2016A&A...585L...5M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.06CEST22:30:46

2016A&A...585L...5M - Astronomy and Astrophysics, volume 585, L5-5 (2016/1-1)

2MASS J18082002-5104378: The brightest (V = 11.9) ultra metal-poor star.

MELENDEZ J., PLACCO V.M., TUCCI-MAIA M., RAMIREZ I., LI T.S. and PEREZ G.

Abstract (from CDS):

The most primitive metal-poor stars are important for studying the conditions of the early galaxy and are also relevant to big bang nucleosynthesis. Our objective is to find the brightest (V<14) most metal-poor stars. Candidates were selected using a new method, which is based on the mismatch between spectral types derived from colors and observed spectral types. They were observed first at low resolution with EFOSC2 at the NTT to obtain an initial set of stellar parameters. The most promising candidate, 2MASS J18082002-5104378 (V=11.9), was observed at high resolution (R=50000) with UVES at the VLT, and a standard abundance analysis was performed. We found that 2MASS J18082002-5104378 is an ultra metal-poor star with stellar parameters Teff=5440K, logg=3.0dex, vt=1.5km/s, [Fe/H]=-4.1dex. The star has [C/Fe]<+0.9 in a 1D analysis, or [C/Fe]≲+0.5 if 3D effects are considered; its abundance pattern is typical of normal (non-CEMP) ultra metal-poor stars. Interestingly, the star has a binary companion. 2MASS J1808-5104 is the brightest (V=11.9) metal-poor star of its category, and it could be studied further with even higher S/N spectroscopy to determine additional chemical abundances, thus providing important constraints to the early chemical evolution of our Galaxy.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: Population II - stars: individual: 2MASS J18082002-5104378

Simbad objects: 7

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Number of rows : 7

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 CD-38 245 Pe* 00 46 36.1954714218 -37 39 33.555736375   12.733 11.929 13.39 10.996 KIIvw 201 0
2 BD+44 493 Pe* 02 26 49.7388403813 +44 57 46.526253277   9.63 9.11     CEMP-no 82 0
3 HD 19445 PM* 03 08 25.5884 +26 19 51.400 8.29 8.52 8.06 7.60 7.27 G2VFe-3 739 0
4 SDSS J120441.38+120111.5 Pe* 12 04 41.3884956228 +12 01 11.515022243           ~ 13 0
5 2MASS J13132688-0019415 Pe* 13 13 26.8883961320 -00 19 41.335927067           CEMP-no 25 0
6 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 852 0
7 2MASS J18082002-5104378 SB* 18 08 20.0313699474 -51 04 37.884231813           ~ 10 0

    Equat.    Gal    SGal    Ecl

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2020.07.06-22:30:46

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