The chemical compositions and evolutionary status of red giants in the open cluster NGC 752


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Topcu G. B. , AFŞAR M. , Schaeuble M., Sneden C.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, cilt.446, ss.3562-3578, 2015 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 446 Konu: 4
  • Basım Tarihi: 2015
  • Doi Numarası: 10.1093/mnras/stu2380
  • Dergi Adı: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Sayfa Sayıları: ss.3562-3578

Özet

We present detailed chemical compositions of 10 red giant star members of the Galactic (open) cluster NGC 752, derived from high-resolution (R approximate to 60 000), high signal-to-noise (S/N >= 140) spectra. We confirmed cluster memberships by measuring the stellar radial velocities, and by deriving model atmosphere parameters (T-eff, log g, [Fe/H] and xi(t)) from equivalent widths of Fe I, FeII, Ti I, and Ti II lines. The metallicity we obtained for NGC 752 ([Fe/H]= -0.02 +/- 0.05) is in good agreement with previous studies. We derived abundances of alpha (Mg, Si, Ca), light odd-Z (Na, A1), Fe-group (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), n-capture (Y, La, Nd, Eu), and p-capture (Li, C, N, O) species for each star. Furthermore, we also derived abundances of the LiCNO p-capture element group and carbon isotopic ratios, using synthetic spectrum analyses of the Li I 6707 angstrom resonance doublet, the [O I] line at 6300 angstrom, the CH G-band features near 4311 and 4325 angstrom, the C-2 bandheads at 5160 and 5631 angstrom, and (CN)-C-12,13 red system lines in the 7995-8040 angstrom region. By applying recent isochrones to NGC 752 photometry, and comparing the colour-magnitude diagram information to our Li abundances and C-12/C-13 ratios, we suggest that the 10 observed red giants can be separated into three first-ascent, six red-clump and one red horizontal branch star.