Hyades Stream
Encyclopedia
The Hyades Stream 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. 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 Eggen 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
; their common motion is attributed to tidal effects of the massive rotating bar
at the center of the Milky Way Galaxy
. 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.
Hyades (star cluster)
The Hyades is the nearest open cluster to the Solar System and one of the best-studied of all star clusters. The Hipparcos satellite, the Hubble Space Telescope, and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster's center of ~153 ly...
. In 1869, Richard A. Proctor observed that numerous stars at large distances from the Hyades share a similar motion through space. In 1908, Lewis Boss
Lewis Boss
-Life:He was born in Providence, Rhode Island and attended secondary school at the Lapham Institute in North Scituate and the New Hampton Institution in New Hampshire. In 1870 he graduated from Dartmouth College, then went to work as a clerk for the U.S. Government. He served as an assistant...
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 Eggen 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
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
; their common motion is attributed to tidal effects of the massive rotating bar
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies...
at the center of the Milky Way Galaxy
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. Among the remaining members of the Hyades Stream, the exoplanet host star Iota Horologii
Iota Horologii
Iota Horologii is a solar twin, yellow dwarf star approximately 56 light-years away in the constellation of Horologium . The star is classified as a G0Vp yellow dwarf...
has recently been proposed as an escaped member of the primordial Hyades Cluster.