NGC 3921 is an
interacting galaxy
Interacting galaxies (''colliding galaxies'') are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy disturbing the primary galaxy's spiral arms. An example of a ...
in the northern
constellation of
Ursa Major
Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...
. Estimates using
redshift put it at about 59 million
light years (18
megaparsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...
s) from Earth.
[ It was discovered on 14 April 1789 by William Herschel, and was described as "pretty faint, small, round" by John Louis Emil Dreyer, the compiler of the New General Catalogue.][ The image shows noticeable star formation and structures like loops, indicative of galaxies interacting.][
Being a starburst galaxy, NGC 3921 has important features. One of them is an ultraluminous X-ray source, designated ''X-2'', with an X-ray luminosity of erg/s.][ They are both fairly young, and about half as massive as Omega Centauri, demonstrating that mergers of gas-rich galaxies can also create more metal-rich globular clusters.]
References
Notes
External links
*
{{Ngc40
Ursa Major
Arp objects, 224
NGC objects, 3921
UGC objects, 06823
Principal Galaxies Catalogue objects, 037063
Starburst galaxies
Interacting galaxies
Peculiar galaxies
Ring galaxies