Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars

Details Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars

1997-04-15

arxiv.org/abs/astro-ph/9704144v1

Astron.Astrophys.327:1054-1069,1997

Astronomy and Astrophysics

Astrophysics

20 pages, Latex file, uses l-aa.sty, accepted for publication in A&A

Scientific paper

We have performed evolutionary calculations of very-low-mass stars from 0.08 to 0.8 $\msol$ for different metallicites from [M/H]= -2.0 to -1.0 and we have tabulated the mechanical, thermal and photometric characteristics of these models. The calculations include the most recent interior physics and improved non-grey atmosphere models. The models reproduce the entire main sequences of the globular clusters observed with the Hubble Space Telescope over the afore-mentioned range of metallicity. Comparisons are made in the WFPC2 Flight system including the F555, F606 and F814 filters, and in the standard Johnson-Cousins system. We examine the effects of different physical parameters, mixing-length, $\alpha$-enriched elements, helium fraction, as well as the accuracy of the photometric transformations of the HST data into standard systems. We derive mass-effective temperature and mass-magnitude relationships and we compare the results with the ones obtained with different grey-like approximations. These latter are shown to yield inaccurate relations, in particular near the hydrogen-burning limit. We derive new hydrogen-burning minimum masses, and the corresponding absolute magnitudes, for the different metallicities. We predict color-magnitude diagrams in the infrared NICMOS filters, to be used for the next generation of the HST observations, providing mass-magnitudes relationships in these colors down to the brown-dwarf limit. We show that the expected signature of the stellar to substellar transition in color-magnitude diagrams is a severe blueshift in the infrared colors, due to the increasing collision-induced absorption of molecular hydrogen with increasing density and decreasing temperature.

Affiliated with

Also associated with

No associations

Rating

Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field 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 Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-489745