Messier 107

Right Ascension	16 : 32.5 (h:m)
Declination	-13 : 03 (deg:m)
Distance	18.35 (kly)
Visual Brightness	7.9 (mag)
Apparent Dimension	13.0 (arc min)

Discovered by Pierre Méchain in 1782.

Messier 107 (M107, NGC 6171) is another additional object found by Pierre Méchain in April, 1782. Herewith, it is probably the Messier object which was the latest to be discovered. Eventually, Helen Sawyer Hogg added it to the Messier Catalog in 1947, together with M105 and M106, although it appears probable that already Méchain had intended to add it to a future edition of Charles Messier's list. William Herschel, who had independently discovered it on May 12, 1793, cataloged this object as H VI.40; Herschel was the first observer to resolve this globular cluster into stars.

M107 apparently contains some dark obscured regions, which is unusual for globular clusters. The star distribution is called "very open" by Kenneth Glyn Jones, who points out that this cluster "enables the interstellar regions to be examined more easily, and globular clusters are important `laboratories' in which to study the process by which galaxies evolve."

Visually, M107 is about 3 minutes of arc across, while in photos it extends over a region more than 4 times this diameter (about 13'). As its distance is about 18,000 light years, this corresponds to roughly 70 light years. As a globular cluster, M107 is of intermediate metallicity (abundances of elements heavier than Helium).

According to Christine Clement (2015), the moderate number of 26 variables has been found in this globular cluster, one of them a Mira variable; this star is probably not a member of the cluster.

Holger Baumgardt et.al. (2023) investigated astrometrical data from the GAIA satellite, and from the position and velocity, derived M107's simulated orbit. They found that M107 is currently about 18.4 kly (5.63 kpc) from us and 12.2 kly (3.74 kpc) from Galactic Center. Ist orbit stays within 3.9 kly (1.21 kpc) perigalactic and 12.5 kly (3.83 kpc) apogalactic distance, with an orbital period of about 50 Myr. It has just passed its apogalacticum roughly about 1 Myr ago, after being in perigalactic approach about 25 Myr in the past. From fitting of its Color-Magnitude Diagram (CMD), they also found an age of 12.0 Gyr for M107, a half-mass radius of 12.1 ly (3.72 pc), and from the velocity dispersion of its stars, an estimated mass of 61,200 solar masses.

NGC Online data for M107

References:

• Holger Baumgardt et.al., 2023. Fundamental parameters of Galactic globular clusters. Version of March 2023 (4th): https://people.smp.uq.edu.au/HolgerBaumgardt/globular/, authors: Holger Baumgardt, Antonio Sollima, Michael Hilker, Andrea Bellini, Eugene Vasiliev, Vincent Henault-Brunet & Nolan Dickson.
  Related paper publications are referenced in that webpage.
• Christine Clement, 2015, 2024. Variable stars in NGC 6171 / C1629-129 / Messier 107. Updated March 2015, minor updates, in particular membership probabilities, in 2024. https://www.astro.utoronto.ca/~cclement/cat/C1629m129. 26 variables: 16 RR Lyrae type RR0, 7 type RR1, 1 Long-period and 1 Mira variable, 1 SX Phe. The Mira is probably not a cluster member. No pulsars found in M107 yet.

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Hartmut Frommert
Christine Kronberg
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Last Modification: May 4, 2025
Former Definitive Version: August 30, 2007