NGC 6755

NGC 6755 is an open cluster of stars in the equatorial constellation of Aquila, positioned about 3° to the east of the star Delta Aquilae.[2] It was discovered by the Anglo-German astronomer William Herschel on July 30, 1785[5] and is located at a distance of 8,060 light years from the Sun.[1] NGC 6756 lies 30′ to the northeast of NGC 6755, with the pair forming a visual double cluster. However, they probably do not form a binary cluster system since they have different ages and are too distant from each other.[2]

NGC 6755
NGC 6755 (taken from Stellarium)
Observation data (J2000 epoch)
Right ascension19h 07m 46.1s[1]
Declination+04° 13′ 26″[1]
Distance8,060 ly (2,471.2 pc)[1]
Apparent magnitude (V)7.5[2]
Apparent dimensions (V)15'[2]
Physical characteristics
Estimated age250 Myr[3]
Other designationsNGC 6755, Cr 397[4]
Associations
ConstellationAquila

This cluster has a Trumpler class of II2r with a visual magnitude of 7.5 and it spans an angular size 15′.[2] It has an estimated age of 250 million years, based on the main sequence turnoff.[3] A total of 71 variable stars have been detected in the field of this cluster, of which 31 are eclipsing binaries, seven are pulsating variables, and 28 are most likely irregular variable red giants.[6]

  • Map showing location of NGC 6755 (Roberto Mura)
    Map showing location of NGC 6755 (Roberto Mura)

References
  1. Cantat-Gaudin, T.; Anders, F. (January 2020). "Clusters and mirages: cataloguing stellar aggregates in the Milky Way". Astronomy & Astrophysics. 633: 22. arXiv:1911.07075. Bibcode:2020A&A...633A..99C. doi:10.1051/0004-6361/201936691. S2CID 208138247. A99.
  2. O'Meara, Stephen James (2011). Deep-Sky Companions: The Secret Deep. Vol. 4. Cambridge University Press. p. 371. ISBN 9780521198769.
  3. Kjeldsen, H.; Frandsen, S. (January 1991). "Stellar photometric stability. II. Ages and distances for 13 open clusters with time series observations". Astronomy and Astrophysics, Supplemental Series. 87: 119. Bibcode:1991A&AS...87..119K.
  4. "NGC 6755". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-25.
  5. Seligman, Courtney. "NGC Objects: NGC 6750 - 6799". Celestial Atlas. Retrieved 2022-01-07.
  6. Ciechanowska, A.; et al. (September 2007). "The Optical Gravitational Lensing Experiment. Variable Stars in the Field of Open Cluster NGC 6755". Acta Astronomica. 57: 249–266. Bibcode:2007AcA....57..249C.
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