NGC 6652

NGC 6652
NGC 6652 seen by the Hubble Space Telescope
Observation data
ConstellationSagittarius
Right ascension18h 35m 45.63s
Declination−32° 59′ 26.6″
Distance~30,000
Apparent magnitude (V)9.75
Apparent dimensions (V)5.1' x 5.1'
Physical characteristics
Estimated age13.6 billion years
Other designationsNGC 6652, GCl 98, RX J1835.7-3259, 4FGL J1835.7-3258
See also: Globular cluster, List of globular clusters

NGC 6652 is a globular cluster in Sagittarius. It is located about 6,500 light years from the Galactic Center and about 30,000 light years away from Earth. The cluster was discovered on September 3, 1826 by James Dunlop.

Observations

According to a study published in 2011 by J. Boyles and his colleagues, the metallicity of the globular cluster NGC 6652 is -0.81 and its mass is 109,000 M☉. In the same study, the distance to the cluster is also estimated at approximately 10.0 kpc (∼32,600 ly). The study published by Forbes and Bridges indicates a metallicity of -0.70.

Stars

As of November 2022, 267 pulsars had been discovered in 36 globular clusters of the Milky Way. Out of 267 pulsars, two millisecond binary pulsars are located in NGC 6652. The first pulsar in this globular cluster was discovered using the Green Bank Telescope and is known as PSR J1835-3259A. Its period is 3.9 ms and it has an elliptical orbit with eccentricity of 0.95 and a period of 9.25 days. Assuming a mass of 1.4 M☉ the mass of its companion would be 0.74 M☉. The second is PSR J1835−3259B, a millisecond pulsar with a period of 1.83 ms. It is in a nearly circular orbit around a companion with an estimated mass of about 0.2 M☉, probably a white dwarf. This pulsar is probably the source of the gamma radiation from NGC 6652.

Finally, a third candidate was discovered in this cluster based on simultaneous observations from the Chandra X-ray Observatory and the Karl G. Jansky Very Large Array. It was given the name NGC 6652B and is possibly a transitional millisecond pulsar (tMSP), that is, a pulsar that switches between a rotationally powered state and an accretion-powered state. Other hypotheses must also be considered to explain the behavior of NGC 6625B, although less likely than the tMSP. Confirmation that it is indeed a tMSP will come from a direct observation of its state change.

Observations made with the Chandra X-ray Observatory have detected eleven X-ray sources, six of which were already known and five of which are new. Source A is a low-mass X-ray binary (LMXB). Source B suggests the presence of a neutron star in an LMXB system, but with unusual variability. The spectrum of source C suggests it is a cataclysmic variable. The spectrum of source D suggests the presence of a neutron star in an LMXB system, which would make it the third LMXB source of NGC 6652. Finally, sources E and F show spectra located relatively in the hard X-ray region, suggesting the presence of high-energy plasma.

References

  1. 1 2 3 "NGC 6652". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-07-06.
  2. ↑ "NGC 6652 - Globular Cluster in Sagittarius". The Sky Live.
  3. ↑ Carter, Jamie (13 August 2023). "Space photo of the week: Hubble captures one of our galaxy's oldest objects". Live Science.
  4. ↑ Segilman, Courtney. "The Celestial Atlas".
  5. ↑ Boyles, J.; Lorimer, D. R.; Turk, P. J.; Mnatsakanov, R.; Lynch, R. S.; Ransom, S. M.; Freire, P. C.; Belczynski, K. (2011-11-20). "Young Radio Pulsars in Galactic Globular Clusters". The Astrophysical Journal. 742 (1): 51. arXiv:1108.4402. Bibcode:2011ApJ...742...51B. doi:10.1088/0004-637X/742/1/51. ISSN 0004-637X.
  6. ↑ Forbes, Duncan A.; Bridges, Terry (2010). "Accreted versus in situ Milky Way globular clusters". Monthly Notices of the Royal Astronomical Society. 404 (3): 1203. arXiv:1001.4289. Bibcode:2010MNRAS.404.1203F. doi:10.1111/j.1365-2966.2010.16373.x.
  7. 1 2 Yin, De-Jiang; Zhang, Li-Yun; Li, Bao-Da; Li, Ming-Hui; Qian, Lei; Pan, Zhichen (2023-05-01). "The Analyses of Globular Cluster Pulsars and Their Detection Efficiency". Research in Astronomy and Astrophysics. 23 (5): 055012. arXiv:2303.09710. Bibcode:2023RAA....23e5012Y. doi:10.1088/1674-4527/acc37e. ISSN 1674-4527.
  8. 1 2 DeCesar, Megan E.; Ransom, Scott M.; Kaplan, David L.; Ray, Paul S.; Geller, Aaron M. (2015-07-07). "A Highly Eccentric 3.9 Millisecond Binary Pulsar in the Globular Cluster NGC 6652". The Astrophysical Journal. 807 (2): L23. arXiv:1506.03367. Bibcode:2015ApJ...807L..23D. doi:10.1088/2041-8205/807/2/L23. ISSN 2041-8213.
  9. ↑ Gautam, T.; Ridolfi, A.; Freire, P. C. C.; Wharton, R. S.; Gupta, Y.; Ransom, S. M.; Oswald, L. S.; Kramer, M.; DeCesar, M. E. (2022). "Upgraded GMRT survey for pulsars in globular clusters: I. Discovery of a millisecond binary pulsar in NGC 6652". Astronomy & Astrophysics. 664: A54. arXiv:2205.15274. Bibcode:2022A&A...664A..54G. doi:10.1051/0004-6361/202243062. ISSN 0004-6361.
  10. ↑ Zhang, Pengfei; Xing, Yi; Wang, Zhongxiang (2022-08-01). "Discovery of γ-Ray Pulsations from PSR J1835–3259B in the Globular Cluster NGC 6652". The Astrophysical Journal Letters. 935 (2): L36. arXiv:2206.13667. Bibcode:2022ApJ...935L..36Z. doi:10.3847/2041-8213/ac88bf. ISSN 2041-8205.
  11. 1 2 Paduano, Alessandro; Bahramian, Arash; Miller-Jones, James C A; Kawka, Adela; Strader, Jay; Chomiuk, Laura; Heinke, Craig O; Maccarone, Thomas J; Britt, Christopher T; Plotkin, Richard M; Shaw, Aarran W; Shishkovsky, Laura; Tremou, Evangelia; Tudor, Vlad; Sivakoff, Gregory R (2021-07-31). "The MAVERIC Survey: Simultaneous Chandra and VLA observations of the transitional millisecond pulsar candidate NGC 6652B". Monthly Notices of the Royal Astronomical Society. 506 (3): 4107–4120. arXiv:2107.02344. doi:10.1093/mnras/stab1928. ISSN 0035-8711.
  12. 1 2 3 Stacey, W. S.; Heinke, C. O.; Cohn, H. N.; Lugger, P. M.; Bahramian, A. (2012-05-20). "An Examination of the X-Ray Sources in the Globular Cluster NGC 6652". The Astrophysical Journal. 751 (1): 62. arXiv:1204.0552. Bibcode:2012ApJ...751...62S. doi:10.1088/0004-637X/751/1/62. ISSN 0004-637X.

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