Spectral Type of the Candidate Microlensing Event ASASSN-19cq
ATel #12507; B. McCollum (AU), S. Laine (Caltech/IPAC)
on 16 Feb 2019; 01:41 UT
Credential Certification: Bruce McCollum (mccollub@cua.edu)
Subjects: Infra-Red, Optical, A Comment, Microlensing Event
Sokolovsky et al. (ATel #12495) report that ASASSN-19cq is a candidate microlensing event associated with a 14th magnitude (V) star which appears in several catalogs. Sokolovsky et al. further report that a low-resolution spectrum of the star reveals a spectral class of K, but do not classify it more specifically.
To refine the spectral classification, using the tool of Bayo et al. (2008, A&A, 492, 277) we fitted the optical and infrared SED to the set of BT-Settl stellar models (Allard et al. 2012, RSPTA, 370, 2765). The Av was varied as a free parameter, with a lower limit of Av = 1.5 set according to the 3D Galactic extinction map of Green et al. (2018, MNRAS, 478, 651) and the one-sigma lower limit distance based on Gaia data (Bailer-Jones et al. 2018, AJ, 156, 58). A total of 20 data points were used for the fitting.
A good fit was obtained for a star with the following characteristics: Teff = 4600 +/- 99 K, log g = 3.5 +/- 0.6, and Av = 1.5 +/- 0.09, consistent with a K4 giant having only interstellar extinction. Infrared measurements extending to the WISE W3 bandpass (11.6 um) and an upper limit in WISE W4 (22 um) show no infrared excess. From the distance and SED, the fitting tool obtains Lbol = 206 +/- 67 Lsol.
The SED and best-fit model may be viewed at
http://spider.ipac.caltech.edu/staff/seppo/plots/ATel_2495_candidate_microlens_fit.png
This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MICINN through grant AyA2008-02156. This work uses data from the European Space Agency (ESA) space mission Gaia. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France. This work presents results from the European Space Agency (ESA) space mission Gaia. This work has made use of the Pan-STARRS1 Survey (PS1) and the PS1 public science archive.
