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RE: Algol
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Minimum of Beta Perseus variable star at 0.3h

Magnitude=3.4mag  
Max=2.1mag  
Period= 2.9days   
RA= 3h08.2m  Dec=+40°57'

Eclipse begins at about 19:29 and ends at  5:07 UT

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Minimum of Beta Perseus variable star at 1.8h, 28th May 2010

Magnitude=3.4mag  
Max=2.1mag 
Period= 2.9days  
RA= 3h08.2m  Dec=+40°57'

Eclipse begins at about 20:58 and ends at  6:36 UT

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Title: The Algol triple system spatially resolved at optical wavelengths
Authors: R. T. Zavala (1), C. A. Hummel (2), D. A. Boboltz (3), R. Ojha (3), D. B. Shaffer (4), C. Tycner (5), M. T. Richards (6), D. J. Hutter (1) ((1) U.S. Naval Observatory, Flagstaff Station, (2) ESO, (3) U.S. Naval Observatory, Washington, D.C., (4) Lowell Observatory, (5) Central Michigan University, (6) The Pennsylvania State University)

Interacting binaries typically have separations in the milli-arcsecond regime and hence it has been challenging to resolve them at any wavelength. However, recent advances in optical interferometry have improved our ability to discern the components in these systems and have now enabled the direct determination of physical parameters. We used the Navy Prototype Optical Interferometer to produce for the first time images resolving all three components in the well-known Algol triple system. Specifically, we have separated the tertiary component from the binary and simultaneously resolved the eclipsing binary pair, which represents the nearest and brightest eclipsing binary in the sky. We present revised orbital elements for the triple system, and we have rectified the 180-degree ambiguity in the position angle of Algol C. Our directly determined magnitude differences and masses for this triple star system are consistent with earlier light curve modelling results.

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Minimum of Beta Persei variable star at 18.8h

Eclipse begins at about 14:02 and ends at 23:40 UT

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L

Posts: 129162
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Minimum of Beta Persei Variable Star at  22:00 UT

Magnitude=3.4mag  
Max=2.1mag  
Period= 2.9days   
RA= 3h08.2m  Dec=+40°57'

Eclipse begins at about 17:12 and ends at  2:50 UT

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Minimum of the variable star Beta Persei at 23.4h
Magnitude=3.4mag 
Max=2.1mag 
Period= 2.9days  
RA= 3h08.2m  Dec=+40°57'

Eclipse begins at about 18:37 and ends at  4:15 UT

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Radio Telescopes Help Astronomers Find Double-Star System

Astronomers have found a giant magnetic loop stretched outward from one of the stars making up the famous double-star system Algol. The scientists used an international collection of radio telescopes to discover the feature, which may help explain details of previous observations of the stellar system.
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UI astronomers capture first-of-kind image at distant star

Two University of Iowa researchers have made the first direct radio image of a stellar coronal loop at a star, other than the sun, thereby providing scientists with information that may lead to a better understanding of how such phenomena as space weather affect the Earth.
Robert Mutel, professor in the University of Iowa College of Liberal Arts and Sciences Department of Physics and Astronomy, and his graduate student William Peterson of Marshalltown, Iowa, spearheaded the research, which included astronomers from New Mexico and Switzerland. They published their findings in the Jan. 14 issue of the Journal Nature.

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Giant Magnetic Loop Sweeps Through Space Between Stellar Pair

Astronomers have found a giant magnetic loop stretched outward from one of the stars making up the famous double-star system Algol. The scientists used an international collection of radio telescopes to discover the feature, which may help explain details of previous observations of the stellar system.

"This is the first time we've seen a feature like this in the magnetic field of any star other than the Sun" - William Peterson, of the University of Iowa.

The pair, 93 light-years from Earth, includes a star about 3 times more massive than the Sun and a less-massive companion, orbiting it at a distance of 5.8 million miles, only about six percent of the distance between Earth and the Sun. The newly-discovered magnetic loop emerges from the poles of the less-massive star and stretches outward in the direction of the primary star. As the secondary star orbits its companion, one side -- the side with the magnetic loop -- constantly faces the more-massive star, just as the same side of our Moon always faces the Earth.

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Title: Interferometric Observations of Algol
Authors: Sz. Csizmadia, T. Borkovits, Zs. Paragi, P. Abraham, L. Szabados, L. Mosoni, L. Sturmann, J. Sturmann, C. Farrington, H. A. McAlister, T. A. ten Brummelaar, N. H. Turner, P. Klagyivik

Algol is a triple stellar system consisting of a close semidetached binary orbited by a third object. Due to the disputed spatial orientation of the close pair, the third body perturbation of this pair is a subject of much research. In this study, we determine the spatial orientation of the close pair orbital plane using the CHARA Array, a six-element optical/IR interferometer located on Mount Wilson, and state-of-the-art e-EVN interferometric techniques. We find that the longitude of the line of nodes for the close pair is \Omega_1=48° ±2° and the mutual inclination of the orbital planes of the close and the wide pairs is 95° ±3°. This latter value differs by 5° from the formerly known 100° which would imply a very fast inclination variation of the system, not borne out by the photometric observations. We also investigated the dynamics of the system with numerical integration of the equations of motions using our result as an initial condition. We found large variations in the inclination of the close pair (its amplitude ~ 170°) with a period of about 20 millennia. This result is in good agreement with the photometrically observed change of amplitude in Algol's primary minimum.

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