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J/A+A/528/A127   Radial velocities in the globular NGC 2808  (Moni Bidin+, 2011)

A lack of close binaries among hot horizontal branch stars in globular clusters. II. NGC 2808. Moni Bidin C., Villanova S., Piotto G., Momany Y. <Astron. Astrophys., 528, A127 (2011)> =2011A&A...528A.127M
ADC_Keywords: Clusters, globular ; Binaries, spectroscopic ; Stars, horizontal branch Keywords: stars: horizontal-branch - binaries: close - binaries: spectroscopic - globular clusters: individual: NGC 2808 Abstract: The formation mechanism of hot horizontal branch (HB) stars is still one of the most uncertain points of stellar evolution theories. In the past decade, models based on their binary origin have been very successful in reproducing the properties of field subdwarf-B stars, but the observations of their analogues in globular clusters has posed new problems. In addition, the discovery of multiple populations offered an appealing alternative scenario for the formation of these stars. We search for binaries of period P≤200days among a sample of 83 blue horizontal branch stars (Teff=12000-22000K) in NGC 2808, a cluster known to host three distinct stellar populations and a multimodal horizontal branch. The final sample, after the rejection of stars with incomplete observations or poor quality data, consists of 64 targets. The radial velocity of the targets was measured in fourteen epochs, spanning a temporal interval of ∼75days. The significant variations were identified by means of a detailed error analysis and a statistical study. Description: Twenty-four single spectra of target stars were collected in fourteen epochs between January 11 and March 24, 2007, with the GIRAFFE spectrograph at the VLT-UT2 telescope, in both visitor and service mode. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 65 83 Data of program stars
See also: J/A+AS/84/59 : Photometry of NGC 2808 (Ferraro+, 1990) J/ApJ/562/368 : UV photometry in NGC 2808 (Brown+, 2001) J/A+A/413/343 : RGB stars in NGC 2808 (Cacciari+, 2004) J/ApJ/625/156 : FUV-NUV observations of NGC 2808 (Dieball+, 2005) J/AJ/131/1766 : Abundances and equivalent widths in NGC 2808 (Carretta, 2006) J/A+A/490/641 : X-ray sources toward NGC 2808 (Servillat+, 2008) J/A+A/480/397 : XMM observations of NGC 2808 and NGC 4372 (Servillat+, 2008) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 5 I5 --- Seq Sequential number (<[MVP2011] NNNNN> in Simbad) 7- 8 I2 h RAh Right ascension (J2000) 10- 11 I2 min RAm Right ascension (J2000) 13- 17 F5.2 s RAs Right ascension (J2000) 19 A1 --- DE- Declination sign (J2000) 20- 21 I2 deg DEd Declination (J2000) 23- 24 I2 arcmin DEm Declination (J2000) 26- 29 F4.1 arcsec DEs Declination (J2000) 31- 36 F6.3 mag Vmag V magnitude 38- 43 F6.3 mag U-V U-V colour index 45- 49 I5 K Teff Effective temperature 51 A1 --- l_<RV> [~] Limit flag on <RV> 52- 56 F5.1 km/s <RV> ?=- Weighted average radial velocity 58- 60 F3.1 km/s e_<RV> ?=- rms uncertainty on <RV> 62- 65 F4.2 km/s Dmax ?=- Maximum residual of Δi=(RVi-<RV>)/σi
History: From electronic version of the journal References: Moni bidin et al., NGC 6752 2006A&A...451..499M Moni bidin et al., M80 and NGC 5986 2009A&A...498..737M
(End) Patricia Vannier [CDS] 18-Aug-2011
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