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 o star with D LS = 0.53 0.11 kpc, where D LS 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 star with D LS = 0.40 0.12 kpc or a star with D LS = 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.
Zang, W., Shvartzvald, Y., Wang, T., Udalski, A., Lee, C.-., Sumi, T., et al. (2020). Spitzer Microlensing Parallax Reveals Two Isolated Stars in the Galactic Bulge. THE ASTROPHYSICAL JOURNAL, 891(1), 3 [10.3847/1538-4357/ab6ff8].
Spitzer Microlensing Parallax Reveals Two Isolated Stars in the Galactic Bulge
Han C.;Mancini L.;
2020-01-01
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 o star with D LS = 0.53 0.11 kpc, where D LS 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 star with D LS = 0.40 0.12 kpc or a star with D LS = 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.File | Dimensione | Formato | |
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