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The Origins and Evolutionary Status of B Stars Found Far from the Galactic Plane. I. Composition and Spectral Features The existence of faint blue stars far above the Galactic plane that havespectra that are similar to nearby Population I B stars presents severalinteresting questions. Among them are the following: Can a Population IB star travel from the disk to a position many kiloparsecs above theplane in a relatively short main-sequence lifetime? Is it possible thatsingle massive star formation is occurring far from the Galactic plane?Are these objects something else masquerading as main-sequence B stars?This paper (the first of two) analyzes the abundances of a sample ofthese stars and reveals several that are chemically similar to nearbyPopulation I B stars, whereas others clearly have abundance patternsmore like those expected in blue horizontal-branch (BHB) orpost-asymptotic giant branch stars. Several of those with old evolvedstar abundances also have interesting features of note in their spectra.We also consider why this sample does not have any classical Be starsand identify at least two nearby solar-metallicity BHB stars.Based on observations made at the 2.1 m Otto Struve Telescope ofMcDonald Observatory operated by the University of Texas at Austin.
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Takýmyýldýz: | Baliklar |
Sað Açýklýk: | 00h15m09.87s |
Yükselim: | +17°41'30.0" |
Görünürdeki Parlaklýk: | 9.003 |
Uzaklýk: | 167.504 parsek |
özdevim Sað Açýklýk: | 55.9 |
özdevim Yükselim: | 10.7 |
B-T magnitude: | 9.537 |
V-T magnitude: | 9.048 |
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