Moth Nebula Sh 1-89 + Cluster IC 1369

Sh 1-89, IC 1369
Sh 1-89, IC 1369: Planetary Nebula and open cluster in Cygnus; 500 mm Cassegrain f=3625 mm f/7.2; SBIG STL11K; 260-40-40-40 min LRGB; Bernese Highlands; © 2015 Radek Chromik

History

The open cluster IC 1369 was discovered on April 27, 1891 by the Danish astronomer Frederick Pechüle using the 11 inch Merz refractor at the Copenhagen Observatory. Dreyers description «small nebula cluster of stars of 13 mag» suggests that he thought to see a faint nebula in the cluster. [277, 313]

While searching the photo plates of the «Palomar Observatory Sky Survey» made with the 48 inch Schmidt telescope, the American astronomer Stewart Sharpless came across the nebulae Sh 1-89 and published it in 1959 together with a total of 313 H-II Regions in a catalog. In 1967 the nebula was classified as planetary nebula by Hromov and Kohoutek and received the designation PK 89-0.1. [310, 391]

Physical Properties of Sh 1-89

Sh 1-89 is a small bipolar planetary nebula. The distance is estimated to be 1959 pc. [145] The visual apparent brightness is 14.5 mag. [149]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G089.8-00.6: Sh 1- 89, PK 89-00.1, ARO 357, VV' 544
Right Ascension (J2000.0)21h 14m 04s
Declination (J2000.0)47° 44' 29"
Dimensions 35." (optical)
Distance 2.0 kpc
Expansion Velocity 7.5 km/s (O-III), 16. km/s (N-II)
C-Star DesignationsAG82 423
C-Star Magnitude19.7 mag (B filter)
DiscovererSHARPLESS 1959

Physical Properties of IC 1369

The open cluster IC 1369 is of Trumpler type I1m. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥ 0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400–500 pc. The cluster age is found to be between 300 and 350 million years. Among the cluster members six red giants of spectral classes G5–G8 and luminosities II–III, 17 Am stars, one Ap star, and one B5 blue straggler were identified. [424]

«Revised New General Catalogue and Index Catalogue» Dr. Wolfgang Steinicke, 2021 [277]
DesignationIC 1369
TypeOCL (I1m)
Right Ascension21h 12m 09.0s
Declination+47° 46' 00"
Diameter5.00 arcmin
Visual magnitude8.8 mag
Dreyer DescriptionS neb Cl of st 13m
IdentificationOCL 204

Finder Chart

The planetary nebula Sh 1-89 and open cluster IC 1369 are located in the constellation Cygnus. The open cluster is useful to identify the exact position of the PN as it is located about half a degree east of it. The best observation time is from March to December.

Chart Sh 1-89
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

141Strasbourg-ESO Catalogue of Galactic Planetary Nebulae; A. Acker, F. Ochsenbein, B. Stenholm, R. Tylenda, J. Marcout, C. Schohn; European Southern Observatory; ISBN 3-923524-41-2 (1992); cdsarc.unistra.fr/viz-bin/cat/V/84 (2021-02-18)
145SIMBAD astronomical database; simbad.u-strasbg.fr/simbad
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
310«A Catalogue of H II Regions» Stewart Sharpless, US Naval Observatory, 1959; DOI:10.1086/190049; Bibcode:1959ApJS....4..257S
313«A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
391«Morphological study of planetary nebulae. I. Observed forms of planetary nebulae.» Kromov, G. S.; Kohoutek, L.; Bulletin of the Astronomical Institutes of Czechoslovakia, Vol. 19, p. 1-11 (1968); Bibcode:1968BAICz..19....1K
424«Open Cluster IC 1369 and Its Vicinity: Multicolor Photometry and Gaia DR2 Astrometry» V. Straižys, R. P. Boyle, S. Raudeliūnas, J. Zdanavičius, R. Janusz, M. Macijauskas, R. Lazauskaitė, K. Černis, K. Zdanavičius, M. Maskoliūnas, V. Čepas, and A. Kazlauskas; The Astronomical Journal, Volume 159, Number 3, 2020; DOI:10.3847/1538-3881/ab67b5