J/A+A/641/A42 Main-sequence companions to massive Be stars (Bodensteiner+, 2020)
Investigating the lack of main-sequence companions to massive Be stars.
Bodensteiner J., Shenar T., Sana H.
<Astron. Astrophys. 641, A42 (2020)>
=2020A&A...641A..42B 2020A&A...641A..42B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Stars, dwarfs ; Spectral types
Keywords: binaries: spectroscopic - binaries: close - stars: emission-line, Be -
stars: massive - stars: massive
Abstract:
About 20% of all B-type stars are classical Be stars. The Be
phenomenon is strongly correlated with rapid rotation, the origin of
which remains unclear. It may be rooted in single- or binary-star
evolution. In the framework of the binary channel, the initially more
massive star transfers mass and angular momentum to the original
secondary, which becomes a Be star. The system then evolves into a Be
binary with a post-main-sequence companion, which may later be
disrupted in a supernova event. Hence, if the binary channel dominates
the formation of Be stars, one may expect a strong lack of close Be
binaries with main sequence (MS) companions. Through an extensive,
star-by-star review of the literature of a magnitude-limited sample of
Galactic early-type Be stars, we investigate whether Be binaries with
MS companions are known to exist. Our sample is constructed from the
BeSS database and cross-matched with all available literature on the
individual stars. Out of an initial list of 505 Be stars, we compile a
final sample of 287 Galactic Be stars earlier than B1.5 with V≤12mag.
Out of those, 13 objects were reported as Be binaries with known
post-MS companions and 11 as binaries with unknown, uncertain or
debated companions. We find no confirmed reports of Be binaries with
MS companions. For the remaining 263 targets, no significant reports
of multiplicity exist in the literature, implying that they are either
Be binaries with faint companions, or truly single. The clear lack of
reported MS companions to Be stars, which stands in contrast to the
high number of detected B+B MS binaries, strongly supports the
hypothesis that early-type Be stars are binary interaction products
that spun up after mass and angular momentum transfer from a companion
star. Taken at face value, our results may suggest that a large
majority of the early-type Be stars have formed through binary
mass-transfer.
Description:
Overview over the stellar parameters found the literature study we
performed.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 228 287 Stars in the final sample
tablec2.dat 147 71 Stars that are probably not classical Be stars
tablec3.dat 104 147 Be stars with spectral types later than B1.5
or unknown spectral type
refs.dat 160 173 References
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Star name
17- 22 A6 --- HD ? HD number
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 35 F6.3 s RAs Right ascension (J2000)
37 A1 --- DE- Declination sign (J2000)
38- 39 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
44- 49 F6.3 arcsec DEs Declination (J2000)
51- 54 F4.1 mag Vmag V magnitude
56- 73 A18 --- SpType Spectral type
75- 82 A8 --- r_SpType Spectral type reference, in refs.dat file
84-225 A142 --- Comments Comments (G1)
227-228 A2 --- Class [i ii iv] Class
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Byte-by-byte Description of file: tablec2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Star name
13- 18 I6 --- HD ? HD number
20- 21 I2 h RAh Right Ascension (J2000)
23- 24 I2 min RAm Right Ascension (J2000)
26- 31 F6.3 s RAs Right Ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
34- 35 I2 deg DEd Declination (J2000)
37- 38 I2 arcmin DEm Declination (J2000)
40- 45 F6.3 arcsec DEs Declination (J2000)
47- 50 F4.1 mag Vmag V magnitude
52- 88 A37 --- SpType Spectral type
90- 93 A4 --- r_SpType Spectral type reference, in refs.dat file
95-147 A53 --- Comments Comments (G1)
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Byte-by-byte Description of file: tablec3.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Star name
22- 27 I6 --- HD ? HD number
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)
56- 59 F4.1 mag Vmag V magnitude
61- 72 A12 --- SpType Spectral type
74- 77 A4 --- r_SpType Spectral type reference, in refs.dat file
78-104 A27 --- Comments Comments (G1)
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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- 6 A6 --- Ref Reference code
8- 26 A19 --- BibCode BibCode
28- 52 A25 --- Aut Atuhor's name
53-160 A108 --- Com Comments
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Global notes:
Note (G1): Abbreviations used in the comment column:
App = indicates that the there is a more detailed comment in the appendix B
Ker19 = indicates that Kervella et al. (2019, Cat. J/A+A/623/A72) detect the
star in their sample (see Appendix B.1).
W18 = means that Wang et al. (2018ApJ...853..156W 2018ApJ...853..156W) included the star in
their sample but did not detect the signature of a companion.
runaway = indicates that the star was classified as runaway candidate in the
literature.
Kle19 = indicates that Klement et al. (2019ApJ...885..147K 2019ApJ...885..147K) find an SED
turndown indicative of a close binary companion.
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Acknowledgements:
Julia Bodensteiner, julia.bodensteiner(at)kuleuven.be
(End) Patricia Vannier [CDS] 17-Jul-2020