carbon stars


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carbon stars

(C stars) Red giant stars of low temperature that have an over-abundance of carbon relative to oxygen in their surface layers. In cool stars carbon and oxygen atoms combine to form stable carbon monoxide, and in carbon stars the excess carbon can then form other molecules. Their spectra therefore show strong bands of carbon compounds, including C2, CN, and CH. All carbon stars undergo mass loss, enriching the interstellar medium with considerable carbon, some nitrogen and oxygen, and also s-process elements. In the earlier Harvard classification (see spectral types) carbon stars were divided into R stars and N stars : N stars are the ‘classical’ carbon stars, discovered spectroscopically by Angelo Secchi (1868). They are very cool and very luminous and many have been discovered in the Magellanic Clouds and other galaxies. They are observed to be losing mass rapidly and are much further evolved than the hotter less luminous R stars. The R stars are enriched in the isotopes 13C and 14N, but unlike most N stars, show no enhancement in s-process elements. See also R Coronae Borealis stars; S stars.
References in periodicals archive ?
Spectroscopic changes and the variable mean light of carbon stars Monthly Notices of the Royal Astronomical Society, 286, 839-847.
And finally, carbon stars are notoriously variable, not just in magnitude but in colour too, and it is probably no more than fortuitous that WZ Cas should happen to have one of the largest numerical values of (B-V) in the database consulted by Mr Ahad.
Decin and her colleagues now plan to extend the observations to other carbon stars.
Since Betelgeuse and upper Orion are so familiar these evenings, here are three carbon stars you probably didn't know about that lurk there, hiding in plain (telescopic) sight.
Based on an analysis of 110 carbon stars dotted across the sky brighter than magnitude 8.
Of all the stars recorded by 2MASS, the astronomers chose to analyze carbon stars first because of three remarkable properties.
Among the carbon stars, I give my nod to beautiful, deeply reddish orange Y Canum Venaticorum.
Stars more massive than the sun end their lives as carbon stars, which in our galaxy are a rich source of dust.
Double stars, Cepheid variable stars, Viewing galaxies, Black holes, Main-sequence stars, Globular clusters, Discovery of Proxima, Extra-solar planets, Open star clusters, Sub-giant stars, Nebulae, Yellow-dwarf star, Barred spiral galaxies, Galaxies and time, Close double stars, Coloured double stars, Super galaxy clusters, Mira variable stars, Giant stars, Carbon stars, Observing double stars, Solar type stars, Nicolas Louis de Lacaille, Astrophotography, Light year, Sub-dwarf stars, Venial equinox, Hot Jupiters, Delta-Scuti variable star, Apparent brightness.
Otherwise, the orbits of the carbon stars would spread out rather than remain in a circle, Ibata says.
Most carbon stars are variable, but V Aquilae remains within the
The section of Hydra draped over the meridian this month includes a couple of nice carbon stars and a bright, though small, planetary nebula.