| Resolving the Effects of Rotation in Altair with Long-Baseline Interferometry |
10 JAN 2006 |
12 pages |
| Authors:
D. M. Peterson; C. A. Hummel; T. A. Pauls; J. T. Armstrong; J. A. Benson; G. C. Gilbreath; D. J. Hutter; K. J. Johnston; D. Mozurkewich; H. Schmitt; STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF PHYSICS AND ASTRONOMY
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 | We report the successful fitting of a Roche model, with a surface temperature gradient following the von Zeipel gravity darkening law, to observations of Altair made with the Navy Prototype Optical Interferometer. We confirm the claim by Ohishi et al. that Altair displays an asymmetric intensity distribution due to rotation, the first such detection in an isolated star. Instrumental effects due to the high visible flux of this first magnitude ... |
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| Vega is a Rapidly Rotating Star |
13 APR 2006 |
5 pages |
| Authors:
D. M. Peterson; C. A. Hummel; T. A. Pauls; J. T. Armstrong; J. A. Benson; G. C. Gilbreath; R. B. Hindsley; D. J. Hutter; K. J. Johnston; D. Mozurkewich; STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF PHYSICS AND ASTRONOMY
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| Vega, the second brightest star in the northern hemisphere, serves as a primary spectral type standard. Although its spectrum is dominated by broad hydrogen lines, the narrower lines of the heavy elements suggested slow to moderate rotation, giving confidence that the ground-based calibration of its visible spectrum could be safely extrapolated into the ultraviolet near-infrared (through atmosphere models), where it also serves as the primary photometric calibrator. But there have ... |
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| The Hyades Binary Theta2 Tauri: Confronting Evolutionary Models With Optical Interferometry |
MAY 2006 |
10 pages |
| Authors:
J. T. Armstrong; D. Mozurkewich; Arsen R. Hajian; K. J. Johnston; R. N. Thessin; Deane M. Peterson; C. A. Hummel; G. C. Gilbreath; NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV
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| We determine the masses and magnitude difference of the components of the Hyades spectroscopic binary theta(2) Tauri. We find that both components appear to be less massive and/or brighter than predicted from some recent evolutionary models. The rapid rotation and unknown rotational inclination of both components introduce uncertainty in their luminosities and colors, but not enough to reconcile both of them with the evolutionary models. We measured the visual orbit ... |
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| The HgMn Binary Star Phi Herculis: Detection and Properties of the Secondary and Revision of the Elemental Abundances of the Primary |
26 OCT 2006 |
46 pages |
| Authors:
R. T. Zavala; S. J. Adelman; C. A. Hummel; A. F. Gulliver; H. Caliskan; J. T. Armstrong; D. J. Hutter; K. J. Johnston; T. A. Pauls; NAVAL OBSERVATORY WASHINGTON DC
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| Observations of the Mercury-Manganese star phi Her with the Navy Prototype Optical Interferometer (NPOI) conclusively reveal the previously unseen companion in this single-lined binary system. The NPOI data were used to predict a spectral type of A8V for the secondary star phi Her B. This prediction was subsequently confirmed by spectroscopic observations obtained at the Dominion Astrophysical Observatory. Phi Her B is rotating at 50 +/- 3 km s(-1), in ... |
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| Optical Interferometric Observations of Theta1 Orionis C from NPOI and Implications for the System Orbit (Preprint) |
2007 |
14 pages |
| Authors:
J. Patience; R. T. Zavala; L. Prato; O. Franz; L. Wasserman; C. Tycner; D. J. Hutter; C. A. Hummel; EXETER UNIV (UNITED KINGDOM) SCHOOL OF PHYSICS
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| With the Navy Prototype Optical Interferometer (NPOI), the binary system Theta 1 Orionis C, the most massive member of the Trapezium, was spatially resolved over a time period extending from February 2006 to March 2007. The data show significant orbital motion over the 14 months, and, after combining the NPOI data with previous measurements of the system from the literature, the observations span 10 years of the orbit. Our results ... |
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