[M13]

M13 Barnard 29

Cluster Star M13 Barnard 29 (NGC 6205 222),
a Post-AGB Star (proto-Planetary Nebula, pPN) in Globular Cluster M13 in Hercules

Globular cluster M13 contains a particular star, first cataloged by Ludendorff (1905) as Cluster Star NGC 6205 222, and frequently referred to as Barnard 29 (or M13 Barnard 29) from Barnard (1931). Arp (1955) determined its spectral type as B2, unusual for such a bright star in the globular cluster M13.

Longly considered a peculiar young star and perhaps captured by the cluster, it was recognized as an evolved star, a genuine member of the cluster (Conlon 1993). This star is now classified as a post-AGB star, which has evolved behind its Mira stage, ejected most of its envelop, and is in process to develop a planetary nebula. This planetary will become a particular nice addition for astronomers observing globular cluster M13 in the semi-near future.

In the images of M13 below, the position of this star is marked for location.

Post-AGB star Barnard 29 in DSS image of M13 (Source: SIMBAD)

Post-AGB star Barnard 29 in 2MASS image of M13 (Source: SIMBAD)

SIMBAD data for M13 star Barnard 29

Refernces

Halton C. Arp, 1955. Color-magnitude diagrams for seven globular clusters. Astronomical Journal, Vol. 60, No. 1232 (October 1955), pp. 317-337 [ADS: 1955AJ.....60..317A]
Edward E. Barnard, 1931. Micrometric measures of star clusters. Publications of the Yerkes Observatory, Vol. 6, pp. 1-106 [ADS: 1931PYerO...6....1B]
L. Conlon, 1993. UES spectroscopy of the hot post-AGB star Barnard 29. Gemini, No. 42, pp. 22 - 24 (December 1993) [ADS: 1993Gemin..42...22C]
Hans Ludendorff, 1905. Der grosse Sternhaufen im Herkules Messier 13. Publikationen des Astrophysikalischen Observatoriums zu Potsdam; 15. Bd., 6. Stuck = Nr. 50. 56p. [ADS: 1905POPot..50....1L]

Hartmut Frommert
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Last Modification: January 10, 2021