Skip to main content

Research Repository

Advanced Search

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

Shvartzvald, Yossi; Yee, Jennifer C.; Skowron, Jan; Lee, Chung-Uk; Udalski, Andrzej; Calchi Novati, Sebastiano; Bozza, Valerio; Beichman, Charles A.; Bryden, Geoffery; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Zhu, Wei; Bachelet, Etienne; Bolt, Greg; Christie, Grant; Maoz, Dan; Natusch, Tim; Pogge, Richard W.; Street, Rachel A.; Tan, Thiam-Guan; Tsapras, Yiannis; Pietrukowicz, Paweł; Soszyński, Igor; Szymański, Michał K.; Mróz, Przemek; Poleski, Radoslaw; Kozłowski, Szymon; Ulaczyk, Krzysztof; Pawlak, Michał; Rybicki, Krzysztof A.; Iwanek, Patryk; Albrow, Michael D.; Cha, Sang-Mok; Chung, Sun-Ju; Gould, Andrew; Han, Cheongho; Hwang, Kyu-Ha; Kil Jung, Youn; Kim, Dong-Jin; Kim, Hyoun-Woo; Kim, Seung-Lee; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Ryu, Yoon-Hyun; Shin, In-Gu; Zang, Weicheng; Dominik, Martin; Helling, Christiane; Hundertmark, Markus; Jørgensen, Uffe G.; Longa-Peña, Penelope; Lowry, Stephen; Sajadian, Sedighe; Burgdorf, Martin J.; Campbell-White, Justyn; Cicer...

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


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

Dong-Jin Kim

Hyoun-Woo Kim

Seung-Lee Kim

Dong-Joo Lee

Yongseok Lee

Byeong-Gon Park

Yoon-Hyun Ryu

In-Gu Shin

Weicheng Zang

Martin Dominik

Christiane Helling

Markus Hundertmark

Uffe G. Jørgensen

Penelope Longa-Peña

Stephen Lowry

Sedighe Sajadian

Martin J. Burgdorf

Justyn Campbell-White

Simona Ciceri

Daniel F. Evans

Yuri I. Fujii

Tobias C. Hinse

Sohrab Rahvar

Markus Rabus

Jesper Skottfelt

Colin Snodgrass


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.

Journal Article Type Article
Acceptance Date Jan 10, 2019
Online Publication Date Feb 11, 2019
Publication Date Mar 1, 2019
Publicly Available Date May 26, 2023
Journal The Astronomical Journal
Print ISSN 0004-6256
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 157
Issue 3
Article Number 106
Keywords stars, galaxy, bulge, gravitational lensing, micro
Publisher URL


You might also like

Downloadable Citations