ATTENZIONE! IL REPOSITORY E’ APERTO ESCLUSIVAMENTE ALL’IMMISSIONE DEI RAPPORTI TECNICI (COLLEZIONE 4.01). NON E’ POSSIBILE INSERIRE PRODOTTI IN TUTTE LE ALTRE COLLEZIONI, A CAUSA DI PROBLEMI TECNICI. THE REPOSITORY IS OPEN EXCLUSIVELY FOR THE SUBMISSION OF TECHNICAL REPORTS (COLLECTION 4.01). SUBMISSIONS TO ALL OTHER COLLECTIONS ARE TEMPORARILY UNAVAILABLE, DUE TO TECHNICAL ISSUES.
 

Observational Constraints on First-star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-No Stars

Journal
Date Issued
2016
Author(s)
Yoon, Jinmi
•
Beers, Timothy C.
•
Placco, Vinicius M.
•
Rasmussen, Kaitlin C.
•
•
He, Siyu
•
Hansen, Terese T.
•
Roederer, Ian U.
•
Zeanah, Jeff
DOI
Abstract
We investigate anew the distribution of absolute carbon abundance, A(C) = log ∊(C), for carbon-enhanced metal-poor (CEMP) stars in the halo of the Milky Way, based on high-resolution spectroscopic data for a total sample of 305 CEMP stars. The sample includes 147 CEMP-s (and CEMP-r/s) stars, 127 CEMP-no stars, and 31 CEMP stars that are unclassified, based on the currently employed [Ba/Fe] criterion. We confirm previous claims that the distribution of A(C) for CEMP stars is (at least) bimodal, with newly determined peaks centered on A(C) = 7.96 (the high-C region) and A(C) = 6.28 (the low-C region). A very high fraction of CEMP-s (and CEMP-r/s) stars belongs to the high-C region, while the great majority of CEMP-no stars resides in the low-C region. However, there exists complexity in the morphology of the A(C)-[Fe/H] space for the CEMP-no stars, a first indication that more than one class of first-generation stellar progenitors may be required to account for their observed abundances. The two groups of CEMP-no stars we identify exhibit clearly different locations in the A(Na)-A(C) and A(Mg)-A(C) spaces, also suggesting multiple progenitors. The clear distinction in A(C) between the CEMP-s (and CEMP-r/s) stars and the CEMP-no stars appears to be as successful, and likely more astrophysically fundamental, for the separation of these sub-classes as the previously recommended criterion based on [Ba/Fe] (and [Ba/Eu]) abundance ratios. This result opens the window for its application to present and future large-scale low- and medium-resolution spectroscopic surveys.
Volume
833
Issue
1
Start page
20
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...833...20Y
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

1607.06336.pdf

Description
preprint
Size

886.51 KB

Format

Adobe PDF

Checksum (MD5)

7d63555cfba456b94cc0b9640d9ddc6a

Loading...
Thumbnail Image
Name

Yoon_2016_ApJ_833_20.pdf

Description
Pdf editoriale
Size

1015.31 KB

Format

Adobe PDF

Checksum (MD5)

037bf717a81d865830d751056d89e591