GEMINI/GMOS-N spectroscopic classification of Gaia microlensing event candidates

ATel #15158; Gezer I., Zielinski P., Wyrzykowski L., Gromadzki M., Kruszynska K., Rybicki K. A., Ihanec N. (Warsaw University Astronomical Observatory, Poland), Zdanavicius J., Maskoliunas M., Pakstiene E. (Institute of Theoretical Physics and Astronomy, Vilnius University, Lithuania), Hodgkin S. (Institute of Astronomy, University of Cambridge)
on 11 Jan 2022; 08:03 UT
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Credential Certification: Ilknur Gezer (igezer@astrouw.edu.pl)

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We report on spectroscopic observations of 6 candidates for microlensing events detected by the Gaia Science Alerts program (http://gsaweb.ast.cam.ac.uk/alerts). We have obtained Gemini/GMOS long-slit spectra (GMOS; Hook et al. 2002) for 6 objects with R400 gratings which provides resolution power of R ~ 2000 and covers the wavelength range from 400 to 900 nm. The spectra are available on IAU's Transient Name Server. 

 
Gaia Name | IAU Name  | RA (J2000)  | Dec (J2000)  | Discovery date | Discovery G mag | Spectrum date| Class  
----------|-----------|-------------|--------------|----------------|-----------------|--------------|------------ 
Gaia18cmy | AT2018fxb | 05:49:54.86 | 20:17:39.70  |   2018-09-05   |  15.78          | 2018-11-27   | TTauri (1)  
Gaia18cnz | AT2018gde | 18:47:09.44 | 01:28:06.17  |   2018-09-06   |  16.16          | 2018-11-15   | AGB/Mira (2) 
Gaia18cov | AT2018gfm | 07:14:27.83 | -20:59:10.75 |   2018-09-09   |  18.02          | 2018-12-10   | Be star? (3) 
Gaia18cud | AT2018gvg | 14:33:08.31 | 49:41:14.93  |   2018-09-25   |  17.26          | 2018-11-22   | M star/ULENS (4) 
Gaia18doo | AT2018jdb | 06:59:51.41 | -09:16:19.16 |   2018-11-20   |  13.60          | 2019-01-11   | Be star (5) 
Gaia19aau | AT2018lhm | 03:10:09.07 | 59:23:45.85  |   2018-12-29   |  15.75          | 2019-01-15   | TTauri (6) 
 

Notes:
(1) D Na I and weak TiO bands are clearly distinguishable, continuum shape suggests that late-type star showing emission in Halpha line, very likely TTauri star .
(2) showing strong molecular absorptions, M-type supergiant, very likely Mira varaibale.
(3) it is A/F (or even reddened B) type-star, hydrogen absorption are strong including Paschen series, likely Be star.
(4) spectra shows weak hydrogen absoption lines with molecular bands, M-type star/ULENS .
(5) strong emission in Halpha, the continuum shape suggest that it is an early type star, very likely Be star.
(6) D Na I and TiO bands are visible, continuum shape suggests that it is a late-type star showing emission in Halpha line, very likely TTauri star.

Acknowledgments. This project has received funding from the EU Horizon 2020 research and innovation programme under grant agreement No. No 101004719, as well as Polish NCN DAINA grant 2017/27/L/ST9/03221 and Research Council of Lithuania grant No. S-LL-19-2. We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts).