IMPROVED SPECTROSCOPIC PARAMETERS FOR TRANSITING PLANET HOSTS

By G. Torres, Debra A. Fischer, A. Sozzetti, Lars A. Buchhave, J. Winn, M. Holman, J. Carter. 2012

232 citations recorded by the source corpus.

We report homogeneous spectroscopic determinations of the effective temperature, metallicity, and projected rotational velocity for the host stars of 56 transiting planets. Our analysis is based primarily on the stellar parameter classification (SPC) technique. We investigate systematic errors by examining subsets of the data with two other methods that have often been used in previous studies (Spectroscopy Made Easy (SME) and MOOG). The SPC and SME results, both based on comparisons between synthetic spectra and actual spectra, show strong correlations between Teff, [Fe/H], and log g when solving for all three quantities simultaneously. In contrast the MOOG results, based on a more traditional curve-of-growth approach, show no such correlations. To combat the correlations and improve the accuracy of the temperatures and metallicities, we repeat the SPC analysis with a constraint on log g based on the mean stellar density that can be derived from the analysis of the transit light curves. Previous studies that have not taken advantage of this constraint have been subject to systematic errors in the stellar masses and radii of up to 20% and 10%, respectively, which can be larger than other observational uncertainties, and which also cause systematic errors in the planetary mass and radius.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/12b5d06ef864c9dab0ed5ba508dcbf0bee028554

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Citations in the corpus

SOPHIE velocimetry of Kepler transit candidates XVII. The physical properties of giant exoplanets within 400 days of period (2015, methodology): “Similarly, we adopted the stellar parameters from, e.g. Torres et al. (2012) or Santos et al. (2013), when available, because those studies used higher-S/N data than in the discovery papers, leading to more reliable results.”
Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes (2016, background): “Furthermore, while spectroscopic determinations of glog and [Fe/H] can be subject to larger uncertainties and systematics (e.g., Torres et al. 2012), our results are almost entirely independent of these quantities, at least for the transiting-planet systems.”
Gaia FGK benchmark stars: Metallicity (2013, methodology): “Recently, Torres et al. (2012) made a comparative spectral analysis of FG dwarfs using three different methods to determine parameters.”
Asteroseismology of Solar-Type and Red-Giant Stars (2013, methodology): “A similar approach has been adopted using stellar densities measured from transit lightcurves (Torres et al. 2012).”
FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY (2013, unknown): “This is analogous to the work of Torres et al. (2012), who used stellar densities derived from transits to independently determine log g for a sample of main-sequence stars.”
AN ANCIENT EXTRASOLAR SYSTEM WITH FIVE SUB-EARTH-SIZE PLANETS (2015, methodology): “Contributions of 59 K in Teff and 0.062 dex in metallicity, [Fe/H], were added in quadrature to the formal uncertainties to account for systematic differences between spectroscopic methods (Torres et al. 2012).”
SPECTRAL PROPERTIES OF COOL STARS: EXTENDED ABUNDANCE ANALYSIS OF 1,617 PLANET-SEARCH STARS (2016, background): “However, those were the stars which have been hardest to accurately characterize with spectral analysis (Torres et al. 2012).”
Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2 (2018, methodology): “Highresolution spectroscopy delivers typical precisions of ≈ 0.15 dex in log g (Torres et al. 2012) for solar-type stars, while methods calibrated to benchmark stars can achieve precisions down to ≈ 0.07 dex (Brewer et al. 2015; Petigura 2015).”
Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters (2016, methodology): “We added in quadrature to the derived uncertainties on Teff and [Fe/H] systematic uncertainties of ±59 K and ±0.062 dex, as suggested by Torres et al. (2012).”
HOW TO CONSTRAIN YOUR M DWARF: MEASURING EFFECTIVE TEMPERATURE, BOLOMETRIC LUMINOSITY, MASS, AND RADIUS (2015, unknown): “This might be due to overlap in the calibration sample of the aforementioned studies, or underestimated errors in the FGK star metallicities (Torres et al. 2012; Hinkel et al. 2014).”
VALIDATION OF KEPLER'S MULTIPLE PLANET CANDIDATES. III. LIGHT CURVE ANALYSIS AND ANNOUNCEMENT OF HUNDREDS OF NEW MULTI-PLANET SYSTEMS (2014, methodology): “For SME parameters, we added 59 K to Teff and 0.062 dex to [Fe/H] in quadrature following the Torres et al. (2012) recommendation.”
REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN (2013, methodology): “…dynamically measured masses and radii, which can be combined to calculate log g. • Spectroscopy: Modeling spectra is one of the most traditional methods to derive Teff , log g and [Fe/H], although some limitations of spectroscopic surface gravities exist (Torres et al. 2012; Huber et al. 2013a).”
Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes (2017, methodology): “The SPC analysis was performed with externally constrained asteroseismic glog values, which prevents degeneracies between Teff , glog , and [ ]Fe H (Torres et al. 2012; Huber et al. 2013b).”
SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs - I. New atmospheric parameters and masses for 48 stars with planets (2013, background): “In may cases, comparisons have shown that the diff rences are residual (see e.g. Sousa et al. 2008), but in other cases the discrepani s have significant impact on the knowledge of the planet parameters (for a recent discussion on the possible offsets see Torres et al. 2012).”
LARGER PLANET RADII INFERRED FROM STELLAR “FLICKER” BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS (2014, background): “Through community followup observations, a number of the Kepler targets have been observed spectroscopically, typically reducing the reported uncertainty in log g to ∼0.1–0.2 dex (though with the possibility of systematic offsets up to ∼0.4 dex; Torres et al. 2012).”
THE KEPLER-10 PLANETARY SYSTEM REVISITED BY HARPS-N: A HOT ROCKY WORLD AND A SOLID NEPTUNE-MASS PLANET (2014, methodology): “…the asteroseismic stellar density ρ as measured by Fogtmann-Schulz et al. (2014), the Teff , and [Fe/H] with the Yonsei-Yale evolutionary tracks (Torres et al. 2012; Sozzetti et al. 2007; Demarque et al. 2004) and by performing the same chi-square minimization as in Santerne et al. (2011).”
H− Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18b (2018, background): “…a log-linear relationship but should approach the metallicity of the host star, as seen in WASP18 b where the stellar metallicity is 0.11±0.08 (Torres et al. 2012) . well as their joint effects on the spectrum make it difficult to attribute the retrieved metallicity solely to the H−…”