MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary

被引：19

作者：

Miyazaki, S. ^{[1
]}

Sumi, T. ^{[1
]}

Bennett, D. P. ^{[2
,3
]}

Gould, A. ^{[4
,5
,6
]}

Udalski, A. ^{[7
]}

Bond, I. A. ^{[8
]}

Koshimoto, N. ^{[1
]}

Nagakane, M. ^{[1
]}

Rattenbury, N. ^{[9
]}

Abe, F. ^{[10
]}

Bhattacharya, A. ^{[2
,3
]}

Barry, R. ^{[3
]}

Donachie, M. ^{[9
]}

Fukui, A. ^{[11
]}

Hirao, Y. ^{[1
]}

Itow, Y. ^{[12
]}

Kawasaki, K. ^{[1
]}

Li, M. C. A. ^{[9
]}

Ling, C. H. ^{[8
]}

Matsubara, Y. ^{[12
]}

Matsuo, T. ^{[1
]}

Muraki, Y. ^{[12
]}

Ohnishi, K. ^{[13
]}

Ranc, C. ^{[3
]}

Saito, T. ^{[14
]}

Sharan, A. ^{[9
]}

Shibai, H. ^{[1
]}

Suematsu, H. ^{[1
]}

Suzuki, D. ^{[15
]}

Sullivan, D. J. ^{[16
]}

Tristram, P. J. ^{[17
]}

Yamada, T. ^{[1
]}

Yonehara, A. ^{[18
]}

KozLowski, S. ^{[7
]}

Mroz, P. ^{[7
]}

Pawlak, M. ^{[7
]}

Poleski, R. ^{[19
]}

Pietrukowicz, P. ^{[7
]}

Skowron, J. ^{[7
]}

Soszynski, I. ^{[7
]}

Szymanski, M. K. ^{[7
]}

Ulaczyk, K. ^{[7
]}

Albrow, M. D. ^{[20
]}

Chung, S. -J. ^{[4
,21
]}

Han, C. ^{[22
]}

Jung, Y. K. ^{[4
]}

Hwang, K. -H. ^{[4
]}

Ryu, Y. -H. ^{[23
]}

Shin, I. -G. ^{[24
]}

Shvartzvald, Y. ^{[25
]}

机构：

[1] Osaka Univ, Grad Sch Sci, Dept Earth & Space Sci, 1-1 Machikaneyama, Toyonaka, Osaka 5600043, Japan

[2] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA

[3] NASA, Goddard Space Flight Ctr, Lab Exoplanets & Stellar Astrophys, Greenbelt, MD 20771 USA

[4] Korea Astron & Space Sci Inst, Daejon 34055, South Korea

[5] Ohio State Univ, Dept Astron, 140 W 18th Ave, Columbus, OH 43210 USA

[6] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany

[7] Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw, Poland

[8] Massey Univ, Inst Informat & Math Sci, North Shore Mail Ctr, Private Bag 102-904, Auckland, New Zealand

[9] Univ Auckland, Dept Phys, Private Bag 92019, Auckland, New Zealand

[10] Nagoya Univ, Inst Space Earth Environm Res, Nagoya, Aichi 4648601, Japan

[11] Natl Astron Observ, Okayama Astrophys Observ, 3037-5 Honjo, Okayama 7190232, Japan

[12] Nagoya Univ, Inst Space Earth Environm Res, Nagoya, Aichi 4648601, Japan

[13] Nagano Natl Coll Technol, Nagano 3818550, Japan

[14] Tokyo Metropolitan Coll Ind Technol, Tokyo 1168523, Japan

[15] Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2525210, Japan

[16] Victoria Univ, Sch Chem & Phys Sci, Wellington, New Zealand

[17] Univ Canterbury, Mt John Observ, POB 56, Lake Tekapo 8770, New Zealand

[18] Kyoto Sangyo Univ, Dept Phys, Fac Sci, Kyoto 6038555, Japan

[19] Ohio State Univ, Dept Astron, 140 W 18th Ave, Columbus, OH 43210 USA

[20] Univ Canterbury, Dept Phys & Astron, Private Bag 4800, Christchurch 8020, New Zealand

[21] Korea Univ Sci & Technol, 217 Gajeong Ro, Daejeon 34113, South Korea

[22] Chungbuk Natl Univ, Dept Phys, Cheongju 28644, South Korea

[23] Korea Astron & Space Sci Inst, Daejon 34055, South Korea

[24] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA

[25] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[26] Tsinghua Univ, Phys Dept, Beijing 100084, Peoples R China

[27] Tsinghua Univ, Tsinghua Ctr Astrophys, Beijing 100084, Peoples R China

[28] Zhejiang Univ, Dept Phys, Hangzhou 310058, Zhejiang, Peoples R China

[29] Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada

[30] Kyung Hee Univ, Sch Space Res, Yongin 17104, Kyeonggi, South Korea

来源：

ASTRONOMICAL JOURNAL | 2018年 / 156卷 / 03期

基金：

新加坡国家研究基金会;

关键词：

brown dwarfs; gravitational lensing: micro; planetary systems; MAGNIFICATION MICROLENSING EVENTS; DIFFERENCE IMAGE-ANALYSIS; GALACTIC BULGE; EXTRASOLAR PLANETS; GREAT ESCAPE; GAS GIANTS; SNOW LINE; STARS; PHOTOMETRY; EXOPLANETS;

D O I：

10.3847/1538-3881/aad5ee

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report on the discovery and analysis of the short-timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low-mass host, around the brown dwarf (BD)/planetary-mass boundary, or a BD binary. We found two competing models that explain the observed light curves with companion/host mass ratios of q similar to 0.01 and similar to 0.17, respectively. A significant finite source effect in the best-fit planetary model (q similar to 0.01) reveals a small angular Einstein radius of theta(E) similar or equal to 0.03 mas, which favors a low-mass lens. We obtain the posterior probability distribution of the lens properties from a Bayesian analysis. The results for the planetary models strongly depend on a power-law index in planetary-mass regime, alpha(pl), in the assumed mass function. In summary, there are two solutions of the lens system: (1) a BD/planetary-mass boundary object orbited by a super-Neptune (the planetary model with alpha(pl) = 0.49) and (2) a BD binary (the binary model). If the planetary models are correct, this system can be one of a new class of planetary system, having a low host mass and also a planetary-mass ratio (q < 0.03) between the companion and its host. The discovery of the event is important for the study of planetary formation in very low-mass objects. In addition, it is important to consider all viable solutions in these kinds of ambiguous events in order for the future comprehensive statistical analyses of planetary/binary microlensing events.

引用

页数：11

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