Intergalactic star

The Virgo cluster of galaxies where the phenomenon known as intergalactic stars was discovered.

An intergalactic star, also known as a rogue star, is a star that is not located within a galaxy. These stars were a source of much discussion in the scientific community during the late 1990s and are generally thought to be the result of galaxies colliding.

Discovery

The common belief that stars exist only in galaxies was disproven in 1997 with the discovery of intergalactic stars.^[1] The first to be discovered were in the Virgo cluster of galaxies, where some one trillion are now surmised to exist.^[2]

Formation

Although the way in which these stars form is still a mystery, the most common theory is that the collision of two or more galaxies can toss certain stars out into the vast regions of empty space.

A collision between galaxies is commonly thought to be the source of intergalactic stars.

Another theory states (an example of which is shown in the image below) that stars can be ejected from their galaxy by supermassive black holes.

Proposed mechanisms for the ejection of intergalactic stars by supermassive black holes.

Observation history

In 1997, the Hubble telescope discovered a large number of intergalactic stars in the Virgo cluster of galaxies. Later in the 1990s scientists discovered another group of intergalactic stars in the Fornax cluster of galaxies.

Mass

Although the precise mass of these stars cannot be known, it is estimated that they take up 10 percent of the mass of the Virgo cluster of galaxies. This means that, most likely, these stars have a larger mass than any particular one of the 2500 galaxies that form the Virgo cluster.^{[citation needed]}

Location

The first intergalactic stars were discovered in the Virgo cluster of galaxies. These stars form a massive group approximately 300,000 light years away from the nearest galaxy.

See also

• Blue straggler
• HE 0437-5439
• Intergalactic dust
• Stars
• Stellar kinematics

References

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