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TOPIC: HR 8752 Cassiopeiae

Blobrana

L

Posts: 131433

Date: Dec 27 01:33 2012

V509 Cassiopeiae	Permalink

V509 Cassiopeiae (= V509 Cas = HR 8752) is a star in the constellation Cassiopeia. V509 Cassiopeiae is yellow hypergiant with a G-type and an apparent magnitude that has varied from below +6 in historical times to a peak of +4.3 and now around +5.2. It is around 4,500 light years from Earth. It is classified as a semiregular variable star and is undergoing strong mass loss. It has recently passed through the yellow evolutionary void by ejecting around a solar mass of material in less than 50 years. Read more __________________

Blobrana

L

Posts: 131433

Date: Dec 27 01:30 2012

HR 8752	Permalink

A Hypergiant Star (Partially) Traversing the Yellow Evolutionary Void After thirty years of investigation, a team of scientists from six European countries reports that the hypergiant star HR 8752 is partially traversing the Yellow Evolutionary Void, an area in the Hertzsprung-Russell diagram empty of hypergiant stars with surface temperatures between 5000 and 12000 degrees kelvin. Some of the observations were carried out using the Utrecht Echelle Spectrograph (UES, now retired) on the William Herschel Telescope. They show that in the twenty years from 1985 to 2005, the star's surface temperature rose from 5000 to 8000 degrees, while undergoing a series of strong mass-loss events. During this time, the radius of HR 8752 shrank from 750 to 400 times that of the Sun. These observations indicate that HR 8752 is traversing (part of) the Yellow Evolutionary Void. Read more __________________

Blobrana

L

Posts: 131433

Date: Dec 9 15:17 2012

HR 8752 Cassiopeiae	Permalink

Hypergiant star amazes for 30 years A European research team has published the results of a 30-year study of an extraordinary hypergiant star. They have found that the surface temperature of the super-luminous star HR 8752 increased by about 3000 degrees in less than three decades, while it went through an extremely rare stage called the 'Yellow Evolutionary Void'. The discovery marks an important step closer to unravelling the evolution of the most massive stars. A team of astronomers from six European countries, including the Royal Observatory of Belgium (ROB), has investigated the hypergiant star HR 8752 for 30 years while it traversed the 'Yellow Evolutionary Void'. The 'Void' is a short stage in the lives of the most massive stars when they become very unstable. The team finds that the surface temperature of HR 8752 rose surprisingly fast from 5000 to 8000 degrees in less than 30 years. The research results were very recently published in the journal Astronomy and Astrophysics, available at http://dx.doi.org/10.1051/0004-6361/201117166. The discovery is an important step forward to resolve the enigma of the hypergiants, the most luminous and massive stars of the Galaxy. Read more __________________

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