Spitzer 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 ± 0.03 M ⊙ 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 0.51-0.10+0.12 M⊙ star with D LS = 0.40 ± 0.12 kpc or a 0.38-0.12+0.13 M⊙ 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-U , Sumi , T , Skottfelt , J , Li , S-S , Mao , S , Zhu , W , Yee , J C , Calchi Novati , S , Beichman , C A , Bryden , G , Carey , S , Gaudi , B S , Henderson , C B , Mróz , P , Skowron , J , Poleski , R , Szymański , M K , Soszyński , I , Pietrukowicz , P , Kozłowski , S , Ulaczyk , K , Rybicki , K A , Iwanek , P , Bachelet , E , Christie , G , Green , J , Hennerley , S , Maoz , D , Natusch , T , Pogge , R W , Street , R A , Tsapras , Y , Albrow , M D , Chung , S-J , Gould , A , Han , C , Hwang , K-H , Jung , Y K , Ryu , Y-H , Shin , I-G , Cha , S-M , Kim , D-J , Kim , H-W , Kim , S-L , Lee , D-J , Lee , Y , Park , B-G , Pogge , R W , Bond , I A , Abe , F , Barry , R , Bennett , D P , Bhattacharya , A , Donachie , M , Fukui , A , Hirao , Y , Itow , Y , Kondo , I , Koshimoto , N , Li , M C A , Matsubara , Y , Muraki , Y , Miyazaki , S , Nagakane , M , Ranc , C , Rattenbury , N J , Suematsu , H , Sullivan , D J , Suzuki , D , Tristram , P J , Yonehara , A , Dominik , M , Hundertmark , M , Jørgensen , U G , Rahvar , S , Sajadian , S , Snodgrass , C , Bozza , V , Burgdorf , M J , Evans , D F , Figuera Jaimes , R , Fujii , Y I , Mancini , L , Longa-Peña , P , Helling , C , Peixinho , N , Rabus , M , Southworth , J , Unda-Sanzana , E & von Essen , C 2020 , ' Spitzer microlensing parallax reveals two isolated stars in the Galactic bulge ' , Astrophysical Journal , vol. 891 , no. 1 , 3 . https://doi.org/10.3847/1538-4357/ab6ff8
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