2013A&A...552A.107S


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.08CEST15:09:54

2013A&A...552A.107S - Astronomy and Astrophysics, volume 552A, 107-107 (2013/4-1)

Carbon-enhanced metal-poor stars: the most pristine objects?

SPITE M., CAFFAU E., BONIFACIO P., SPITE F., LUDWIG H.-G., PLEZ B. and CHRISTLIEB N.

Abstract (from CDS):

Carbon-enhanced metal-poor stars (CEMP) form a significant proportion of the metal-poor stars, their origin is not well understood, and this carbon-enhancement appears in stars that exhibit different abundance patterns. Three very metal-poor C-rich turnoff stars were selected from the SDSS survey, observed with the ESO VLT (UVES) to precisely determine the element abundances. In turnoff stars (unlike giants) the carbon abundance has not been affected by mixing with deep layers and is therefore easier to interpret. The analysis was performed with one dimensional (1D) local thermodynamical equilibrium (LTE) static model atmospheres. When available, non-LTE corrections were applied to the classical LTE abundances. The 3D effects on the CH and CN molecular bands were computed using hydrodynamical simulations of the stellar atmosphere (CO5BOLD) and are found to be very important. To facilitate a comparison with previous results, only 1D abundances are used in the discussion. The abundances (or upper limits) of the elements enable us to place these stars in different CEMP classes. The carbon abundances confirm the existence of a plateau at A(C)=8.25 for [Fe/H]≥-3.4. The most metal-poor stars ([Fe/H]←3.4) have significantly lower carbon abundances, suggesting a lower plateau at A(C)≃6.5. Detailed analyses of a larger sample of very low metallicity carbon-rich stars are required to confirm (or refute) this possible second plateau and specify the behavior of the CEMP stars at very low metallicity.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: carbon - stars: AGB and post-AGB - stars: Population II - Galaxy: evolution

CDS comments: Paragraph.1 SDSS J02915+172927 is a misprint for SDSS J102915+172927.

Simbad objects: 9

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Number of rows : 9

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 BPS CS 29528-0041 Pe* 02 29 25.2507036195 -18 13 28.042501354 14.83 15.20 14.59 14.67   CEMP-no 25 0
2 UCAC3 215-112497 Pe* 10 29 15.1491308300 +17 29 27.926665478         15.98 ~ 92 0
3 NAME SDSS J1036+1212 Pe* 10 36 49.9302951768 +12 12 19.888898997           CEMP-s 24 0
4 SDSS J111407.08+182831.7 Pe* 11 14 07.0923398165 +18 28 31.820666507           CEMP-s 5 0
5 SDSS J114323.42+202058.0 Pe* 11 43 23.4372181638 +20 20 58.124191218           CEMP-s 7 0
6 HE 1327-2326 Pe* 13 30 05.9395582011 -23 41 49.699027289 13.761 14.01 13.55 13.50 12.803 CEMP-no 214 0
7 Wolf 1492 Pe* 13 40 02.4921790616 -00 02 18.750321114 11.601 11.832 11.451 11.184 10.892 sdF0: 261 0
8 SDSS J220924.74-002859.8 Pe* 22 09 24.7439327850 -00 28 59.836030379           CEMP-no 12 0
9 HE 2356-0410 Pe* 23 59 13.1417869434 -03 53 48.220053208   14.39 13.60 13.164 12.713 CEMP-no 81 0

    Equat.    Gal    SGal    Ecl

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2020.08.08-15:09:54

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