منابع مشابه
Ten-micron Observations of Nearby Young Stars
We present new 10μm photometry of 21 nearby young stars obtained at the Palomar 5-meter and at the Keck I 10-meter telescopes as part of a program to search for dust in the habitable zone of young stars. Thirteen of the stars are in the F–K spectral type range (“solar analogs”), 4 have B or A spectral types, and 4 have spectral type M. We confirm existing IRAS 12μm and ground-based 10μm photome...
متن کاملinvestigation of the electronic properties of carbon and iii-v nanotubes
boron nitride semiconducting zigzag swcnt, $b_{cb}$$n_{cn}$$c_{1-cb-cn}$, as a potential candidate for making nanoelectronic devices was examined. in contrast to the previous dft calculations, wherein just one boron and nitrogen doping configuration have been considered, here for the average over all possible configurations, density of states (dos) was calculated in terms of boron and nitrogen ...
15 صفحه اولThe Brightest Carbon Stars
It is currently accepted that Hot-Bottom-Burning (HBB) in intermediate-mass asymptotic giant branch (AGB) stars prevents the formation of C stars. Nevertheless, we present the results of some detailed evolutionary calculations which show that even with HBB we obtain C stars at the highest luminosities reached on the AGB. This is due to mass-loss reducing the envelope mass so that HBB ceases but...
متن کاملCarbon Stars
In this review we rst describe basic information for carbon stars starting with the most recent spectral classi cation system of P.C. Keenan and luminosities derived from data in the Hipparcos Catalogue. For the SRb and Lb variables MK = 6:8 1:2 (21 stars). Only two R stars (non-variables) have measured K magnitudes and showMK = 5:2. The four N stars show MV = +0:76 1:06. Using the Magellanic C...
متن کاملThe R Stars: Carbon Stars of a Different Kind
After ∼16 years of radial-velocity observations of a sample of 22 R-type carbon stars, no evidence for binary motion has been detected in any of them. This is surprising considering that approximately 20% of normal late-type giants are spectroscopic binaries, and the fraction is close to 100% in barium, CH, and subgiant/dwarf CH and barium stars. It is suggested, therefore, that a process that ...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 1995
ISSN: 0004-637X,1538-4357
DOI: 10.1086/176052