Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf

Spitzer Team; OGLE Collaboration; KMTNet Collaboration; MiNDSTEp Collaboration; Yossi Shvartzvald; Jennifer C. Yee; Jan Skowron; Chung-Uk Lee; Andrzej Udalski; Sebastiano Calchi Novati; Valerio Bozza; Charles A. Beichman; Geoffery Bryden; Sean Carey; B. Scott Gaudi; Calen B. Henderson; Wei Zhu; Etienne Bachelet; Greg Bolt; Grant Christie; Dan Maoz; Tim Natusch; Richard W. Pogge; Rachel A. Street; Thiam-Guan Tan; Yiannis Tsapras; Paweł Pietrukowicz; Igor Soszyński; Michał K. Szymański; Przemek Mróz; Radoslaw Poleski; Szymon Kozłowski; Krzysztof Ulaczyk; Michał Pawlak; Krzysztof A. Rybicki; Patryk Iwanek; Michael D. Albrow; Sang-Mok Cha; Sun-Ju Chung; Andrew Gould; Cheongho Han; Kyu-Ha Hwang; Youn Kil Jung; Hyoun-Woo Kim; Seung-Lee Kim; Dong-Joo Lee; Yongseok Lee; Byeong-Gon Park; Yoon-Hyun Ryu; Justyn Campbell-White

doi:10.3847/1538-3881/aafe12

Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf

Spitzer Team, , OGLE Collaboration, KMTNet Collaboration, MiNDSTEp Collaboration, Yossi Shvartzvald (Lead / Corresponding author), Jennifer C. Yee, Jan Skowron, Chung-Uk Lee, Andrzej Udalski, Sebastiano Calchi Novati, Valerio Bozza, Charles A. Beichman, Geoffery Bryden, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Wei Zhu, Etienne Bachelet, Greg BoltGrant Christie, Dan Maoz, Tim Natusch, Richard W. Pogge, Rachel A. Street, Thiam-Guan Tan, Yiannis Tsapras, Paweł Pietrukowicz, Igor Soszyński, Michał K. Szymański, Przemek Mróz, Radoslaw Poleski, Szymon Kozłowski, Krzysztof Ulaczyk, Michał Pawlak, Krzysztof A. Rybicki, Patryk Iwanek, Michael D. Albrow, Sang-Mok Cha, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Yoon-Hyun Ryu, Justyn Campbell-White

Physics

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Abstract

The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens-parallax and finite-source effects are needed in order to recover the full information. Here, we combine the Spitzer satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find two degenerate solutions for the lens (due to the known satellite-parallax degeneracy), which are consistent with each other except for their proper motion. The lens is an isolated brown dwarf with a mass of either 18 ± 1 M _J or 20 ± 1 M _J. This is the lowest isolated-object mass measurement to date, only ̃45% more massive than the theoretical deuterium-fusion boundary at solar metallicity, which is the common definition of a free-floating planet. The brown dwarf is located at either 3.9 ± 0.1 kpc or 4.1 ± 0.1 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, with one solution suggesting it is moving within the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.

Original language	English
Article number	106
Pages (from-to)	1-8
Number of pages	8
Journal	Astronomical Journal
Volume	157
Issue number	3
Early online date	11 Feb 2019
DOIs	https://doi.org/10.3847/1538-3881/aafe12
Publication status	Published - Mar 2019

Keywords

Galaxy: bulge
gravitational lensing: micro

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-3881/aafe12

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Spitzer Team, OGLE Collaboration, KMTNet Collaboration, MiNDSTEp Collaboration, Shvartzvald, Y., Yee, J. C., Skowron, J., Lee, C.-U., Udalski, A., Calchi Novati, S., Bozza, V., Beichman, C. A., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Zhu, W., Bachelet, E., ... Campbell-White, J. (2019). Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf. Astronomical Journal, 157(3), 1-8. Article 106. https://doi.org/10.3847/1538-3881/aafe12

@article{354ecea406ab440daf41ef6b06553f28,

title = "Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf",

abstract = "The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens-parallax and finite-source effects are needed in order to recover the full information. Here, we combine the Spitzer satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find two degenerate solutions for the lens (due to the known satellite-parallax degeneracy), which are consistent with each other except for their proper motion. The lens is an isolated brown dwarf with a mass of either 18 ± 1 M J or 20 ± 1 M J . This is the lowest isolated-object mass measurement to date, only{\~ }45% more massive than the theoretical deuterium-fusion boundary at solar metallicity, which is the common definition of a free-floating planet. The brown dwarf is located at either 3.9 ± 0.1 kpc or 4.1 ± 0.1 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, with one solution suggesting it is moving within the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.",

keywords = "Galaxy: bulge, gravitational lensing: micro",

author = "{Spitzer Team} and {OGLE Collaboration} and {KMTNet Collaboration} and {MiNDSTEp Collaboration} and Yossi Shvartzvald and Yee, {Jennifer C.} and Jan Skowron and Chung-Uk Lee and Andrzej Udalski and {Calchi Novati}, Sebastiano and Valerio Bozza and Beichman, {Charles A.} and Geoffery Bryden and Sean Carey and Gaudi, {B. Scott} and Henderson, {Calen B.} and Wei Zhu and Etienne Bachelet and Greg Bolt and Grant Christie and Dan Maoz and Tim Natusch and Pogge, {Richard W.} and Street, {Rachel A.} and Thiam-Guan Tan and Yiannis Tsapras and Pawe{\l} Pietrukowicz and Igor Soszy{\'n}ski and Szyma{\'n}ski, {Micha{\l} K.} and Przemek Mr{\'o}z and Radoslaw Poleski and Szymon Koz{\l}owski and Krzysztof Ulaczyk and Micha{\l} Pawlak and Rybicki, {Krzysztof A.} and Patryk Iwanek and Albrow, {Michael D.} and Sang-Mok Cha and Sun-Ju Chung and Andrew Gould and Cheongho Han and Kyu-Ha Hwang and Jung, {Youn Kil} and Hyoun-Woo Kim and Seung-Lee Kim and Dong-Joo Lee and Yongseok Lee and Byeong-Gon Park and Yoon-Hyun Ryu and Justyn Campbell-White",

