Spitzer Microlensing Parallax Reveals Two Isolated Stars in the Galactic Bulge
Abstract
We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-source effects, and the microlens parallaxes are derived from the joint analysis of ground-based observations and Spitzer observations. We find that the lens of OGLE-2017-BLG-1254 is a 0.60 ± 0.03 M⊙ star with DLS = 0.53 ± 0.11 kpc, where DLS is the distance between the lens and the source. The second event, OGLE-2017-BLG-1161, is subject to the known satellite parallax degeneracy, and thus is either a 0.51-0.10+0.12 M_{⊙} star with DLS = 0.40 ± 0.12 kpc or a 0.38-0.12+0.13 M_{⊙} star with DLS = 0.53 ± 0.19 kpc. Both of the lenses are therefore isolated stars in the Galactic bulge. By comparing the mass and distance distributions of the eight published Spitzer finite-source events with the expectations from a Galactic model, we find that the Spitzer sample is in agreement with the probability of finite-source effects occurring in single-lens events.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2020
- DOI:
- 10.3847/1538-4357/ab6ff8
- arXiv:
- arXiv:1904.11204
- Bibcode:
- 2020ApJ...891....3Z
- Keywords:
-
- Gravitational microlensing;
- Satellite microlensing parallax;
- Stellar masses;
- Stellar distance;
- 672;
- 2148;
- 1614;
- 1595;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 16 pages, 6 Figures. Submitted to AAS journal