J/MNRAS/521/1674 Hydrogen-deficient carbon stars spectra (Crawford+, 2023)
A spectral classification system for hydrogen-deficient carbon stars.
Crawford C.L., Tisserand P., Clayton G.C., Soon J., Bessel M., Wood P.,
Garcia-Hernandez D.A., Ruiter A.J., Seitenzahl I.R.
<Mon. Not. R. Astron. Soc. 521, 1674-1699 (2023)>
=2023MNRAS.521.1674C 2023MNRAS.521.1674C (SIMBAD/NED BibCode)
ADC_Keywords: Atlases ; Spectral types ; Stars, variable ; Stars, carbon
Keywords: atlases - stars: carbon - stars: chemically peculiar -
stars: variables: general
Abstract:
Stellar spectral classification has been highly useful in the study
of stars. While there is a currently accepted spectral classification
system for carbon stars, the subset of hydrogen-deficient carbon (HdC)
stars has not been well described by such a system, due predominantly
to their rarity and their variability. Here we present the first
system for the classification of HdCs based on their spectra, which is
made wholly on their observable appearance. We use a combination of
dimensionality reduction and clustering algorithms with human
classification to create such a system with eight total classes
corresponding to temperature, and an additional second axis
corresponding to the carbon molecular band strength. We classify over
half of the known sample of HdC stars using this, and roughly
calibrate the temperatures of each class using their colours.
Additionally, we express trends in the occurrence of certain spectral
peculiarities such as the presence of hydrogen and lithium lines. We
also present three previously unpublished spectra, report the
discovery of two new Galactic dustless HdC stars, and additionally
discuss one especially unique star that appears to border between the
hottest HdCs and the coolest extreme helium stars.
Description:
We present all spectra presented in the article, along with a full
ASCII version of Table 2, and all V-I colour information used.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 169 188 HdC spectral classes at or near maximum light
refs.dat 69 70 References
list.dat 154 287 List of individual fits spectra
sp/* . 287 Individual fits spectra
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1 A1 --- Code [123] Code (1)
3- 26 A24 --- Name Star name
29- 30 I2 h RAh Right ascension (J2000)
32- 33 I2 min RAm Right ascension (J2000)
35- 40 F6.3 s RAs Right ascension (J2000)
42 A1 --- DE- Declination sign (J2000)
43- 44 I2 deg DEd Declination (J2000)
46- 47 I2 arcmin DEm Declination (J2000)
49- 54 F6.3 arcsec DEs Declination (J2000)
55 A1 --- Inst [WDT] Instrument Code
57 A1 --- l_AV Limit flag on AV
58- 61 F4.2 mag AV V-band extinction
63- 71 A9 --- TempGroup Temperature group (warm, mild, cool)
73- 96 A24 --- Class HdC Spectral Type
98-104 A7 --- PhotStatus Photometric Status at Observation
106-113 A8 "DD/MM/YY" Obs.date Observation Date
115-128 A14 --- discRef Discovery Paper Reference, in refs.dat file
130-134 F5.2 mag Vmag ? V-band Magnitude
136-140 F5.2 mag Imag ? I-band Magntiude
142-169 A28 --- SimbadId SIMBAD Identifier (2)
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Note (1): Code as follows:
1 = Galactic RCB stars
2 = Magellanic RCB stars
3 = Galactic dLHdC star
Note (2): The main identifier used by SIMBAD for the star, which is
generally not the same as the star name used in the first column.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Ref Reference code
6- 24 A19 --- BibCode BibCode
26- 40 A15 --- Aut Author's name
42- 69 A28 --- Com Comments
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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- 24 A24 --- Name Star name
26- 29 I4 --- Nx Number of pixels along X-axis
31- 53 A23 "datime" Obs.date Observation date
55- 62 F8.3 0.1nm blambda Lower value of wavelength interval
63- 70 F8.2 0.1nm Blambda Lower value of wavelength interval
72- 79 F8.6 0.1nm dlambda Wavelentgh resolution
81- 82 I2 Kibyte size Size of FITS file
84-113 A30 --- FileName Name of FITS file, in subdirectory sp
115-154 A40 --- Title Title of the FITS file
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Acknowledgements:
Courtney Crawford, courtney.crawford(at)sydney.edu.au
(End) Courtney Crawford [USyd], Patricia Vannier [CDS] 13-Apr-2023