J/A+A/657/A17 Gaia 19bld spectroscopic follow-up (Bachelet+, 2022)
A spectroscopic follow-up for Gaia 19bld.
Bachelet E., Zielinski P., Gromadzki M., Gezer I., Rybicki K.,
Kruszynska K., Ihanec N., Wyrzykowski L., Street R.A., Tsapras Y.,
Hundertmark M., Cassan A., Harbeck D., Rabus M.
<Astron. Astrophys. 657, A17 (2022)>
=2022A&A...657A..17B 2022A&A...657A..17B (SIMBAD/NED BibCode)
ADC_Keywords: Gravitational lensing ; Spectroscopy
Keywords: gravitational lensing: micro - techniques: spectroscopic -
stars: fundamental parameters
Abstract: Due to their scarcity, microlensing events in the Galactic
disk are of great interest and high-cadence photometric observations,
supplemented by spectroscopic follow-up, are necessary for
constraining the physical parameters of the lensing system. In
particular, a precise estimate of the source characteristics is
required to accurately measure the lens distance and mass.
We conducted a spectroscopic follow-up of microlensing event Gaia19bld
to derive the properties of the microlensing source and, ultimately,
to estimate the mass and distance of the lens.
We obtained low- and high-resolution spectroscopy from multiple sites
around the world during the course of the event. The spectral lines
and template matching analysis has led to two independent, consistent
characterizations of the source.
We found that the source is a red giant located at ∼8.5kpc from the
Earth. Combining our results with the photometric analysis has led to
a lens mass of Ml∼1.1M☉ at a distance of Dl∼5.5kpc. We did not
find any significant blend light in the spectra (with an upper
detection limit of V≤17mag), which is in agreement with photometric
observations. Therefore, we cannot exclude the possibility that the
lens is a main-sequence star. Indeed, we predict in this scenario a
lens brightness of V∼20mag, a value that would make it much fainter
than the detection limit.
Description:
As the event displayed an increased brightness, spectroscopic
follow-up observations were immediately scheduled. Low-resolution
spectra (R∼500) were obtained using the FLOYDS spectrograph, which
is mounted on the Las Cumbres Observatory (LCO) 2-m telescope at
Siding Spring Observatory
In addition,we used the X-shooter instrument mounted on the ESO Very
Large Telescope (VLT) which is a multi-wavelength, medium-resolution
spectrograph consisted of three spectroscopic arms allowing for
simultaneous observations at three wavelength ranges: UVB
(300-559.5nm), VIS (559.5-1024nm), and NIR (1024-2480nm).
Spectra used in this publication.
Objects:
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RA (2000) DE Designation(s)
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12 37 32.56 -66 06 40.9 Gaia 19bld = NAME AT 2019dqb
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 49 12 List of spectra
sp/* . 12 Individual spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Inst Instrument
14- 23 A10 "date" Obs.date Observaton date
25- 49 A25 --- FileName Name of the table with spectrum
in subdirectory sp
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 20 F20.14 0.1nm lambda Wavelength
22- 43 E22.17 10mW/m2/nm Flux Flux (erg/s/cm2/Å)
45- 66 E22.17 10mW/m2/nm e_Flux ?=- Error in Flux (erg/s/cm2/Å)
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Acknowledgements:
Etienne Bachelet, etibachelet(at)gmail.com
(End) Patricia Vannier [CDS] 27-Oct-2021