Messier 32
Encyclopedia
Messier 32 is a dwarf elliptical galaxy
about 2.65 million
light-year
s away in the constellation
Andromeda
. M32 is a satellite galaxy
of the famous Andromeda Galaxy
(M31) and was discovered by Le Gentil in 1749. M32 measures only 6.5 ± 0.2 kly in diameter at the widest point. Like most elliptical galaxies, M32 contains mostly older faint red and yellow stars with practically no dust or gas and consequently no current star formation
. It does, however, show hints of star formation in the relatively recent past.
The structure and stellar content of M32 is difficult to explain by traditional galaxy formation models. Recent simulations suggest a new scenario in which the strong tidal field
of M31 can transform a spiral galaxy
into a compact elliptical. As a small spiral galaxy falls into the central parts of M31, most of the outer layers of the smaller spiral are stripped away. The central bulge of the galaxy is much less affected and retains its morphology. Tidal effects trigger a massive star burst in the core, resulting in the high density of M32 we observe today. There is also evidence that M32 has an outer disk.
s distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges. The distance measured to M32 using this technique is 2.46 ± 0.09 Mly
(755 ± 28 kpc
). However, M32 is close enough that the tip of the red giant branch (TRGB) method may be used to estimate its distance. The estimated distance to M32 using this technique is 2.51 ± 0.13 Mly (770 ± 40 kpc). Averaged together, these distance measurements give a distance estimate of 2.49 ± 0.08 Mly (763 ± 24 kpc).
. Its mass has been estimated to lie between 1.5 and 5 million solar masses.
Dwarf elliptical galaxy
Dwarf elliptical galaxies, or dEs, are elliptical galaxies that are much smaller than others. They are classified as dE, and are quite common in galaxy groups and clusters, and are usually companions to other galaxies.- Examples :...
about 2.65 million
1 E22 m
To help compare different orders of magnitude, this page lists distances starting at 10 Zm .Distances shorter than 10 Zm* 24 Zm — 2.5 million light years — Distance to the Andromeda Galaxy...
light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Andromeda
Andromeda (constellation)
Andromeda is a constellation in the northern sky. It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by the sea monster Cetus...
. M32 is a satellite galaxy
Satellite galaxy
A satellite galaxy orbits a larger galaxy due to gravitational attraction. Although a galaxy is made of a large number of objects which are not connected to each other, it has a center of mass, which represents a weighted average of the positions of each component object...
of the famous Andromeda Galaxy
Andromeda Galaxy
The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the...
(M31) and was discovered by Le Gentil in 1749. M32 measures only 6.5 ± 0.2 kly in diameter at the widest point. Like most elliptical galaxies, M32 contains mostly older faint red and yellow stars with practically no dust or gas and consequently no current star formation
Star formation
Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy star formation includes the study of the interstellar medium and giant molecular clouds as precursors to the star formation process and the study of young...
. It does, however, show hints of star formation in the relatively recent past.
The structure and stellar content of M32 is difficult to explain by traditional galaxy formation models. Recent simulations suggest a new scenario in which the strong tidal field
Galactic tide
A galactic tide is a tidal force experienced by objects subject to the gravitational field of a galaxy such as the Milky Way. Particular areas of interest concerning galactic tides include galactic collisions, the disruption of dwarf or satellite galaxies, and the Milky Way's tidal effect on the...
of M31 can transform a spiral galaxy
Spiral galaxy
A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
into a compact elliptical. As a small spiral galaxy falls into the central parts of M31, most of the outer layers of the smaller spiral are stripped away. The central bulge of the galaxy is much less affected and retains its morphology. Tidal effects trigger a massive star burst in the core, resulting in the high density of M32 we observe today. There is also evidence that M32 has an outer disk.
Distance measurements
At least two techniques have been used to measure distances to M32. The infrared surface brightness fluctuationSurface brightness fluctuation
Surface brightness fluctuation is a secondary distance indicator used to estimate distances to galaxies. The technique uses the fact that galaxies are made up of a finite number of stars. The number of stars in any small patch of the galaxy will vary from point to point, creating a noise-like...
s distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges. The distance measured to M32 using this technique is 2.46 ± 0.09 Mly
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
(755 ± 28 kpc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
). However, M32 is close enough that the tip of the red giant branch (TRGB) method may be used to estimate its distance. The estimated distance to M32 using this technique is 2.51 ± 0.13 Mly (770 ± 40 kpc). Averaged together, these distance measurements give a distance estimate of 2.49 ± 0.08 Mly (763 ± 24 kpc).
Black Hole
M32 contains a supermassive black holeSupermassive black hole
A supermassive black hole is the largest type of black hole in a galaxy, in the order of hundreds of thousands to billions of solar masses. Most, and possibly all galaxies, including the Milky Way, are believed to contain supermassive black holes at their centers.Supermassive black holes have...
. Its mass has been estimated to lie between 1.5 and 5 million solar masses.