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Spitzer Microlensing parallax reveals two isolated stars in the Galactic bulge

Zang, Weicheng and Shvartzvald, Yossi and Calchi Novati, Sebastiano and Beichman, Charles A. and Carey, Sean and Henderson, Calen B. (2020) Spitzer Microlensing parallax reveals two isolated stars in the Galactic bulge. Astrophysical Journal, 891 (1). Art. No. 3. ISSN 1538-4357. doi:10.3847/1538-4357/ab6ff8.

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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±0.03M⊙ 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^(+0.12)_(−0.10)M⊙ star with D_(LS) = 0.40±0.12 kpc or a 0.38^(+0.13)_(−0.12)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 occurrence in single lens events.

Item Type:Article
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URLURL TypeDescription Paper
Zang, Weicheng0000-0001-6000-3463
Shvartzvald, Yossi0000-0003-1525-5041
Calchi Novati, Sebastiano0000-0002-7669-1069
Beichman, Charles A.0000-0002-5627-5471
Carey, Sean0000-0002-0221-6871
Henderson, Calen B.0000-0001-8877-9060
Additional Information:© 2020 The American Astronomical Society. Received 2019 April 24; revised 2020 January 10; accepted 2020 January 17; published 2020 February 27. W.Z., W.T., S.-S.L., and S.M. acknowledge support by the National Science Foundation of China (grants No. 11821303 and 11761131004). This work is based (in part) on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. The OGLE has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. The MOA project is supported by JSPS KAKENHI grants No. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, and JP17H02871. The research has made use of data obtained at the Danish 1.54 m telescope at ESO's La Silla Observatory. CITEUC is funded by National Funds through FCT—Foundation for Science and Technology (project: UID/Multi/00611/2013) and FEDER—European Regional Development Fund through COMPETE 2020—Operational Programme Competitiveness and Internationalization (project: POCI-01-0145-FEDER-006922). Work by A.G. was supported by AST-1516842 and by JPL grant 1500811. A.G. received support from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC grant Agreement No. [321035]. Wei Zhu was supported by the Beatrice and Vincent Tremaine Fellowship at CITA. Work by C.H. was supported by the grant (2017R1A4A1015178) of the National Research Foundation of Korea. Y.T. acknowledges the support of DFG priority program SPP 1992 "Exploring the Diversity of Extrasolar Planets" (WA 1047/11-1). L.M. acknowledges support from the Italian Minister of Instruction, University and Research (MIUR) through the FFABR 2017 fund.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Natural Science Foundation of China11821303
National Natural Science Foundation of China11761131004
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
Japan Society for the Promotion of Science (JSPS)JSPS24253004
Japan Society for the Promotion of Science (JSPS)JSPS26247023
Japan Society for the Promotion of Science (JSPS)JSPS23340064
Japan Society for the Promotion of Science (JSPS)JSPS15H00781
Japan Society for the Promotion of Science (JSPS)JP16H06287
Japan Society for the Promotion of Science (JSPS)JP17H02871
Fundação para a Ciência e a Tecnologia (FCT)UID/Multi/00611/2013
Fundação para a Ciência e a Tecnologia (FCT)COMPETE 2020
Fondo Europeo de Desarrollo Regional (FEDER)POCI-01-0145-FEDER-006922
Canadian Institute for Theoretical AstrophysicsUNSPECIFIED
National Research Foundation of Korea2017R1A4A1015178
Deutsche Forschungsgemeinschaft (DFG)SPP 1992
Deutsche Forschungsgemeinschaft (DFG)WA 1047/11-1
Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)FFABR 2017
European Research Council (ERC)321035
Subject Keywords:Gravitational microlensing; Satellite microlensing parallax; Stellar masses; Stellar distance
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Gravitational microlensing (672); Satellite microlensing parallax (2148); Stellar masses (1614); Stellar distance (1595)
Record Number:CaltechAUTHORS:20191122-083849996
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Official Citation:Weicheng Zang et al 2020 ApJ 891 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100009
Deposited By: Tony Diaz
Deposited On:22 Nov 2019 17:11
Last Modified:16 Nov 2021 17:51

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