Spitzer Microlensing Parallax Reveals Two Isolated Stars in the Galactic Bulge

March 2020 • 2020ApJ...891....3Z

Authors • Zang, Weicheng • Shvartzvald, Yossi • Wang, Tianshu • Udalski, Andrzej • Lee, Chung-Uk • Sumi, Takahiro • Skottfelt, Jesper • Li, Shun-Sheng • Mao, Shude • Zhu, Wei • Yee, Jennifer C. • Calchi Novati, Sebastiano • Beichman, Charles A. • Bryden, Geoffery • Carey, Sean • Gaudi, B. Scott • Henderson, Calen B. • Spitzer Team • Mróz, Przemek • Skowron, Jan • Poleski, Radoslaw • Szymański, Michał K. • Soszyński, Igor • Pietrukowicz, Paweł • Kozłowski, Szymon • Ulaczyk, Krzysztof • Rybicki, Krzysztof A. • Iwanek, Patryk • OGLE Collaboration • Bachelet, Etienne • Christie, Grant • Green, Jonathan • Hennerley, Steve • Maoz, Dan • Natusch, Tim • Pogge, Richard W. • Street, Rachel A. • Tsapras, Yiannis • LCO Follow-Up Team • μFUN Follow-Up Team • Albrow, Michael D. • Chung, Sun-Ju • Gould, Andrew • Han, Cheongho • Hwang, Kyu-Ha • Jung, Youn Kil • Ryu, Yoon-Hyun • Shin, In-Gu • Cha, Sang-Mok • Kim, Dong-Jin • Kim, Hyoun-Woo • Kim, Seung-Lee • Lee, Dong-Joo • Lee, Yongseok • Park, Byeong-Gon • KMTNet Collaboration • Bond, Ian A. • Abe, Fumio • Barry, Richard • Bennett, David P. • Bhattacharya, Aparna • Donachie, Martin • Fukui, Akihiko • Hirao, Yuki • Itow, Yoshitaka • Kondo, Iona • Koshimoto, Naoki • Alex Li, Man Cheung • Matsubara, Yutaka • Muraki, Yasushi • Miyazaki, Shota • Nagakane, Masayuki • Ranc, Clément • Rattenbury, Nicholas J. • Suematsu, Haruno • Sullivan, Denis J. • Suzuki, Daisuke • Tristram, Paul J. • Yonehara, Atsunori • MOA Collaboration • Dominik, Martin • Hundertmark, Markus • Jørgensen, Uffe G. • Rahvar, Sohrab • Sajadian, Sedighe • Snodgrass, Colin • Bozza, Valerio • Burgdorf, Martin J. • Evans, Daniel F. • Figuera Jaimes, R. • Fujii, Yuri I. • Mancini, Luigi • Longa-Peña, Penelope • Helling, Christiane • Peixinho, Nuno • Rabus, Markus • Southworth, John • Unda-Sanzana, Eduardo • von Essen, Carolina • MiNDSTEp Collaboration

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 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.

Links

• PREPRINT http://arxiv.org/abs/1904.11204
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fab6ff8
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2020ApJ...891....3Z
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ab6ff8/pdf
• PDF https://stacks.iop.org/0004-637X/891/3/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/891/3
• DATA https://irsa.ipac.caltech.edu/bibdata/2020/Z/2020ApJ...891....3Z.html