NGC 6604 is a young[6] open cluster of stars in the equatorial constellation of Serpens, positioned about 1.5° north of the Eagle Nebula (NGC 6611).[7] The cluster was discovered by William Herschel on July 15, 1784.[8] It is located at a distance of 4,580[2] light years from the Sun, about 210 ly (65 pc) above the galactic plane.[7] NGC 6604 forms the densest part of the Ser OB2 association of co-moving stars.[9]
NGC 6604 | |
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Observation data (J2000 epoch) | |
Right ascension | 18h 18m 03.0s[1] |
Declination | −12° 14′ 30″[1] |
Distance | 4,580 ly (1,403 pc)[2] |
Apparent magnitude (V) | 6.5[3] |
Physical characteristics | |
Estimated age | 6.5 Myr[1] |
Other designations | NGC 6604, Cr 373, MM 23, OCl 56, C 1815-122, CTB 50, NRL 17, [KPR2004b] 439, Cl Mrk 39, LMH 24, OCISM 11[4] |
Associations | |
Constellation | Serpens[5] |
This cluster is fairly compact with a Trumpler class of I3p,[6] and is still undergoing star formation.[10][7] It lies at the heart of an H II region with the identifier S54, and the two are most likely linked.[6] The cluster has an estimated age of 6.5[1] million years and contains several massive stars of the OB type.[6] One of these is the high mass triple star system HD 167971, which includes the over-contact eclipsing binary MY Ser. It is one of the most luminous stars in the galaxy.[10] HD 168112 is another colliding-wind binary in the cluster; both systems are over-luminous in their X-ray emission.[11]
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