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تسجيل مستخدم جديدSpitzer Microlensing parallax reveals two isolated stars in the Galactic bulge
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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 $0.60 pm 0.03 M_{odot}$ star with $D_{rm LS} = 0.53 pm 0.11~text{kpc}$, where $D_{rm LS}$ 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 $0.51^{+0.12}_{-0.10} M_{odot}$ star with $D_{rm LS} = 0.40 pm 0.12~text{kpc}$ or a $0.38^{+0.13}_{-0.12} M_{odot}$ star with $D_{rm LS} = 0.53 pm 0.19~text{kpc}$. 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 occurrence in single lens events.
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