J/A+A/626/A128 Main-sequence and subgiant Barium stars (Escorza+, 2019)
Barium and related stars, and their white-dwarf companions.
II. Main-sequence and subgiant stars.
Escorza A., Karinkuzhi D., Jorissen A., Siess L., Van Winckel H.,
Pourbaix D., Johnston C., Miszalski B., Oomen G-M., Abdul-Masih M.
Boffin H.M.J., North P., Manick R., Shetye S., Mikolajewska J.
<Astron. Astrophys. 626, A128 (2019)>
=2019A&A...626A.128E 2019A&A...626A.128E (SIMBAD/NED BibCode)
ADC_Keywords: Stars, barium ; Stars, white dwarf ; Stars, masses ;
Binaries, spectroscopic
Keywords: stars: late-type - stars: chemically peculiar -
binaries: spectroscopic - techniques: imaging spectroscopy
Abstract:
Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of
Ba and CH giants. They are F- to G-type main-sequence stars polluted
with heavy elements by their binary companions when the companion was
on the asymptotic giant branch (AGB). This companion is now a white
dwarf that in most cases cannot be directly detected. We present a
large systematic study of 60 objects classified as Ba dwarfs or CH
subgiants. Combining radial-velocity measurements from HERMES and SALT
high-resolution spectra with radial-velocity data from CORAVEL and
CORALIE, we determine the orbital parameters of 27 systems. We also
derive their masses by comparing their location in the
Hertzsprung-Russell diagram with evolutionary models. We confirm
that Ba dwarfs and CH subgiants are not at different evolutionary
stages, and that they have similar metallicities, despite their
different names. Additionally, Ba giants appear significantly more
massive than their main-sequence analogues. This is likely due to
observational biases against the detection of hotter main- sequence
post-mass-transfer objects. Combining our spectroscopic orbits with
the Hipparcos astrometric data, we derive the orbital inclination and
the mass of the WD companion for four systems. Since this cannot be
done for all systems in our sample yet (but should be possible with
upcoming Gaia data releases), we also analyse the mass-function
distribution of our binaries. We can model this distribution with
very narrow mass distributions for the two components and random
orbital orientations on the sky. Finally, based on BINSTAR
evolutionary models, we suggest that the orbital evolution of low-mass
Ba systems can be affected by a second phase of interactions along the
red giant branch of the Ba star, which impact the eccentricities and
periods of the giants.
Description:
This catalogue contains radial-velocity data for a sample of
main-sequence and subgiants barium and related stars. The catalogue
includes data obtained with HERMES, CORAVEL, SALT-HRS, CORALIE and
ELODIE.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 34 57 List of studied stars
rvdata.dat 52 2000 Radial velocity data of Ba dwarfs
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See also:
J/A+A/626/A127 : Barium and related stars and WD companions (Jorissen+, 2019)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 13 I2 h RAh Simbad Right ascension (J2000)
15- 16 I2 min RAm Simbad Right ascension (J2000)
18- 22 F5.2 s RAs Simbad Right ascension (J2000)
24 A1 --- DE- Simbad Declination sign (J2000)
25- 26 I2 deg DEd Simbad Declination (J2000)
28- 29 I2 arcmin DEm Simbad Declination (J2000)
31- 34 F4.1 arcsec DEs Simbad Declination (J2000)
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Byte-by-byte Description of file: rvdata.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 22 F11.3 d HJD Heliocentric Julian Date
24- 30 F7.3 km/s RV Radial-velocity measurement
32- 36 F5.3 km/s e_RV Error on the RV value
38- 46 A9 --- Inst Instrument
47- 52 F6.3 km/s Offset ?=- Proposed offset to CORAVEL data (1)
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Note (1): Some CORAVEL radial velocities are from before 1999 and are tied to
an old velocity system, previous to the ELODIE velocity system (Udry
et al. 1999). Hence, a zero-point offset needs to be applied in
order to convert them to the ELODIE system and combine them with
HERMES data. We proposed zero-point offsets that depend on the B-V
index (see Sect. 2.1 of the paper).
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Acknowledgements:
Ana Escorza, ana.escorza(at)kuleuven.be
References:
Jorissen et al., Paper I, 2019A&A...626A.127J 2019A&A...626A.127J, Cat. J/A+A/626/A127
History:
25-Jun-2019: on-line data
03-Jul-2019: RV offset of HD 50264 corrected
(End) Ana Escorza [KU Leuven], Patricia Vannier [CDS] 27-Apr-2019