NGC 4725

NGC 4725 is an intermediate barred spiral galaxy with a prominent ring structure,[9] located in the northern constellation of Coma Berenices near the north galactic pole.[10] It was discovered by German-born astronomer William Herschel on April 6, 1785.[11] The galaxy lies at a distance of approximately 40 megalight-years[4] from the Milky Way.

NGC 4725
A mid-infrared image of NGC 4725 taken by the Spitzer Space Telescope (SST).
Credit: Spitzer Infrared Nearby Galaxies Survey/SST/NASA.
Observation data (J2000 epoch)
ConstellationComa Berenices[1]
Right ascension12h 50m 26.56929s[2]
Declination+25° 30′ 02.7376″[2]
Helio radial velocity1,206±3 km/s[3]
Distance40.1 ± 6.2 Mly (12.3 ± 1.9 Mpc)[4]
Apparent magnitude (V)10.1[3]
Characteristics
TypeSAB(r)ab pec[5] or Sb/SB(r)II[6]
Apparent size (V)9′.77 × 6′.76[7]
Other designations
IRAS 12480+2547, NGC 4725, UGC 7989, LEDA 43451, PGC 43451[7][8]

NGC 4725 is the brightest member of the Coma I Group[12] of the Coma-Sculptor Cloud, although it is relatively isolated from the other members of this group.[6] This galaxy is strongly disturbed and is interacting with neighboring spiral galaxy NGC 4747, with its spiral arms showing indications of warping. The pair have an angular separation of 24′, which corresponds to a projected linear separation of 370 kly.[5] A tidal plume extends from NGC 4747 toward NGC 4725.[10]

This is a suspected type 2 Seyfert galaxy with a supermassive black hole at the core.[13] The morphological classification of this galaxy is SAB(r)ab pec,[5] indicating a peculiar, weakly-barred spiral galaxy (SAB) with a complete ring surrounding the bar (r) and somewhat tightly-wound spiral arms (ab). It is actually double-barred, a feature found among about a third of all barred spirals.[14] The galactic plane is inclined by approximately 46° to the line of sight from the Earth.[6]

The ring structure of the galaxy is a region of star formation. It is offset from the galactic center and displays non-circular motion.[15] There is a compact radio source positioned approximately 6.2 kly from the nucleus of NGC 4725. Since there is no optical counterpart at that position, this may be a star forming region that is heavily obscured by dust.[9]

Multiple supernova candidate events have been detected in this galaxy:

  • SN 1940B was detected on a photograph taken May 5, 1940, about 2.5′ northeast of the galactic core.[16] The light curve indicates this was a type II supernova.[17]
  • Candidate SN 1987E was detected April 24, 1987 with a magnitude of 15.65.[18] A follow-up study failed to detect this event, so it may have been the result of gravitational lensing.[19]
  • SN 1999gs was detected on December 28, 1999 with a magnitude of 19.3. It was positioned 3″ west and 105″ south of the nucleus of NGC 4725.[20]
  • On automated images taken July 5, 2016, a magnitude 17.0 transient source was discovered at an angular separation of 324″ from the galactic nucleus. Designated ASASSN-16gu (AT 2016cyu), this was most likely a supernova event. It had an estimated absolute visual magnitude of –13.6.[21]
  • NGC 4725 taken with a 24-inch telescope

