deriving accurate surface gravity values for planet host stars … · 2014-10-16 · deriving...

Deriving accurate surface gravityvalues for planet host stars

Annelies Mortier

Nuno C. Santos, S.G. Sousa, V.Zh. Adibekyan, I.M. Brandao

Towards Other Earths IIThe Star-Planet Connection

17 September 2014, Porto

Deriving accurate surface gravityvalues for planet host stars FGK dwarfs

Annelies Mortier

Nuno C. Santos, S.G. Sousa, V.Zh. Adibekyan, I.M. Brandao

Towards Other Earths IIThe Star-Planet Connection

17 September 2014, Porto

Outline

1 Introduction

2 Deriving stellar parametersMethodLine list

3 Surface gravity determinationTransitsAsteroseismologyCorrection formulaeCompare with IRFM

4 Conclusions

Annelies Mortier (St Andrews) Accurate loggs for FGK dwarfs 1 / 15

Introduction

Precise, homogeneous, and accurate stellar parameterscrucial in astronomy

�1.0 �0.8 �0.6 �0.4 �0.2 0.0 0.2 0.4[Fe/H]

0.00

0.05

0.10

0.15

0.20

0.25

Rela

tive

freq

uenc

y

exponential [Fe/H], linear masswith constantwith drop + cteHARPS

(Pepe et al. 2013) (Mortier et al. 2013)

Stellar and planetary characterization – Star-planetconnection – Galactic evolution – . . .


Introduction

(Torres et al. 2012)


Spectroscopic analysis: high-resolution spectroscopy

Spectral synthesis


Spectroscopic analysis: high-resolution spectroscopy

Individual spectral line analysis


FGK stars - Method overview


FGK stars - Method overview

Masses and radii

Dwarfs: corrected Torres et al. (2010) calibration(Sub)giants: Padova stellar evolutionary models


Carefully chosen stable line list set

-400

-200

0

200

4500 5000 5500 6000 6500

Thi

s W

ork

- SO

08

Teff (K) This Work

4500

5000

5500

6000

6500

Tef

f (K

) SO

08

<∆Teff

>=-31 K

σ=53 K

-400

-200

0

200

4400 4600 4800 5000

IRFM

- T

eff (

K)

Teff (K) IRFM

(Tsantaki et al. 2013)

Sousa et al. (2008) for stars with Teff > 5200 K

Tsantaki et al. (2013) for stars with Teff ≤ 5200 K


SWEETCat

(Santos et al. 2013)

Catalogue of homogeneously derived parameters for planet hosts


Surface gravity from photometric transit

90 transit hosts analysed

3.8 4.0 4.2 4.4 4.6 4.8 5.0loggspec

3.8

4.0

4.2

4.4

4.6

4.8

5.0

logg L

C

mean ∆logg = -0.12σ = 0.26

ρ∗ + k3ρp =

3π

GP2

(

a

R∗

)3

Spectroscopic surface gravitynot well constrained.

Transit light curve surfacegravity more precise and

accurate


Marginal effect on temperature and metallicity

−0.8 −0.6 −0.4 −0.2 0.0 0.2 0.4∆logg

−600

−400

−200

0

200

400

600

∆ T

eff

−0.8 −0.6 −0.4 −0.2 0.0 0.2 0.4∆logg

−0.4−0.3−0.2−0.1

0.00.10.20.30.4

∆ [F

e/H]

Mean differences

19 K and 0.02 dex

Mean absolute deviation

66.5 K and 0.03 dex

Systematic, but smalltrends, even for very large

logg differences


Transit logg may also be inaccurate (Huber et al. 2013)


Surface gravity from asteroseismology

86 FGK stars analysed

3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0loggspec

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

logg s

eis

Use large separation ∆ν,maximum frequency νmax ,effective temperature Teff ,metallicity [Fe/H], andPARSEC isochrones

Asteroseismic surface gravitymore precise and accurate


Marginal effect on temperature and metallicity

−1.2 −1.0 −0.8 −0.6 −0.4 −0.2 0.0 0.2∆logg

−600

−400

−200

0

200

400

600

∆Teff

−1.2 −1.0 −0.8 −0.6 −0.4 −0.2 0.0 0.2∆logg

−0.4−0.3−0.2−0.10.00.10.20.30.4

∆[Fe/H]

Mean differences

68 K and 0.04 dex

Mean absolute deviation

28.5 K and 0.02 dex

Same systematic, but smalltrends as with the transit

sample


Linear correction formula

4500 5000 5500 6000 6500 7000Teff

−1.0

−0.5

0.0

0.5

1.0

∆logg

y=(−4.57±0.25) ·10−4 ·x+(2.59±0.15)

5000 5500 6000 6500 7000Teff

−1.0

−0.8

−0.6

−0.4

−0.2

0.0

0.2

0.4

∆logg

y=(−3.89±0.23) ·10−4 ·x+(2.10±0.14)

Correcting for the spectroscopic logg will not make it more precise, but itwill make it more accurate!


Comparison with accurate IRFM

5000 5500 6000 6500 7000Teff,IRFM

5000

5500

6000

6500

7000

T eff,spec

Unconstrained

5000 5500 6000 6500 7000Teff,IRFM

5000

5500

6000

6500

7000

T eff,spec

Constrained

Our unconstrained spectroscopic results can be trusted!


Conclusions

Precise, homogeneous, and accurate stellar parameters are crucial

Our long-standing spectroscopic method to analyse FGK stars

provides precise, accurate, and homogeneous results

Surface gravity is not well constrained by spectroscopy but by usingthe ARES+MOOG method combined with SO08+TS13 line list

set, there is only a marginal effect on the other atmosphericparameters

Planetary mass and radius differ only by 1.3 − 2%1.3 − 2%1.3 − 2% and 1 − 1.5%1 − 1.5%1 − 1.5%

Temperatures, metallicities, and microturbulences developed byour method+linelist have been proven to be consistent with variousmethods

Our spectroscopic surface gravity can be easily corrected with a

linear formula


Conclusions

Precise, homogeneous, and accurate stellar parameters are crucial

Our long-standing spectroscopic method to analyse FGK stars

provides precise, accurate, and homogeneous results

Surface gravity is not well constrained by spectroscopy but by usingthe ARES+MOOG method combined with SO08+TS13 line list

set, there is only a marginal effect on the other atmosphericparameters

Planetary mass and radius differ only by 1.3 − 2%1.3 − 2%1.3 − 2% and 1 − 1.5%1 − 1.5%1 − 1.5%

Temperatures, metallicities, and microturbulences developed byour method+linelist have been proven to be consistent with variousmethods

Our spectroscopic surface gravity can be easily corrected with a

linear formula

Thank you!Annelies Mortier (St Andrews) Accurate loggs for FGK dwarfs 15 / 15

deriving accurate surface gravity values for planet host stars … · 2014-10-16 · deriving...

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