On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood.

Details On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood. On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood.

Jul 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996a%26a...311..127f&link_type=abstract

Astronomy and Astrophysics, v.311, p.127-134

Astronomy and Astrophysics

Astrophysics

21

Galaxy: Solar Neighbourhood, Stars: Abundances, Stars: Low Mass, Stars: Hr Diagram, Galaxy: Abundances

Scientific paper

We discuss the relation between the main sequence thickness and chemical composition variations. With the help of theoretical zero-age main sequence models between 0.7 and 1.0Msun_, computed with an advanced physical description of the stellar interiors, in a range of metallicities typical from Population I stars (0.008<=Z<=0.034), we establish a theoretical relation between the relative helium to metal enrichment, {DELTA}Y/{DELTA}Z, and the main-sequence broadening, represented in this work by {DELTA}M_bol_. The locus in the Hertzsprung-Russell diagram of 69 low mass stars closer than 25pc is analyzed, taking into account the present available metallicities for 25 of them. Models show that {DELTA}Y/{DELTA}Z should be higher than 2.0 in the solar neighbourhood to account for the observational main sequence width. As a consequence an helium abundance lower limit of Y=0.246 is found in the solar neighbourhood. This value is presently loosely constrained by the observational uncertainties. A new step towards the {DELTA}Y/{DELTA}Z determination is expected in the very near future, when accurate values of the stellar luminosities as determined by Hipparcos will permit more definite conclusions.

Affiliated with

Also associated with

No associations

Rating

On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood. 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 On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1114704