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J/A+A/475/539   BV photometry and Li abundances in NGC3960   (Prisinzano+, 2007)

Lithium abundances in the old open cluster NGC 3960 from VLT/FLAMES observations. Prisinzano L., Randich S. <Astron. Astrophys. 475, 539 (2007)> =2007A&A...475..539P
ADC_Keywords: Clusters, open ; Photometry, UBV ; Abundances Keywords: stars: abundances - stars: evolution - Galaxy: open clusters and associations: individual: NGC 3960 Abstract: Old open clusters are very useful targets to investigate mechanisms responsible for lithium (Li) depletion during the main sequence. Comparison of the Li abundances in clusters of different age allows us to understand the efficiency of the Li destruction process. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age ∼1Gyr), aiming to fill the gap between 0.6 and 2Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. We use VLT/FLAMES Giraffe spectra to determine the radial velocities and thus the membership of a sample of 113 photometrically selected candidate cluster members. From the analysis of the Li line we derive Li abundances for both cluster members and non-members. 39 stars have radial velocities consistent with membership, with an expected fraction of contaminating field stars of about 20%. Li is detected in 29 of the radial velocity members; we consider these stars as cluster members, while we make the reasonable assumption that the remaining 10 radial velocity members without Li are among the contaminating stars. Li abundances of the stars hotter than about 6000K are similar to those of stars in the Hyades, while they are slightly smaller for cooler stars. This confirms that NGC 3960 is older than the Hyades. The average Li abundance of stars cooler than about 6000K indicates that the Li Pop. I plateau might start at ∼1Gyr, rather than 2Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (>1.5) is about one third of the whole sample, which is in agreement with previous estimates. The fraction of contaminating field stars is consistent with that previously derived by us from photometry. Description: The observations were carried out in Service Mode during February, March and April 2004. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 135 113 Stellar parameters for the NGC 3960 stars observed with GIRAFFE
See also: J/A+A/417/945 : BVI & JHK photometry of NGC 3960 (Prisinzano+, 2004) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 6 I6 --- P04 Identification number of Prisinzano et al., Cat. J/A+A/417/945, Cl* NGC 3960 PMS NNNNNN in Simbad (1) 8- 16 A9 --- Name Giraffe identification name, OC21-MNNN 18- 20 I3 --- Nsp Spectrum number 22- 33 F12.8 deg RAdeg Right ascension in decimal degrees (J2000) 35- 46 F12.8 deg DEdeg Declination in decimal degrees (J2000) 48- 53 F6.3 mag Vmag V magnitude 55- 59 F5.3 mag e_Vmag rms uncertainty on Vmag 61- 66 F6.3 mag Bmag B magnitude 68- 72 F5.3 mag e_Bmag rms uncertainty on Bmag 74- 79 F6.3 mag V0mag V magnitude corrected for differential reddening 81- 86 F6.3 mag B0mag B magnitude corrected for differential reddening 88- 93 F6.2 km/s RV Radial velocity 95- 99 F5.2 km/s e_RV rms uncertainty on RV 101 I1 --- Mmb [0/2] Membership flag based on RV: 0=non-member, 1=member, 2=binary 103-106 I4 K Teff Effective temperature computed for the (B-V)0 colour index, corrected for differential reddening 108-110 I3 K e_Teff rms uncertainty on Teff 112 A1 --- l_EW(Li) Limit flag on EW(Li) 113-115 I3 0.1pm EW(Li) ? Li equivalent width (in mÅ) 117-118 I2 0.1pm e_EW(Li) ? rms uncertainty on EW(Li) 120 A1 --- l_A(Li)LTE Limit flag on A(Li)LTE 121-124 F4.2 [-] A(Li)LTE ? LTE Li abundance (H=12, LTE model) 126 A1 --- l_A(Li)NLTE Limit flag on A(Li)NLTE 127-130 F4.2 [-] A(Li)NLTE ? NLTE Li abundance (H=12, non-LTE model) 132-135 F4.2 [-] e_A(Li)NLTE ? rms uncertainty on A(Li)NLTE
Note (1): Numbers as in the second version of the table (13-Nov-2007)
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Nov-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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