Bibcode
Narita, Norio; Hirano, Teruyuki; Fukui, Akihiko; Hori, Yasunori; Dai, Fei; Yu, Liang; Livingston, John; Ryu, Tsuguru; Nowak, Grzegorz; Kuzuhara, Masayuki; Sato, Bun'ei; Takeda, Yoichi; Albrecht, Simon; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Palle, E.; Ribas, Ignasi; Tamura, Motohide; Van Eylen, Vincent; Winn, Joshua N.
Referencia bibliográfica
Publications of the Astronomical Society of Japan, Volume 69, Issue 2, id.29
Fecha de publicación:
4
2017
Número de citas
9
Número de citas referidas
7
Descripción
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 multi-color 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/R⋆ ∼ 0.035 or
(Rp/R⋆)2 ∼ 0.0012. The transit
depth corresponds to a planetary radius of R_p = 3.59_{-0.39}^{+0.44}
R_{\oplus }, 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.
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Enric
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