HE 1523-0901

HE 1523-0901

"Oldest star" redirects here. For other uses, see Star#Age.

HE 1523-0901

Artist's Impression of the oldest star in our galaxy
Observation data
Epoch J2000      Equinox J2000
Constellation Libra
Right ascension 15h 26m 01.2s [1]
Declination −9° 11′ 38″ [1]
Apparent magnitude (V)11.1 [1]
Distance~7500 [2] ly
(~2,300 [2] pc)

HE 1523-0901 is the designation given to a red giant star in the Milky Way galaxy approximately 7500 light years 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 stars 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.[3]

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,[4] and nearly as old as the estimated age of the universe itself (13.8 billion years as measured by Planck). 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.[5] 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.


The designation "HE 1523-0901" indicates that the star is part of the Hamburg/ESO Survey 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.


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.


External links

  • ESO press release
  • McDonald Observatory / UT press release
  • Hamburg/ESO Survey Homepage
  • Astronomy magazine
  • CCD image based on 2-hrs total exposure

, −09° 11′ 38″