Abundance analysis of a CEMP-no star in the Carina dwarf spheroidal galaxy

Susmitha, A and Koch, A and Sivarani, T (2017) Abundance analysis of a CEMP-no star in the Carina dwarf spheroidal galaxy. In: ASTRONOMY & ASTROPHYSICS, 606 .

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Abstract

Carbon-enhanced metal-poor (CEMP) stars bear important imprints of the early chemical enrichment of any stellar system. While these stars are known to exist in copious amounts in the Milky Way halo, detailed chemical abundance data from the faint dwarf spheroidal (dSph) satellites are still sparse, although the relative fraction of these stars increases with decreasing metallicity. Here, we report the abundance analysis of a metal-poor (Fe/H] = 2 : 5 dex), carbon-rich ( C/Fe] = 1.4 dex) star, ALW-8, in the Carina dSph using high-resolution spectroscopy obtained with the ESO/UVES instrument. Its spectrum does not indicate any over-enhancements of neutron capture elements. Thus classified as a CEMP-no star, this is the first detection of this kind of star in Carina. Another of our sample stars, ALW-1, is shown to be a CEMP-s star, but its immediate binarity prompted us to discard it from a detailed analysis. The majority of the 18 chemical elements we measured are typical of Carina's field star population and also agree with CEMP stars in other dSph galaxies. Similar to the only known CEMP-no star in the Sculptor dSph and the weak-r-process star HD 122563, the lack of any strong barium-enhancement is accompanied by a moderate overabundance in yttrium, indicating a weak r-process activity. The overall abundance pattern confirms that, also in Carina, the formation site for CEMP-no stars has been affected by both faint supernovae and by standard core collapse supernovae. Whichever process was responsible for the heavy element production in ALW-8 must be a ubiquitous source to pollute the CEMP-no stars, acting independently of the environment such as in the Galactic halo or in dSphs.

Item Type:	Journal Article
Publication:	ASTRONOMY & ASTROPHYSICS
Additional Information:	Copy right for this article belongs to the EDP SCIENCES S A, 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE
Department/Centre:	Division of Physical & Mathematical Sciences > Astronomy and Astrophysics Programme
Date Deposited:	11 Nov 2017 07:14
Last Modified:	11 Nov 2017 07:14
URI:	http://eprints.iisc.ac.in/id/eprint/58191

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