The Hyades Stream (or Hyades
moving group) is a large collection of scattered stars that also share a similar trajectory with the
Hyades Cluster
The Hyades (; Greek Ὑάδες, also known as Caldwell 41, Collinder 50, or Melotte 25) is the nearest open cluster and one of the best-studied star clusters. Located about away from the Sun, it consists of a roughly spherical group of hundreds ...
. In 1869,
Richard A. Proctor
Richard Anthony Proctor (23 March 1837 – 12 September 1888) was an English astronomer. He is best remembered for having produced one of the earliest maps of Mars in 1867 from 27 drawings by the English observer William Rutter Dawes. His map w ...
observed that numerous stars at large distances from the Hyades share a similar motion through space.
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
Olin Jeuck Eggen (July 9, 1919 – October 2, 1998) was an American astronomer.
Biography
Olin Jeuck Eggen was born to Olin Eggen and Bertha Clare Jeuck in the village of Orfordville in Rock County, Wisconsin. Both of his parents were of Norw ...
who assumed that it was a vestige of an initially more massive cluster which had partly evaporated, the Hyades Supercluster
). Boss published a chart that traced the scattered stars' movements back to a common point of convergence.
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
In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...
; their common motion is attributed to tidal effects of the massive rotating
bar
Bar or BAR may refer to:
Food and drink
* Bar (establishment), selling alcoholic beverages
* Candy bar
* Chocolate bar
Science and technology
* Bar (river morphology), a deposit of sediment
* Bar (tropical cyclone), a layer of cloud
* Bar (u ...
at the center of the
Milky Way Galaxy.
Among the remaining members of the Hyades Stream, the
exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
host star
Iota Horologii has recently been proposed as an escaped member of the primordial Hyades Cluster.
[, announced in ]
References
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