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Bubbles from dying stars

Journal Article · · Sky Telesc.; (United States)
OSTI ID:5636495
Stars between one and five solar masses climb the giant branch of the Hertzsprung-Russell diagram twice. At the top of the second ascent, internal upheavals produce the final event: much of remaining hydrogen atmosphere is gently pushed into space. The remaining stellar core becomes very hot. At this stage, a planetary nebula is seen, a low-density shell with a hot blue star at the center. The star will cool and become a white dwarf and the nebula will expand and its gases will blend in with the interstellar medium. These planetaries represent the connecting link between red giants and white dwarfs. In studying planetaries, several phenomena have arisen which will require further research to explain. Several of these phenomena are discussed in this article. The first is that the carbon to oxygen ratio remains constant as helium increases, contrary to the theoretical predictions. The second phenomenon is the existence of helium knots that have been observed in planetary nebulae. Another problem arises when trying to calculate distance to planetaries. They are not satisfactory methods. Without accurate distances, the nebular masses need to find stellar mass-loss rates cannot be determined. (SC)
OSTI ID:
5636495
Journal Information:
Sky Telesc.; (United States), Journal Name: Sky Telesc.; (United States) Vol. 63:2; ISSN SKTEA
Country of Publication:
United States
Language:
English