The Magellanic Clouds and the Primordial Helium Abundance
2000 ◽
Vol 198
◽
pp. 194-203
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Keyword(s):
A new determination of the pregalactic helium abundance based on the Magellanic Clouds H II regions is discussed. This determination amounts to Yp = 0.2345 ± 0.0030 and is compared with those derived from giant extragalactic H II regions in systems with extremely low heavy elements content. It is suggested that the higher primordial value derived by other authors from giant H II region complexes could be due to two systematic effects: the presence of neutral hydrogen inside the helium Strömgren sphere and the presence of temperature variations inside the observed volume.
2021 ◽
Vol 502
(2)
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pp. 3045-3056
Keyword(s):
2009 ◽
Vol 5
(S268)
◽
pp. 91-100
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Keyword(s):
Keyword(s):
2001 ◽
Vol 378
(3)
◽
pp. 817-825
◽
1989 ◽
Vol 131
◽
pp. 213-213
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Keyword(s):