We report the discovery of K2-56b, a high-density sub-Neptune exoplanet, made using photometry from Campaign 4 of the two-wheeled Kepler (K2) mission, ground-based radial velocity (RV) follow-up from HARPS and high-resolution lucky and adaptive optics imaging obtained using AstraLux and MagAO, respectively. The host star is a bright (V - 11.04, K-s - 9.37), slightly metal-poor ([Fe/H] - -0.15 +/- 0.05 dex) solar analogue located at 152.1(-7.4)(+9.7) pc from Earth, for which we find a radius of R-* = 0.928(-04040)(+0.055) and a mass of M-* = 0.961(-0.029)(+0.032) M-circle dot. A joint analysis of the K2 photometry and HARPS RVs reveal that the planet is in a approximate to 42 day orbit around its host star, has a radius of 2.23(011)(+0.14)R(circle plus), and a mass of 16.3(6.1)(+6.0) M-circle plus. Although the data at hand put the planet in the region of the massradius diagram where we could expect planets with a pure rock (i.e., magnesium silicate) composition using two-layer models (i.e., between rock/iron and rock/ice compositions), we discuss more realistic three-layer composition models which can explain the high density of the discovered exoplanet. The fact that the planet lies in the boundary between "possibly rocky" and "non-rocky" exoplanets makes it an interesting planet for future RV follow-up.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624071 |
| Date | 10 October 2016 |
| Creators | Espinoza, Nestor, Brahm, Rafael, Jordan, Andres, Jenkins, James S., Rojas, Felipe, Jofre, Paula, Madler, Thomas, Rabus, Markus, Chaname, Julio, Pantoja, Blake, Soto, Maritza G., Morzinski, Katie M., Males, Jared R., Ward-Duong, Kimberly, Close, Laird M. |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2016. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/830/i=1/a=43?key=crossref.2397df04f9f37c10f54db77ec5ee83f5 |
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