5/29/2023 0 Comments Stars in cassiopeia constellationThe star is likely ejecting mass at a rapid rate. With an absolute magnitude of -9.5, some 500,000 times as bright as our Sun, it still appears visible without optical aid. The star is unstable, bouncing back and forth between red and blue as it burns through its nuclear fuel at a profligate clip. Astronomers classify rho Cass as a yellow hypergiant, one of only a few known in the galaxy. It’s not a double star, but it’s an astounding star nonetheless, so large and luminous that the word “supergiant” doesn’t fit. Credit: Roberto Mura/Wikipedia Commons.Īlso while you’re in this region have a look at the star ρ (rho) Cassiopeiae. The star cluster NGC 7789 lies between the hypergiant star rho Cassiopeia and the double star sigma Cassiopeiae. You’ll need at least a 3-inch scope to resolve some of the stars in this cluster. It was discovered by Caroline Herschel in 1783, and her nephew John Herschel called it a “most superb” cluster. Because it’s so old, many blue-white stars have turned into red giants, so the cluster is quite colorful. While you’re in the area… just a degree to the north of σ Cass lies the very fine and large open star cluster NGC 7789. This cluster is old (more than one billion years), far (more than 8,000 light years), and faint (most stars are magnitude 11 or 12). Both stars are massive B-type dwarfs, and they lie at a considerable distance of 4,200 light years, more than 200 times farther than eta Cass. The colors of each component are blue to blue-white. If the air is moving and the stars are shimmering, it may not be possible to resolve this star at all. You will need all the magnification you can muster to split this star. The components are magnitude 5.0 and 7.1 and their separation is 3″. This pair is fainter and much tighter than eta. Any telescope at 50x or more will split this pair. They’re now spaced by about 13″ and getting wider, and they will continue to move apart until 2150 when they will be separated by 16″. In 1890, the stars were just 5″ (arcseconds) apart. Since their discovery by William Herschel in 1779, the stars have executed a considerable portion of their full revolution. The two stars of the η Cas system are just 19 light year away, right next door in cosmic terms, and they make a turn around each other every 480 years. Because of its coloring, some call this star the “Easter Egg” double. The 7th-magnitude secondary is officially red-orange, but the visual contrast with the primary makes it appear reddish-purple, or perhaps garnet. The primary star shines at magnitude 3.5 with a yellow-gold color. Also called Achird, it’s one of the most colorful and appealing doubles anywhere in the sky. Let’s begin with an easy one, the fine double star η (eta) Cassiopeiae. – – – – – Now Available from Cosmic Pursuits – – – – – The map above shows you where to find these relatively bright star systems and ‘bonus objects’…. So grab a small telescope and head out to see them for yourself. In this instalment of Cosmic Pursuits, I share with you three double and multiple stars in and around the throne of the legendary Ethiopian queen (along with a couple of extraordinary ‘bonus objects’). But many more present a lovely appearance in a small telescope, revealing color, brightness contrast, and a jewel-like appearance that appeal to the artistically inclined while also packing plenty of physics and sheer challenge to the observer. There are thousands of these objects visible during the year. When time is tight and the weather turns cold, I turn to a class of celestial objects that are very forgiving of observing conditions, light pollution, and telescope aperture: double and multiple stars. White arrows point to the objects in this brief tour of the constellation Cassiopeia.
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