منابع مشابه
Fluorine in R Coronae Borealis Stars
Neutral fluorine (F i) lines are identified in the optical spectra of several RCoronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by factors of 800 to 8000 relative to its likely initial abundance. The overabundances of fluorine are evidence for the synthesis of fluorine. These res...
متن کاملWinds in R Coronae Borealis Stars
We present new spectroscopic observations of the He I λ10830 line in R Coronae Borealis (RCB) stars which provide the first strong evidence that most, if not all, RCB stars have winds. It has long been suggested that when dust forms around an RCB star, radiation pressure accelerates the dust away from the star, dragging the gas along with it. The new spectra show that nine of the ten stars obse...
متن کاملThe R Coronae Borealis stars – atmospheres and abundances
An abundance analysis of the H-deficient and Heand C-rich R Coronae Borealis (R CrB) stars has been undertaken to examine the ancestry of the stars. The investigation is based on high-resolution spectra and line-blanketed H-deficient model atmospheres. The models successfully reproduce the flux distributions and all spectral features, both molecular bands and high-excitation transitions, with o...
متن کاملThe Newly Active R Coronae Borealis Star, V2552 Oph
In 2001, V2552 Oph (CD -22 12017, HadV98) quickly faded by several magnitudes in a manner typical of the R Coronae Borealis (RCB) stars. Photometry of V2552 Oph obtained over 70 years previous to 2001 shows no indication of variability. Optical spectra of this star subsequently confirmed that V2552 Oph is a member of the hydrogen deficient, carbon-rich RCB class of variables. It resembles the w...
متن کاملUBV JHKLM photometry and modeling of R Coronae Borealis
We present the results of UBV JHKLM photometry of RCrB spanning the period from 1976 to 2001. Studies of the optical light curve have shown no evidence of any stable harmonics in the variations of the stellar emission. In the L band we found semi-regular oscillations with the two main periods of ∼ 3.3 yr and ∼ 11.9 yr and the full amplitude of ∼ 0. 8 and ∼ 0. 6, respectively. The colors of the ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1975
ISSN: 0074-1809
DOI: 10.1017/s0074180900010160