Extremely Metal-poor Stars. Ix. Cs 22949-037 and the Role of Hypernovae
نویسندگان
چکیده
We have obtained high-resolution spectra of the extremely metal-poor star CS 22949-037 ( ) [Fe/H] p 3.79 in the region of the ultraviolet NH bands at 3360–3370 Å, which confirm our earlier report that it exhibits extreme nitrogen enhancement. We find . The star is also known to have large relative overabundances, [N/Fe] p 2.3 0.4 of order 0.5–1 dex, of carbon and the a-elements. This abundance pattern is not explained by any standard Galactic chemical enrichment model of which we are aware. The large N enhancement is, however, predicted by the zero heavy element, , hypernova models of Woosley & Weaver and Fryer, Woosley, & Heger. M 200 M, If the rotating models of Fryer et al. are relevant to the enrichment of CS 22949-037, one might expect it to possess a large overabundance of oxygen, with a mass fraction similar to or larger than that of nitrogen, and an [O i] l6300.3 line strength of ∼2–8 mÅ. Subject headings: nuclear reactions, nucleosynthesis, abundances — stars: abundances — stars: Population II
منابع مشابه
Chemical Composition of the Carbon-rich, Extremely Metal-Poor Star CS 29498–043: A New Class of Extremely Metal-Poor Stars with Excesses of Magnesium and Silicon
We analyze a high-resolution, high signal-to-noise spectrum of the carbon-rich, extremely metal-poor star CS 29498–043, obtained with the Subaru Telescope High Dispersion Spectrograph. We find its iron abundance is extremely low ([Fe/H] = −3.7), placing it among the few stars known with [Fe/H] ≤ −3.5, while Mg and Si are significantly overabundant ([Mg/Fe] = +1.8, and [Si/Fe] = +1.1) compared w...
متن کاملOxygen Overabundance in the Extremely Iron-poor Star
An abundance analysis for the carbon-enhanced, extremely iron-poor (1⁄2Fe=H 3:5) star CS 29498-043 has been obtained using new high-resolution, high signal-to-noise ratio spectra from the Subaru Telescope. The [O i] forbidden line at 6300 8 and the O i triplet feature at 7771–7776 8 are both clearly detected. The overabundance of oxygen is significant (1⁄2O=Fe > 2). In addition, Na, Co, and Ni ...
متن کاملOxygen and Magnesium Abundance in the Ultra-Metal-Poor Giants CS 22949-037 and CS 29498-043: Challenges in Models of Atmospheres
We report the results of a non-LTE Fe, O and Mg abundance analysis of the carbon-nitrogen-rich ultrametal-poor giants CS 29498–043 and CS22949–037. The abundance of oxygen has been derived from measurements of the oxygen triplet at 7771–5 Å in high resolution spectra obtained with KeckI/HIRES and the forbidden line [O i] 6300 Å detected in the TNG/SARG spectra of CS 29498-043. Detailed non-LTE ...
متن کاملar X iv : a st ro - p h / 04 02 58 5 v 1 2 5 Fe b 20 04 Oxygen Overabundance in the Extremely Iron - Poor Star CS 29498 – 043 1
An abundance analysis for the carbon-enhanced, extremely iron-poor ([Fe/H]∼ −3.5) star CS 29498–043 has been obtained using new high-resolution, high signalto-noise spectra from the Subaru Telescope. The [O I] forbidden line at 6300 Å and the O I triplet feature at 7771-7776 Å are both clearly detected. The overabundance of oxygen is significant ([O/Fe]> 2). In addition, Na, Co, and Ni abundanc...
متن کاملar X iv : a st ro - p h / 04 02 58 5 v 1 2 5 Fe b 20 04 Oxygen Overabundance in the Extremely Iron - Poor Star CS 29498
An abundance analysis for the carbon-enhanced, extremely iron-poor ([Fe/H]∼ −3.5) star CS 29498–043 has been obtained using new high-resolution, high signalto-noise spectra from the Subaru Telescope. The [O I] forbidden line at 6300 Å and the O I triplet feature at 7771-7776 Å are both clearly detected. The overabundance of oxygen is significant ([O/Fe]> 2). In addition, Na, Co, and Ni abundanc...
متن کامل