Outliers in the 0Z Survey
Abstract
We have now completed detailed abundance analyses of more than 100 stars selected as candidate extremely metal-poor stars with [Fe/H] < –3.0 dex. Of these 18 are below –3.3 dex on the scale of the First Stars VLT project led by Cayrel, and 57 are below –3.0 dex on that scale. Ignoring enhancement of carbon which ranges up to very large values, and two C-rich stars with very high N as well, there are 0 to 3 high or low strong outliers for each abundance ratio tested from Mg to Ni. The outliers have been checked and they are real. Ignoring the outliers, the dispersions are in most cases approximately consistent with the uncertainties, except those for [Sr/Fe] and [Ba/Fe], which are much larger. Approximately 6% of the sample are strong outliers in one or more elements between Mg and Ni. This rises to ∼15% if minor outliers for these elements and strong outliers for Sr and Ba are included. There are 6 stars with extremely low [Sr/Fe] and [Ba/Fe], including one which has lower [Ba/H] than Draco 119, the star found by Fulbright, Rich & Castro to have the lowest such ratio known previously. There is one extreme r-process star.
Additional Information
© 2012 Astronomical Society of the Pacific. We are very grateful to the Palomar, Las Campanas, and Keck time allocation committees for their long-term support of this effort. J. Cohen acknowledges partial support from NSF grants AST-0507219 and AST-0908139. I. Thompson acknowledges partial support from NSF AST-0507325. We are grateful to the many people who have worked to make the Keck Telescopes and their instruments, and the Magellan Telescopes and their instruments, a reality and to operate and maintain these observatories.Attached Files
Published - Cohen_ASP458p61.pdf
Accepted Version - 1201.4190.pdf
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Additional details
- Eprint ID
- 35011
- Resolver ID
- CaltechAUTHORS:20121022-131934431
- AST-0507219
- NSF
- AST-0908139
- NSF
- AST-0507325
- NSF
- Created
-
2012-10-22Created from EPrint's datestamp field
- Updated
-
2023-06-02Created from EPrint's last_modified field
- Series Name
- Astronomical Society of the Pacific Conference Series
- Series Volume or Issue Number
- 458