IC 4665

IC 4665
Cluster IC 4665 with star Beta Ophiuchi below
Observation data (J2000 epoch)
Right ascension17h 46m 13.0s[1]
Declination+05° 36′ 54″[1]
Distance1.12 kly (343.6 pc[2])
Apparent magnitude (V)4.2[3]
Apparent dimensions (V)40′ × 40′[3]
Physical characteristics
Estimated age55±3 Myr[2]
Other designationsCr 349, Mel 179[4]
Associations
ConstellationOphiuchus
See also: Open cluster, List of open clusters

IC 4665 (Collinder 349 / Melotte 179) is an open cluster of stars in the constellation Ophiuchus, about 1° to the northeast of the star Beta Ophiuchi.[3] It was discovered by Swiss astronomer Philippe Loys de Chéseaux in 1745. The cluster lies about 1,100 light years away from Earth.[2] It is easily visible in the smallest of telescopes and also with binoculars.[3] From a sufficiently dark place it is also visible to the naked eye. It is one of the brightest clusters not to be cataloged by Charles Messier or William Herschel, probably because it is so loose and coarse.

Age estimates for this cluster have ranged from 20 up to as high as 100 million years. Comparison of the stellar lithium depletion with other clusters suggests it began to develop about 55 million years ago.[2] The upper main sequence turnoff age is 42±12 Myr.[5] 819 candidate cluster members have been identified.[6] Two chemically peculiar stars were found to be members in 1977.[7]

There is evidence that IC 4665 is undergoing a collision with the older cluster Collinder 350, located about 4° away. Currently they are separated by a distance of 118.2 ly (36.25 pc), after having formed at least 1,600 ly (500 pc) apart. It is unclear whether the two clusters will merge as a result of the collision.[8]

References

  1. ^ a b Tarricq, Y.; et al. (March 2021). "3D kinematics and age distribution of the open cluster population". Astronomy & Astrophysics. 647. id. A19. arXiv:2012.04017. Bibcode:2021A&A...647A..19T. doi:10.1051/0004-6361/202039388.
  2. ^ a b c d Jeffries, R. D.; et al. (2023). "A revised age greater than 50 Myr for the young cluster IC 4665". Monthly Notices of the Royal Astronomical Society. 526: 1260–1267. arXiv:2309.07619. Bibcode:2023MNRAS.526.1260J. doi:10.1093/mnras/stad2845.
  3. ^ a b c d Crossen, Craig; Rhemann, Gerald (2012). Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes. Springer Science & Business Media. p. 60. ISBN 9783709106266.
  4. ^ "IC 4665". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-17.
  5. ^ Cargile, P. A.; James, D. J. (September 2010). "Employing a New, BVIc Photometric Survey of IC 4665 to Investigate the Age of This Young Open Cluster". The Astronomical Journal. 140 (3): 677–691. arXiv:1005.3329. Bibcode:2010AJ....140..677C. doi:10.1088/0004-6256/140/3/677.
  6. ^ Miret-Roig, N.; et al. (September 2020). "Searching for debris discs in the 30 Myr open cluster IC 4665". Astronomy & Astrophysics. 641. id. A156. arXiv:2007.04992. Bibcode:2020A&A...641A.156M. doi:10.1051/0004-6361/202038205.
  7. ^ Levato, H.; Malaroda, S. (February 1977). "Spectroscopic study of two peculiar stars in IC 4665 : HD 161480 and HD 161733". Publications of the Astronomical Society of the Pacific. 89: 84–94. Bibcode:1977PASP...89...84L. doi:10.1086/130078.
  8. ^ Piatti, Andrés E.; Malhan, Khyati (March 2022). "First evidence of a collision between two unrelated open clusters in the Milky Way". Monthly Notices of the Royal Astronomical Society: Letters. 511 (1): L1–L7. arXiv:2112.03786. Bibcode:2022MNRAS.511L...1P. doi:10.1093/mnrasl/slab130.