y=0.28 & Y=0.25

Broomhall et al. in preparation

Outline


Global parameters

He abundance

B. From mixed modes

Evolutionary state



Asymptotic approximation

g-mode periods

p-mode frequencies

Tassoul ApJS 43 1980

constant frequency spacing

constant period spacing

Number of modes by

Tassoul 80

Interaction between p and

g modes increases when

the evanescent region

decreases (see also

Christensen-Dalsgaard 2011)

Spectrum properties

Montalbán et al. 2012

Houdek 1999




Spectrum properties

Δν

PopI RGB


Number of modes by

Tassoul 80

Interaction between p and

g modes increases when

the evanescent region

decreases (see also

Christensen-Dalsgaard 2011)

Houdek 1999

Spectrum properties

Montalbán et al. 2012 IAU-GA-SpS13 ; 2013




Spectrum properties

CLUMP 1.5Msun

Montalbán et al. 2010 ApJ; AN; 2012 ApSS ; 2013 ApJ

Red giants: evolution

1 Msun

5 Msun

2.5 Msun

1.5 M

R=12.3 R

<D> = 3.84

Red-Clumplog L/L

= 1.76

log rc/<r> = 7.3Yc = 0.25DP~250sMcc = 0.08M*

RGBlog L/L

= 1.72

log rc/<r> = 8.3Yc = 0.98DP~80s

Echelle Diagram : RC vs RGBM=1.5 Msun

l = 2 l = 0 l = 1 l = 2 l = 0 l = 1

Red-Clump

log L/L = 1.76

log c/< > = 7.3

Yc = 0.25

P~250s

Mcc = 0.08M*

RGB

log L/L = 1.72

log c/< > = 8.3

Yc = 0.98

P~80s

Montalbán et al. 2012;

Echelle Diagram : RC vs RGBM=1.5 Msun

l = 2 l = 0 l = 1 l = 2 l = 0 l = 1

Red-ClumpRGB

AA51CH09-Chaplin ARI 16June2013 12:6

Fre

quency

(µH

z)

Frequency modulo 103.94 µHz

a b

d e

c

02 3 1


Fre

quency

(µH

z) 02 3 1

Fre

quency

(µH

z)


02 3 1

Fre

quency

(µH

z)

021


Fre

quency

(µH

z)


021

Figure 2

Echellediagramsof theoscillation spectraof fivestarsobserved byKepler. Annotationsmark theangular degrees, l. (a) The

main-sequencestar 16CygA, showingvertically aligned ridgesof oscillation power. Notethefaint (but significant) power of thel = 3

ridge. (b) Thesubgiant KIC 6442183showingabeautiful avoidedcrossingof the l = 1modesat afrequencyof ∼1,000µHz. (c) The

first-ascent red-giant branch (RGB) star KIC 6949816, which showsclustersof closely spaced l = 1mixedmodesin itsspectrum.

(d,e) RGB(KIC 3100193) andredclump(RC) (KIC 7522297) starsthat havesimilar surfaceproperties(notethecomplexityof the l =

1modesin thespectrumof KIC 7522297comparedtoKIC 3100193).

358 Chaplin·Miglio

AA51CH09-Chaplin ARI 16June2013 12:6

Fre

quency

(µH

z)


a b

d e

c

02 3 1


Fre

quency

(µH

z)

02 3 1

Fre

quency

(µH

z)


02 3 1

Fre

quency

(µH

z)

021


Fre

quency

(µH

z)


021

Figure 2

Echellediagramsof theoscillation spectraof fivestarsobserved byKepler. Annotationsmark theangular degrees, l. (a) The

main-sequencestar 16CygA, showingvertically aligned ridgesof oscillation power. Notethefaint (but significant) power of the l = 3

ridge. (b) Thesubgiant KIC 6442183showingabeautiful avoidedcrossingof the l = 1modesat afrequencyof ∼1,000µHz. (c) The

first-ascent red-giant branch (RGB) star KIC 6949816, which showsclustersof closely spaced l = 1mixedmodesin itsspectrum.

(d,e) RGB(KIC 3100193) andredclump(RC) (KIC 7522297) starsthat havesimilar surfaceproperties(notethecomplexityof the l =

1modesin thespectrumof KIC 7522297comparedtoKIC 3100193).

