THE<i>K2</i>-ESPRINT PROJECT III: A CLOSE-IN SUPER-EARTH AROUND A METAL-RICH MID-M DWARF

Hirano, Teruyuki; Fukui, A.; Mann, Andrew W.; Sanchis-Ojeda, Roberto; Gaidos, Eric; Narita, Norio; Dai, Fei; Eylen, Vincent Van; Lee, Chien‐Hsiu; Onozato, Hiroki; Ryu, Tsuguru; Kusakabe, Nobuhiko; Ito, Ayaka; Kuzuhara, Masayuki; Onitsuka, Masahiro; Tatsuuma, Misako; Nowak, G.; Πάλλη, Ε.; Ribas, I.; Tamura, Motohide; Yu, Li

doi:10.3847/0004-637x/820/1/41

Cited by 72 publications

(71 citation statements)

References 51 publications

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“…The total scientific exposure times for the saturated frames of K2-180 and K2-140 were 450 s and 750 s, respectively. The IRCS data were reduced to extract the median-combined, distortion-corrected images for saturated and unsaturated frames (Hirano et al 2016). The full-width-at-half-maximum (FWHM) was measured for unsaturated images to be 0.114 and 0.095 .…”

Section: Ircs Ao Imagingmentioning

confidence: 99%

K2-140b and K2-180b – Characterization of a hot Jupiter and a mini-Neptune from theK2mission

Korth

Csizmadia

Gandolfi

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We report the independent discovery and characterization of two K2 planets: K2-180b, a mini-Neptune-size planet in an 8.9-day orbit transiting a V = 12.6 mag, metal-poor ([Fe/H] = −0.65 ± 0.10) K2V star in K2 campaign 5; K2-140b, a transiting hot Jupiter in a 6.6-day orbit around a V = 12.6 mag G6V ([Fe/H] = +0.10 ± 0.10) star in K2 campaign 10. Our results are based on K2 time-series photometry combined with highspatial resolution imaging and high-precision radial velocity measurements. We present the first mass measurement of K2-180b. K2-180b has a mass of M p = 11.3 ± 1.9 M ⊕ and a radius of R p = 2.2 ± 0.1 R ⊕ , yielding a mean density of ρ p = 5.6 ± 1.9 g cm −3 , suggesting a rock composition. Given its radius, K2-180b is above the region of the so-called "planetary radius gap". K2-180b is in addition not only one of the densest mini-Neptune-size planets, but also one of the few mini-Neptune-size planets known to transit a metal-poor star. We also constrain the planetary and orbital parameters of K2-140b and show that, given the currently available Doppler measurements, the eccentricity is consistent with zero, contrary to the results of a previous study.

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Section: Ircs Ao Imagingmentioning

confidence: 99%

K2-140b and K2-180b – Characterization of a hot Jupiter and a mini-Neptune from theK2mission

Korth

Csizmadia

Gandolfi

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Kepler (Borucki et al 2010) included relatively few such stars in its target list, but its extended mission K2 has revealed several systems of small planets orbiting very low-mass stars (e.g. Mann et al 2016;Hirano et al 2016). TESS (Ricker et al 2015) has started science operations, and will add many more systems to the catalog of exoplanets around late-type stars.…”

Section: Introductionmentioning

confidence: 99%

Aliasing in the Radial Velocities of YZ Ceti: An Ultra-short Period for YZ Ceti c?

Robertson

2018

ApJL

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Mid-late M stars are opportunistic targets for the study of low-mass exoplanets in transit because of the high planet-to-star radius ratios of their planets. Recent studies of such stars have shown that, like their early-M counterparts, they often host multi-resonant networks of small planets. Here, we reanalyze radial velocity measurements of YZ Ceti, an active M4 dwarf for which the HARPS exoplanet survey recently discovered three exoplanets on short-period (P = 4.66, 3.06, 1.97 days) orbits. Our analysis finds that the orbital periods of the inner two planets cannot be uniquely determined using the published HARPS velocities. In particular, it appears likely that the 3.06-day period of YZ Ceti c is an alias, and that its true period is 0.75 days. If so, the revised minimum mass of this planet is less than 0.6 Earth masses, and its geometric transit probability increases to 10%. We encourage additional observations to determine the true periods of YZ Ceti b and c, and suggest a search for transits at the 0.75-day period in TESS lightcurves.

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“…We conducted RV follow-up observations using HARPS (Mayor et al 2003), FIES (Telting et al 2014), and PFS (Crane et al 2010), which result in a s 5 measurement of the mass, both confirming the planetary nature of the system and constraining its bulk density. This work is part of the Equipo de Seguimiento de Planetas Rocosos INterpretando sus Tránsitos (ESPRINT) project (see Hirano et al 2016;Sanchis-Ojeda et al 2015;Van Eylen et al 2016).…”

Section: Introductionmentioning

confidence: 99%

The K2-Esprint Project. V. A Short-Period Giant Planet Orbiting a Subgiant Star*

Eylen

Albrecht

Gandolfi

et al. 2016

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We report on the discovery and characterization of the transiting planet K2-39b (EPIC 206247743b). With an orbital period of 4.6 days, it is the shortest-period planet orbiting a subgiant star known to date. Such planets are rare, with only a handful of known cases. The reason for this is poorly understood but may reflect differences in planet occurrence around the relatively high-mass stars that have been surveyed, or may be the result of tidal destruction of such planets. K2-39 (EPIC206247743) is an evolved star with a spectroscopically derived stellar radius and mass of . We furthermore discover a long-term RV trend, which may be caused by a longperiod planet or stellar companion. Because K2-39b has a short orbital period, its existence makes it seem unlikely that tidal destruction is wholly responsible for the differences in planet populations around subgiant and mainsequence stars. Future monitoring of the transits of this system may enable the detection of period decay and constrain the tidal dissipation rates of subgiant stars.

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THEK2-ESPRINT PROJECT III: A CLOSE-IN SUPER-EARTH AROUND A METAL-RICH MID-M DWARF

Cited by 72 publications

References 51 publications

K2-140b and K2-180b – Characterization of a hot Jupiter and a mini-Neptune from theK2mission

K2-140b and K2-180b – Characterization of a hot Jupiter and a mini-Neptune from theK2mission

Aliasing in the Radial Velocities of YZ Ceti: An Ultra-short Period for YZ Ceti c?

The K2-Esprint Project. V. A Short-Period Giant Planet Orbiting a Subgiant Star*

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