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. =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; Catanzarite et al. 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)) 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