J/A+A/678/A93 Multiples among B-stars in Sco-Cen (Gratton+, 2023)
Multiples among B stars in the Scorpius-Centaurus association.
Gratton R., Squicciarini V., Nascimbeni V., Janson M., Reffert S.,
Meyer M., Delorme P., Mamajek E.E., Bonavita M., Desidera S., Mesa D.,
Rigliaco E., D'Orazi V., Vigan A., Lazzoni C., Chauvin G., Langlois M.
<Astron. Astrophys. 678, A93 (2023)>
=2023A&A...678A..93G 2023A&A...678A..93G (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Stars, double and multiple ;
Stars, B-type ; Photometry ; Optical ; Radial velocities ;
Stars, masses
Keywords: binaries: general - binaries: eclipsing - binaries: spectroscopic -
binaries: visual - stars: formation -
techniques: high angular resolution
Abstract:
The frequency, semi-major axis, and mass distribution of stellar
companions likely depend on the mass of the primaries and on the
environment where the stars form. These properties are very different
for early- and late-type stars. However, data are largely incomplete,
even for the closest environments to the Sun, preventing a cleaner
view of the problem. This paper provides basic information about the
properties of companions to B stars in the Scorpius-Centaurus
association (age ∼15Myr); this is the closest association containing
a large population of 181 B-stars. We gathered available data
combining high contrast imaging samples from BEAST, SHINE, and
previous surveys with evidence of companions from Gaia (both through
direct detection and astrometry), from eclipsing binaries, and from
spectroscopy. We evaluated the completeness of the binary search and
estimated the mass and semi-major axis for all detected companions.
These data provide a complete sample of stellar secondaries (extending
well in the substellar regime) for separation >3au, and they are
highly informative as to closer companions. We found evidence for 200
companions around 181 stars. We did not find evidence for companions
for only 43 (23.8±3.6%) of the targets, with the fraction being as
low as 15.2±4.1% for stars with MA>3.5M☉ while it is
31.5±5.9% for lower-mass stars. This confirms earlier findings for a
clear trend of a binary fraction with stellar mass. The median
semi-major axis of the orbits of the companions is smaller for B than
in A stars, confirming a turn-over previously found for OB stars. The
mass distribution of the very wide (a>1000au) and closer companions
is different. Very few companions of massive stars MA>5.0M☉
have a mass below solar and even fewer are M stars with a semi-major
axis <1000au. However, the scarcity of low-mass companions extends
throughout the whole sample. Period and mass ratio distributions are
different for early B stars (up to B7 spectral type) and stars of a
later spectral type: most early B stars are in compact systems with
massive secondaries, while less massive stars are mainly in wider
systems with a larger spread in mass ratios. We derived log-normal
fits to the distribution of the semi-major axis and mass ratios for
low and high-mass B stars; these relations suggest that it is not
probable that the planets and brown dwarf (BD) companions to b Cen and
mu2 Sco are extreme cases in the distribution of stellar companions.
We interpret our results as the formation of secondaries with a
semi-major axis <1000au (about 80% of the total) by fragmentation of
the disk of the primary and selective mass accretion on the
secondaries. The formation of secondaries within the disk of primaries
in close binaries has been proposed by many others before; it unifies
the scenarios for formation of close binaries with that of substellar
companions that also form within the primary disk, though on a
different timescale. We also find that the observed trends with
primary mass may be explained by a more prolonged phase of accretion
episodes on the disk and by a more effective inward migration.
Finally, in the Appendices we describe the detection of twelve new
stellar companions from the BEAST survey and of a new BD companion at
9.599 arcsec from HIP 74752 using Gaia data, and we discuss the cases
of possible BD and low-mass stellar companions to HIP 59173,
HIP 62058, and HIP 64053.
