A Caltech Library Service

OGLE-2017-BLG-1038: A Possible Brown-dwarf Binary Revealed by Spitzer Microlensing Parallax

Malpas, Amber and Albrow, Michael D. and Yee, Jennifer C. and Gould, Andrew and Udalski, Andrzej and Martin, Antonio Herrera and Beichman, Charles A. and Bryden, Geoffery and Novati, Sebastiano Calchi and Carey, Sean and Henderson, Calen B. and Gaudi, B. Scott and Shvartzvald, Yossi and Zhu, Wei and Cha, Sang-Mok and Chung, Sun-Ju and Han, Cheongho and Hwang, Kyu-Ha and Jung, Youn Kil and Kim, Dong-Jin and Kim, Hyoun-Woo and Kim, Seung-Lee and Lee, Chung-Uk and Lee, Dong-Joo and Lee, Yongseok and Park, Byeong-Gon and Pogge, Richard W. and Ryu, Yoon-Hyun and Shin, In-Gu and Zang, Weicheng and Iwanek, Patryk and Kozłowski, Szymon and Mróz, Przemek and Pietrukowicz, Paweł and Poleski, Radoslaw and Rybicki, Krzysztof A. and Skowron, Jan and Soszyński, Igor and Szymański, Michał K. and Ulaczyk, Krzysztof (2022) OGLE-2017-BLG-1038: A Possible Brown-dwarf Binary Revealed by Spitzer Microlensing Parallax. Astronomical Journal, 164 (3). p. 102. ISSN 0004-6256. doi:10.3847/1538-3881/ac7d4c.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


We report the analysis of microlensing event OGLE-2017-BLG-1038, observed by the Optical Gravitational Lensing Experiment, Korean Microlensing Telescope Network, and Spitzer telescopes. The event is caused by a giant source star in the Galactic Bulge passing over a large resonant binary-lens caustic. The availability of space-based data allows the full set of physical parameters to be calculated. However, there exists an eightfold degeneracy in the parallax measurement. The four best solutions correspond to very-low-mass binaries near (${M}_{1}={170}_{-50}^{+40}{M}_{J}$ and ${M}_{2}={110}_{-30}^{+20}{M}_{J}$), or well below (${M}_{1}={22.5}_{-0.4}^{+0.7}{M}_{J}$ and ${M}_{2}={13.3}_{-0.3}^{+0.4}{M}_{J}$) the boundary between stars and brown dwarfs. A conventional analysis, with scaled uncertainties for Spitzer data, implies a very-low-mass brown-dwarf binary lens at a distance of 2 kpc. Compensating for systematic Spitzer errors using a Gaussian process model suggests that a higher mass M-dwarf binary at 6 kpc is equally likely. A Bayesian comparison based on a galactic model favors the larger-mass solutions. We demonstrate how this degeneracy can be resolved within the next 10 years through infrared adaptive-optics imaging with a 40 m class telescope.

Item Type:Article
Related URLs:
URLURL TypeDescription article
Malpas, Amber0000-0001-5924-8885
Albrow, Michael D.0000-0003-3316-4012
Yee, Jennifer C.0000-0001-9481-7123
Udalski, Andrzej0000-0001-5207-5619
Martin, Antonio Herrera0000-0002-3654-4662
Beichman, Charles A.0000-0002-5627-5471
Bryden, Geoffery0000-0001-5966-837X
Novati, Sebastiano Calchi0000-0002-7669-1069
Carey, Sean0000-0002-0221-6871
Henderson, Calen B.0000-0001-8877-9060
Gaudi, B. Scott0000-0003-0395-9869
Shvartzvald, Yossi0000-0003-1525-5041
Zhu, Wei0000-0003-4027-4711
Cha, Sang-Mok0000-0002-7511-2950
Chung, Sun-Ju0000-0001-6285-4528
Han, Cheongho0000-0002-2641-9964
Hwang, Kyu-Ha0000-0002-9241-4117
Jung, Youn Kil0000-0002-0314-6000
Kim, Hyoun-Woo0000-0001-8263-1006
Kim, Seung-Lee0000-0003-0562-5643
Lee, Chung-Uk0000-0003-0043-3925
Lee, Yongseok0000-0001-7594-8072
Park, Byeong-Gon0000-0002-6982-7722
Pogge, Richard W.0000-0003-1435-3053
Ryu, Yoon-Hyun0000-0001-9823-2907
Shin, In-Gu0000-0002-4355-9838
Zang, Weicheng0000-0001-6000-3463
Iwanek, Patryk0000-0002-6212-7221
Kozłowski, Szymon0000-0003-4084-880X
Mróz, Przemek0000-0001-7016-1692
Pietrukowicz, Paweł0000-0002-2339-5899
Poleski, Radoslaw0000-0002-9245-6368
Skowron, Jan0000-0002-2335-1730
Soszyński, Igor0000-0002-7777-0842
Szymański, Michał K.0000-0002-0548-8995
Ulaczyk, Krzysztof0000-0001-6364-408X
Additional Information:This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI), and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. Work by C.H. was supported by grants of the National Research Foundation of Korea (grant No. 2020R1A4A2002885 and 2019R1A2C2085965). This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Funding AgencyGrant Number
National Research Foundation of Korea2020R1A4A2002885
National Research Foundation of Korea2019R1A2C2085965
Royal Society of New Zealand ∣ Marsden FundUOC1602
Issue or Number:3
Record Number:CaltechAUTHORS:20220908-161023637
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116624
Deposited By: Melissa Ray
Deposited On:07 Sep 2022 22:21
Last Modified:08 Sep 2022 16:11

Repository Staff Only: item control page