Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 2019 | Accepted Version + Published
Journal Article Open

A Hot Saturn Near (but Unassociated with) the Open Cluster NGC 1817

Abstract

We report on the discovery of a hot Saturn-sized planet (9.916 ± 0.985 R ⊕) around a late F-star, K2-308, observed in Campaign 13 of the K2 mission. We began studying this planet candidate because prior to the release of Gaia DR2, the host star was thought to have been a member (⩾90% membership probability) of the ≈1 Gyr open cluster NGC 1817 based on its kinematics and photometric distance. We identify the host star (among three stars within the K2 photometric aperture) using seeing-limited photometry and rule out false-positive scenarios using adaptive optics imaging and radial velocity observations. We statistically validate K2-308b by calculating a false-positive probability rate of 0.01%. However, we also show using new kinematic measurements provided by Gaia DR2 and our measured radial velocity of the system that K2-308 is unassociated with the cluster NGC 1817. Therefore, the long running search for a giant transiting planet in an open cluster remains fruitless. Finally, we note that our use of seeing-limited photometry is a good demonstration of similar techniques that are already being used to follow up Transiting Exoplanet Survey Satellite (TESS) planet candidates, especially in crowded regions.

Additional Information

© 2019 The American Astronomical Society. Received 2019 April 23; revised 2019 June 3; accepted 2019 June 4; published 2019 July 17. We thank the anonymous referee for a quick and constructive review. R.R. gratefully acknowledges the support of the Columbia University Bridge to the Ph.D. Program in STEM. The work of A.V. was performed in part under contract with the California Institute of Technology/Jet Propulsion Laboratory funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. C.B. acknowledges support from the Alfred P. Sloan Foundation. D.W.L. acknowledges partial support from the TESS mission through a sub-award from the Massachusetts Institute of Technology to the Smithsonian Astrophysical Observatory (SAO) and from the Kepler mission under NASA Cooperative agreement NNX13AB58A with SAO. This research has made use of NASA's Astrophysics Data System and 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. The National Geographic Society–Palomar Observatory Sky Atlas (POSS-I) was made by the California Institute of Technology with grants from the National Geographic Society. The Oschin Schmidt Telescope is operated by the California Institute of Technology and Palomar Observatory. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX13AC07G and by other grants and contracts. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Robo-AO instrument was developed with support from the National Science Foundation under grants AST-0906060, AST-0960343, and AST-1207891, IUCAA, the Mt. Cuba Astronomical Foundation, and by a gift from Samuel Oschin. The Robo-AO team thanks NSF and NOAO for making the Kitt Peak 2.1 m telescope available. We thank the observatory staff at Kitt Peak for their efforts to assist Robo-AO KP operations. Robo-AO KP is a partnership between the California Institute of Technology, the University of Hawai'i, the University of North Carolina at Chapel Hill, the Inter-University Centre for Astronomy and Astrophysics (IUCAA) at Pune, India, and the National Central University, Taiwan. The Murty family feels very happy to have added a small value to this important project. Robo-AO KP is also supported by grants from the John Templeton Foundation and the Mt. Cuba Astronomical Foundation. Some data are based on observations at Kitt Peak National Observatory, National Optical Astronomy Observatory (NOAO Prop. ID: 15B-3001), which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. We are honored to be permitted to conduct observations on Iolkam Duag (Kitt Peak), a mountain within the Tohono O'odham Nation with particular significance to the Tohono O'odham people. Facilities: Kepler/K2, FLWO:1.5 m (TRES), FLWO:1.2 m (KeplerCam), KPNO2.1 m (Robo-AO), Smith (Tull), Gaia, Exoplanet Archive, MAST, CDS, ADS. Software: AstroImageJ (Collins et al. 2017), astropy (Astropy Collaboration et al. 2013), batman (Kreidberg 2015), emcee (Foreman-Mackey et al. 2013), VESPA (Morton 2015).

Attached Files

Published - Rampalli_2019_AJ_158_62.pdf

Accepted Version - 1906.02395.pdf

Files

1906.02395.pdf
Files (6.1 MB)
Name Size Download all
md5:f2dae04a00440473d2265383d48916cb
4.8 MB Preview Download
md5:8da76e5ac8d58dc6b7622e0c9163d1c8
1.2 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023