Description:
Files containing the basic data for B stars in the Scorpio-Centaurus
association and their companions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablee1.dat 94 181 Target list
tablee2.dat 83 191 Information about binarity
tablee3.dat 107 247 Photometry
tablee4.dat 204 246 Masses of primaries and companions
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See also:
J/AJ/152/40 : Spectroscopy of 341 bright A- and B-type stars
(Gullikson+, 2016)
J/A+A/636/A74 : HARPS radial velocity database (Trifonov+, 2020)
J/A+A/657/A7 : Stellar and substellar companions from Gaia EDR3
(Kervella+, 2022)
Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- HIP HIP number
7- 20 A14 --- OName Alternative designation
21- 26 I6 --- HD HD number
28- 35 F8.4 deg RAdeg Right ascension (J2000)
37- 44 F8.4 deg DEdeg Declination (J2000)
46- 50 F5.1 pc Dist Distance from Gaia
53- 55 I3 --- Pmemb ? Membership probability using Banyan
57- 71 A15 --- SpType Spectral type from SIMBAD
72- 76 F5.3 mag E(B-V) ? Reddening
78- 81 F4.1 Myr Age ? Age
83- 94 A12 --- Note Note
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Byte-by-byte Description of file: tablee2.dat
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Bytes Format Units Label Explanations
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2- 6 I5 --- HIP HIP number
8 I1 --- Line [1/3] Line number for this star
10- 11 A2 --- K2/TESS [T/K2 ] K2 or TESS
13- 19 A7 --- RVvar Variable type ftom RV (SB/SB2/EB/RV Var/C)
20- 26 F7.2 d dt ? HARPS dt from Trifonov et al.
(2020A&A...636A..74T 2020A&A...636A..74T, Cat. J/A+A/636/A74)
28- 31 F4.2 km/s sigma ? HARPS sigma RV from Trifonov et al.
(2020A&A...636A..74T 2020A&A...636A..74T, Cat. J/A+A/636/A74)
33- 37 F5.1 km/s RV ? Radial velocity From Gaia DR3
39- 42 F4.1 km/s e_RV ? Radial velocity error From Gaia DR3
44- 49 F6.4 --- PctRV ? Probability of constant RV from Gaia DR3
51- 55 F5.1 km/s AmpRV ? Amplitude of RV variation from Gaia DR3
57 A1 --- Det [YNx] Detection of secondary by Gullikson
et al. (2016AJ....152...40G 2016AJ....152...40G, Cat. J/AJ/152/40)
59- 64 F6.3 --- RUWE ? RUWE from Gaia DR3
66- 71 F6.2 --- PMaSNR ? GaiaDR3-Hipparcos proper motion anomaly S/N
from Kervella et al.
(2022A&A...657A...7K 2022A&A...657A...7K, Cat. J/A+A/657/A7)
74 I1 --- HCIobs ? Number of HCI observations
76 A1 --- Int [y] Interferometric observation
78- 83 F6.3 arcsec Sep ? Separataion of Gaia cpm companions
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Byte-by-byte Description of file: tablee3.dat
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Bytes Format Units Label Explanations
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2- 6 I5 --- HIP HIP number
8- 9 I2 --- Line [1/4] Line number for this star
11- 16 F6.3 arcsec Sep ? Companion projected separation
19- 26 F8.3 au a ? Semi-major axis
29- 33 F5.3 mag GmagA Gaia G magnitude of primary
35- 40 F6.3 mag GmagB ? Gaia G magnitude of secondary
43- 47 F5.3 mag KmagA ? 2MASS K magnitude of primary
51- 56 F6.3 mag KmagB ? 2MASS K magnitude of secondary
59- 64 F6.3 mag GMAGA Gaia absolute G mag of primary
67- 72 F6.3 mag GMAGB ? Gaia absolute G mag of secondary
75- 80 F6.3 mag KMAGA ? 2MASS K absolute mag of primary
85- 90 F6.3 mag KMAGB ? 2MASS K absolute mag of secondary
94- 99 F6.3 mag G-K ? Corrected G-K colour of primary
102-107 A6 --- Method Binary detection method
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Byte-by-byte Description of file: tablee4.dat
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Bytes Format Units Label Explanations
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3- 7 I5 --- HIP HIP number
10- 11 I2 --- Line [1/4] Line number for this star
16- 21 F6.3 Msun MassA Primary mass
26- 31 F6.3 Msun MassB ? Secondary mass
36- 41 F6.3 Msun MassBdyn ? Secondary mass (from RUWE or PMa or RV)
47- 52 F6.4 --- q ? Mass ratio
55-204 A150 --- Note Source
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Acknowledgements:
Raffaele Gratton, raffaele.gratton(at)inaf.it
(End) Patricia Vannier [CDS] 23-Aug-2023