Open Cluster IC 1311

IC 1311
IC 1311: Open cluster in Cygnus; 500 mm Cassegrain 3625 mm f/7.2, SBIG STL11K; 90+3*40 min LRGB; Bernese Highlands; © 2015 Radek Chromik

History

The open star cluster IC 1311 was discovered on October 6, 1893 by the British astronomer Thomas Espin. He described it as «very faint, in a circle of stars». The astronomer Robert Trümpler, who comes from Switzerland and lives in the USA, classified this star cluster as type II3rn: II = somewhat weaker concentration, 3 = some bright, many weak stars, r = rich (100 ... 500) stars, n = connection with nebula. [196]

Physical Properties

IC 1311
IC 1311: Image taken with the 4 m Mayall telescope on Kitt Peak [377]

The cluster has around 850 stars and its age is estimated to be around 1.6 billion years. Due to the reddening caused by interstellar gas and dust, the distance information is rather imprecise: They range from 5.8 kpc to 15.8 kpc (18900 to 51'000 light years). [146, 376]

IC 1311 is located on the north-western edge of the large, faintly red glowing Gamma Cygni Nebula (IC 1318), which is stimulated to glow by the strong ultraviolet radiation of massive, hot, blue stars. But probably the star cluster IC 1318 has no connection with this H-II region. If its distance information is correct, it would have to be far in the background. The star Sadr (γ Cygni) is 1'800 light years away. [149]

«Revised NGC/IC», «Historic NGC/IC», Version 2022-09-01, © Dr. Wolfgang Steinicke [277]
DesignationIC 1311
TypeOCL (II3rn)
Right Ascension20h 10m 48.0s
Declination+41° 10' 24"
Diameter5 arcmin
Visual magnitude13.1 mag
Metric Distance5.333 Mpc
Dreyer DescriptioneF, within circle of st
Identification, RemarksOCL 173, COU 45, URA 50

Finder Chart

The open star cluster IC 1311 is located in the constellation Cygnus (Swan). The best observation time is April to November.

Cygnus: IC 1311
Chart IC 1311
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

146«Version 2000 of the Catalogue of Galactic Planetary Nebulae» L. Kohoutek, A&A Volume 378, Number 3, November II 2001; DOI:10.1051/0004-6361:20011162
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
376«Physical Parameters of the Intermediate age Open Cluster IC 1311: Clues for the Theory of Stellar Evolution» Delgado, A. J.; Alfaro, E. J.; Aparicio, A.; Cabrera-Cano, J.; Astronomical Journal v.108, p.2193; December 1994; DOI:10.1086/117230
377Open Cluster IC 1311; noirlab.edu/public/images/noao-ic1311 (2021-06-03)