2013A&A...560A..15C


Query : 2013A&A...560A..15C

2013A&A...560A..15C - Astronomy and Astrophysics, volume 560A, 15-15 (2013/12-1)

X-shooter GTO: evidence for a population of extremely metal-poor, alpha-poor stars.

CAFFAU E., BONIFACIO P., FRANCOIS P., SBORDONE L., SPITE M., MONACO L., PLEZ B., SPITE F., ZAGGIA S., LUDWIG H.-G., CAYREL R., MOLARO P., RANDICH S., HAMMER F. and HILL V.

Abstract (from CDS):

The extremely metal-poor stars are the direct descendants of the first generation stars. They carry the chemical signature of the pristine Universe at the time they formed, shortly after the Big Bang. We aim to derive information about extremely metal-poor stars from their observed spectra. Four extremely metal-poor stars were selected from the Sloan Digital Sky Survey (SDSS) and observed during the guaranteed observing time of X-shooter. The X-shooter spectra were analysed using an automatic code, MyGIsFOS, which is based on a traditional analysis method. It makes use of a synthetic grid computed from one-dimensional, plane-parallel, hydrostatic model atmospheres. The low metallicity derived from the SDSS spectra is confirmed here. Two kinds of stars are found. Two stars are confirmed to be extremely metal-poor, with no evidence of any enhancement in carbon. The two other stars are strongly enhanced in carbon. We could not derive iron abundance for one of them, while [Ca/H] is below -4.5. Two of the stars are members of the rare population of extremely metal-poor stars low in alpha elements.

Abstract Copyright:

Journal keyword(s): stars: Population II - stars: abundances - Galaxy: abundances - Galaxy: formation - Galaxy: halo

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 - 2024
#notes
1 SB 44 SB* 00 07 37.5160264968 -35 31 17.704959708   13.23 12.76 12.76   sdF 80 0
2 SDSS J082511.45+163459.9 Pe* 08 25 11.4567356976 +16 35 00.012656940           F5 6 0
3 UCAC3 215-112497 Pe* 10 29 15.1489854864 +17 29 27.924626724         15.98 sdA 105 0
4 HE 1327-2326 Pe* 13 30 05.9394958608 -23 41 49.699340844 13.761 14.01 13.55 13.50 12.803 CEMP-no 242 0
5 SDSS J135046.74+134651.1 Pe* 13 50 46.7504473944 +13 46 51.165697152           A0 3 0
6 CRTS J135516.2+001319 RR* 13 55 16.2928183896 +00 13 19.109856216   19.25 18.69     A0 6 0
7 SDSS J144256.37-001542.7 * 14 42 56.3774466000 -00 15 42.801804792           A0 9 0
8 SDSS J153346.28+155701.8 * 15 33 46.2890970792 +15 57 01.834281432           A0 4 0
9 SDSS J161956.33+170539.9 * 16 19 56.3325751704 +17 05 39.850017036           sdA 6 0
10 SDSS J174259.67+253135.8 Pe* 17 42 59.6805182976 +25 31 35.892397632           CEMP-no 22 0
11 BPS CS 22873-0139 SB* 20 05 55.1466054456 -59 17 11.461854084     13.8 13.810   ~ 34 0

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