• DOI:10.3847/1538-3881/aaff69
• Corpus ID: 119074652

Spitzer Transit Follow-up of Planet Candidates from the K2 Mission

@article{Livingston2019SpitzerTF,
  title={Spitzer Transit Follow-up of Planet Candidates from the K2 Mission},
  author={John H. Livingston and Ian J. M. Crossfield and Michael W. Werner and Varoujan Gorjian and Erik A. Petigura and David R. Ciardi and Courtney D. Dressing and Benjamin J. Fulton and Teruyuki Hirano and Joshua E. Schlieder and Evan J. Sinukoff and Molly R. Kosiarek and Rachel L. Akeson and Charles A. Beichman and Bj{\"o}rn Benneke and Jessie L. Christiansen and Brad Hansen and Andrew W. Howard and Howard T. Isaacson and Heather A. Knutson and Jessica E. Krick and Arturo O. Martinez and Bun’ei Sato and Motohide Tamura},
  journal={The Astronomical Journal},
  year={2019},
  volume={157}
}

• J. Livingston, I. Crossfield, +21 authors M. Tamura
• Published 17 January 2019
• Physics, Geology
• The Astronomical Journal

We present precision 4.5 Spitzer transit photometry of eight planet candidates discovered by the K2 mission: K2-52 b, K2-53 b, EPIC 205084841.01, K2-289 b, K2-174 b, K2-87 b, K2-90 b, and K2-124 b. The sample includes four sub-Neptunes and two sub-Saturns, with radii between 2.6 and 18 and equilibrium temperatures between 440 and 2000 K. In this paper we identify several targets of potential interest for future characterization studies, demonstrate the utility of transit follow-up observations for planet validation and ephemeris refinement, and present new imaging and spectroscopy data. Our simultaneous analysis of the K2 and Spitzer light curves yields improved estimates of the planet radii and multiwavelength information that helps validate their planetary nature, including the previously unvalidated candidate EPIC 205686202.01 (K2-289 b). Our Spitzer observations yield an order-of-magnitude increase in ephemeris precision, thus paving the way for efficient future study of these interesting systems by reducing the typical transit timing uncertainty in mid-2021 from several hours to a dozen or so minutes. K2-53 b, K2-289 b, K2-174 b, K2-87 b, and K2-90 b are promising radial velocity (RV) targets given the performance of spectrographs available today or in development, and the M3V star K2-124 hosts a temperate sub-Neptune that is potentially a good target for both RV and atmospheric characterization studies.