metallicity effect on stellar granulation detected from ... · metallicity effect on stellar...

Metallicity effect on stellar granulation detected from red

giants in open clusters

S . M AT H U R , R . A . G A R C Í A , P. G A U L M E , M . P I N S O N N E A U LT, K . S TA S S U N , D . S T E L L O , J . TAYA R , R . T R A M P E D A C H , C . J I A N G , C . N I T S C H E L M , A N D D . S A L A B E RT

E N R I C O C O R S A R O

Asteroseismology and Optical Interferometry

Workshop 5 October 2017

Marie Sklodowska-Curie Fellow AstroFIt2INAF - Osservatorio Astrofisico di Catania

S T E L L A R G R A N U L AT I O N

• A type of stellar variability

• Manifestation of surface convection

• First observed and studied in the Sun

• Typical for low- and intermediate-mass stars (many!!)

• Time-scale accurately probes surface gravity

• Understand stellar granulation improves treatment of convection, hence stellar models

I N T R O D U C T I O N

E N R I C O C O R S A R O - 5 O C T O B E R 2 0 1 7 - A S T E R O S E I S M O L O G Y A N D O P T I C A L I N T E R F E R O M E T R Y W O R K S H O P

© S V S T S O L A R G R A N U L AT I O N

B R O W N E T A L . 1 9 9 1 ; B A S T I E N E T A L . 2 0 1 3 ; K A L L I N G E R E T A L . 2 0 1 6

H E R S C H E L 1 8 0 1 ; H A R V E Y 1 9 8 5

E . G . M AT H U R E T A L . 2 0 1 1 ; K A R O F F E T A L . 2 0 1 3 ; K A L L I N G E R E T A L . 2 0 1 4


• 3D HD simulations predict dependency on [Fe/H]

• Increased opacity makes granules bigger

• Amplitude of granulation signal increases because

• No evidence from past observations (e.g. CoRoT, Kepler)

M E TA L L I C I T Y E F F E C T


B R O W N E T A L . 1 9 9 1 ; M AT H U R E T A L . 2 0 1 1 ; B A S T I E N E T A L . 2 0 1 3 ; K A L L I N G E R E T A L . 2 0 1 4

C O L L E T E T A L . 2 0 0 7 ; TA N N E R E T A L . 2 0 1 3 ; M A G I C E T A L . 2 0 1 5 A , B ; L U D W I G & S T E F F E N 2 0 1 6

L U D W I G 2 0 0 6

agran / n�0.5gran

[Fe/H] = 0.0


• 3D HD simulations predict dependency on [Fe/H]

• Increased opacity makes granules bigger

• Amplitude of granulation signal increases because

• No evidence from past observations (e.g. CoRoT, Kepler)

M E TA L L I C I T Y E F F E C T


B R O W N E T A L . 1 9 9 1 ; M AT H U R E T A L . 2 0 1 1 ; B A S T I E N E T A L . 2 0 1 3 ; K A L L I N G E R E T A L . 2 0 1 4

C O L L E T E T A L . 2 0 0 7 ; TA N N E R E T A L . 2 0 1 3 ; M A G I C E T A L . 2 0 1 5 A , B ; L U D W I G & S T E F F E N 2 0 1 6

© C O L L E T E T A L . 2 0 0 7

L U D W I G 2 0 0 6

Why? Lack of accurate [Fe/H] for many stars

agran / n�0.5gran

O B S E R VAT I O N S A N D D ATA

• To better isolate and study effect of [Fe/H] we need:

S E L E C T I N G T H E S A M P L E


N G C 6 7 9 1 N G C 6 8 1 9

N G C 6 8 1 1

stars with homogeneous set of stellar properties

accurate [Fe/H], Teff for many stars

4 years photometry with Kepler

Spectroscopy with DR13 APOGEE-2 + KASC

P I N S O N N E A U LT E T A L . 2 0 1 4

R E D G I A N T S

© T. K A L L I N G E R

Main Sequence Red Giant Branch (RGB)

