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An ultramassive, fast-spinning white dwarf in a peculiar binary system
S Mereghetti1, A Tiengo, P Esposito
1Istituto Nazionale di Astrofisica-Istituto di Astrofisica Spaziale e Fisica cosmica di Milano, via E. Bassini 15, 20133 Milano, Italy. sandro@iasf-milano.inaf.it
Science (New York, N.Y.)
|September 5, 2009
Summary
Researchers discovered an ultramassive white dwarf star exceeding 1.2 solar masses. This massive star, RX J0648.0-4418, could explode as a Type Ia supernova due to mass transfer in its binary system.
Area of Science:
- Astrophysics
- Stellar Evolution
Background:
- White dwarfs typically have masses around 0.6 solar mass.
- Ultramassive white dwarfs (mass > 1.2 solar mass) are rare.
- White dwarfs in binary systems are crucial for understanding stellar evolution and supernovae.
Purpose of the Study:
- To identify and characterize ultramassive white dwarfs.
- To investigate the potential of RX J0648.0-4418 to reach the Chandrasekhar limit.
- To explore the implications for Type Ia supernova progenitors.
Main Methods:
- Utilized data from the X-ray Multi-Mirror Mission (XMM)-Newton satellite.
- Performed dynamical measurements to determine the white dwarf's mass.
- Analyzed the binary system's configuration (post-common envelope binary with a hot subdwarf).
Main Results:
- Confirmed RX J0648.0-4418 as an ultramassive white dwarf with mass > 1.2 solar mass.
- The white dwarf is part of a binary system with a hot subdwarf companion.
- The system is poised for mass transfer that could trigger a supernova.
Conclusions:
- RX J0648.0-4418 is a key example of an ultramassive white dwarf.
- This white dwarf has the potential to exceed the Chandrasekhar limit and explode as a Type Ia supernova.
- The study highlights the importance of binary systems in understanding extreme stellar objects and explosive events.
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