R CORONAE BOREALIS STARS ARE VIABLE FACTORIES OF PRE-SOLAR GRAINS
- Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia)
We present a new theoretical estimate for the birthrate of R Coronae Borealis (RCB) stars that is in agreement with recent observational data. We find the current Galactic birthrate of RCB stars to be ≈25% of the Galactic rate of Type Ia supernovae, assuming that RCB stars are formed through the merger of carbon–oxygen and helium-rich white dwarfs. Our new RCB birthrate (1.8 × 10{sup −3} yr{sup −1}) is a factor of 10 lower than previous theoretical estimates. This results in roughly 180–540 RCB stars in the Galaxy, depending on the RCB lifetime. From the theoretical and observational estimates, we calculate the total dust production from RCB stars and compare this rate to dust production from novae and born-again asymptotic giant branch (AGB) stars. We find that the amount of dust produced by RCB stars is comparable to the amounts produced by novae or born-again post-AGB stars, indicating that these merger objects are a viable source of carbonaceous pre-solar grains in the Galaxy. There are graphite grains with carbon and oxygen isotopic ratios consistent with the observed composition of RCB stars, adding weight to the suggestion that these rare objects are a source of stardust grains.
- OSTI ID:
- 22525544
- Journal Information:
- Astrophysical Journal, Vol. 809, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE DUST PROPERTIES OF TWO HOT R CORONAE BOREALIS STARS AND A WOLF-RAYET CENTRAL STAR OF A PLANETARY NEBULA: IN SEARCH OF A POSSIBLE LINK
DO R CORONAE BOREALIS STARS FORM FROM DOUBLE WHITE DWARF MERGERS?