Jump to content
 







Main menu
   


Navigation  



Main page
Contents
Current events
Random article
About Wikipedia
Contact us
Donate
 




Contribute  



Help
Learn to edit
Community portal
Recent changes
Upload file
 








Search  

































Create account

Log in
 









Create account
 Log in
 




Pages for logged out editors learn more  



Contributions
Talk
 



















Contents

   



(Top)
 


1 Terminology  





2 Description  





3 See also  





4 References  














Helium star






Català
Español
Français

Italiano

Português
Русский

 

Edit links
 









Article
Talk
 

















Read
Edit
View history
 








Tools
   


Actions  



Read
Edit
View history
 




General  



What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Cite this page
Get shortened URL
Download QR code
Wikidata item
 




Print/export  



Download as PDF
Printable version
 
















Appearance
   

 






From Wikipedia, the free encyclopedia
 


Ahelium star is a class O or B star (blue), which has extraordinarily strong helium lines and weaker than normal hydrogen lines, indicating strong stellar winds and a mass loss of the outer envelope. Extreme helium stars (EHe) entirely lack hydrogen in their spectra. Pure helium stars lie on or near a helium main sequence, analogous to the main sequence formed by the more common hydrogen stars.[1]

Terminology[edit]

Previously, a helium star was a synonym for a B-type star, but this use of for the term is considered obsolete.[2]

Ahelium star is also a term for a hypothetical star that could occur if two helium white dwarfs with a combined mass of at least 0.5 solar masses merge and subsequently start nuclear fusion of helium, with a lifetime of a few hundred million years. This may only happen if these two binary masses share the same type of envelope phase. It is believed this is the origin of the extreme helium stars.

Description[edit]

The helium main sequence is a line in the HR diagram where unevolved helium stars lie. It lies mostly parallel and to the left (i.e. higher temperatures) of the better-known hydrogen main sequence, although at high masses and luminosities it bends to the right and even crosses the hydrogen main sequence. Therefore, pure helium stars have a maximum temperature, between about 100,000 K and 150,000 K depending on metallicity, because high luminosity causes dramatic inflation of the stellar envelope.[3]

Helium stars' great capability of transforming into other stellar objects has been observed over recent years since they were first identified. The blue progenitor system of the supernova type Iax SN 2012Z in the spiral galaxy NGC 1309 is similar to the progenitor of the Galactic helium nova V445 Puppis, suggesting that SN 2012Z was the explosion of a white dwarf accreting from a helium-star companion. It is observed to have caused a growing helium star that has the potential to transform into a red giant after losing its hydrogen envelope in the future.[4]

See also[edit]

References[edit]

  1. ^ Yoon, S.-C.; Langer, N. (2004). "Helium accreting CO white dwarfs with rotation: Helium novae instead of double detonation". Astronomy and Astrophysics. 419 (2): 645–652. arXiv:astro-ph/0402288. Bibcode:2004A&A...419..645Y. doi:10.1051/0004-6361:20035823. S2CID 7367981.
  • ^ Frost, E. B.; Barrett, S. B.; Struve, O. (1926). "Radial velocities of 368 helium stars". The Astrophysical Journal. 64: 1. Bibcode:1926ApJ....64....1F. doi:10.1086/142986. PMC 1084541.
  • ^ Köhler, K.; Langer, N.; de Koter, A.; De Mink, S.E.; Crowther, P.A.; Evans, C.J.; et al. (2015). "The evolution of rotating very massive stars with LMC composition". Astronomy & Astrophysics. 573: A71. arXiv:1501.03794. Bibcode:2015A&A...573A..71K. doi:10.1051/0004-6361/201424356. S2CID 28962151.
  • ^ McCully, Curtis (2014). "A luminous, blue progenitor system for the type Iax supernova 2012Z". Nature. 512 (7512): 54–56. arXiv:1408.1089. Bibcode:2014Natur.512...54M. doi:10.1038/nature13615. PMID 25100479. S2CID 4464556.

  • Retrieved from "https://en.wikipedia.org/w/index.php?title=Helium_star&oldid=1226346926"

    Categories: 
    Star types
    Chemically peculiar stars
    Helium
    Hidden categories: 
    Articles with short description
    Short description is different from Wikidata
     



    This page was last edited on 30 May 2024, at 01:45 (UTC).

    Text is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.



    Privacy policy

    About Wikipedia

    Disclaimers

    Contact Wikipedia

    Code of Conduct

    Developers

    Statistics

    Cookie statement

    Mobile view



    Wikimedia Foundation
    Powered by MediaWiki