J/ApJ/732/39 Rotational velocities of K giant stars (Carlberg+, 2011)
The frequency of rapid rotation among K giant stars.
Carlberg J.K., Majewski S.R., Patterson R.J., Bizyaev D., Smith V.V.,
Cunha K.
<Astrophys. J., 732, 39 (2011)>
=2011ApJ...732...39C 2011ApJ...732...39C
ADC_Keywords: Rotational velocities ; Stars, giant ; Stars, K-type ;
Effective temperatures
Keywords: stars: late-type - stars: rotation
Abstract:
We present the results of a search for unusually rapidly rotating
giant stars in a large sample of K giants (∼1300 stars) that had been
spectroscopically monitored as potential targets for the Space
Interferometry Mission's Astrometric Grid. The stars in this catalog
are much fainter and typically more metal-poor than those of other
catalogs of red giant star rotational velocities, but the spectra
generally only have signal-to-noise ratio (S/N) of ∼20-60, making the
measurement of the widths of individual lines difficult. To compensate
for this, we have developed a cross-correlation method to derive
rotational velocities in moderate S/N echelle spectra to efficiently
probe this sample for rapid rotator candidates. We have discovered 28
new red giant rapid rotators as well as one extreme rapid rotator with
a vsin i of 86.4km/s. Rapid rotators comprise 2.2% of our sample,
which is consistent with other surveys of brighter, more metal-rich K
giant stars. Although we find that the temperature distribution of
rapid rotators is similar to that of the slow rotators, this may not
be the case with the distributions of surface gravity and metallicity.
The rapid rotators show a slight overabundance of low-gravity stars
and as a group are significantly more metal-poor than the slow
rotators, which may indicate that the rotators are tidally locked
binaries.
Description:
The giant stars comprising our sample were observed for RV stability
and characterization by Bizyaev et al. (2006, Cat. J/AJ/131/1784 and
2010, Cat. J/AJ/140/1911) as candidates for SIM's Astrometric Grid
(Ciardi 2004AAS...204.6109C 2004AAS...204.6109C; Catanzarite et al. 2004AAS...205.9111C 2004AAS...205.9111C);
we use these same spectra here for the vsin i measurements. The total
sample presented in this work is composed of 603 GGSS (Grid Giant Star
Survey (Patterson et al. 2001ASPC..246...65P 2001ASPC..246...65P)) and 684 Tycho (Hog et
al. 2000, Cat. I/259) stars.
The observations were carried out with the 2.1m telescope at McDonald
Observatory with the Sandiford Cassegrain Echelle spectrograph between
2001 January and 2006 July. The spectra have high nominal resolution
(R∼55000) and a typical S/N between 20 and 60.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 57 1287 Program stars and aliases
table2.dat 58 1274 Properties of stars not flagged in the vsini
derivation
table3.dat 58 13 Properties of stars that were flagged in the
vsini derivation (potentially unreliable)
--------------------------------------------------------------------------------
See also:
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
J/A+A/536/A71 : Atmospheric parameters of nearby giant stars (Jones+, 2011)
J/AJ/140/1911 : Astrometric Grid Giant Star Survey. II. (Bizyaev+, 2010)
J/AJ/135/209 : Rotational and radial velocities 761 HIP giants (Massarotti+,
2008)
J/A+A/475/1003 : Stellar parameters of G and K giant stars (Hekker+, 2007)
J/AJ/131/1784 : Astrometric Grid Giant Star Survey. I. (Bizyaev+, 2006)
J/A+AS/127/277 : Rotation and binary rate among giant F stars (Kunzli+ 1998)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Stellar name (Gllll+bb.bbbbb or TycNNNN-NNNNN-N)
or
in Simbad
17- 19 A3 --- --- [Tyc]
20- 31 A12 --- TYC The Tycho designation (FFFF-NNNNN-N) (Cat. I/259)
33- 38 A6 --- HIP The HIP number (Cat. I/311)
40- 45 A6 --- HD The HD number
47- 57 A11 --- BD The BD designation (BD+DD NNNNa)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Stellar Name
17- 18 I2 h RAh Hour of Right Ascension (J2000)
20- 21 I2 min RAm Minute of Right Ascension (J2000)
23- 27 F5.2 s RAs Second of Right Ascension (J2000)
29 A1 --- DE- Sign of the Declination (J2000)
30- 31 I2 deg DEd Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 40 F5.2 arcsec DEs Arcsecond of Declination (J2000)
42 A1 --- l_vsini Upper limit indicator on vsini
43- 46 F4.1 km/s vsini Projected rotational velocity
48- 50 F3.1 km/s e_vsini Uncertainty in vsini
52- 53 I2 --- o_vsini Number of individual measures in vsini measure
55- 58 I4 K Teff Effective temperature from photometry
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Oct-2012