M32p is a hypothesized former

galaxy A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...

that was incorporated into the

Andromeda Galaxy The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a Galaxy#Isophotal diameter, D25 isop ...

. It was a sister galaxy to the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

and Andromeda galaxies, previously the third or fourth largest galaxy in the

Local Group The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a " dumbbell" shape; the Milky Way ...

, and was

merged Mergers and acquisitions (M&A) are business transactions in which the ownership of a company, business organization, or one of their operating units is transferred to or consolidated with another entity. They may happen through direct absorpt ...

into the larger Andromeda Galaxy an estimated 2 billion years ago. The merger is thought to have created the thick disc and contributed the majority of the halo stars of Andromeda and caused its burst of star formation at the time of the merger. The former galaxy is likely associated with the Andromeda

satellite galaxy A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and Luminosity, luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents ...

Messier 32 Messier 32 (also known as M32 and NGC 221) is a dwarf "early-type" galaxy about from the Solar System, appearing in the constellation Andromeda (constellation), Andromeda. M32 is a satellite galaxy of the Andromeda Galaxy (M31) and was discover ...

(M32), which may be the remains of its dense core. M32's unusual characteristics of dense compactness and burst of star formation 2 billion years ago would be explained by this theory as a remnant of an earlier large galaxy, given its unlikeness to other similarly sized elliptical galaxies. It was described in 2018 by scientists at the

University of Michigan The University of Michigan (U-M, U of M, or Michigan) is a public university, public research university in Ann Arbor, Michigan, United States. Founded in 1817, it is the oldest institution of higher education in the state. The University of Mi ...

. It is thought to have had a stellar mass of around 2.5×10¹⁰ M_☉.

See also

References

Further reading