- HE 1523-0901
ra=RA|15|26|01.2 cite web|url=http://www.perseus.gr/Astro-Star-Oldest-HE-1523-0901.htm|title=Oldest Star Image Gallery|publisher=Anthony Ayiomamitis|accessdate=2008-02-20]
dist_ly=~7,500 cite web|url=http://www.as.utexas.edu/~anna/he1523.html|title=Homepage of Anna Frebel|publisher=Anna Frebel|accessdate=2008-02-20]
HE 1523-0901 is the designation given to a
red giant starlocated in the Milky Waygalaxy. It is thought to be a second generation Population II, or metal-poor, star ( [Fe/H] =-2.95). The star was found in the sample of bright metal-poor halo stars from the Hamburg/ European Southern Observatorysurvey by Anna Frebel and collaborators. The group's research was published in the May 102007 issue of the " Astrophysical Journal".
The star's age, as measured by ESO's
Very Large Telescope, is 13.2 billion years. This makes it the oldest object yet discovered in the galaxy, [cite news|author=Frebel, A.; Norris, J. E.; Christlieb, N.; Thom, C.; Beers, T. C.; Rhee, J.|title=Nearby Star Is A Galactic Fossil|publisher=Science Daily|date=May 11, 2007|url=http://www.sciencedaily.com/releases/2007/05/070510151902.htm|accessdate=2007-05-10] and nearly as old as the estimated age of the universeitself (13.7 billion years as measured by WMAP). HE 1523-0901 is the first star whose age was determined using the decay of the radioactive elements uraniumand thoriumin tandem with measurements of several neutron captureelements. [cite news|title=A galactic fossil: Star is found to be 13.2 billion years old|publisher=physorg.com|date=May 10, 2007|url=http://physorg.com/news98033554.html|accessdate=2007-05-12] It is believed to have formed directly from the remnants of the first generation stars that reached the end of their lifespans and exploded as supernovas early in the history of the universe.
The designation "HE 1523-0901" indicates that the star is part of the
Hamburg/SO Surveycatalog. A list of astronomical cataloguescan be used to find which catalog a star or other object is from based on its prefix. Most objects are listed in several catalogs and will often be known by several different designations.
HE 1523-0901 is approximately eight-tenths the size of the
Sun. It can be viewed particularly well from the Southern Hemisphere with the use of a small telescope. It can also be observed from southern locations in the northern hemisphere, such as Greece.
*cite web|url=http://www.itwire.com.au/content/view/12098/1066/|title=Astronomers discover HE 1523-0901 star: Almost as old as universe|publisher=iTWire|accessdate=2007-05-15
*cite web|url=http://www.msnbc.msn.com/id/18612697/|title=Ancient star nearly as old as the universe|publisher=MSNBC.com|accessdate=2007-05-14
* [http://www.eso.org/public/outreach/press-rel/pr-2007/pr-23-07.html ESO press release]
* [http://mcdonaldobservatory.org/news/releases/2007/0510.html McDonald Observatory / UT press release]
* [http://www.hs.uni-hamburg.de/DE/For/Exg/Sur/hes/index.html Hamburg/ESO Survey Homepage]
* [http://www.astronomy.com/asy/default.aspx?c=a&id=5533 Astronomy magazine]
* [http://www.perseus.gr/Astro-Star-Oldest-HE-1523-0901.htm CCD image based on 2-hrs total exposure]
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