학술논문
Kepler K2 Campaign 9: II. First space-based discovery of an exoplanet using microlensing
Document Type
Working Paper
Author
Specht, D.; Poleski, R.; Penny, M. T.; Kerins, E.; McDonald, I.; Lee, Chung-Uk; Udalski, A.; Bond, I. A.; Shvartzvald, Y.; Zang, Weicheng; Street, R. A.; Hogg, D. W.; Gaudi, B. S.; Barclay, T.; Barentsen, G.; Howell, S. B.; Mullally, F.; Henderson, C. B.; Bryson, S. T.; Caldwell, D. A.; Haas, M. R.; Van Cleve, J. E.; Larson, K.; McCalmont, K.; Peterson, C.; Putnam, D.; Ross, S.; Packard, M.; Reedy, L.; Albrow, Michael D.; Chung, Sun-Ju; Jung, Youn Kil; Gould, Andrew; Han, Cheongho; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Shin, In-Gu; Yang, Hongjing; Yee, Jennifer C.; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Seung-Lee; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard W.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, Sz.; Skowron, J.; Mróz, P.; Mao, Shude; Fouqué, Pascal; Zhu, Wei; Abe, F.; Barry, R.; Bennett, D. P.; Bhattacharya, A.; Fukui, A.; Fujii, H.; Hirao, Y.; Itow, Y.; Kirikawa, R.; Kondo, I.; Koshimoto, N.; Matsubara, Y.; Matsumoto, S.; Miyazaki, S.; Muraki, Y.; Olmschenk, G.; Ranc, C.; Okamura, A.; Rattenbury, N. J.; Satoh, Y.; Sumi, T.; Suzuki, D.; Silva, S. I.; Toda, T.; Tristram, P. J.; Vandorou, A.; Yama, H.; Beichman, C.; Bryden, G.; Novati, S. Calchi
Source
Subject
Language
Abstract
We present K2-2016-BLG-0005Lb, a densely sampled, planetary binary caustic-crossing microlensing event found from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is the first bound microlensing exoplanet discovered from space-based data. The event has caustic entry and exit points that are resolved in the K2C9 data, enabling the lens--source relative proper motion to be measured. We have fitted a binary microlens model to the Kepler data, and to simultaneous observations from multiple ground-based surveys. Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing mass--position--velocity degeneracy and measure the planet's mass directly. We find a host mass of $0.58\pm0.04 ~{\rm M}_\odot$ and a planetary mass of $1.1\pm0.1 ~{\rm M_J}$. The system lies at a distance of $5.2\pm0.2~$kpc from Earth towards the Galactic bulge, more than twice the distance of the previous most distant planet found by Kepler. The sky-projected separation of the planet from its host is found to be $4.2\pm0.3~$au which, for circular orbits, deprojects to a host separation $a = 4.4^{+1.9}_{-0.4}~$au and orbital period $P = 13^{+9}_{-2}~$yr. This makes K2-2016-BLG-0005Lb a close Jupiter analogue orbiting a low-mass host star. According to current planet formation models, this system is very close to the host mass threshold below which Jupiters are not expected to form. Upcoming space-based exoplanet microlensing surveys by NASA's Nancy Grace Roman Space Telescope and, possibly, ESA's Euclid mission, will provide demanding tests of current planet formation models.
Comment: 18 pages. Accepted for publication in MNRAS Published by Oxford University Press on behalf of the Royal Astronomical Society
Comment: 18 pages. Accepted for publication in MNRAS Published by Oxford University Press on behalf of the Royal Astronomical Society