Stellar density is the average number of

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

s within a unit volume. It is similar to the stellar mass density, which is the total

solar mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass o ...

es (M_Sun) found within a unit volume. Typically, the volume used by astronomers to describe the stellar density is a cubic

parsec 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, a ...

(pc³). In the

solar neighborhood The Local Interstellar Cloud (LIC), also known as the Local Fluff, is an interstellar cloud roughly across, through which the Solar System is moving. This feature overlaps a region around the Sun referred to as the solar neighborhood. It is unk ...

, this value can be determined from surveys of nearby stars, combined with estimates of the number of faint stars that may have been missed. The true stellar density near the Sun is estimated as 0.004 stars per cubic

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 ...

, or . When combined with estimates of the stellar masses, this yields a mass density estimate of or 0.059 solar masses per cubic parsec. The density estimate varies across space, with the density decreasing rapidly in the direction out of the galactic plane. The locations within the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...

that have the highest stellar density are the central core and the interior of

globular clusters A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

. A typical mass density for a globular cluster is , which is 500 times the mass density near the Sun. In the solar neighborhood, the stellar density of a star cluster must be greater than in order to avoid tidal disruption.

References

{{reflist, refs= {{cite book , title=The Milky Way and beyond , first=Erik , last=Gregersen , date=2010 , publisher=The Rosen Publishing Group , isbn=1-61530-053-8 , pages=35–36 {{cite book , author=Marx, Siegfried , author2=Pfau, Werner , date=1992 , title=Astrophotography with the Schmidt telescope , page=124 , publisher=

Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambr ...

, isbn=0-521-39549-6 {{cite book , author=Max-Planck-Institut für Astronomie , title=Modes of star formation and the origin of field populations: proceedings of a workshop , location=Max-Planck Institute of Astronomy, Heidelberg, Germany , orig-year=October 9–13, 2000 , publication-date=2002 , volume=285 , series=Astronomical Society of the Pacific conference series , editor=Eva K. Grebel , editor2=Wolfgang Brandner , publisher=Astronomical Society of the Pacific , isbn=1-58381-128-1 , page=165 Stellar astronomy