AN EMPIRICAL CALIBRATION TO ESTIMATE COOL DWARF FUNDAMENTAL PARAMETERS FROM H-BAND SPECTRA

By E. Newton, D. Charbonneau, J. Irwin, A. Mann. 2014

79 citations recorded by the source corpus.

Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs. However, interferometry is within reach for only a limited sample of nearby, bright stars. We use interferometrically measured radii, bolometric luminosities, and effective temperatures to develop new empirical calibrations based on low-resolution, near-infrared spectra. We find that H-band Mg and Al spectral features are good tracers of stellar properties, and derive functions that relate effective temperature, radius, and log luminosity to these features. The standard deviations in the residuals of our best fits are, respectively, 73 K, 0.027 R☉, and 0.049 dex (an 11% error on luminosity). Our calibrations are valid from mid K to mid M dwarf stars, roughly corresponding to temperatures between 3100 and 4800 K. We apply our H-band relationships to M dwarfs targeted by the MEarth transiting planet survey and to the cool Kepler Objects of Interest (KOIs). We present spectral measurements and estimated stellar parameters for these stars. Parallaxes are also available for many of the MEarth targets, allowing us to independently validate our calibrations by demonstrating a clear relationship between our inferred parameters and the stars' absolute K magnitudes. We identify objects with magnitudes that are too bright for their inferred luminosities as candidate multiple systems. We also use our estimated luminosities to address the applicability of near-infrared metallicity calibrations to mid and late M dwarfs. The temperatures we infer for the KOIs agree remarkably well with those from the literature; however, our stellar radii are systematically larger than those presented in previous works that derive radii from model isochrones. This results in a mean planet radius that is 15% larger than one would infer using the stellar properties from recent catalogs. Our results confirm the derived parameters from previous in-depth studies of KOIs 961 (Kepler-42), 254 (Kepler-45), and 571 (Kepler-186), the latter of which hosts a rocky planet orbiting in its star's habitable zone.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

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In Astronomy and Astrophysics

1. E. Gaidos
2. A. Mann
3. D. Charbonneau
4. C. Dressing
5. A. Kraus
6. J. Johnson
7. Michael J. Ireland
8. Timothy Morton

In Instrumentation

1. A. Mann
2. E. Gaidos
3. D. Charbonneau
4. A. Kraus
5. C. Dressing
6. J. Johnson
7. Michael J. Ireland
8. Timothy Morton

In Statistical and Nonlinear Physics

1. D. Charbonneau
2. E. Gaidos
3. C. Dressing
4. A. Mann
5. G. Feiden
6. J. Johnson
7. K. von Braun
8. G. Esquerdo

Citations in the corpus

• STELLAR AND PLANETARY PROPERTIES OF K2 CAMPAIGN 1 CANDIDATES AND VALIDATION OF 17 PLANETS, INCLUDING A PLANET RECEIVING EARTH-LIKE INSOLATION (2015, neutral): “There is some evidence that the Dartmouth models may under-predict radii of M dwarfs by 15%~ when compared to other methods (Montet et al. 2015; Newton et al. 2015).”
• PLANETARY CANDIDATES FROM THE FIRST YEAR OF THE K2 MISSION (2015, methodology): “…we converted the g and r SDSS colors to Johnson V and Cousins R using the transformations from Jordi et al. (2006), and for stars with only infrared colors, we interpolated the Mamajek H−K colors instead of J − K, because in M-dwarfs, J − K is more sensitive to metallicity (Newton et al. 2015).”
• THE SOLAR NEIGHBORHOOD. XXXVII. THE MASS–LUMINOSITY RELATION FOR MAIN-SEQUENCE M DWARFS (2016, background): “There has been considerable work on M dwarf metallicities in recent years (Rojas-Ayala et al. 2012; Önehag et al. 2012; Terrien et al. 2012; Neves et al. 2014; Mann et al. 2014, 2015; Newton et al. 2015; Lindgren & Heiter 2015).”
• The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “Newton et al. (2015) have since demonstrated that equivalent widths alone of some M dwarf spectral features encode not only metallicity, but their stellar radii and effective temperature as well (Newton et al., 2015).”
• HOW TO CONSTRAIN YOUR M DWARF: MEASURING EFFECTIVE TEMPERATURE, BOLOMETRIC LUMINOSITY, MASS, AND RADIUS (2015, background): “…lines in infrared spectra, combined with calibration by observations of common proper-motion pairs of solar-type stars and M dwarfs, have been recently found to estimate [Fe/H] to a precision as good as 0.07 dex (e.g., Neves et al. 2012; Terrien et al. 2012; Mann et al. 2013b; Newton et al. 2014).”
• They are small worlds after all: revised properties of Kepler M dwarf stars and their planets (2015, background): “We identified 101 dwarfs in our catalog (esssentially all KOIs) with spectroscopic properties (Teff or [Fe/H]) tabulated in Muirhead et al. (2012a), Mann et al. (2012), Mann, Gaidos & Ansdell (2013), Muirhead et al. (2014), or Newton et al. (2015).”
• THE OCCURRENCE OF POTENTIALLY HABITABLE PLANETS ORBITING M DWARFS ESTIMATED FROM THE FULL KEPLER DATASET AND AN EMPIRICAL MEASUREMENT OF THE DETECTION SENSITIVITY (2015, methodology): “We did not consider changes in the stellar temperatures, but Newton et al. (2014) demonstrated that the temperatures we estimated in Dressing & Charbonneau (2013) were consistent with predictions based on empirical observations (our values were lower by 40 ± 110K).”
• THE INNER EDGE OF THE HABITABLE ZONE FOR SYNCHRONOUSLY ROTATING PLANETS AROUND LOW-MASS STARS USING GENERAL CIRCULATION MODELS (2016, background): “Recent work (Boyajian et al. 2012, Boyajian et al. 2014, Terrien et al. 2015, Mann et al. 2015, Newton et al. 2015) has resulted in better stellar characterization and more accurate temperatures and radii for the M dwarfs.”