E V O LV E D S O L A R - T Y P E S TA R S

Red Clump (RC)


O B S E R VAT I O N A L P R O P E R T I E S

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

• MRG ~ 1.1 MSun

• [Fe/H] ≃ 0.32 dex

M I G L I O E T A L . 2 0 1 2

B R O G A A R D E T A L . 2 0 1 1 ; C O R S A R O E T A L . 2 0 1 7 B

• MRG ~ 1.7 MSun

• [Fe/H] ≃ 0.04 dex

M I G L I O E T A L . 2 0 1 2

B R A G A G L I A E T A L . 2 0 0 1 ; C O R S A R O E T A L . 2 0 1 7 B

• MRG ~ 2.3 MSun

• [Fe/H] ≃ -0.09 dex

S T E L L O E T A L . 2 0 1 1 A , B

M O L E N D A - Z A K O W I C Z E T A L . 2 0 1 4 ; C O R S A R O E T A L . 2 0 1 7 B

S E L E C T I N G T H E S A M P L E

N G C 6 7 9 1

N G C 6 8 1 9

N G C 6 8 1 1

60 Oscillating Red Giants

C O R S A R O E T A L . 2 0 1 2 ; C O R S A R O E T A L . 2 0 1 7 AE N R I C O C O R S A R O - 5 O C T O B E R 2 0 1 7 - A S T E R O S E I S M O L O G Y A N D O P T I C A L I N T E R F E R O M E T R Y W O R K S H O P

• Masses computed from asteroseismology with acoustic modes νmax from global fit + Δν from peak bagging

• Correction to Δν with stellar population synthesis modeling

• Precision 3 - 4 %

S T E L L A R M A S S E S

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

A S T E R O S E I S M O L O G Y


S H A R M A E T A L . 2 0 1 6

C O R S A R O E T A L . I N P R E P.

M

M�=

✓⌫max

⌫max,�

◆3

✓�⌫

��⌫�

◆�4

✓Te↵

Te↵,�

◆1.5

T H E B A C K G R O U N D M O D E L I N G• Bayesian inference code DIAMONDS

https://github.com/EnricoCorsaro/DIAMONDS

• Background signal modeled with granulation and meso-granulation

M E A S U R I N G G R A N U L A T I O N P R O P E R T I E S

C O R S A R O & D E R I D D E R , 2 0 1 4 , A & A , 5 7 1 , 7 1C O R S A R O , D E R I D D E R , G A R C I A , 2 0 1 5 , A & A , 5 7 9 , 8 3

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

ameso

/agran

= 1.31± 0.18bmeso

/bgran

= 0.32± 0.04C O R S A R O E T A L . 2 0 1 7 B

H A R V E Y 1 9 8 5 ; K A L L I N G E R E T A L . 2 0 1 4 ; 2 0 1 6

• Both components scale linearly


B A C K G R O U N D F I T R E S U LT ST H E M E S O - G R A N U L A T I O N S I G N A L


• Two distinct groups, mostly coinciding with the two different [Fe/H] regimes

• Difference systematic along surface gravity range 2.3 < log g < 3.1

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

G E N E R A L S C A L I N G R E L AT I O N SB A Y E S I A N I N F E R E N C E

✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

✓bmeso

bmeso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

ln

✓ameso

ameso,�

◆= ln� ++s ln

✓⌫max

⌫max,�

◆+ t ln

✓M

M�

◆+ u[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]


C O R S A R O E T A L . 2 0 1 3 ; B O N A N N O E T A L . 2 0 1 4

L I N E A R I Z AT I O N

T O TA L U N C E R TA I N T Y

S E L E C T I N G T H E B E S T M O D E LB A Y E S I A N I N F E R E N C E


✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]



✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]

t = u = 0 M1 surf. gravity



✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]

t = u = 0 M1

u = 0 M2

surf. gravity

+ mass



✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]

t = u = 0 M1

u = 0 M2

t = 0 M3

surf. gravity

+ mass

+ metallicity



✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]

t = u = 0 M1

u = 0 M2

t = 0 M3

t ≠ 0; u ≠ 0 M4

surf. gravity

+ mass

+ metallicity

+ mass & metallicity



✓ameso

ameso,�

◆= �

✓⌫max

⌫max,�

◆s ✓ M

M�

◆t

eu[Fe/H]

e�2a(s, t, u) = e�2

ameso

+ s2e�2⌫max

+ t2e�2M + u2e�2

[Fe/H]

t = u = 0 M1

u = 0 M2

t = 0 M3

t ≠ 0; u ≠ 0 M4

surf. gravity

+ mass

+ metallicity

+ mass & metallicity

Oij =EiEj

⇡i

⇡j

O D D S R AT I O

• Amplitude increases with increasing [Fe/H]

• No dependency on ev. stage (RC vs RGB)

• 11% increase in amplitude for 0.32 dex increase in [Fe/H] vs. 12% from 3D HD simulations

• Metallicity dependence 1.5 times stronger than g

M E TA L L I C I T Y E F F E C T O N A M P L I T U D ER E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

u = 0.89+0.08�0.08

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

K A L L I N G E R E T A L . 2 0 1 4

agran

/ ⌫�0.5max

s = �0.59+0.01�0.01

M E TA L L I C I T Y E F F E C T O N A M P L I T U D ER E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

• Amplitude increases with increasing [Fe/H]


• 11% increase in amplitude for 0.32 dex increase in [Fe/H] vs. 12% from 3D HD simulations

• Metallicity dependence 1.5 times stronger than gu = 0.89+0.08�0.08

s = �0.59+0.01�0.01

L U D W I G & S T E F F E N 2 0 1 6

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

M E TA L L I C I T Y E F F E C T O N F R E Q U E N C YR E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

• Frequency decreases with increasing [Fe/H]

• No clear evidence from 3D HD simulations

• Metallicity dependence has strength comparable to that of g

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

L U D W I G & S T E F F E N 2 0 1 6

s = 0.90+0.01�0.01

u = �1.15+0.12�0.10

bmax

/ ⌫max


M A S S ( R A D I U S ) E F F E C T O N A M P L I T U D ER E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

• Amplitude decreases with increasing M

• Real effect comes from increasing R for constant g

K A L L I N G E R E T A L . 2 0 1 4

M A S S ( R A D I U S ) E F F E C T O N A M P L I T U D ER E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

t = �0.21+0.04�0.05

ngran / R2

agran / M�0.5

agran / R�1

agran / n�0.5gran

g / MR�2

C O N S TA N T

• Amplitude decreases with increasing M

• Real effect comes from increasing R for constant g

• Mass effect weaker than [Fe/H]

K A L L I N G E R E T A L . 2 0 1 4

M A S S ( R A D I U S ) E F F E C T O N F R E Q U E N C YR E S U LT S F R O M T H E FA V O R E D S C A L I N G R E L A T I O N


© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

© C O R S A R O E T A L . 2 0 1 7 , A & A , 6 0 5 , A 3

• Frequency decreases with increasing M (like amplitude)

• Mass effect weaker than [Fe/H]t = �0.38+0.06

�0.06


ameso

, agran [Fe/H]

M Rameso

, agran because

M Rbecausebmeso

, bgran

[Fe/H]bmeso

, bgran

• Both metallicity and mass play a significant role in changing the granulation properties — [Fe/H] more important

• No influence from ev. stage — Granulation depends on atmospheric parameters only

Needs more/new models to compare

In agreement with simulations

S U M M A R Y & C O N C L U S I O N

TA K E H O M E M E S S A G E S


• We can obtain accurate+precise surface gravity for many stars

• If accurate+precise radii provided (e.g. asteroseismology, interferometry), we get accurate+precise mass

• If mass known, scaling relations can be used to estimate [Fe/H] for large samples of stars without spectroscopy

Thank you!

E N R I C O C O R S A R O

metallicity effect on stellar granulation detected from ... · metallicity effect on stellar...

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