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 - Funding Information:
This work was supported by Japan Society for Promotion of Science (JSPS) KAKENHI Grant Numbers JP25247026, JP16K17660, 25-8826, JP16K17671, and JP15H02063. This work was also supported by the Astrobiology Center Project of National Institutes of Natural Sciences (NINS) (Grant Numbers AB271009, AB281012 and JY280092). I.R. acknowledges support by the Spanish Ministry of Economy and Competitiveness (MINECO) through grant ESP2014-57495-C2-2-R. We acknowledge Roberto Sanchis-Ojeda, who established the ESPRINT collaboration. We thank Akito Tajitsu and Hikaru Nagumo for support for our Subaru HDS observation, Jun Hashimoto for the Subaru HiCIAO observation, and Timothy Brandt for the HiCIAO data reduction. This paper is based on data collected at the Subaru telescope and Okayama 188 cm telescope, which are operated by the National Astronomical Observatory of Japan. The data analysis was in part carried out on a common use data analysis computer system at the Astronomy Data Center, ADC, of the National Astronomical Observatory of Japan. PyFITS and PyRAF were useful for our data reduction. PyFITS and PyRAF are products of the Space Telescope Science Institute, which is operated by AURA for NASA. Our analysis is also based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute, the Space Telescope European Coordinating Facility (ST-ECF/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA). This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous people in Hawai'i.
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 - Publication of the Astronomical Society of Japan
JF - Publication of the Astronomical Society of Japan
IS - 2
M1 - 29
ER -