First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy

Details First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy

2007-09-21

arxiv.org/abs/0709.3454v1

Astronomy and Astrophysics

Astrophysics

19 pages, 16 figures, A&A accepted

Scientific paper

10.1051/0004-6361:20077706

Our aim is to measure accurate, homogeneous neutron-capture element abundances for the sample of 32 EMP giant stars studied earlier in this series, including 22 stars with [Fe/H] $< -$3.0. Based on high-resolution, high S/N spectra from the ESO VLT/UVES, 1D, LTE model atmospheres, and synthetic spectrum fits, we determine abundances or upper limits for the 16 elements Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb in all stars. As found earlier, [Sr/Fe], [Y/Fe], [Zr/Fe] and [Ba/Fe] are below Solar in the EMP stars, with very large scatter. However, we find a tight anti-correlation of [Sr/Ba], [Y/Ba], and [Zr/Ba] with [Ba/H] for $-4.5 <$ [Ba/H] $< -2.5$, also when subtracting the contribution of the main $r$-process as measured by [Ba/H]. The huge, well-characterised scatter of the [n-capture/Fe] ratios in our EMP stars is in stark contrast to the negligible dispersion in the [$\alpha$/Fe] and [Fe-peak/Fe] ratios for the same stars found in Paper V. These results demonstrate that a second (``weak'' or LEPP) $r$-process dominates the production of the lighter neutron-capture elements for [Ba/H] $< -2.5$. The combination of very consistent [$\alpha$/Fe] and erratic [n-capture/Fe] ratios indicates that inhomogeneous models for the early evolution of the halo are needed. Our accurate data provide strong constraints on future models of the production and mixing of the heavy elements in the early Galaxy.

Affiliated with

Also associated with

No associations

Rating

First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-256885