The Pegasus Dwarf Spheroidal (also known as ''Andromeda VI'' or ''Peg dSph'' for short) is a dwarf spheroidal galaxy about 2.7 million

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Pegasus Pegasus ( grc-gre, Πήγασος, Pḗgasos; la, Pegasus, Pegasos) is one of the best known creatures in Greek mythology. He is a winged divine stallion usually depicted as pure white in color. He was sired by Poseidon, in his role as hor ...

. The Pegasus Dwarf is a member of the

Local Group The Local Group is the galaxy group that includes the Milky Way. 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 its satellites form ...

and a

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

of the Andromeda Galaxy (M31).

General information

The Pegasus Dwarf Spheroidal is a galaxy with mainly metal-poor stellar populations. Its

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

is e/H≃ −1.3. It is located at the

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired w ...

23h51m46.30s and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

+24d34m57.0s in the equatorial coordinate system (

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

J2000.0), and in a distance of 820 ± 20 kpc from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

and a distance of 294 ± 8 kpc from the Andromeda Galaxy. The galaxy was discovered in 1999 by various authors on the Second Palomar Observatory Sky Survey (POSS II) films.

Notes

For an angular distance θ between ''C'' and ''G'', their mutual linear distance ''R'' is given by:
''R''² = ''D'' + ''D'' - 2 × ''D''_''g'' × ''D''_''c'' × cos(θ)

References

External links

NASA/IPAC Extragalactic Database: ''Pegasus Dwarf Spheroidal''
{{Andromeda galaxy Dwarf spheroidal galaxies 2807158 Local Group Low surface brightness galaxies Andromeda Subgroup Pegasus (constellation) Astronomical objects discovered in 1999

General information

See also

Notes

References

External links