Pazmino's Cluster (Stock 23)

Stock 23
Stock 23: Section of DSS2 [147]

History

This star cluster was discovered in the second half of the 1950s by the German astronomer Jürgen Stock and first appeared in the first edition of the «Catalogue of Star Clusters and Associations» in 1958. [570] Jürgen Stock was later responsible for selecting the sites of the observatories on Cerro Tololo and La Silla in Chile. [571]

Sometimes you will also find the term «Pazmino's Cluster», which goes back to an article by John Pazmino in the March 1978 issue of «Sky & Telescope».

Physical Properties

Some sources refer to Stock 23 as an asterism and not a true cluster, as the brighter stars have different parallaxes and proper motions (see table 1). However, a study of the 3D morphology using Gaia EDR3 data revealed that Stock 23 is an open cluster with a filamentary structure. The distance is given as 606.7 pc and the cluster of 78 stars with about 106 solar masses is moving towards us at -18.57 km/s. The age of the cluster is estimated to be -18.57 km/s. The age of the cluster is estimated to be -18.57 km/s. The age of the cluster is estimated at 94 million years. [573] Most scientific sources referenced in Simbad refer to an open cluster. Simbad gives an extent of 90 arcminutes for Stock 23, with the centre about 15 arcminutes north of the conspicuous V-shaped asterism. [145]

The one 9 mag star (HD 237090), which is conspicuously further away at 1136 parsecs, has a high radial velocity of 128.8 km/s away from us. Presumably it was ejected from the cluster due to gravitational interaction.

Data from Simbad, distances and proper motions based on Gaia EDR3 [145]
Name RA [hms] Dec [dms] vMag spType PM RA [mas/y] PM Dec [mas/y] RV [km/s] PLX [mas] Dist [pc]
HD 20040 03 16 10.818 +60 06 57.41 7.54 G2III -13.398 -1.686 -34.5 2.5105 398
HD 20053 03 16 17.370 +60 02 7.10 OB- -28
HD 20095 03 16 41.919 +59 59 26.70 8.12 A0V 17.640 -17.383 1 4.1324 242
HD 20134 03 16 59.751 +60 04 2.97 7.47 B2.5IV-V -4.377 -1.021 -12.50 1.6648 601
HD 237090 03 15 10.928 +59 54 42.80 9.03 B0.5IV:nn 1.263 -0.807 128.80 0.8799 1136
HD 237091 03 15 16.751 +59 54 49.18 9.3 B1:V:nnep -0.200 -2.857 7.60 5.1230
HD 237097 03 15 58.799 +60 12 1.71 9.03 F6IV 53.002 -101.384 -5.40 7.1175 140
HD 237104 03 16 45.559 +60 05 6.76 9.05 F6IV -25.629 9.943 -14 6.3699 157
HD 237106 03 16 55.226 +60 04 41.92 9.81 A0 -4.137 1.939 1.973 507

The cluster is embedded in a faint H-II region (Sh 2-202, LBN 676), crossed by some dark clouds (LDN 1383, 1385). About three degrees west is the well-known Soul Nebula (IC 1848), which together with Heart Nebula (IC 1805) is a popular target for astrophotographers.

Further infos at CDS: Stock 23

Finder Chart

Stock 23 is located in the constellation Camelopardalis, close to the two fourth magnitude stars CE and CS Camelopardalis. The IAU boundary line to the constellation Cassiopeia runs right through the middle of this asterism. The best observation time is from September to March, when the constellation, which is circumpolar in Central Europe, is highest in the sky.

Chart Pazmino's Cluster (Stock 23)
Pazmino's Cluster (Stock 23) in constellation Camelopardalis. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±15°)

References

145SIMBAD astronomical database; simbad.u-strasbg.fr/simbad
147Aladin Lite; aladin.u-strasbg.fr/AladinLite (2020-12-23)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
570«Catalogue of star clusters and associations» Alter, G. ; Ruprecht, J. ; Vanýsek, V.; Prague, Pub. House of the Czechoslavak Academy of Sciences, 1958.; Bibcode:1958csca.book.....A
571«Wer kennt Jürgen Stock?» von Florian Freistetter, 5. April 2011; scienceblogs.de/astrodicticum-simplex/2011/04/05/wer-kennt-jurgen-stock (2022-12-21)
573«3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR 3. II. Hierarchical Star Formation Revealed by Spatial and Kinematic Substructures» Xiaoying Pang, Shih-Yun Tang, Yuqian Li, Zeqiu Yu, Long Wang, Jiayu Li, Yezhang Li, Yifan Wang, Yanshu Wang, Teng Zhang, Mario Pasquato, and M. B. N. Kouwenhoven; The Astrophysical Journal, Volume 931, Number 2, 2022; DOI:10.3847/1538-4357/ac674e