HE 1523-0901 is the designation given to a red giantstar in the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
Population II
During 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations.
In the abstract of the article by Baade, he recognizes that Jan Oort originally conceived this type of classification in 1926:
Baade noticed ...
, or metal-poor, star ( e/Hnbsp;= −2.95). The star was found in the sample of bright metal-poor
halo star
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''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 Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and ...
''.
Age
The star's age, as measured by
ESO
The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based ast ...
's
Very Large Telescope
The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m acro ...
, is 13.2 billion years. This makes it among the oldest stars and nearly as old as the estimated age of the
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
itself (13.8 billion years as measured by
Planck
Max Karl Ernst Ludwig Planck (, ; 23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.
Planck made many substantial contributions to theoretical p ...
). The measurement uncertainty in the age estimate is 0.7 to 2.7 billion years, depending upon the assumptions made to estimate the uncertainty, although the uncertainty in the relative age of this and other stars using the same method is smaller. HE 1523-0901 is the first star whose age was determined using the decay of the radioactive elements
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
and
thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
in tandem with measurements of several
neutron capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...
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 Survey catalog. A
list of astronomical catalogues
An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. Astronomical catalogs are usually the result of ...
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.
Observation
HE 1523-0901 is approximately 0.8 solar masses. It can be viewed particularly well from the southern hemisphere with the use of a small telescope. It can also be observed from central European latitudes.
See also
*
HD 140283
HD 140283 (also known as the Methuselah star) is a metal-poor subgiant star about 190 light years away from the Earth in the constellation Libra, near the boundary with Ophiuchus in the Milky Way Galaxy. Its apparent magnitude i ...