TY - JOUR
T1 - The K2-ESPRINT project. VI. K2-105 b, a hot Neptune around a metal-rich G-dwarf
AU - Narita, Norio
AU - Hirano, Teruyuki
AU - Fukui, Akihiko
AU - Hori, Yasunori
AU - Dai, Fei
AU - Yu, Liang
AU - Livingston, John
AU - Ryu, Tsuguru
AU - Nowak, Grzegorz
AU - Kuzuhara, Masayuki
AU - Sato, Bun'ei
AU - Takeda, Yoichi
AU - Albrecht, Simon
AU - Kudo, Tomoyuki
AU - Kusakabe, Nobuhiko
AU - Palle, Enric
AU - Ribas, Ignasi
AU - Tamura, Motohide
AU - Van Eylen, Vincent
AU - Winn, Joshua N.
N1 - Publisher Copyright:
© The Author 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved.
PY - 2017/4
Y1 - 2017/4
N2 - We report on the confirmation that the candidate transits observed for the star EPIC 211525389 are due to a short-period Neptune-sized planet. The host star, located in K2 campaign field 5, is a metal-rich ([Fe/H] = 0.26 ± 0.05) G-dwarf (Teff = 5430 ± 70 K and log g = 4.48 ± 0.09), based on observations with the High Dispersion Spectrograph (HDS) on the Subaru 8.2 m telescope. High spatial resolution AO imaging with HiCIAO on the Subaru telescope excludes faint companions near the host star, and the false positive probability of this target is found to be <10-6 using the open source vespa code. A joint analysis of transit light curves from K2 and additional ground-based multicolor transit photometry with MuSCAT on the Okayama 1.88 m telescope gives an orbital period of P = 8.266902 ± 0.000070 d and consistent transit depths of Rp/Rblack star ∼ 0.035 or (Rp/Rblack star)2 ∼ 0.0012. The transit depth corresponds to a planetary radius of Rp = 3.59-0.39+0.44 R⊕, indicating that EPIC 211525389 b is a short-period Neptune-sized planet. Radial velocities of the host star, obtained with the Subaru HDS, lead to a 3 σ upper limit of 90 M⊕ (0.00027 M⊙) on the mass of EPIC 211525389 b, confirming its planetary nature. We expect this planet, newly named K2-105 b, to be the subject of future studies to characterize its mass, atmosphere, and spin-orbit (mis)alignment, as well as investigate the possibility of additional planets in the system.
AB - We report on the confirmation that the candidate transits observed for the star EPIC 211525389 are due to a short-period Neptune-sized planet. The host star, located in K2 campaign field 5, is a metal-rich ([Fe/H] = 0.26 ± 0.05) G-dwarf (Teff = 5430 ± 70 K and log g = 4.48 ± 0.09), based on observations with the High Dispersion Spectrograph (HDS) on the Subaru 8.2 m telescope. High spatial resolution AO imaging with HiCIAO on the Subaru telescope excludes faint companions near the host star, and the false positive probability of this target is found to be <10-6 using the open source vespa code. A joint analysis of transit light curves from K2 and additional ground-based multicolor transit photometry with MuSCAT on the Okayama 1.88 m telescope gives an orbital period of P = 8.266902 ± 0.000070 d and consistent transit depths of Rp/Rblack star ∼ 0.035 or (Rp/Rblack star)2 ∼ 0.0012. The transit depth corresponds to a planetary radius of Rp = 3.59-0.39+0.44 R⊕, indicating that EPIC 211525389 b is a short-period Neptune-sized planet. Radial velocities of the host star, obtained with the Subaru HDS, lead to a 3 σ upper limit of 90 M⊕ (0.00027 M⊙) on the mass of EPIC 211525389 b, confirming its planetary nature. We expect this planet, newly named K2-105 b, to be the subject of future studies to characterize its mass, atmosphere, and spin-orbit (mis)alignment, as well as investigate the possibility of additional planets in the system.
KW - Planets and satellites: individual (K2-105 b = EPIC 211525389 b)
KW - Stars: individual (TYC 807-1019-1 = EPIC 211525389)
KW - Techniques: high angular resolution
KW - Techniques: photometric
KW - Techniques: radial velocities
KW - Techniques: spectroscopic
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U2 - 10.1093/pasj/psx002
DO - 10.1093/pasj/psx002
M3 - Article
AN - SCOPUS:85019448276
SN - 0004-6264
VL - 69
JO - Publications of the Astronomical Society of Japan
JF - Publications of the Astronomical Society of Japan
IS - 2
M1 - 29
ER -