J/A+A/639/A7 Li-rich and non-Li-rich K giants RVs (Jorissen+, 2020)
Li-rich K giants, dust excess, and binarity.
Jorissen A., Van Winckel H., Siess L., Escorza A., Pourbaix D., Van Eck S.
<Astron. Astrophys. 639, A7 (2020)>
=2020A&A...639A...7J 2020A&A...639A...7J (SIMBAD/NED BibCode)
ADC_Keywords: Stars, K-type ; Stars, giant ; Binaries, spectroscopic ;
Radial velocities
Keywords: binaries: general - stars: evolution - stars: late-type
Abstract:
The origin of the Li-rich K giants is still highly debated. Here, we
investigate the incidence of binarity among this family from a
nine-year radial-velocity monitoring of a sample of 11 Li-rich K
giants using the HERMES spectrograph attached to the 1.2m Mercator
Telescope. A sample of 13 non-Li-rich giants (8 of them being
surrounded by dust according to IRAS, WISE, and ISO data) was
monitored alongside. When compared to the binary frequency in a
reference sample of 190K giants (containing 17.4% of definite
spectroscopic binaries - SB - and 6.3% of possible spectroscopic
binaries - SB?), the binary frequency appears normal among the
Li-rich giants (2/11 definite binaries plus 2 possible binaries, or
18.2% SB + 18.2% SB?), after taking account of the small sample size
through the hypergeometric probability distribution. Therefore, there
appears to be no causal relationship between Li enrichment and
binarity. Moreover, there is no correlation between Li enrichment and
the presence of circumstellar dust, and the only correlation that
could be found between Li enrichment and rapid rotation is that the
most Li-enriched K giants appear to be fast-rotating stars. However,
among the dusty K giants, the binary frequency is much higher (4/8
definite binaries plus 1 possible binary). The remaining 3 dusty K
giants suffer from a radial-velocity jitter, as is expected for the
most luminous K giants, which these are.
Description:
The table provides individual radial velocities (RVs) for a sample
consisting in 11 Li-rich K giants and 13 non-Li-rich K giants
(described as sample S1 in the paper). The RV monitoring of this
sample was performed (from 2009 till 2019) with the HERMES
spectrograph attached to the 1.2m Mercator telescope from the KU
Leuven installed at the Roque de los Muchachos Observatory (La Palma,
Spain). The spectrograph is fully described in Raskin et al.
(2011A&A...526A..69R 2011A&A...526A..69R). The RVs are tied to the IAU system thanks to
the monitoring of RV standard stars from the list of Udry et al.
(1999ASPC..185..367U 1999ASPC..185..367U). The uncertainty on these measurements is
0.07km/s. Most of the older measurements (with uncertainties on the
order of 0.3km/s) are from Famaey et al. (2005A&A...430..165F 2005A&A...430..165F, Cat.
J/A+A/430/165), and were obtained with the CORAVEL spectro-velocimeter
(Baranne et al., 1979VA.....23..279B 1979VA.....23..279B), also tied to the IAU RV system.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
stars.dat 36 23 List of studied stars
rv.dat 33 1238 List of individual radial velocities
tablea2.dat 108 190 Sample R (Kepler and CoRoT K giants) and its
binary properties (see Sect. 5.1)
--------------------------------------------------------------------------------
See also:
J/A+A/430/165 : Radial velocities for 6691 K and M giants (Famaey+, 2005)
Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [HD]
4- 9 I6 --- HD HD number of target star
11- 12 I2 h RAh Simbad right Ascension (J2000.0)
14- 15 I2 min RAm Simbad right Ascension (J2000.0)
17- 21 F5.2 s RAs Simbad right Ascension (J2000.0)
23 A1 --- DE- Simbad declination sign (J2000.0)
24- 25 I2 deg DEd Simbad declination (J2000.0)
27- 28 I2 arcmin DEm Simbad declination (J2000.0)
30- 33 F4.1 arcsec DEs Simbad DEclination (J2000.0)
35- 36 I2 --- Nobs Number of RV measurements on rv.dat file
--------------------------------------------------------------------------------
Byte-by-byte Description of file: rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 8 I6 --- HD HD number of target star
11- 19 F9.3 d JD Julian date (JD-2400000)
22- 27 F6.2 km/s RV Radial velocity
30- 33 F4.2 km/s e_RV Uncertainty on radial velocity
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- KIC/CoRoT KIC/Corot identification number
11- 14 F4.2 km/s sigmaj(RV) RV standard deviation
16- 20 F5.3 km/s sigma(O-C) ? Standard deviation of the O-C residuals
(for systems with orbital solutions)
22- 28 F7.2 km/s Mean HERMES radial velocity
30- 31 I2 --- NobsHj Number of HERMES RV observations
33- 36 I4 d DELTAt HERMES RV observations time span
38- 45 F8.2 --- chi2j/nuj Reduced chi2, with nuj=NobsHj-1
48- 51 F4.2 --- Prob Associated probability that the star has
a variable RV
53- 58 F6.2 --- F2j F2 statistic
60- 66 F7.2 km/s ? Mean Gaia DR2 radial velocity
68- 71 F4.2 km/s sigma ? Gaia DR2 radial velocity standard
deviation
73- 76 F4.2 km/s eps(RVG) ? Expected uncertainty on the Gaia DR2
RV (see Eq. (3))
78- 82 F5.2 km/s |-| ? Velocity difference, HERMES - Gaia DR2
84- 88 F5.2 mag Gmag ? Gaia DR2 G magnitude
90- 94 F5.2 mag GRVS ? Gaia DR2 stellar magnitude GRVS in the
Radial Velocity Spectrometer pass band
96-108 A13 --- SB Final decision about binarity, from HERMES
and Gaia DR2 data (1)
--------------------------------------------------------------------------------
Note (1): In column SB, "outlier" means that one data point is responsible for
the larger than expected sigmaj(RV) value.
--------------------------------------------------------------------------------
Acknowledgements:
Alain Jorissen, ajorisse(at)astro.ulb.ac.be
(End) Patricia Vannier [CDS] 22-May-2020