Astronomy:NGC 2173

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NGC 2173
Observation data (J2000 epoch)
ConstellationMensa[1]
Right ascension 05h 57m 58.0s[2]
Declination−72° 58′ 42″[2]
Distance158.8 ± 3.3 kly (48.7 ± 1.0 kpc)[3]
Apparent magnitude (V)11.88[4]
Apparent dimensions (V)2.60″[2]
Physical characteristics
Mass~105[5] M☉
Metallicity[Fe/H] = −0.42[4] dex
Estimated age1.7±0.2 Gyr.[5]
Other designationsNGC 2173, SL 807, LW 348, ESO 33SC34[2][6]
See also: Globular cluster, List of globular clusters

NGC 2173 is a globular cluster of stars in the southern constellation of Mensa.[1] It was discovered on February 8, 1836 by English astronomer John Herschel.[7] The cluster has an apparent visual magnitude of 11.88,[4] and an angular size of 2.60″.[2] It is located at a distance of approximately 159,000 ly (48.7 kpc) from the Sun.[3]

The cluster is located within the Large Magellanic Cloud, to the southeast of the galaxy's center at a separation of around 11,000 ly (3.5 kpc). A 1986 age estimate based on the main sequence turnoff found a value of 1.8±0.7 Gyr.[8] This was later refined to 1.7±0.2 Gyr.[5] Variations in lower mass element abundances suggest that the cluster has at least two distinct stellar populations with different ages.[5]

In 2018, it was announced by Li et al (2018) that the blue straggler stars in the cluster formed two distinct sequences.[9] However, an objection was raised that this finding was an artifact of field contamination: by applying decontamination techniques, one of the sequences could be shown to be unrelated to the cluster.[10] With the availability of higher precision proper motion data, the existence of the bifurcatated sequence was apparently reconfirmed by Wang et al (2025).[11]

References

  1. ↑ 1.0 1.1 Frommert, Hartmut. "Revised NGC Data for NGC 2173". Students for the Exploration and Development of Space. https://spider.seds.org/ngc/revngcic.cgi?NGC2173. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Bica, E. (September 2008). "A general catalogue of extended objects in the Magellanic System". Monthly Notices of the Royal Astronomical Society 389 (2): 678−690. doi:10.1111/j.1365-2966.2008.13612.x. Bibcode: 2008MNRAS.389..678B. 
  3. ↑ 3.0 3.1 Grocholski, Aaron J. (August 2007). "Distances to Populous Clusters in the Large Magellanic Cloud via the K-band Luminosity of the Red Clump". The Astronomical Journal 134 (2): 680–693. doi:10.1086/519735. Bibcode: 2007AJ....134..680G. 
  4. ↑ 4.0 4.1 4.2 Grocholski, Aaron J. (October 2006). "Ca II Triplet Spectroscopy of Large Magellanic Cloud Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters". The Astronomical Journal 132 (4): 1630–1644. doi:10.1086/507303. Bibcode: 2006AJ....132.1630G. 
  5. ↑ 5.0 5.1 5.2 5.3 Kapse, Shalmalee (March 2022). "Decoding the Bifurcated Red Giant Branch as a Tracer of Multiple Stellar Populations in the Young Large Magellanic Cloud Cluster NGC 2173". The Astrophysical Journal Letters 927 (1): id. L10. doi:10.3847/2041-8213/ac551a. Bibcode: 2022ApJ...927L..10K. 
  6. ↑ "NGC 2173". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+2173. 
  7. ↑ Seligman, Courtney (September 1, 2020). "New General Catalog Objects: NGC 2150 - 2199". Celestial Atlas. https://cseligman.com/text/atlas/ngc21a.htm#2173. 
  8. ↑ Mould, J. R. et al. (1986). "The Age of the Large Magellanic Cloud Globular Cluster NGC 2173 - ADS". The Astrophysical Journal 309: 39. doi:10.1086/164575. Bibcode: 1986ApJ...309...39M. 
  9. ↑ Li, Chengyuan (March 2018). "An Unexpected Detection of Bifurcated Blue Straggler Sequences in the Young Globular Cluster NGC 2173". The Astrophysical Journal 856 (1): id. 25. doi:10.3847/1538-4357/aaad65. Bibcode: 2018ApJ...856...25L. 
  10. ↑ Dalessandro, E. (January 2019). "The double blue-straggler sequence in NGC 2173: an artifact of field contamination". Astronomy & Astrophysics 621: id. A45. doi:10.1051/0004-6361/201834011. Bibcode: 2019A&A...621A..45D. 
  11. ↑ Wang, Li et al. (March 25, 2025). "Unveiling Bifurcated Blue Straggler Sequences in NGC 2173: Insights from Binary Evolution". The Astrophysical Journal 984 (1): 52. doi:10.3847/1538-4357/adc575. Bibcode: 2025ApJ...984...52W. 

Template:NGC objects:2001-3000



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