J/A+A/695/A227 Optical spectra of new WR stars and candidates (Mulato+, 2025)
Search for new Galactic Wolf-Rayet stars using Gaia DR3.
I. Candidate selection and the follow-up of the bright sample.
Mulato L., Merc J., Charbonnel S., Garde O., Le Du P., Petit T.
<Astron. Astrophys. 695, A227 (2025)>
=2025A&A...695A.227M 2025A&A...695A.227M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Wolf-Rayet ; Stars, early-type ; Spectra, optical
Keywords: stars: early-type - stars: massive - stars: Wolf-Rayet
Abstract:
Gaia DR3, released in June 2022, included low-resolution XP spectra
that have been used for the classification of various types of
emission-line objects through machine-learning techniques. The Gaia
Extended Stellar Parametrizer for Emission-Line Stars (ESP-ELS)
algorithm identified 565 sources as potential Wolf-Rayet (WR) stars.
Over half of them were already known as WR stars in the Milky Way and
Magellanic Clouds.
We utilized Gaia DR3 data to identify new Galactic WR stars.
We extracted all sources classified as WC or WN type stars by the
ESP-ELS algorithm from the Gaia catalog. By applying judicious 2MASS
color selection criteria, leveraging Gaia Hα measurements, and
filtering out objects already cataloged in various databases, we
selected 37 bright candidates (G≤16mag) and 22 faint candidates
(G>16mag). Spectroscopic follow-up observations of these candidates
were conducted using the 2SPOT facilities in Chile and France, as well
as 1-m C2PU's Epsilon telescope at the Calern Observatory.
This paper focuses on the brighter sample. Among the 37 targets, we
confirmed 17 and 16 new Galactic WC and WN type WR stars,
respectively. Three of them were recently reported as new WR stars in
an independent study.
The Gaia mission provides a valuable resource for uncovering WR stars
missed in earlier surveys. While this work concentrated on a
relatively small starting sample provided by the ESP-ELS algorithm,
our findings highlight the potential for refining selection criteria
to identify additional candidates not included in the outputs of the
algorithm. Furthermore, the observation program underscores the
utility of small telescopes in acquiring initial spectral data for
sources with magnitudes up to G∼16mag.
Description:
We present the spectroscopic observations of all our 37 bright WR
candidates (G<16mag). The data were obtained using facilities of
the Southern Spectroscopic Project Observatory Team (2SPOT) consortium
and C2PU's Epsilon 1-m Telescope at the Calern Observatory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 123 37 List of spectra
fits/* . 37 Individual spectra
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 17 F17.13 deg RAdeg Right Ascension of center (ICRS) at Ep=2016.0
19- 35 F17.13 deg DEdeg Declination of center (ICRS) at Ep=2016.0
37- 40 I4 --- Nx Number of pixels along X-axis
42- 60 A19 "datime" Obs.date Observation date
62- 68 F7.2 0.1nm blambda Lower value of wavelength interval
70- 76 F7.2 0.1nm Blambda Upper value of wavelength interval
78- 85 F8.6 0.1nm dlambda Wavelength resolution
87- 88 I2 Kibyte size Size of FITS file
90-100 A11 --- FileName Name of FITS file, in subdirectory fits
102-123 A22 --- Title Title of the FITS file
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Acknowledgements:
Lionel Mulato, lionelmulato(at)gmail.com
(End) Lionel Mulato [2SPOT], Patricia Vannier [CDS] 25-Feb-2025