J/AJ/166/68 30 new Wolf-Rayet stars in M31 (Neugent+, 2023)
Newly Discovered Wolf-Rayet Stars in M31.
Neugent K.F., Massey P.
<Astron. J., 166, 68 (2023)>
=2023AJ....166...68N 2023AJ....166...68N
ADC_Keywords: Stars, Wolf-Rayet ; Photometry ; Spectral types
Keywords: Wolf-Rayet stars ; Massive stars ; Evolved stars ; Andromeda
Galaxy ; Stellar populations
Abstract:
The evolved massive star populations of the Local Group galaxies are
generally thought to be well understood. However, recent work has
suggested that the Wolf-Rayet (WR) content of M31 may have been
underestimated. We therefore began a pilot project to search for new
WRs in M31 and to reexamine the completeness of our previous WR
survey, finished almost a decade prior. Our improved imaging data and
spectroscopic follow-up confirmed 19 new WRs across three small fields
in M31. These newly discovered WRs are generally fainter than the
previously known sample due to slightly increased reddening as opposed
to intrinsic faintness. From these findings, we estimate that there
are another ∼60 WRs left to be discovered in M31; however, the overall
ratio of WN-type (nitrogen-rich) to WC-type (carbon-rich) WRs remains
unchanged with our latest additions to the M31 WR census. We are in
the process of extending this pilot WR survey to include the rest of
M31, and a more complete population will be detailed in our future
work.
Description:
We observed three regions of M31 with LMI on the 4.3m LDT during dark
time in Fall 2021. Our overall goal was to obtain multiple 20 minute
exposures in each of the WN, WC, and CT filters and then produce
final, combined images to identify candidate WRs using image
subtraction and photometry. The LMI detector is a 92.2mm by 92.4mm
single array of 6144x6160e2v CCD231-C6 with a multilayer
anti-reflective coatingAll images were taken with the detector binned
by 2x2, resulting in a scale of 0.24"/pixel, and covering a field of
view of 12x3'x12x3'.
Object:
-----------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------
00 42 44.33 +41 16 07.5 M31 = 2C 56
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 70 22 Re-observed known WRs
table3.dat 71 30 Spectroscopic results of new WR candidates
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See also:
III/143 : Spectrophotometry of Wolf-Rayet Stars (Torres-Dodgen+ 1988)
III/215 : 7th Catalog of Galactic Wolf-Rayet stars (van der Hucht, 2001)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/ApJ/339/53 : Planetary nebulae as standard candles. II. (Ciardullo+, 1989)
J/ApJ/505/793 : New WR star in M33 (Massey+, 1998)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/MNRAS/369/120 : Kinematic survey of planetary nebulae in M31 (Merrett+, 2006)
J/ApJ/733/123 : The Wolf-Rayet content of M33 (NGC 598) (Neugent+, 2011)
J/ApJ/759/11 : Wolf-Rayet content of M31 (Neugent+, 2012)
J/ApJ/789/10 : M33 WR and Of-type Stars (Neugent+, 2014)
J/AJ/152/62 : LGGS UBVRI photometry of M31 and M33 stars (Massey+, 2016)
J/ApJ/863/181 : The fifth catalog of LMC Wolf-Rayet stars (Neugent+, 2018)
J/ApJ/922/177 : 2MASS red supergiants in the SMC (Massey+, 2021)
J/AJ/161/79 : Red supergiant stars in M31 and M33 (Massey+, 2021)
J/A+A/664/A93 : Northern WNE star spectra (Dsilva+, 2022)
J/ApJS/259/12 : Dust extinction law in nearby galaxies. I. M31 (Wang+, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- ID Position-based LGGS designations
21- 28 A8 --- SpTOld Old Spectral Type (1)
30- 37 A8 --- SpTNew New Spectral Type
39- 70 A32 --- Comments Comments
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Note (1): Classifications from Neugent+, 2012, J/ApJ/759/11 and
references therein.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- ID Position-based LGGS designations (1)
21- 22 I2 h RAh [0] Hour of Right Ascension (J2000)
24- 25 I2 min RAm [40/44] Minute of Right Ascension (J2000)
27- 32 F6.3 s RAs [4/60] Second of Right Ascension (J2000)
34- 34 A1 --- DE- Sign of the Declination (J2000)
35- 36 I2 deg DEd Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000)
47- 50 I4 0.1nm EW [-900/-4]? Equivalent Width, Angstroms (2)
52- 52 A1 --- q_EW Quality flag for EW
54- 57 F4.1 0.1nm FWHM [4/90]? Full Width at Half Maximum, Angstroms (2)
59- 59 A1 --- q_FWHM Quality flag for FWHM
61- 71 A11 --- Class Classification
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Note (1): Continuing the LGGS extension used in Neugent+, 2012,
J/ApJ/759/11, new designations are prefixed with an "X". For new
sources, the designations are based on positions oriented to the ICRS
(Gaia), while for "J" sources in this table the positions are from the
LGGS, tied to the USNO-B.
Note (2): Equivalent Width (EW) and Full Width at Half Maximum (FWHM)
for HeII4686 for WN stars, and CIII/IV4650 for WC stars.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 15-Apr-2024