Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star

doi:10.3847/1538-3881/ab487f

	Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star
	Fukui,A.1,2; Suzuki,D.3; Koshimoto,N.4,5,6; Bachelet,E.7; Vanmunster,T.8; Storey,D.9; Maehara,H.10; Yanagisawa,K.11; Yamada,T.12; Yonehara,A.12
刊名	The Astronomical Journal
	2019-10-31
卷号	158 期号:5
关键词	Gravitational microlensing Exoplanet systems
ISSN号	0004-6256
DOI	10.3847/1538-3881/ab487f
英文摘要	Abstract We report the analysis of additional multiband photometry and spectroscopy and new adaptive optics (AO) imaging of the nearby planetary microlensing event TCP?J05074264+2447555 (Kojima-1), which was discovered toward the Galactic anticenter in 2017 (Nucita et al.). We confirm the planetary nature of the light-curve anomaly around the peak while finding no additional planetary feature in this event. We also confirm the presence of apparent blending flux and the absence of significant parallax signal reported in the literature. The AO image reveals no contaminating sources, making it most likely that the blending flux comes from the lens star. The measured multiband lens flux, combined with a constraint from the microlensing model, allows us to narrow down the previously unresolved mass and distance of the lens system. We find that the primary lens is a dwarf on the K/M boundary (0.581 ± 0.033 M⊙) located at 505?±?47 pc, and the companion (Kojima-1Lb) is a Neptune-mass planet (20.0 ± 2.0 M⊕) with a semimajor axis of au. This orbit is a few times smaller than those of typical microlensing planets and is comparable to the snow-line location at young ages. We calculate that the a priori detection probability of Kojima-1Lb is only ～35%, which may imply that Neptunes are common around the snow line, as recently suggested by the transit and radial velocity techniques. The host star is the brightest among the microlensing planetary systems (Ks = 13.7), offering a great opportunity to spectroscopically characterize this system, even with current facilities.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0004-6256-158-5-AB487F
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/28303]
专题	中国科学院紫金山天文台
作者单位	1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 2.Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, Japan 4.Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 5.National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 6.Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 7.Las Cumbres Observatory, 6740 Cortona Drive, Suite 102, Goleta, CA 93117, USA 8.Center for Backyard Astrophysics Belgium, Walhostraat 1A, B-3401 Landen, Belgium 9.American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138, USA 10.Okayama Branch Office, Subaru Telescope, National Astronomical Observatory of Japan, NINS, Kamogata, Asakuchi, Okayama 719-0232, Japan
推荐引用方式 GB/T 7714	Fukui,A.,Suzuki,D.,Koshimoto,N.,et al. Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star[J]. The Astronomical Journal,2019,158(5).
APA	Fukui,A..,Suzuki,D..,Koshimoto,N..,Bachelet,E..,Vanmunster,T..,...&Tamura,M..(2019).Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star.The Astronomical Journal,158(5).
MLA	Fukui,A.,et al."Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star".The Astronomical Journal 158.5(2019).