The CNO-Cycle Elements in Atmospheres of B-Type Main Sequence Stars
نویسندگان
چکیده
منابع مشابه
the investigation of the relationship between type a and type b personalities and quality of translation
چکیده ندارد.
Boron Abundances in Main Sequence B-type Stars: A Test of Rotational Depletion during Main Sequence Evolution
Boron abundances have been derived for seven main sequence B-type stars from HST STIS spectra around the B III 2066Å line. In two stars, boron appears to be undepleted with respect to the presumed initial abundance. In one star, boron is detectable but it is clearly depleted. In the other four stars, boron is undetectable implying depletions of 1 to 2 dex. Three of these four stars are nitrogen...
متن کاملConvection in the atmospheres and envelopes of Pre-Main Sequence stars
The Teff location of Pre-Main Sequence (PMS) evolutionary tracks depends on the treatment of over-adiabaticity (D’Antona & Mazzitelli 1994, 1998). Since the convection penetrates into the stellar atmosphere, also the treatment of convection in the modeling of stellar atmospheres will affect the location of the Hayashi tracks. In this paper we present new non-grey PMS tracks for Teff > 4000 K. W...
متن کاملThe carbon abundance in main-sequence B-type stars towards the Galactic anti-centre
Differential carbon abundances (based on the C ii doublet at 6580Å) are presented for eight early type stars, towards the Galactic anti-centre. All the stars have similar atmospheric parameters with effective temperatures in the range 25000 − 29000 K and surface gravities between log g = 3.9− 4.3 dex. The derived photospheric abundances vary by up to 0.6 dex, and with the exception of one star,...
متن کاملThe Pre–Main-Sequence of A-type stars
Young A-type stars in the pre–main-sequence (PMS) evolutionary phase are particularly interesting objects since they cover the mass range (∼1.5-4 M⊙) which is most sensitive to the internal conditions inherited during the protostellar phase. In particular, they undergo a process of thermal relaxation from which they emerge as fully radiative objects contracting towards the main sequence. A-type...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1991
ISSN: 0074-1809
DOI: 10.1017/s0074180900227319