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Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. IV. Updated Properties for 86 Cool Dwarfs Observed during Campaigns 1–17

Dressing, Courtney D. and Hardegree-Ullman, Kevin and Schlieder, Joshua E. and Newton, Elisabeth R. and Vanderburg, Andrew and Feinstein, Adina D. and Duvvuri, Girish M. and Arnold, Lauren and Bristow, Makennah and Thackeray, Beverly and Abrahams, Ellianna Schwab and Ciardi, David R. and Crossfield, Ian J. M. and Yu, Liang and Martinez, Arturo O. and Christiansen, Jessie L. and Crepp, Justin R. and Isaacson, Howard (2019) Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. IV. Updated Properties for 86 Cool Dwarfs Observed during Campaigns 1–17. Astronomical Journal, 158 (2). Art. No. 87. ISSN 1538-3881. PMCID PMC8793203. doi:10.3847/1538-3881/ab2895.

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We present revised stellar properties for 172 K2 target stars that were identified as possible hosts of transiting planets during Campaigns 1–17. Using medium-resolution near-infrared spectra acquired with the NASA Infrared Telescope Facility/SpeX and Palomar/TripleSpec, we found that 86 of our targets were bona fide cool dwarfs, 74 were hotter dwarfs, and 12 were giants. Combining our spectroscopic metallicities with Gaia parallaxes and archival photometry, we derived photometric stellar parameters and compared them to our spectroscopic estimates. Although our spectroscopic and photometric radius and temperature estimates are consistent, our photometric mass estimates are systematically ΔM★ = 0.11 M⊙ (34%) higher than our spectroscopic mass estimates for the least massive stars (M★(phot) < 0.4 M⊙). Adopting the photometric parameters and comparing our results to parameters reported in the Ecliptic Plane Input Catalog, our revised stellar radii are ΔR★ = 0.15 R⊙ (40%) larger, and our revised stellar effective temperatures are roughly ΔT_(eff) = 65 K cooler. Correctly determining the properties of K2 target stars is essential for characterizing any associated planet candidates, estimating the planet search sensitivity, and calculating planet occurrence rates. Even though Gaia parallaxes have increased the power of photometric surveys, spectroscopic characterization remains essential for determining stellar metallicities and investigating correlations between stellar metallicity and planetary properties.

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URLURL TypeDescription CentralArticle Paper
Dressing, Courtney D.0000-0001-8189-0233
Hardegree-Ullman, Kevin0000-0003-3702-0382
Schlieder, Joshua E.0000-0001-5347-7062
Newton, Elisabeth R.0000-0003-4150-841X
Vanderburg, Andrew0000-0001-7246-5438
Feinstein, Adina D.0000-0002-9464-8101
Duvvuri, Girish M.0000-0002-7119-2543
Abrahams, Ellianna Schwab0000-0002-9879-1183
Ciardi, David R.0000-0002-5741-3047
Crossfield, Ian J. M.0000-0002-1835-1891
Yu, Liang0000-0003-1667-5427
Martinez, Arturo O.0000-0002-3311-4085
Christiansen, Jessie L.0000-0002-8035-4778
Crepp, Justin R.0000-0003-0800-0593
Isaacson, Howard0000-0002-0531-1073
Additional Information:© 2019 The American Astronomical Society. Received 2018 October 8; revised 2019 May 23; accepted 2019 May 24; published 2019 July 30. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. C.D.D. and I.J.M.C. acknowledge support from the NASA K2 Guest Observer Program; this project was supported by NASA K2 GO grant 80NSSC19K0098. This paper was motivated by data collected by the K2 mission, which is funded by the NASA Science Mission directorate. Our follow-up observations were obtained at the IRTF, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration, and at Palomar Observatory. We thank the staff at both observatories and the Caltech Remote Observing Facilities staff for supporting us during our many observing runs. We are grateful to the IRTF and Caltech TACs for awarding us telescope time. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work initially made use of the crossmatch database created by Megan Bedell. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: IRTF (SpeX) - , Palomar (TripleSpec) - , Palomar (PHARO) - , Keck (NIRC2) - , Gemini-N (NIRI) - , Lick-3 m (ShaneAO) - , WIYN (NESSI). - Software: am_getmetal (Mann et al. 2013a), astropy (Astropy Collaboration et al. 2018), astroquery (Ginsburg et al. 2016), iPython (Perez & Granger 2007), matplotlib (Hunter 2007), nirew (Newton et al. 2014, 2015), numpy (Oliphant 2015), pandas (McKinney 2010), Spextool (Cushing et al. 2004), RV_code by Andrew Mann,27 scipy (Jones et al. 2001), tellrv (Newton et al. 2014), xtellcor (Vacca et al. 2003).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:planetary systems – stars: fundamental parameters – stars: late-type – stars: low-mass – techniques: photometric – techniques: spectroscopic
Issue or Number:2
PubMed Central ID:PMC8793203
Record Number:CaltechAUTHORS:20190731-104952376
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Official Citation:Courtney D. Dressing et al 2019 AJ 158 87
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97549
Deposited By: Tony Diaz
Deposited On:31 Jul 2019 19:54
Last Modified:01 Feb 2022 17:20

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