Holmberg II is an irregular

dwarf galaxy A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is so ...

in the constellation

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 M ...

. Its

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

is 11,1^m and it is 11 million

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s away from Earth. The galaxy is dominated by huge glowing gas bubbles, which are regions of

star formation Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...

. Holmberg II also hosts an ultraluminous X-ray source. One hypothesis suggests that is caused by an intermediate mass

black hole A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...

that is pulling surrounding material. Holmberg II was discovered by Erik Bertil Holmberg.

References

External links

* {{commons category-inline Ursa Major Dwarf galaxies

268 __NOTOC__ Year 268 (Roman numerals, CCLXVIII) was a leap year starting on Wednesday of the Julian calendar. At the time, it was known in Rome as the Year of the Consulship of Paternus and Egnatius (or, less frequently, the year 1021 ''Ab urbe ...

23324 04305 M81 Group