Exoplanets around Low-mass Stars Unveiled by K2
(2018) In Astronomical Journal 155(3).- Abstract
We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R p on stellar... (More)
We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R p on stellar insolation and metallicity [Fe/H]. We confirm that for periods P ≲ 2 days, planets with a radius Rp ≳ 2 R⊕ are less common than planets with a radius between 1-2 R ⊕. We also see a hint of the "radius valley" between 1.5 and 2 R ⊕, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R ⊕ are found around the most metal-rich M dwarfs.
(Less)
- author
- publishing date
- 2018-03
- type
- Contribution to journal
- publication status
- published
- keywords
- methods: observational, planets and satellites: detection, techniques: high angular resolution, techniques: photometric, techniques: radial velocities, techniques: spectroscopic
- in
- Astronomical Journal
- volume
- 155
- issue
- 3
- article number
- 127
- publisher
- IOP Publishing
- external identifiers
-
- scopus:85043605542
- ISSN
- 0004-6256
- DOI
- 10.3847/1538-3881/aaa9c1
- language
- English
- LU publication?
- no
- additional info
- Publisher Copyright: © 2018. The American Astronomical Society. All rights reserved.
- id
- 8e4a8b9a-e2b2-4118-9b87-0139170b74b8
- date added to LUP
- 2023-02-02 12:23:09
- date last changed
- 2023-02-20 14:22:12
@article{8e4a8b9a-e2b2-4118-9b87-0139170b74b8,
abstract = {{<p>We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R <sub>p</sub> on stellar insolation and metallicity [Fe/H]. We confirm that for periods P ≲ 2 days, planets with a radius R<sub>p</sub> ≳ 2 R<sub>⊕</sub> are less common than planets with a radius between 1-2 R <sub>⊕</sub>. We also see a hint of the "radius valley" between 1.5 and 2 R <sub>⊕</sub>, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R <sub>⊕</sub> are found around the most metal-rich M dwarfs.</p>}},
author = {{Hirano, Teruyuki and Dai, Fei and Gandolfi, Davide and Fukui, Akihiko and Livingston, John H. and Miyakawa, Kohei and Endl, Michael and Cochran, William D. and Alonso-Floriano, Francisco J. and Kuzuhara, Masayuki and Montes, David and Ryu, Tsuguru and Albrecht, Simon and Barragan, Oscar and Cabrera, Juan and Csizmadia, Szilard and Deeg, Hans and Eigmüller, Philipp and Erikson, Anders and Fridlund, Malcolm and Grziwa, Sascha and Guenther, Eike W. and Hatzes, Artie P. and Korth, Judith and Kudo, Tomoyuki and Kusakabe, Nobuhiko and Narita, Norio and Nespral, David and Nowak, Grzegorz and Pätzold, Martin and Palle, Enric and Persson, Carina M. and Prieto-Arranz, Jorge and Rauer, Heike and Ribas, Ignasi and Sato, Bun'Ei and Smith, Alexis M.S. and Tamura, Motohide and Tanaka, Yusuke and Van Eylen, Vincent and Winn, Joshua N.}},
issn = {{0004-6256}},
keywords = {{methods: observational; planets and satellites: detection; techniques: high angular resolution; techniques: photometric; techniques: radial velocities; techniques: spectroscopic}},
language = {{eng}},
number = {{3}},
publisher = {{IOP Publishing}},
series = {{Astronomical Journal}},
title = {{Exoplanets around Low-mass Stars Unveiled by K2}},
url = {{http://dx.doi.org/10.3847/1538-3881/aaa9c1}},
doi = {{10.3847/1538-3881/aaa9c1}},
volume = {{155}},
year = {{2018}},
}