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The Angular Diameter and Effective Temperature of the Lithium-Rich K Giant HD 148293 from the CHARA Array

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 Added by Ellyn Baines
 Publication date 2011
  fields Physics
and research's language is English




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We measured the angular diameter of the lithium-rich K giant star HD 148293 using Georgia State Universitys Center for High Angular Resolution Astronomy (CHARA) Array interferometer. We used our measurement to calculate the stars effective temperature, which allowed us to place it on an H-R diagram to compare it with other Li-rich giants. Its placement supports the evidence presented by Charbonnel & Balachandran that it is undergoing a brief stage in its evolution where Li is being created.



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We present interferometric observations of six O-type stars that were made with the Precision Astronomical Visible Observations (PAVO) beam combiner at the Center for High Angular Resolution Astronomy (CHARA) Array. The observations include multiple brackets for three targets, $lambda$~Ori~A, $zeta$~Oph, and 10~Lac, but there are only preliminary, single observations of the other three stars, $xi$~Per, $alpha$~Cam, and $zeta$~Ori~A. The stellar angular diameters range from 0.55 milliarcsec for $zeta$~Ori~A down to 0.11 mas for 10~Lac, the smallest star yet resolved with the CHARA Array. The rotational oblateness of the rapidly rotating star $zeta$ Oph is directly measured for the first time. We assembled ultraviolet to infrared flux measurements for these stars, and then derived angular diameters and reddening estimates using model atmospheres and an effective temperature set by published results from analysis of the line spectrum. The model-based angular diameters are in good agreement with observed angular diameters. We also present estimates for the effective temperatures of these stars derived by setting the interferometric angular size and fitting the spectrophotometry.
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