On the Chemical Abundances of Miras in Clusters: V1 in the Metal-rich Globular NGC 5927
V. d'Orazi
(1)
,
D. Magurno
(2)
,
G. Bono
(2)
,
N. Matsunaga
(3)
,
V. F. Braga
(4)
,
S. S. Elgueta
(3)
,
K. Fukue
(5)
,
S. Hamano
(5)
,
L. Inno
(6)
,
N. Kobayashi
(5)
,
S. Kondo
(5)
,
M. Monelli
(7)
,
M. Nonino
(1)
,
Norbert Przybilla
(8)
,
H. Sameshima
(5)
,
Ivo Saviane
(9)
,
D. Taniguchi
(3)
,
Frédéric Thévenin
(10)
,
M. Urbaneja-Perez
(8)
,
A. Watase
(11)
,
A. Arai
(5)
,
M. Bergemann
(6)
,
R. Buonanno
(2)
,
M. Dall'Ora
(1)
,
C. Correia da Silva
(1)
,
M. Fabrizio
(1)
,
I. Ferraro
(1)
,
Giuliana Fiorentino
(1)
,
Patrick François
(12)
,
Roberto Gilmozzi
(9)
,
G. Iannicola
(1)
,
Y. Ikeda
(5)
,
M. Jian
(3)
,
Hideyo Kawakita
(5)
,
R. P. Kudritzki
(13)
,
Bertrand Lemasle
(14)
,
Massimo Marengo
(15)
,
S. Marinoni
(1)
,
C. E. Martínez-Vázquez
(16)
,
Dante Minniti
(4)
,
J. Neeley
(17)
,
S. Otsubo
(11)
,
J. L. Prieto
(4)
,
B. Proxauf
(18)
,
M. Romaniello
(9)
,
N. Sanna
(1)
,
Christopher Sneden
(19)
,
K. Takenaka
(11)
,
T. Tsujimoto
(20)
,
E. Valenti
(9)
,
C. Yasui
(20)
,
T. Yoshikawa
(21)
,
M. Zoccali
(4)
1
OAC -
INAF - Osservatorio Astronomico di Cagliari
2 Università degli Studi di Roma Tor Vergata [Roma, Italia] = University of Rome Tor Vergata [Rome, Italy] = Université de Rome Tor Vergata [Rome, Italie]
3 Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
4 UC - Pontificia Universidad Católica de Chile
5 Koyama Astronomical Observatory [Kyoto-City]
6 MPIA - Max-Planck-Institut für Astronomie
7 IAC - Instituto de Astrofisica de Canarias
8 Universität Innsbruck [Innsbruck]
9 ESO - European Southern Observatory
10 Observatoire de la Côte d'Azur
11 Kyoto Sangyo University
12 Observatoire de Paris
13 Institute for Astronomy, University of Hawaii
14 Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg
15 Department of Physics and Astronomy, University of Missouri
16 CTIO - Cerro Tololo Inter-American Observatory
17 Department of Astronomy, University of Florida
18 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
19 Department of Physics, University of Texas
20 NAOJ - National Astronomical Observatory of Japan
21 Nakamura-minami
2 Università degli Studi di Roma Tor Vergata [Roma, Italia] = University of Rome Tor Vergata [Rome, Italy] = Université de Rome Tor Vergata [Rome, Italie]
3 Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
4 UC - Pontificia Universidad Católica de Chile
5 Koyama Astronomical Observatory [Kyoto-City]
6 MPIA - Max-Planck-Institut für Astronomie
7 IAC - Instituto de Astrofisica de Canarias
8 Universität Innsbruck [Innsbruck]
9 ESO - European Southern Observatory
10 Observatoire de la Côte d'Azur
11 Kyoto Sangyo University
12 Observatoire de Paris
13 Institute for Astronomy, University of Hawaii
14 Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg
15 Department of Physics and Astronomy, University of Missouri
16 CTIO - Cerro Tololo Inter-American Observatory
17 Department of Astronomy, University of Florida
18 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
19 Department of Physics, University of Texas
20 NAOJ - National Astronomical Observatory of Japan
21 Nakamura-minami
Résumé
We present the first spectroscopic abundance determination of iron, alpha-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 mum. 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 alpha-enhanced ([alpha/Fe] = 0.15 ± 0.01, sigma = 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, [alpha/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.