Lithium isotopic abundances in metal-poor halo stars

Details Lithium isotopic abundances in metal-poor halo stars Lithium isotopic abundances in metal-poor halo stars

2005-10-21

arxiv.org/abs/astro-ph/0510636v2

Astrophys.J.644:229-259,2006

Astronomy and Astrophysics

Astrophysics

Replaced with version accepted by ApJ. Minor changes compared with previous version (some discussion and references added)

Scientific paper

10.1086/503538

Very high-quality spectra of 24 metal-poor halo dwarfs and subgiants have been acquired with ESO's VLT/UVES for the purpose of determining Li isotopic abundances. The derived 1D, non-LTE 7Li abundances from the LiI 670.8nm line reveal a pronounced dependence on metallicity but with negligible scatter around this trend. Very good agreement is found between the abundances from the LiI 670.8nm line and the LiI 610.4nm line. The estimated primordial 7Li abundance is $7Li/H = 1.1-1.5 x 10^-10, which is a factor of three to four lower than predicted from standard Big Bang nucleosynthesis with the baryon density inferred from the cosmic microwave background. Interestingly, 6Li is detected in nine of our 24 stars at the >2sigma significance level. Our observations suggest the existence of a 6Li plateau at the level of log 6Li = 0.8; however, taking into account predictions for 6Li destruction during the pre-main sequence evolution tilts the plateau such that the 6Li abundances apparently increase with metallicity. Our most noteworthy result is the detection of 6Li in the very metal-poor star LP815-43. Such a high 6Li abundance during these early Galactic epochs is very difficult to achieve by Galactic cosmic ray spallation and alpha-fusion reactions. It is concluded that both Li isotopes have a pre-Galactic origin. Possible 6Li production channels include proto-galactic shocks and late-decaying or annihilating supersymmetric particles during the era of Big Bang nucleosynthesis. The presence of 6Li limits the possible degree of stellar 7Li depletion and thus sharpens the discrepancy with standard Big Bang nucleosynthesis.

Affiliated with

Also associated with

No associations

Rating

Lithium isotopic abundances in metal-poor halo stars 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 Lithium isotopic abundances in metal-poor halo stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lithium isotopic abundances in metal-poor halo stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-88880