| Quantifying Stellar Mass Loss with High Angular Resolution Imaging |
19 Feb 2009 |
9 pages |
| Authors:
Stephen Ridgeway; Jason Aufdenberg; Michelle Creech-Eakman; Nicholas Elias; Steve Howell; Don Hutter; Margarita Karovska; San Ragland; Ed Wishnow; Ming Zhao; NATIONAL OPTICAL ASTRONOMY OBSERVATORIES TUCSON AZ
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 | Mass is constantly being recycled in the universe. One of the most powerful recycling paths is via stellar mass-loss. All stars exhibit mass loss with rates ranging from approximately 10(-14) to 10(-4) solar mass yr(-1), depending on spectral type, luminosity class, rotation rate, companion proximity, and evolutionary stage. The first generation of stars consisted mostly of hydrogen and helium. These shed material - via massive winds, planetary nebulae and supernova ... |
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| Direct Detection of the Close Companion of Polaris With the Hubble Space Telescope |
01-Sep-2008 |
11 pages |
| Authors:
Nancy R Evans; Gail H Schaefer; Howard E Bond; Giuseppe Bono; Margarita Karovska; Edmund Nelan; Dimitar Sasselov; Brian D Mason6; NAVAL OBSERVATORY WASHINGTON DC
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| Polaris, the nearest and brightest classical Cepheid, is a single-lined spectroscopic binary with an orbital period of 30 yr. Using the High Resolution Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST) at a wavelength of <2255 , we have directly detected the faint companion at a separation of 0".17. A second HST observation 1.04 yr later confirms orbital motion in a retrograde direction. By ... |
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| Cepheids in Multiple Systems: ADS 14859 |
NOV 2006 |
6 pages |
| Authors:
Nancy R. Evans; Otto Franz; Derck Massa; Brian Mason; Richard L. Walker; Margarita Karovska; SMITHSONIAN ASTROPHYSICAL OBSERVATORY CAMBRIDGE MA
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| We have attempted to resolve the system containing the Cepheid V1334 Cyg (= ADS 14859) using both the Faint Object Camera (FOC) and the Fine Guidance Sensor (FGS) on the Hubble Space Telescope, and also using ground-based speckle interferometry with 4 m class instruments. None of these approaches was successful, leading to upper limits of approximately 20 mas (depending on the magnitude difference between the stars). We discuss constraints this ... |
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| Polaris: Mass and Multiplicity |
2006 |
4 pages |
| Authors:
Nancy R. Evans; Gail Schaefer; Howard E. Bond; Edmund Nelan; Giuseppe Bono; Margarita Karovska; Scott Wolk; Dimitar Sasselov; Edward Guinan; Scott Engle; NAVAL OBSERVATORY WASHINGTON DC
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| Polaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide (18") physical companion, the F-type dwarf Polaris B. Polaris itself is a single-lined spectroscopic binary with an orbital period of ~30 years (Kamper 1996). By combining Hipparcos measurements of the instantaneous proper motion with long-term measurements and the Kamper radial-velocity orbit, Wielen et al. (2000) have predicted the astrometric orbit ... |
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