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 کاملH α variability of the recurrent nova T Coronae Borealis ⋆
We analyze Hα observations of the recurrent nova T CrB obtained during the last decade. For the first time the Hα emission profile is analyzed after subtraction of the red giant contribution. Based on our new radial velocity measurements of the Hα emission line we estimate the component masses of T CrB. It is found that the hot component is most likely a massive white dwarf. We estimate the inc...
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 RV-variations of γ Coronae Borealis – a frequency analysis
We summarize a longer campaign of spectroscopic observations of the suspected Maia variable star γ CrB . Previously published data are complemented by two-longitudinal observations. We investigate 1262 CCD spectra for short-term radial velocity variations. Results show that A0 stars can pulsate with periods quite similar to those of the well-known δ Scu stars. From a frequency analysis of the d...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1999
ISSN: 0252-9211
DOI: 10.1017/s0252921100048508