358 Chaplin·Miglio

Period spacing in red giants

Core Helium

burning phase

H-shell burning

RGB

Bedding et al. 2011

Kepler

CoRoT Mosser et al. 2011

Theoretically “observable” period spacing

Montalbán et al. 2012 KASC5; 2013 ApJ

“observed period spacing”

<P>obs

Observed period spacing

Stello et al. 2013, ApJFrom 13000 red giants observed by Kepler

Outline


Global parameters

He abundance

B. From mixed modes

Evolutionary state



Observable ΔP also followsThe mass of the He core

Montalbán et al. 2012 IAU-GA-SpS13; 2013 ApJ

• M < 1.6M¤ overshooting during MS

does not change the mass of the

degenerate He core

• M of star with minimum He core

decreases if central mixing during MS

(see also, Sweigart et a. 90, Girardi

1999, Castellani et al 2000)

• Minimum DP occurs at lower stellar

mass. Ov=0.2Hp

=> DM ~ 0.2 Msun

Mass of He-core

DP follows the

mass of He core

ΔP vs He-core mass

2.5 M

2.3 M

2.1 M

0.7-1.8 M

No Overshooting

Z=0.02

Y=0.278

Z=0.02

Y=0.278

• No Overshooting

• Overshooting

2.2M

2.4M

RGB RGB

Montalbán et al. 2012 IAU-GA-SpS13; KACK5; 2013 ApJ

ΔP vs He-core mass

Z=0.02

Y=0.278

• No Overshooting

• Overshooting

2.2M

2.4M Mixing during the MS

evolutionary phase

and max

+

Period spacing

+

metallicity

RGB

Montalbán et al. 2012 IAU-GA-SpS13; KACK5; 2013 ApJ

Convective core mixing during central

He-burning

CC

Asymptotic period

spacing for models with

overshooting

during the He-burning

Montalbán et al. 2013, ApJ

Overshooting during He central burning

No over Overshoot adiab. 0.2 Hp


Asymptotic ΔP & convective core during central He-B phase

Mosser et al. 2012;Christensen-Dalsgaard 2012

From observed DP to asymptotic one

Direct relation between asymptotic DPAnd radius of convective core

Montalbán et al. 2013

Convective core size during He central burning phase


Outline


Global parameters

He abundance

B. From mixed modes

Evolutionary state



Internal rotation

Dipole g modes => smaller rotational splitting than p modes

Internal rotation

Internal rotation

The Sun

García et al. 2007

Internal rotation

Beck et al. 2012

g p g

Differential rotation with the core rotating 10 times faster than the surface

See also Deheuvels et al. 2012

Internal rotation

Evolution and transport of angular momentum

Vini = 50 km/s: δνrot = 32.8 μHz and δνrot wings/δνrot centre = 2.5Vini = 1 km/s: δνrot= 1.6 μHz and δνrot wings/δνrot centre = 2.4Observations: δνrot= 0.135±0.008 μHz and δνrot wings/δνrot centre = 1.5

− Rotating models predict steep rotation profiles(e.g. Palacios et al. 2006; Eggenberger et al. 2010; Marques et al. 2013)

Eggenberger, Montalban & Miglio 2012

An additional mechanism for thetransport of angular momentum is needed. From seismic constraints Δνrot wings/δνrot centre = 1.5 Its efficiency should be ⇒ νadd = 3⋅104 cm2 s-1

Straka et al. 2006, Carrier et al. 2005, Guenther 2004, Kjeldsenet al. 2003, Di Mauro et al 2002 , Christensen-Dalsgaard et al. 1995, Kjeldsen et al 1995, Provost et al. 2006, Claudi et al. 2005, Eggenberger et al. 2004, Martic et al. 2004, Eggenberger&Carrier 2006, Bedding et al. 2006, Carrier&Eggenberger 2006, Bouchy et al. 2005, Bazot et al. 2005, Bedding et al. 2001 Carrier et al. 2001, D’Antona et al 2005 …

• Solar-like oscillations across the HR diagram

Chaplin & Miglio 2013

COROT KEPLER

Stello et al. 2011

NGC6633HD170174

HD170231

HD170031

Poretti et al. 2013

Red giants with solar-like

oscillations in stellar clusters

Summary

A. From acoustic modesGlobal parameters: M, R , etc BUT calibration with

stellar clustersHe abundance => multiple populations

B. From mixed modesEvolutionary state: check with clustersNear core mixing processes:

mixing processes during MS phase for transition mass Size of mixed region in He burning low mass stars

Internal rotation and AM transport : chemical elements abundances / rotation

Documents

Josefina Montalbán Université de Liège · Eggenberger et al. 2010; Mazumdar et al. 2010; Montalban et al. 2010 Number of modes by Tassoul 80 Interaction between p and g modes increases