2015A&A...579L...6B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST04:34:14

2015A&A...579L...6B - Astronomy and Astrophysics, volume 579, L6-6 (2015/7-1)

Chemical abundances of giant stars in the Crater stellar system.

BONIFACIO P., CAFFAU E., ZAGGIA S., FRANCOIS P., SBORDONE L., ANDRIEVSKY S.M. and KOROTIN S.A.

Abstract (from CDS):

We obtained spectra for two giants of Crater (CraterJ113613-105227 and CraterJ113615-105244) using X-Shooter at the VLT, with the purpose of determining their radial velocities and metallicities. Radial velocities were determined by cross-correlating the spectra with that of a standard star. The spectra were analysed with the MyGIsFOS code using a grid of synthetic spectra computed from one-dimensional, local thermodynamic equilibrium (LTE) model atmospheres. Effective temperature and surface gravity were derived from photometry measured from images obtained by the Dark Energy Survey. The radial velocities are 144.3±4.0km/s for CraterJ113613-105227 and and 134.1±4.0km/s for CraterJ113615-105244. The metallicities are [Fe/H]=-1.73 and [Fe/H]=-1.67, respectively. In addition to the iron abundance, we were able to determine abundances for nine elements: Na, Mg, Ca, Ti, V, Cr, Mn, Ni, and Ba. For Na and Ba we took into account deviations from LTE because the corrections are significant. The abundance ratios are similar in the two stars and resemble those of Galactic stars of the same metallicity. In the deep photometric images we detected several stars that lie to the blue of the turn-off. The radial velocities imply that both stars are members of the Crater stellar system. The difference in velocity between the two taken at face value implies a velocity dispersion >3.7km/s at a 95% confidence level. Our spectroscopic metallicities agree excellently well with those determined by previous investigations using photometry. Our deep photometry and the spectroscopic metallicity imply an age of 7Gyr for the main population of the system. The stars to the blue of the turn-off can be interpreted as a younger population that is of the same metallicity and an age of 2.2Gyr. Finally, spatial and kinematical parameters support the idea that this system is associated with the galaxies Leo IV and Leo V. All the observations favour the interpretation of Crater as a dwarf galaxy.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: Population II - globular clusters: general - galaxies: abundances - Local Group

Status at CDS:   Examining the need for a new acronym.

Simbad objects: 11

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Number of rows : 11

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3547 0
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5665 1
3 NAME Leo V G 11 31 09.60 +02 13 12.0     16.0     ~ 163 0
4 NAME Leo IV Dwarf Galaxy G 11 32 57.0 -00 32 00     15.1     ~ 318 1
5 NAME Crater J113613-105227 * 11 36 13.90 -10 52 27.3           ~ 3 0
6 NAME Crater J113615-105244 * 11 36 15.91 -10 52 43.6           ~ 3 0
7 NAME Crater Cluster GlC 11 36 16.20 -10 52 38.8           ~ 60 1
8 HD 122563 Pe* 14 02 31.8456299772 +09 41 09.942736952 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 746 0
9 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11535 0
10 V* V2564 Oph LP? 18 04 40.0713993238 +03 46 44.716089845 9.53 8.59 7.30 6.24 5.43 F6/7V 243 0
11 NAME Local Group GrG ~ ~           ~ 6970 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-04:34:14

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