ﻻ يوجد ملخص باللغة العربية
CEMP-no stars, a subclass of carbon-enhanced metal-poor (CEMP) stars, are one of the most significant stellar populations in Galactic Archaeology, because they dominate the low end of the metallicity distribution function, providing information on the early star-formation and chemical-evolution history of the Milky Way and its satellite galaxies. Here we present an analysis of medium-resolution ($R sim 1,800$) optical spectroscopy for a CEMP giant, SDSS J132755.56+333521.7, observed with the Large Binocular Telescope (LBT), one of the brightest ($g sim 20.5$) members of the classical dwarf spheroidal galaxy, Canes Venatici I (CVn I). Many CEMP stars discovered to date have very cool effective temperatures ($T_{mathrm{eff}}< 4500$ K), resulting in strong veiling by molecular carbon bands over their optical spectra at low/medium spectral resolution. We introduce a technique to mitigate the carbon-veiling problem to obtain reliable stellar parameters and validate this method with the LBT medium-resolution optical spectra of the ultra metal-poor ([Fe/H] = $-4.0$) CEMP-no dwarf, G 77-61, and seven additional very cool CEMP stars, which have published high-resolution spectroscopic parameters. We apply this technique to the LBT spectrum of SDSS J132755.56+333521.7. We find that this star is well-described with parameters $T_{mathrm{eff}}=4530$ K, log $g=$ 0.7, [Fe/H] $ = -3.38$, and absolute carbon abundance $A$(C) = 7.23, indicating that it is likely the first Group III CEMP-no star identified in CVn I. The Group III identification of this star suggests that it is a member of the extremely metal-poor population in CVn I, which may have been accreted into its halo.
The aim of this work is to find a progenitor for Canes Venatici I (CVn I), under the assumption that it is a dark matter free object that is undergoing tidal disruption. With a simple point mass integrator, we searched for an orbit for this galaxy us
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 dwa
We want to get insight into the nature, i.e. the formation mechanism and the evolution, of UGC 7639, a dwarf galaxy in the Canes Venatici I Cloud (CVnIC). We used archival GALEX (FUV and NUV) and SDSS images, as well as Hyperleda and NED databases, t
We have identified 23 RR Lyrae stars and 3 possible Anomalous Cepheids among 84 candidate variables in the recently discovered Canes Venatici I dwarf spheroidal galaxy. The mean period of 18 RRab type stars is <Pab> = 0.60 +/-0.01 days. This period,
We report on the discovery and chemical abundance analysis of the first CEMP-r/s star detected in the Sagittarius dwarf Spheroidal Galaxy, by means of UVES high resolution spectra. The star, found in the outskirts of Sgr dSph, along the main body maj