Virgo Stellar Stream
| Virgo Stellar Stream | |
|---|---|
Stellar streams (artist's impression)
|
|
| Observation data (J2000 epoch) | |
| Constellation | Virgo |
| Right ascension | ? |
| Declination | ? |
| Distance | 30 kly |
| Apparent magnitude (V) | ? |
| Absolute magnitude (V) | ? |
| Characteristics | |
| Type | remains of a dSph |
| Apparent size (V) | 30° × 10° |
| Other designations | |
| none | |
The Virgo Stellar Stream, also known as Virgo Overdensity, is the proposed name for a stellar stream in the constellation of Virgo which was discovered in 2005. The stream is thought to be the remains of a dwarf spheroidal galaxy that is in the process of merging with the Milky Way. It is the largest galaxy visible from the Earth, in terms of the area of the night sky covered.
The stream was discovered from photometric data from the Sloan Digital Sky Survey, which was used to create a three-dimensional map of the Milky Way, using the colors and brightness of certain characteristic types of stars to estimate their distance (a method known as "photometric parallax"). The first suggestion of a new galaxy in Virgo was made in 2001 from data obtained as part of the QUEST survey, which used the 1.0 metre Schmidt telescope at the Llano del Hato National Astronomical Observatory in Venezuela to look for RR Lyrae variable stars. Five were found in a clump with a right ascension near 12.4 hours, and the astronomers speculated that this clump was part of a small galaxy being "cannibalised" by the Milky Way.
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