Characterization of Low-mass K2 Planet Hosts Using Near-infrared Spectroscopy

Romy Rodríguez Martínez, Sarah Ballard, Andrew Mayo, Andrew Vanderburg, Benjamin T. Montet, Jessie L. Christiansen

Research output: Contribution to journalJournal articleResearchpeer-review


We present moderate resolution near-infrared spectra in the H, J, and K band of M-dwarf hosts to candidate transiting exoplanets discovered by NASA’s K2 mission. We employ known empirical relationships between spectral features and physical stellar properties to measure the effective temperature, radius, metallicity, and luminosity of our sample. Out of an initial sample of 56 late-type stars in K2, we identify 35 objects as M dwarfs. For that subsample, we derive temperatures ranging from 2870 to 4187 K, radii of 0.09–0.83 R⊙, luminosities of -2.67 < log L/L , < -0.67 and [Fe/H] metallicities between −0.49 and 0.51 dex. We then employ the stellar properties derived from spectra, in tandem with the K2 light curves, to characterize their planets. We report 33 exoplanet candidates with orbital periods ranging from 0.19 to 21.16 days, and median radii and equilibrium temperatures of 2.3 R⊕ and 986 K, respectively. Using planet mass–radius relationships from the literature, we identify seven exoplanets as potentially rocky, although we conclude that probably none reside in the habitable zone of their parent stars.
Original languageEnglish
Article number135
JournalAstrophysical Journal
Issue number4
Number of pages14
Publication statusPublished - 2019


  • Planetary systems
  • Planets and satellites: fundamental parameters
  • Stars: fundamental parameters
  • Stars: late-type
  • Stars: low-mass
  • Techniques: spectroscopic

Cite this

Martínez, R. R., Ballard, S., Mayo, A., Vanderburg, A., Montet, B. T., & Christiansen, J. L. (2019). Characterization of Low-mass K2 Planet Hosts Using Near-infrared Spectroscopy. Astrophysical Journal, 158(4), [135].