IYA Live Telescope Today: Delta Gruis and the "Tarantula Nebula"
Written by Tammy Plotner
Hey, folks! What a treat. The skies were clear and dark in central Victoria earlier and the beautiful double star – Delta Gruis – came out to play. Afterwards we homed in on the incredibly bright Tarantula Nebula. While you're at it, you might want to update your bookmarks to this IYA Live Telescope link. Now… Go and look at our new video! Once in awhile you can even see other portions the Magellanic Cloud in there, too!
The stars that form Grus were originally considered part of Piscis Austrinus (the southern fish), and the Arabic names of many of its stars reflect this classification.
The stars were first defined as a separate constellation by Petrus Plancius, who created twelve new constellations based on the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-cm diameter celestial globe published in 1597 (or 1598) in Amsterdam by Plancius with Jodocus Hondius. Its first depiction in a celestial atlas was in Johann Bayer's Uranometria of 1603. Plancius chose the crane because that bird was considered to symbolise watchfulness. An alternative name for the constellation, Phoenicopterus (Latin for flamingo), was used briefly in England during the 17th century.
Now that it's good and dark and we've got a bit before the Moon, let's take a look at something even more fantastic… the Tarantula Nebula!
The Tarantula Nebula (also known as 30 Doradus, or NGC 2070) is an H II region in the Large Magellanic Cloud. It was originally thought to be a star, but in 1751 Nicolas Louis de Lacaille recognized its nebular nature.
The Tarantula Nebula has an apparent magnitude of 8. Considering its distance of about 180,000 light years, this is an extremely luminous non-stellar object. Its luminosity is so great that if it were as close to Earth as the Orion Nebula, the Tarantula Nebula would cast shadows. In fact, it is the most active starburst region known in the Local Group of galaxies. It is also the largest and most active such region in the Local Group with an estimated diameter of 200 pc.
The nebula resides on the leading edge of the LMC, where ram pressure stripping, and the compression of the interstellar medium
likely resulting from this, is at a maximum. At its core lies the extremely compact cluster of stars (~2.5 pc diameter) – R136a – that produces most of the energy that makes the nebula visible. The estimated mass of the cluster is 450,000 solar masses, suggesting it will likely become a globular cluster in future.
In addition to R136, the Tarantula Nebula also contains an older star cluster—catalogued as Hodge 301—with an age of 20–25 million years. The most massive stars of this cluster have already exploded in supernovae. The closest supernova since the invention of the telescope, Supernova 1987A, occurred in the outskirts of the Tarantula Nebula.
As always, check back periodically on the IYA "Live" telescope. It can't be cloudy forever!
Factual Information Source: Wikipedia
Filed under: IYA 2009, IYA Live Telescope Library
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