VIRGOHI21
Sign in to saveVIRGOHI21 is an extended region of neutral hydrogen (HI) in the Virgo Cluster discovered in 2005. Analysis of its internal motion indicates that it may contain a large amount of dark matter, as much as a small galaxy. Since VIRGOHI21 apparently contains no stars, this would make it one of the first detected dark galaxies. Skeptics of this interpretation argue that VIRGOHI21 is simply a tidal tail of the nearby galaxy NGC 4254.
In the Vinony graph
Within Vinony's link graph, VIRGOHI21 is referenced by 289 other articles, and connects out to epoch, Messier 98 and Messier 99.
It sits within the topics Astronomical objects discovered in 2005, Coma Berenices and Dark galaxies.
Its subject is documented across 15 Wikipedia language editions.
Key facts
- Galaxy.name
- VIRGOHI 21
- Galaxy.epoch
- J2000
- Galaxy.constellation name
- Virgo
- Galaxy.dist_ly
- 50 Mly
- Galaxy.z
- 1966 km/s
- Galaxy.appmag_v
- < 27
- Galaxy.notes
- No stars
via Wikipedia infobox
Wikidata facts
- Part of
- Virgo Cluster
- Constellation
- Virgo
Show 6 more facts
- epoch
- J2000.0
- time of discovery or invention
- 2005-00-00
- right ascension
- 184.4625
- declination
- 14.7750
- radial velocity
- 1966
- catalog code
- VIRGOHI 21
Sources (1)
via Wikidata · CC0
~4 min read
Encyclopedic overview
6 sectionsContents
- Observational properties
- Dark galaxy interpretation
- Tidal tail interpretation
- See also
- References
- External links
VIRGOHI21 is an extended region of neutral hydrogen (HI) in the Virgo Cluster discovered in 2005. Analysis of its internal motion indicates that it may contain a large amount of dark matter, as much as a small galaxy. Since VIRGOHI21 apparently contains no stars, this would make it one of the first detected dark galaxies. Skeptics of this interpretation argue that VIRGOHI21 is simply a tidal tail of the nearby galaxy NGC 4254.
==Observational properties== VIRGOHI21 was detected through radio telescope observations of its neutral hydrogen 21 cm emissions. The detected hydrogen has a mass of about 100 million solar masses and is about 50 million light-years away. By analyzing the Doppler shift of the emissions, astronomers determined that the gas has a high velocity-profile width; that is, different parts of the cloud are moving at high speed relative to other parts. Follow-up Hubble Space Telescope deep observations of the region have detected very few stars (a few hundred).
Excerpted from Wikipedia’s “VIRGOHI21” article, available under the CC BY-SA 4.0 licence.