Bibcode
D’Orazi, V.; Magurno, D.; Bono, G.; Matsunaga, N.; Braga, V. F.; Elgueta, S. S.; Fukue, K.; Hamano, S.; Inno, L.; Kobayashi, N.; Kondo, S.; Monelli, M.; Nonino, M.; Przybilla, N.; Sameshima, H.; Saviane, I.; Taniguchi, D.; Thevenin, F.; Urbaneja-Perez, M.; Watase, A.; Arai, A.; Bergemann, M.; Buonanno, R.; Dall’Ora, M.; Da Silva, R.; Fabrizio, M.; Ferraro, I.; Fiorentino, G.; Francois, P.; Gilmozzi, R.; Iannicola, G.; Ikeda, Y.; Jian, M.; Kawakita, H.; Kudritzki, R. P.; Lemasle, B.; Marengo, M.; Marinoni, S.; Martínez-Vázquez, C. E.; Minniti, D.; Neeley, J.; Otsubo, S.; Prieto, J. L.; Proxauf, B.; Romaniello, M.; Sanna, N.; Sneden, C.; Takenaka, K.; Tsujimoto, T.; Valenti, E.; Yasui, C.; Yoshikawa, T.; Zoccali, M.
Bibliographical reference
The Astrophysical Journal Letters, Volume 855, Issue 1, article id. L9, 7 pp. (2018).
Advertised on:
3
2018
Citations
10
Refereed citations
8
Description
We present the first spectroscopic abundance determination of iron,
α-elements (Si, Ca, and Ti), and sodium for the Mira variable V1
in the metal-rich globular cluster NGC 5927. We use high-resolution (R
∼ 28,000), high signal-to-noise ratio (∼200) spectra collected
with WINERED, a near-infrared (NIR) spectrograph covering simultaneously
the wavelength range 0.91–1.35 μm. The effective temperature
and the surface gravity at the pulsation phase of the spectroscopic
observation were estimated using both optical (V) and NIR time-series
photometric data. We found that the Mira is metal-rich ([Fe/H] =
‑0.55 ± 0.15) and moderately α-enhanced ([α/Fe]
= 0.15 ± 0.01, σ = 0.2). These values agree quite well with
the mean cluster abundances based on high-resolution optical spectra of
several cluster red giants available in the literature ([Fe/H] = ‑
0.47 ± 0.06, [α/Fe] = + 0.24 ± 0.05). We also found
a Na abundance of +0.35 ± 0.20 that is higher than the mean
cluster abundance based on optical spectra (+0.18 ± 0.13).
However, the lack of similar spectra for cluster red giants and that of
corrections for departures from local thermodynamical equilibrium
prevents us from establishing whether the difference is intrinsic or
connected with multiple populations. These findings indicate a strong
similarity between optical and NIR metallicity scales in spite of the
difference in the experimental equipment, data analysis, and in the
adopted spectroscopic diagnostics.
Based on spectra collected with the WINERED spectrograph available as a
visitor instrument at the ESO New Technology Telescope (NTT), La Silla,
Chile (ESO Proposal: 098.D-0878(A), PI: G. Bono).
Related projects
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli