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Two white dwarfs with oxygen-rich atmospheres
B T Gänsicke1, D Koester, J Girven
1Department of Physics, University of Warwick, Coventry CV4 7AL, UK. Boris.Gaensicke@warwick.ac.uk
Science (New York, N.Y.)
|December 8, 2009
Summary
Massive stars (7-10 solar masses) can form oxygen-neon white dwarfs. These findings provide observational evidence for stellar evolution pathways avoiding core collapse supernovae.
Area of Science:
- Astronomy and astrophysics
- Stellar evolution
- White dwarf stars
Background:
- Stars between 7 and 10 solar masses have uncertain evolutionary endpoints.
- These endpoints are massive white dwarfs or weak type II supernovae.
- Observational constraints on these pathways are limited.
Purpose of the Study:
- To investigate the evolutionary pathways of massive stars.
- To identify observational signatures of stars avoiding core collapse.
- To constrain the formation of massive white dwarfs.
Main Methods:
- Detection of white dwarfs with specific photospheric abundances.
- Analysis of oxygen abundance in stellar atmospheres.
- Interpretation of findings within stellar evolution models.
Main Results:
- Two white dwarfs with high photospheric oxygen abundances were detected.
- These white dwarfs are identified as bare oxygen-neon cores.
- This suggests they originated from massive progenitors that avoided core collapse.
Conclusions:
- Massive stars can evolve into oxygen-neon white dwarfs.
- This provides observational evidence for a specific stellar death pathway.
- The findings help constrain models of stellar evolution for intermediate-mass stars.
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