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
S T E L L A R G R A N U L AT I O N
• 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
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
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
S T E L L A R G R A N U L AT I O N
• 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
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
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
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
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)
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
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
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 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
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
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
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
• 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]
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
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
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]
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
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
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
✓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]
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
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
✓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
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
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
✓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
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
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
✓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
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
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
✓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
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
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
✓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
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
© 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
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
© 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]
• 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 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
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
© 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
• No dependency on ev. stage (RC vs RGB)
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
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
© 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
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
© 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
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
© 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
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
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
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
• 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