Sodium abundance variations in main-sequence stars of the globular cluster 47 Tucanae
Article Abstract:
A comparison between the sodium abundances found in main-sequence stars within the 47 Tucanae star cluster and other star clusters was conducted. It was found that the sodium abundances in main-sequence stars in the 47 Tucanae star cluster were different from other clusters and cannot be explained by existing stellar models. Such an observation suggests that the gas from which 47 Tucanae was formed may have been chemically inhomogenous or that some mechanism for changing the surface element abundances of stars exists and occurs while the stars are still in their unevolved stage.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Identification of V1017 Sgr as a cataclysmic variable binary system with unusually long period
Article Abstract:
V1017 Sgr, a binary system combining features of classical novae and dwarf novae, has a period of 5.7 days, far longer than the 0.5 days that is usual for cataclysmic variable binaries. Hence V1017 Sgr and other systems with long periods may constitute a separate group of cataclysmic variable binaries in which the red-dwarf secondary star is larger and more evolved relative to the white-dwarf primary star that it orbits. V1017 Sgr's period was verified using preliminary spectroscopic orbit data.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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Possible cataclysmic variable in the core of the globular cluster 47 Tucanae
Article Abstract:
An object that is both an intermediate polar binary and a magnetic cataclysmic variable may be producing the low-luminosity X-rays from the core of the globular cluster 47 Tucanae. The exact nature of 47 Tucanae's X-ray source, identified as X0021.8-7221, has been difficult to explain. New observations with the Hubble Space Telescope's Faint Object Camera suggest that V1, an object in 47 Tucanae's core, may be the optical counterpart to X0021.8-7221.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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