Lithium abundances in the old open cluster NGC3960 from VLT/FLAMES observations

被引:9
作者
Prisinzano, L.
Randich, S.
机构
[1] INAF Osservatorio Astron Palermo, I-90134 Palermo, Italy
[2] INAF Osservatorio Astrofis Arcetri, I-50125 Florence, Italy
关键词
stars : abundances; stars : evolution; Galaxy : open clusters and associations : individual : NGC3960;
D O I
10.1051/0004-6361:20078341
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Context. 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 effeciency of the Li destruction process. Aims. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age similar to 1 Gyr), aiming to fill the gap between 0.6 and 2 Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. Methods. We use VLT/FLAMES Giraffle 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. Results. 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 6000 K 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. Conclusions. The average Li abundance of stars cooler than about 6000 K indicates that the Li Pop. I plateau might start at similar to 1 Gyr, rather than 2 Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (greater than or similar to 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.
引用
收藏
页码:539 / U41
页数:13
相关论文
共 50 条
[41]   WIYN OPEN CLUSTER STUDY. LXIII. ABUNDANCES IN THE SUPER-METAL-RICH OPEN CLUSTER NGC 6253 FROM HYDRA SPECTROSCOPY OF THE 7774 Å OXYGEN TRIPLET REGION [J].
Maderak, Ryan M. ;
Deliyannis, Constantine P. ;
Anthony-Twarog, Barbara J. ;
Twarog, Bruce A. ;
Cummings, Jeffery D. ;
King, Jeremy R. ;
Steiman-Cameron, Thomas Y. .
ASTRONOMICAL JOURNAL, 2015, 149 (04)
[42]   WIYN open cluster study. XVIII. The tidal circularization cutoff period of the old open cluster NGC 188 [J].
Mathieu, RD ;
Meibom, S ;
Dolan, CJ .
ASTROPHYSICAL JOURNAL, 2004, 602 (02) :L121-L123
[43]   Spectroscopic membership for the populous 300 Myr-old open cluster NGC 3532 [J].
Fritzewski, D. J. ;
Barnes, S. A. ;
James, D. J. ;
Geller, A. M. ;
Meibom, S. ;
Strassmeier, K. G. .
ASTRONOMY & ASTROPHYSICS, 2019, 622
[44]   The age, extinction, and distance of the old, metal-rich open cluster NGC 6791 [J].
Chaboyer, B ;
Green, EM ;
Liebert, J .
ASTRONOMICAL JOURNAL, 1999, 117 (03) :1360-1374
[45]   THREE CLOSE BINARIES IN DIFFERENT EVOLUTIONARY STAGES IN THE OLD OPEN CLUSTER NGC 188 [J].
Zhu, L. Y. ;
Qian, S. B. ;
Soonthornthum, B. ;
Liu, L. ;
He, J. J. ;
Liu, N. P. ;
Zhao, E. G. ;
Zhang, J. ;
Wang, J. J. .
ASTRONOMICAL JOURNAL, 2014, 147 (02)
[46]   ABUNDANCES OF RED GIANTS IN OLD OPEN CLUSTERS. V. Be 31, Be 32, Be 39, M 67, NGC 188, AND NGC 1193 [J].
Friel, Eileen D. ;
Jacobson, Heather R. ;
Pilachowski, Catherine A. .
ASTRONOMICAL JOURNAL, 2010, 139 (05) :1942-1967
[47]   Analysis and calibration of CaII triplet spectroscopy of red giant branch stars from VLT/FLAMES observations [J].
Battaglia, G. ;
Irwin, M. ;
Tolstoy, E. ;
Hill, V. ;
Helmi, A. ;
Letarte, B. ;
Jablonka, P. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2008, 383 (01) :183-199
[48]   Iron abundances from high-resolution spectroscopy of the open clusters NGC 2506, NGC 6134, and IC 4651 [J].
Carretta, E ;
Bragaglia, A ;
Gratton, RG ;
Tosi, M .
ASTRONOMY & ASTROPHYSICS, 2004, 422 (03) :951-962
[49]   The open cluster NGC 2345: a study of chemical abundances with near-infrared IGRINS high-resolution spectra [J].
Holanda, N. ;
Roriz, M. P. ;
Drake, N. A. ;
Junqueira, S. ;
Daflon, S. ;
da Silva, J. R. P. ;
Pereira, C. B. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2023, 527 (01) :1389-1404
[50]   SEARCHING FOR CHEMICAL SIGNATURES OF MULTIPLE STELLAR POPULATIONS IN THE OLD, MASSIVE OPEN CLUSTER NGC 6791 [J].
Bragaglia, Angela ;
Sneden, Christopher ;
Carretta, Eugenio ;
Gratton, Raffaele G. ;
Lucatello, Sara ;
Bernath, Peter F. ;
Brooke, James S. A. ;
Ram, Ram S. .
ASTROPHYSICAL JOURNAL, 2014, 796 (01)