References
  1. Sinnott, R. W., ed. (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN 978-0-933346-51-2.
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. "NASA/IPAC Extragalactic Database". Results for NGC 4725. Retrieved 2006-11-25.
  4. Jensen, Joseph B.; Tonry, John L.; Barris, Brian J.; Thompson, Rodger I.; et al. (February 2003). "Measuring Distances and Probing the Unresolved Stellar Populations of Galaxies Using Infrared Surface Brightness Fluctuations". Astrophysical Journal. 583 (2): 712–726. arXiv:astro-ph/0210129. Bibcode:2003ApJ...583..712J. doi:10.1086/345430. S2CID 551714.
  5. Wevers, B. M. H. R.; et al. (November 1984). "Neutral hydrogen observations of the interacting galaxies NGC 4725 and NGC 4747". Astronomy and Astrophysics. 140: 125–140. Bibcode:1984A&A...140..125W.
  6. Gibson, Brad K.; et al. (February 1999). "The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XVII. The Cepheid Distance to NGC 4725". The Astrophysical Journal. 512 (1): 48–64. arXiv:astro-ph/9810003. Bibcode:1999ApJ...512...48G. doi:10.1086/306762. S2CID 117635398.
  7. Paturel, G.; et al. (December 2003). "HYPERLEDA. I. Identification and designation of galaxies". Astronomy and Astrophysics. 412: 45–55. Bibcode:2003A&A...412...45P. doi:10.1051/0004-6361:20031411.
  8. "NGC 4725". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-10-11.
  9. Murphy, E. J.; et al. (July 2018). "A New Detection of Extragalactic Anomalous Microwave Emission in a Compact, Optically Faint Region of NGC 4725". The Astrophysical Journal. 862 (1): 7. arXiv:1805.05965. Bibcode:2018ApJ...862...20M. doi:10.3847/1538-4357/aac5f5. S2CID 56089579. 20.
  10. Barber, C. R.; Warwick, R. S. (March 1994). "The spectrum of the extragalactic X-ray background below 3 keV". Monthly Notices of the Royal Astronomical Society. 267 (2): 270–282. Bibcode:1994MNRAS.267..270B. doi:10.1093/mnras/267.2.270.
  11. Seligman, Courtney. "NGC Objects: NGC 4700 - 4749". Retrieved 2020-10-13.
  12. Gregory, S.A.; Thompson, L. A. (1977). "The Coma I Galaxy Cloud". The Astrophysical Journal. 213: 345–350. Bibcode:1977ApJ...213..345G. doi:10.1086/155160. ISSN 0004-637X.
  13. Chiaraluce, E.; et al. (May 2019). "From radio-quiet to radio-silent: low-luminosity Seyfert radio cores". Monthly Notices of the Royal Astronomical Society. 485 (3): 3185–3202. arXiv:1902.10670. Bibcode:2019MNRAS.485.3185C. doi:10.1093/mnras/stz595. S2CID 119089306.
  14. de Lorenzo-Cáceres, A.; Falcón-Barroso, J.; Vazdekis, A.; Martínez-Valpuesta, I. (September 2008). "Stellar Kinematics in Double-Barred Galaxies: The σ-Hollows". The Astrophysical Journal Letters. 684 (2): L83. arXiv:0808.0517. Bibcode:2008ApJ...684L..83D. doi:10.1086/592145. S2CID 17252225.
  15. Buta, R. (March 1988). "The Structure and Dynamics of Ringed Galaxies. V. The Kinematics of NGC 1512, NGC 3351, NGC 4725, and NGC 4736". Astrophysical Journal Supplement. 66: 233. Bibcode:1988ApJS...66..233B. doi:10.1086/191255.
  16. Minkowski, R. (June 1940). "Spectra of the Supernova in NGC 4725". Publications of the Astronomical Society of the Pacific. 52 (307): 206. Bibcode:1940PASP...52..206M. doi:10.1086/125169.
  17. Minkowski, R. (1964). "Supernovae and Supernova Remnants". Annual Review of Astronomy and Astrophysics. 2: 247. Bibcode:1964ARA&A...2..247M. doi:10.1146/annurev.aa.02.090164.001335.
  18. Rosa, M.; Koishikawa, M. (April 1987). Green, D. W. E. (ed.). "Supernova 1987E in NGC 4725". IAU Circular. 4374 (2): 2. Bibcode:1987IAUC.4374....2R.
  19. Filippenko, A. V. (May 1987). Green, D. W. E. (ed.). "No Supernova in NGC 4725". IAU Circular. 4385 (2): 2. Bibcode:1987IAUC.4385....2F.
  20. Li, W. D. (January 2000). Green, D. W. E. (ed.). "Supernova 1999gs in NGC 4725". IAU Circulars. 7345 (2): 2. Bibcode:2000IAUC.7345....2L.
  21. Brimacombe, J.; et al. (July 2016). "ASASSN-16gu: Discovery of A Probable Supernova in NGC 4725". The Astronomer's Telegram. 9211: 1. Bibcode:2016ATel.9211....1B.


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