2013/05/14 by C. Lardo, E. Pancino, A. Mucciarelli +6 · 39 citations
Physics and Astronomy · #Artificial intelligence #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Asymptotic giant branch #Blue straggler #Globular cluster #Horizontal branch #Physics #RGB color model #Red giant #Red-giant branch #Spectral line #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stt854
published in Monthly Notices of the Royal Astronomical Society 433(3), 1941-1950 (Oxford University Press) · 11 pages, 8 figures. Accepted for publication in MNRAS
arxiv created 2013/05/14 · openalex publication_date 2013/06/06 · arxiv updated 2015/06/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The globular cluster M2 has a photometrically detected double red giant branch (RGB) sequence. We investigate here the chemical differences between the two RGBs in order to gain insight in the star formation history of this cluster. The low-resolution spectra, covering the blue spectral range, were collected with the Multi-Object Double CCD Spectrograph (MODS) on the Large Binocular Telescope, and analysed via spectrum synthesis technique. The high quality of the spectra allows us to measure C, N, Ba and Sr abundances relative to iron for 15 RGB stars distributed along the two sequences. We add to the MODS sample C and N measurements for 35 additional stars belonging to the blue RGB sequence, presented in Lardo et al. We find a clear separation between the two groups of stars in s-process elements as well as C and N content. Both groups display a C–N anticorrelation and the red RGB stars are on average richer in C and N with respect to the blue RGB. Our results reinforce the suggestion that M2 belongs to the family of globular clusters with complex star formation history, together with ω Cen, NGC 1851 and M22.