2022AJ....164..102M

Query : 2022AJ....164..102M

2022AJ....164..102M - Astron. J., 164, 102 (2022/September-0)

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

MALPAS A., ALBROW M.D., YEE J.C., GOULD A., UDALSKI A., HERRERA MARTIN A., BEICHMAN C.A., BRYDEN G., CALCHI NOVATI S., CAREY S., HENDERSON C.B., GAUDI B.S., SHVARTZVALD Y., ZHU W. (The Spitzer Team), CHA S.-M., CHUNG S.-J., HAN C., HWANG K.-H., JUNG Y.K., KIM D.-J., KIM H.-W., KIM S.-L., LEE C.-U., LEE D.-J., LEE Y., PARK B.-G., POGGE R.W., RYU Y.-H., SHIN I.-G., ZANG W. (The KMTNet Collaboration), IWANEK P., KOZLOWSKI S., MROZ P., PIETRUKOWICZ P., POLESKI R., RYBICKI K.A., SKOWRON J., SOSZYNSKI I., SZYMANSKI M.K., ULACZYK K. (The OGLE Collaboration)

Abstract (from CDS):

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.

Abstract Copyright: © 2022. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Binary lens microlensing - Gravitational microlensing - Satellite microlensing parallax - Brown dwarfs - Gaussian Processes regression

VizieR on-line data: <Available at CDS (J/AJ/164/102): fig1.dat fig6.dat>

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 OGLE-2017-BLG-1038 * 17 58 36.5542846897 -27 18 58.325343982           ~ 3 0
2 NAME Galactic Bulge reg ~ ~           ~ 4794 0

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