Physics
Scientific paper
Apr 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998ssrv...84..115h&link_type=abstract
Space Science Reviews, v. 84, Issue 1/2, p. 115-126 (1998).
Physics
5
Galaxies: Abundances, Ism: Abundances, Stars: Abundances, Stars: Evolution
Scientific paper
The primordial helium abundance YP is important for cosmology and the ratio DeltaY/DeltaZ of the changes relative to primordial abundances constrains models of stellar evolution. While the most accurate estimates of YP come from emission lines in extragalactic H II regions, they involve an extrapolation to zero metallicity which itself is closely tied up with the slope DeltaY/DeltaZ. Recently certain systematic effects have come to light in this exercise which make it useful to have an independent estimate of DeltaY/DeltaZ from fine structure in the main sequence of nearby stars. We derive such an estimate from Hipparcos data for stars with Z <= Zsolar and find values between 2 and 3, which are consistent with stellar models, but still have a large uncertainty.
Girardi Leo
Høg Erik
MacDonald James
Pagel Bernard E. J.
Portinari Laura
No associations
LandOfFree
Primordial Helium and DeltaY/DeltaZ from H II Regions and from Fine Structure in the Main Sequence Based on HIPPARCOS Parallaxes 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 Primordial Helium and DeltaY/DeltaZ from H II Regions and from Fine Structure in the Main Sequence Based on HIPPARCOS Parallaxes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Primordial Helium and DeltaY/DeltaZ from H II Regions and from Fine Structure in the Main Sequence Based on HIPPARCOS Parallaxes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1745345