21h31m08s, 48° 27′00″| Messier 39 | |
|---|---|
Open cluster Messier 39 in Cygnus
| |
| Observation data (J2000 epoch) | |
| Right ascension | 21h31m 48.0s[1] |
| Declination | +48° 26′ 00″[1] |
| Distance | 1,010 ly (311 pc)[2] |
| Apparent magnitude (V) | 4.6[3] |
| Apparent dimensions (V) | 29′[4] |
| Physical characteristics | |
| Mass | 232+210 −110[5] M☉ |
| Estimated age | 278.6[1] Myr |
| Other designations | M 39, NGC 7092,[6] Cr 438 |
| Associations | |
| Constellation | Cygnus |
| See also: Open cluster, List of open clusters | |
Messier 39orM39, also known as NGC 7092, is an open cluster of stars in the constellationofCygnus, positioned two degrees to the south of the star Pi Cygni[7] and around 9° east-northeast of Deneb.[8] The cluster was discovered by Guillaume Le Gentil in 1749, then Charles Messier added it to his catalogue in 1764.[7][9] When observed in a small telescope at low power the cluster shows around two dozen members[7] but is best observed with binoculars.[7] It has a total integrated magnitude (brightness) of 5.5 and spans an angular diameterof29 arcminutes[4] – about the size of the full Moon.[8] It is centered about 1,010 light-years (311 parsecs) away.[2]
This cluster has an estimated mass of 232 M☉ and a linear tidal radiusof8.6±1.8 pc.[5] Of the 15 brightest components, six form binary star systems; one more is suspected. HD 205117 is a probable eclipsing binary system with a period of 113.2 days that varies by 0.051 in visual magnitude. Both members seem to be subgiants.[10] Within are at least five[11] chemically peculiar stars and ten[12] suspected short-period variable stars.
Stars
Outer space|
| ||
|---|---|---|
| List |
|
|
| See also |
| |
| ||
