An Upper Bound to the Space Density of Interstellar Comets

Two well-studied white dwarfs with helium-dominated atmospheres (DBs) each possess less hydrogen than carried by a single average-mass comet. Plausibly, the wind rates from these stars are low enough that most accreted hydrogen remains with the star. If so, and presuming their nominal effective temp...

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Bibliographic Details
Published in:The Astronomical journal 2011-05, Vol.141 (5), p.155-jQuery1323897865395='48'
Main Author: Jura, M
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
COMETS
DWARF STARS
ELEMENTS
FLUIDS
GASES
HELIUM
HYDROGEN
INTERSTELLAR SPACE
NONMETALS
OXYGEN
RARE GASES
SPACE
STARS
STELLAR ATMOSPHERES
WHITE DWARF STARS
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Summary:Two well-studied white dwarfs with helium-dominated atmospheres (DBs) each possess less hydrogen than carried by a single average-mass comet. Plausibly, the wind rates from these stars are low enough that most accreted hydrogen remains with the star. If so, and presuming their nominal effective temperatures, then these DBs have faced minimal impact by interstellar comets during their 50 Myr cooling age; interstellar iceballs with radii between 10 m and 2 km contain less than 1% of all interstellar oxygen. This analysis suggests that most stars do not produce comets at the rate predicted by 'optimistic' scenarios for the formation of the Oort Cloud.
ISSN:1538-3881
0004-6256
1538-3881
DOI:10.1088/0004-6256/141/5/155