CH star

CH stars are particular type of carbon stars which are characterized by the presence of exceedingly strong absorption bands due to CH (methylidyne) in their spectra. They belong to the stellar population II,^[1] meaning they are metal poor and generally pretty middle-aged stars, and are under-luminous compared to the classical C–N carbon stars. The term 'CH star' was coined by Philip C. Keenan in 1942 as a sub-type of the C classification, which he used for carbon stars. The main molecular feature used in identifying the initial set of five CH stars lies in the Fraunhaufer G band.^[2]

In 1975, Yasuho Yamashita noted that some higher temperature carbon stars displayed the typical spectral characteristics of a CH star, but did not have the same kinematic properties. That is, they did not have the higher space velocities characteristic of the older stellar population. These were dubbed CH-like stars.^[3] Many CH stars are known to be members of binary star systems, and it is reasonable to believe this is (or was) the case for all CH stars. Like Barium stars, they are probably the result of a mass transfer from a former classical carbon star companion, now a degenerate white dwarf, to the current CH-classed star.^[4]

References

^ McClure, Robert D.; Woodsworth, A. W. (April 1, 1990), "The binary nature of the barium and CH stars. III - Orbital parameters", Astrophysical Journal, Part 1, 352: 709–723, Bibcode:1990ApJ...352..709M, doi:10.1086/168573.
^ Hearnshaw, John B. (2014), The Analysis of Starlight: Two Centuries of Astronomical Spectroscopy (2nd ed.), Cambridge University Press, p. 233, ISBN 978-1107782914.
^ Sperauskas, J.; et al. (July 2016), "The Binary Nature of CH-Like Stars", The Astrophysical Journal, 826 (1): 13, Bibcode:2016ApJ...826...85S, doi:10.3847/0004-637X/826/1/85, 85.
^ Goswami, Aruna (2005). "CH stars at high Galactic latitudes". Monthly Notices of the Royal Astronomical Society. 359 (2): 531–544. arXiv:astro-ph/0507202. Bibcode:2005MNRAS.359..531G. doi:10.1111/j.1365-2966.2005.08917.x. S2CID 14521922.

External links

David Darling. "CH star". Retrieved 2 January 2009.

Stars

List

Formation

Evolution

Classification

Early Late Main sequence O B A F G K M Subdwarf O B WR OB Subgiant Giant Blue Red Yellow Bright giant Supergiant Blue Red Yellow Hypergiant Yellow Carbon S CN CH White dwarf Chemically peculiar Am Ap/Bp CEMP HgMn He-weak Barium Lambda Boötis Lead Technetium Be Shell B[e] Helium Extreme Blue straggler
Remnants	Compact star Parker's star White dwarf Helium planet Neutron Radio-quiet Pulsar Binary X-ray Magnetar Stellar black hole X-ray binary Burster SGR
Hypothetical	Blue dwarf Green Black dwarf Exotic Boson Electroweak Strange Preon Planck Dark Dark-energy Quark Q Black Gravastar Quasi-star Thorne–Żytkow object Iron Blitzar White hole

Nucleosynthesis

Structure

Properties

Star systems

Earth-centric
observations

Lists

This page was last edited on 12 August 2023, at 16:27

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References

External links