SPECTRO-THERMOMETRY OF M DWARFS AND THEIR CANDIDATE PLANETS: TOO HOT, TOO COOL, OR JUST RIGHT?

By A. Mann, E. Gaidos, M. Ansdell. 2013

145 citations recorded by the source corpus.

We use moderate-resolution spectra of nearby late K and M dwarf stars with parallaxes and interferometrically determined radii to refine their effective temperatures, luminosities, and metallicities. We use these revised values to calibrate spectroscopic techniques to infer the fundamental parameters of more distant late-type dwarf stars. We demonstrate that, after masking out poorly modeled regions, the newest version of the PHOENIX atmosphere models accurately reproduce temperatures derived bolometrically. We apply methods to late-type hosts of transiting planet candidates in the Kepler field, and calculate effective temperature, radius, mass, and luminosity with typical errors of 57 K, 7%, 11%, and 13%, respectively. We find systematic offsets between our values and those from previous analyses of the same stars, which we attribute to differences in atmospheric models utilized for each study. We investigate which of the planets in this sample are likely to orbit in the circumstellar habitable zone. We determine that four candidate planets (KOI 854.01, 1298.02, 1686.01, and 2992.01) are inside of or within 1σ of a conservative definition of the habitable zone, but that several planets identified by previous analyses are not (e.g., KOI 1422.02 and KOI 2626.01). Only one of the four habitable-zone planets is Earth sized, suggesting a downward revision in the occurrence of such planets around M dwarfs. These findings highlight the importance of measuring accurate stellar parameters when deriving parameters of their orbiting planets.

Subfields: Astronomy and Astrophysics

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In Astronomy and Astrophysics

1. D. Charbonneau
2. Timothy Morton
3. E. Gaidos
4. Jon Fortney
5. A. Mann
6. J. Johnson
7. C. Dressing
8. D. Huber

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, methodology): “Metallcity was determined using the procedures from Mann et al. (2013a), in which the authors provide empirical relations between atomic features and M dwarf metallicity, calibrated using wide binaries.”
• Trumpeting M dwarfs with CONCH-SHELL: a catalogue of nearby cool host-stars for habitable exoplanets and life (2014, methodology): “This was done because the Mann et al. (2013a) calibration utilizes at least one feature blueward of 4800Å, which is only covered by our SNIFS spectra, and because the calibration of Mann et al. (2013a) was itself derived from SNIFS spectra.”
• HOW TO CONSTRAIN YOUR M DWARF: MEASURING EFFECTIVE TEMPERATURE, BOLOMETRIC LUMINOSITY, MASS, AND RADIUS (2015, methodology): “Mann et al. (2013a, 2014) provide relations between the equivalent widths of atomic features (e.g., Na, Ca) in NIR spectra and the metallicity of the star, calibrated using wide binaries with an FGK primary and an M dwarf companion.”
• Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, methodology): “For α Cen A and B, δ Eri, and 18 Sco, we adopted the measurements by Boyajian et al. (2013), and for 61 Cyg A and B those by Mann et al. (2013).”
• DENSITIES AND ECCENTRICITIES OF 139 KEPLER PLANETS FROM TRANSIT TIME VARIATIONS (2013, background): “There are 11 host stars among our primary sample for which Mann et al. (2013) have published revised parameters based on spectroscopic models calibrated to nearby late K and Mdwarfs.”
• SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION (2016, methodology): “Based on the SpeX spectrum, we estimate the stellar metallicity using empirical methods based on the spectroscopic indices and equivalent widths calibrated using M dwarfs that have wide, co-moving FGK companions with well determined [Fe/H] (Boyajian et al. 2012; Mann et al. 2013a).”
• AN EMPIRICAL CALIBRATION TO ESTIMATE COOL DWARF FUNDAMENTAL PARAMETERS FROM H-BAND SPECTRA (2014, methodology): “For stars withlogL/L⊙ > −1.75, we use the Mann et al. (2013a) relation, for which the calibration was dominated by early M dwarfs.”
• The Revised TESS Input Catalog and Candidate Target List (2019, methodology): “Effective temperature and T were calculated from GBP and GRP magnitudes using custom relations developed from photometrically calibrated spectra from Mann et al. (2013).”
• A NEARBY M STAR WITH THREE TRANSITING SUPER-EARTHS DISCOVERED BY K2 (2015, methodology): “Following the suggestion of Mann et al. (2013a), we also discard the J-band metallicity, which is often an outlier.”
• ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, unknown): “…We compared the unreddened spectrum to a grid of BT-SETTL CIFIST models5 (Allard et al. 2011, 2012), masking our regions where models poorly reproduce observed spectra and accounting for small errors in the flux and wavelength solution as detailed in Mann et al. (2013) and Gaidos et al. (2014).”
• They are small worlds after all: revised properties of Kepler M dwarf stars and their planets (2015, background): “The dispersion is indistinguishable from that found among nearby M dwarfs as well as the Kepler field (Mann et al. 2013; Gaidos et al. 2014), in part due to a small adjustment in the J-band magnitudes (see Appendix C), and the intrinsic scatter is 0.16 dex after subtracting measurement error.”
• 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): “…stars in the downloaded sample were primarily determined from photometry (Brown et al. 2011; Dressing & Charbonneau 2013; Gaidos 2013; Huber et al. 2014), but 2% of the sample had spectroscopically-derived parameters (Mann et al. 2012; Muirhead et al. 2012a; Mann et al. 2013b; Mart́ın et al. 2013).”
• THE IMPACT OF STELLAR MULTIPLICITY ON PLANETARY SYSTEMS. I. THE RUINOUS INFLUENCE OF CLOSE BINARY COMPANIONS (2016, methodology): “…13 M dwarfs for which we adopted new temperatures and metallicities based on medium resolution spectra obtained with the SNIFS spectrograph following the method given in Mann et al. (2013), and Kepler-444 for which we adopted the Hipparcos distance and input parameters by Campante et al. (2015).”