Hyades Stream

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The Hyades Stream (or Hyades moving group) is a large collection of scattered stars that also share a similar trajectory with the Hyades Cluster. In 1869, Richard A. Proctor observed that numerous stars at large distances from the Hyades share a similar motion through space.[1] In 1908, Lewis Boss reported almost 25 years of observations to support this premise, arguing for the existence of a co-moving group of stars that he called the Taurus Stream (now generally known as the Hyades Stream or following Olin J. Eggen who assumed that it was a vestige of an initially more massive cluster which had partly evaporated, the Hyades Supercluster[2]). Boss published a chart that traced the scattered stars' movements back to a common point of convergence.[3]

Eggen's argument that groups of this type are in fact cluster remnants has been debated. It has been noted that because such phenomena may also be the result of other dynamical mechanisms. Famaey B, et al. report that about 85% of stars in the Hyades Stream have been shown to be completely unrelated to the original cluster on the grounds of dissimilar age and metallicity; their common motion is attributed to tidal effects of the massive rotating bar at the center of the Milky Way Galaxy.[4] Among the remaining members of the Hyades Stream, the exoplanet host star Iota Horologii has recently been proposed as an escaped member of the primordial Hyades Cluster.[5]


  1. ^ Zuckerman B, Song I. (2004) Young stars near the Sun. Annual Review of Astronomy & Astrophysics. Volume 42, 685-721. Abstract at http://adsabs.harvard.edu/abs/2004ARA%26A..42..685Z.
  2. ^ Eggen, O. J. (1958) Stellar groups. I. The Hyades and Sirius groups, Monthly Notices of the Royal Astronomical Society, Vol. 118, p.65
  3. ^ Boss L. (1908) Convergent of a moving cluster in Taurus. Astronomical Journal, 26: 31-36. Full text link at http://adsabs.harvard.edu/abs/1908AJ.....26...31B.
  4. ^ Famaey B, Pont F, Luri X, Udry S, Mayor M, Jorissen A. (2007) The Hyades stream: an evaporated cluster or an intrusion from the inner disk? Astronomy & Astrophysics, 461: 957-962. Abstract at http://adsabs.harvard.edu/abs/2007A%26A...461..957F.
  5. ^ Vauclair, S.; Laymand, M.; Bouchy, F.; Vauclair, G.; Hui Bon Hoa, A.; Charpinet, S.; Bazot, M. (2008). "The exoplanet-host star iota Horologii: an evaporated member of the primordial Hyades cluster". Astronomy and Astrophysics. 482 (2): L5–L8. arXiv:0803.2029v1Freely accessible. Bibcode:2008A&A...482L...5V. doi:10.1051/0004-6361:20079342. , announced in Emily Baldwin. "The Drifting Star". Retrieved 2008-04-18.