HE 1523-0901
Encyclopedia
HE 1523-0901 is the designation given to a red giant
star
located in the Milky Way
galaxy approximately seven and a half light-millennia from Earth. 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 star
s from the Hamburg/ESO Survey
by Anna Frebel and collaborators. The group's research was published in the May 10 2007 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, and nearly as old as the estimated age
of the universe
itself (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 uranium
and thorium
in tandem with measurements of several neutron capture
elements. It is believed to have formed directly from the remnants of the first-generation stars that reached the end of their longevity and exploded as supernovae early in the history of known matter.
catalog. A list of astronomical catalogues can 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.
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
located in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy approximately seven and a half light-millennia from Earth. 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 star
Halo Star
Halo Star is the ninth studio album by the Darkwave band Black Tape for a Blue Girl. It was released in 2004 by Projekt Records. It includes one of the band's most popular songs, "Knock Three Times," which later appeared on the popular 2005 Projekt Presents: A Dark Cabaret compilation, remixed as...
s from the Hamburg/ESO Survey
Hamburg/ESO Survey
The Hamburg/ESO Survey is an astrometric star catalogue published by the University of Hamburg. The catalog contains stars between magnitudes 13 and 18 covering the Southern extragalactic sky.The stated goals of the catalog are...
by Anna Frebel and collaborators. The group's research was published in the May 10 2007 issue of The Astrophysical Journal.
The star's age, as measured by ESO
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
's Very Large Telescope
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...
, is 13.2 billion years. This makes it the oldest object yet discovered in the galaxy, and nearly as old as the estimated age
Age of the universe
The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model...
of the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
itself (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 uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
in tandem with measurements of several neutron capture
Neutron capture
Neutron capture is a kind of nuclear reaction in which an atomic nucleus collides with one or more neutrons and they merge to form a heavier nucleus. Since neutrons have no electric charge they can enter a nucleus more easily than positively charged protons, which are repelled...
elements. It is believed to have formed directly from the remnants of the first-generation stars that reached the end of their longevity and exploded as supernovae early in the history of known matter.
Designation
The designation "HE 1523-0901" indicates that the star is part of the Hamburg/ESO SurveyHamburg/ESO Survey
The Hamburg/ESO Survey is an astrometric star catalogue published by the University of Hamburg. The catalog contains stars between magnitudes 13 and 18 covering the Southern extragalactic sky.The stated goals of the catalog are...
catalog. A list of astronomical catalogues can 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.