year = "2019",

month = mar,

doi = "10.3847/1538-3881/aafe12",

language = "English",

volume = "157",

pages = "1--8",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "3",

}

Spitzer Team, OGLE Collaboration, KMTNet Collaboration, MiNDSTEp Collaboration, Shvartzvald, Y, Yee, JC, Skowron, J, Lee, C-U, Udalski, A, Calchi Novati, S, Bozza, V, Beichman, CA, Bryden, G, Carey, S, Gaudi, BS, Henderson, CB, Zhu, W, Bachelet, E, Bolt, G, Christie, G, Maoz, D, Natusch, T, Pogge, RW, Street, RA, Tan, T-G, Tsapras, Y, Pietrukowicz, P, Soszyński, I, Szymański, MK, Mróz, P, Poleski, R, Kozłowski, S, Ulaczyk, K, Pawlak, M, Rybicki, KA, Iwanek, P, Albrow, MD, Cha, S-M, Chung, S-J, Gould, A, Han, C, Hwang, K-H, Jung, YK, Kim, H-W, Kim, S-L, Lee, D-J, Lee, Y, Park, B-G & Ryu, Y-H & Campbell-White, J 2019, 'Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf', Astronomical Journal, vol. 157, no. 3, 106, pp. 1-8. https://doi.org/10.3847/1538-3881/aafe12

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T1 - Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf

AU - Spitzer Team

AU - OGLE Collaboration

AU - KMTNet Collaboration

AU - MiNDSTEp Collaboration

AU - Shvartzvald, Yossi

AU - Yee, Jennifer C.

AU - Skowron, Jan

AU - Lee, Chung-Uk

AU - Udalski, Andrzej

AU - Calchi Novati, Sebastiano

AU - Bozza, Valerio

AU - Beichman, Charles A.

AU - Bryden, Geoffery

AU - Carey, Sean

AU - Gaudi, B. Scott

AU - Henderson, Calen B.

AU - Zhu, Wei

AU - Bachelet, Etienne

AU - Bolt, Greg

AU - Christie, Grant

AU - Maoz, Dan

AU - Natusch, Tim

AU - Pogge, Richard W.

AU - Street, Rachel A.

AU - Tan, Thiam-Guan

AU - Tsapras, Yiannis

AU - Pietrukowicz, Paweł

AU - Soszyński, Igor

AU - Szymański, Michał K.

AU - Mróz, Przemek

AU - Poleski, Radoslaw

AU - Kozłowski, Szymon

AU - Ulaczyk, Krzysztof

AU - Pawlak, Michał

AU - Rybicki, Krzysztof A.

AU - Iwanek, Patryk

AU - Albrow, Michael D.

AU - Cha, Sang-Mok

AU - Chung, Sun-Ju

AU - Gould, Andrew

AU - Han, Cheongho

AU - Hwang, Kyu-Ha

AU - Jung, Youn Kil

AU - Kim, Hyoun-Woo

AU - Kim, Seung-Lee

AU - Lee, Dong-Joo

AU - Lee, Yongseok

AU - Park, Byeong-Gon

AU - Ryu, Yoon-Hyun

AU - Campbell-White, Justyn

PY - 2019/3

Y1 - 2019/3

N2 - The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens-parallax and finite-source effects are needed in order to recover the full information. Here, we combine the Spitzer satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find two degenerate solutions for the lens (due to the known satellite-parallax degeneracy), which are consistent with each other except for their proper motion. The lens is an isolated brown dwarf with a mass of either 18 ± 1 M J or 20 ± 1 M J . This is the lowest isolated-object mass measurement to date, only ̃45% more massive than the theoretical deuterium-fusion boundary at solar metallicity, which is the common definition of a free-floating planet. The brown dwarf is located at either 3.9 ± 0.1 kpc or 4.1 ± 0.1 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, with one solution suggesting it is moving within the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.

AB - The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens-parallax and finite-source effects are needed in order to recover the full information. Here, we combine the Spitzer satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find two degenerate solutions for the lens (due to the known satellite-parallax degeneracy), which are consistent with each other except for their proper motion. The lens is an isolated brown dwarf with a mass of either 18 ± 1 M J or 20 ± 1 M J . This is the lowest isolated-object mass measurement to date, only ̃45% more massive than the theoretical deuterium-fusion boundary at solar metallicity, which is the common definition of a free-floating planet. The brown dwarf is located at either 3.9 ± 0.1 kpc or 4.1 ± 0.1 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, with one solution suggesting it is moving within the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.

KW - Galaxy: bulge

KW - gravitational lensing: micro

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DO - 10.3847/1538-3881/aafe12

M3 - Article

SN - 0004-6256

VL - 157

SP - 1

EP - 8

JO - Astronomical Journal

JF - Astronomical Journal

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M1 - 106

ER -

Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf

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