Three Small Planets Transiting a Hyades Star

Livingston, John H.; Dai, Fei; Hirano, Teruyuki; Gandolfi, D.; Nowak, G.; Endl, Michael; Velasco, Sergio; Fukui, A.; Narita, Norio; Prieto-Arranz, J.; Barragán, Oscar; Cusano, F.; Albrecht, S.; Cabrera, J.; Cochran, William D.; Csizmadia, Szilárd; Deeg, H. J.; Eigmüller, Philipp; Erikson, A.; Fridlund, M.; Grziwa, S.; Guenther, E. W.; Hatzes, A. P.; Kawauchi, Kiyoe; Korth, J.; Nespral, D.; Πάλλη, Ε.; Pätzold, M.; Persson, C. M.; Rauer, H.; Smith, A. M. S.; Tamura, Motohide; Tanaka, Yosuke; Eylen, Vincent Van; Watanabe, Noriharu; Winn, Joshua N.

doi:10.3847/1538-3881/aaa841

Cited by 49 publications

(40 citation statements)

References 103 publications

(101 reference statements)

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“…However, most transiting planets found around young cluster or field stars of earlier spectral types do not appear to be clear outliers in the period-radius diagram (e.g. Ciardi et al 2017;Mann et al 2017b;Livingston et al 2018a;David et al 2018), with the notable exception of the apparently single planet K2-100 b (Mann et al 2017a).…”

Section: Discussionmentioning

confidence: 99%

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

David

Mamajek

Vanderburg

et al. 2018

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The role of stellar age in the measured properties and occurrence rates of exoplanets is not well understood. This is in part due to a paucity of known young planets and the uncertainties in age-dating for most exoplanet host stars. Exoplanets with well-constrained ages, particularly those which are young, are useful as benchmarks for studies aiming to constrain the evolutionary timescales relevant for planets. Such timescales may concern orbital migration, gravitational contraction, or atmospheric photo-evaporation, among other mechanisms. Here we report the discovery of an adolescent transiting sub-Neptune from K2 photometry of the low-mass star K2-284. From multiple age indicators

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Section: Discussionmentioning

confidence: 99%

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

David

Mamajek

Vanderburg

et al. 2018

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“…The narrow and shallow 36 planet transits used in the analysis are indicated with dotted vertical lines. Dai et al (2016) and Livingston et al (2018), we extracted aperture photometry and image centroid position information from the K2 pixel-level data to decorrelate the flux variation from the rolling motion of the telescope to produce our own light curves. The transit detection routine utilises the standard BLS routine and an optimal frequency sampling (Ofir 2014).…”

Section: K2 Photometry and Transit Detectionmentioning

confidence: 99%

Super-Earth of 8M_⊕in a 2.2-day orbit around the K5V star K2-216

Persson

Fridlund

Barragán

et al. 2018

A&A

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Context. Although thousands of exoplanets have been discovered to date, far fewer have been fully characterised, in particular super-Earths. The KESPRINT consortium identified K2-216 as a planetary candidate host star in the K2 space mission Campaign 8 field with a transiting super-Earth. The planet has recently been validated as well. Aims. Our aim was to confirm the detection and derive the main physical characteristics of K2-216b, including the mass. Methods. We performed a series of follow-up observations: high resolution imaging with the FastCam camera at the TCS and the Infrared Camera and Spectrograph at Subaru, and high resolution spectroscopy with HARPS (La Silla), HARPS-N (TNG) and FIES (NOT). The stellar spectra were analyzed with the SpecMatch-Emp and SME codes to derive the fundamental stellar properties. We analyzed the K2 light curve with the pyaneti software. The radial velocity measurements were modelled with both a Gaussian process (GP) regression and the so-called floating chunk offset (FCO) technique to simultaneously model the planetary signal and correlated noise associated with stellar activity. Results. Imaging confirms that K2-216 is a single star. Our analysis discloses that the star is a moderately active K5V star of mass 0.70 ± 0.03 M and radius 0.72 ± 0.03 R . Planet b is found to have a radius of 1.75 +0.17 −0.10 R ⊕ and a 2.17-day orbit in agreement with previous results. We find consistent results for the planet mass from both models: M p ≈ 7.4 ± 2.2 M ⊕ from the GP regression and M p ≈ 8.0 ± 1.6 M ⊕ from the FCO technique, which implies that this planet is a super-Earth. The incident stellar flux is 248 +220 −48 F ⊕ . Conclusions. The planet parameters put planet b in the middle of, or just below, the gap of the radius distribution of small planets. The density is consistent with a rocky composition of primarily iron and magnesium silicate. In agreement with theoretical predictions, we find that the planet is a remnant core, stripped of its atmosphere, and is one of the largest planets found that has lost its atmosphere.

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“…Planets orbiting stars in young open clusters are thus particularly valuable tests of these models. The exquisite photometry collected by the K2 space mission (Howell et al 2014) and its observing strategy focused on the Ecliptic plane have enabled the detection of the first transiting planet candidates in star forming regions and young stars (e.g., David et al 2016aDavid et al ,b, 2019Libralato et al 2016;Mann et al 2016aMann et al ,b, 2017Mann et al , 2018Pepper et al 2017;Livingston et al 2018aLivingston et al , 2019, but none so far has mass measurements. Recent studies show that these young transiting exoplanets seem to be larger than their counterparts with similar periods orbiting more evolved stars (Mann et al 2016b).…”

Section: Introductionmentioning

confidence: 99%

Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Barragán

Aigrain

Kubyshkina

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of HARPS-N radial velocity observations of K2-100, a young and active star in the Praesepe cluster, which hosts a transiting planet with a period of 1.7 days. We model the activity-induced radial velocity variations of the host star with a multi-dimensional Gaussian Process framework and detect a planetary signal of 10.6 ± 3.0 m s −1 which matches the transit ephemeris, and translates to a planet mass of 21.8 ± 6.2 M ⊕ . We perform a suite of validation tests to confirm that our detected signal is genuine. This is the first mass measurement for a transiting planet in a young open cluster. The relatively low density of the planet, 2.04 +0.66 −0.61 g cm −3 , implies that K2-100b retains a significant volatile envelope. We estimate that the planet is losing its atmosphere at a rate of 10 11 − 10 12 g s −1 due to the high level of radiation it receives from its host star.

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Three Small Planets Transiting a Hyades Star

Cited by 49 publications

References 103 publications

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

Super-Earth of 8M_⊕in a 2.2-day orbit around the K5V star K2-216

Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

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Three Small Planets Transiting a Hyades Star

Cited by 49 publications

References 103 publications

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

Super-Earth of 8M⊕in a 2.2-day orbit around the K5V star K2-216

Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

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Super-Earth of 8M_⊕in a 2.2-day orbit around the K5V star K2-216