2011ApJ...728..155D

Query : 2011ApJ...728..155D

2011ApJ...728..155D - Astrophys. J., 728, 155 (2011/February-3)

Direct evidence for an enhancement of helium in giant stars in omega Centauri.

DUPREE A.K., STRADER J. and SMITH G.H.

Abstract (from CDS):

The double main sequence identified in the globular cluster Omega Centauri has been interpreted using isochrones to indicate a large variation in the abundance of helium. If true, a helium enhancement carries strong implications for the chemical and stellar evolutionary history of this cluster. However, only indirect measures currently support this conjecture. We report the discovery of a variation in the line strength of the near-infrared He I 10830 Å transition in 12 similar red giants in Omega Centauri observed with PHOENIX on Gemini-S. Abundances of these stars derived from Magellan/MIKE spectra taken at the Las Campanas Observatory show that the helium transition is not detected in the most metal-poor population ([Fe/H] < -1.8), yet is present in the majority of stars with [Fe/H] ≥ -1.8. These observations give the first direct evidence for an enhancement of helium in Omega Centauri. The appearance of helium appears better correlated with increased [Al/Fe] and [Na/Fe] abundances than as a function of [Fe/H], giving observational support to the presence of high-temperature H burning in a prior generation of stars.

Abstract Copyright: ∼

Journal keyword(s): globular clusters: general - globular clusters: individual: Omega Centauri - stars: abundances - stars: Population II

Simbad objects: 17

goto Full paper

goto View the references in ADS

Number of rows : 17
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1540 0
2 NGC 5139 591 RG* 13 25 18.9725309256 -47 28 50.858679324 14.53 14.16 13.04     ~ 21 0
3 NGC 5139 2588 RG* 13 25 27.6588684120 -47 34 07.645509984 15.21 14.64 13.49     ~ 19 0
4 Cl* NGC 5139 LEID 58030 Pe* 13 26 10.7779783536 -47 35 37.100858640           ~ 6 0
5 NGC 5139 1898 RG* 13 26 12.2592532176 -47 38 02.637603348   14.20 13.14   11.927 ~ 14 0
6 NGC 5139 2655 RG* 13 26 24.5756447472 -47 34 10.360542252   14.539 13.437   12.381 ~ 10 0
7 NGC 5139 2661 RB? 13 26 28.3764609960 -47 33 41.428727964   14.321 13.273     ~ 8 0
8 NGC 5139 2674 RB? 13 26 37.6537213584 -47 33 55.223124804   14.245 13.201     ~ 7 0
9 NGC 5139 9201 * 13 26 42.8025300864 -47 27 47.858823792   14.378 13.37   12.185 ~ 5 0
10 NGC 5139 5434 RG* 13 26 44.8175315472 -47 23 33.964824516   14.162 13.103     ~ 10 0
11 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3677 0
12 NGC 5139 4528 Y*? 13 27 01.7871904800 -47 26 24.508678128   14.474 13.397     ~ 4 0
13 NGC 5139 518 RG* 13 27 15.4318918488 -47 25 08.680642320   14.051 12.951   11.752 ~ 10 0
14 NGC 5139 5522 RG* 13 27 40.6528096200 -47 23 18.979310220 14.72 14.240 13.194   12.019 ~ 16 0
15 * zet Cen SB* 13 55 32.38565 -47 17 18.1482 1.42 2.33 2.55 2.69 2.89 B2.5IV 184 0
16 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2291 0
17 EGGR 264 WD* 23 19 35.3881861344 -17 05 28.465573380 13.279 14.132 14.111 14.07 14.049 DB3 131 0

To bookmark this query, right click on this link: simbad:objects in 2011ApJ...728..155D and select 'bookmark this link' or equivalent in the popup menu