Scorpius–Centaurus Association

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Map of the Scorpius–Centaurus Association.

The Scorpius–Centaurus Association (sometimes called Sco–Cen or Sco OB2) is a group of stars near the Sun. They are 380 to 470 light years away.[1]

They are young stars which all formed from the same cloud of material. They range from 11 to 15 million years old.[2] They include the massive Antares, and most of the stars in the Southern Cross.[3]

The Sco–Cen OB association is the main part of a large complex of recent (<20 million years) and ongoing star-formation. The complex contains several star-forming molecular clouds in Sco–Cen's immediate vicinity.

The stellar members of the Sco–Cen association have nearly parallel velocity vectors, moving at about 20 km/s with respect to the Sun. The variation of velocity within the subgroups is about 1–2 km/s,[4] and the group is most likely gravitationally unbound.[5] Several supernovae have exploded in Sco–Cen over the past 15 million years, leaving a network of expanding gas superbubbles around the group.[6]

To explain the presence of radioactive 60Fe in Earth's deep ocean ferromanganese crust, it has been suggested that a nearby supernova, perhaps a member of Sco–Cen, exploded in the Sun's vicinity about 3 million years ago.[7]

References[change | change source]

  1. de Zeeuw P.T. et al 1999. "A Hipparcos census of nearby OB Associations". Astronomical Journal 117 (1): 354–399. doi:10.1086/300682.
  2. Mark J. Pecaut, Eric E. Mamajek & Eric J. Bubar 2012. A revised age for Upper Scorpius and the star formation history among the F-type Members of the Scorpius-Centaurus OB Association. Astrophysical Journal 746 (2): 154. doi:10.1088/0004-637X/746/2/154.
  3. Preibisch, T. & Mamajek E. 2009. "The nearest OB Association: Scorpius-Centaurus (Sco OB2)". Handbook of Star-Forming Regions 2: 0.
  4. Madsen S. et al 2002. "Astrometric radial velocities. III. Hipparcos measurements of nearby star clusters and associations". Astronomy & Astrophysics 381 (2): 446–463. doi:10.1051/0004-6361:20011458.
  5. = no longer held together by gravity
  6. de Geus E.J. (1992). "Interaction of stars and interstellar matter in Scorpio Centaurus". Astronomy & Astrophysics 262: 258–270.
  7. Fields B.D; Hochmuth K.A. & Ellis J. (2005). "Deep-Ocean crusts as telescopes: using live radioisotopes to probe supernova nucleosynthesis". Astrophys. J. 621 (2): 902–907. doi:10.1086/427797.