NGC 718

NGC 718 is an intermediate spiral galaxy in the constellation of Pisces. Its velocity with respect to the cosmic microwave background is 1,450 ± 22 km/s, which corresponds to a Hubble distance of 21.38 ± 1.54 Mpc Mly.^[1] Additionally, one non-redshift measurement gives a similar distance of 21.400 Mpc.^[2] It was discovered by German-British astronomer William Herschel on 13 December 1784.^[3][4]

NGC 718 has a possible active galactic nucleus, i.e. it has a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars.^[5][6]

A star-forming disk has been detected around the core of NGC 718. The size of its semi-major axis is estimated at 1,100 ly (330 pc).^[7]

Supermassive black hole

Based on measurements of the near-infrared K-band luminosity of the galaxy's bulge, NGC 718 has a supermassive black hole with a mass of 1E7.5 (32 million solar masses).^[8]

NGC 676 group

NGC 718 is a member of a small group of three galaxies known as the NGC 676 group. The other two galaxies are NGC 676 and NGC 693.^[9]

Intermediate-luminosity red transient

One intermediate-luminosity red transient (ILRT) has been observed in NGC 718:

• AT 2019udc (Type ILRT, mag. 18.813) was discovered by the Distance Less Than 40 Mpc Survey (DLT40) on 4 November 2019.^[10] This object had initially been classified as a luminous blue variable.^[11][12]

See also

• List of NGC objects (1–1000)

References

1. ^ "Results for object NGC 0718". NASA/IPAC Extragalactic Database. NASA and Caltech. Retrieved 27 December 2025.
2. ^ "Distance Results for NGC 0718". NASA/IPAC Extragalactic Database. NASA. Retrieved 27 December 2025.
3. ^ Herschel, William (1786). "Catalogue of One Thousand New Nebulae and Clusters of Stars". Philosophical Transactions of the Royal Society of London. 76: 457–499. Bibcode:1786RSPT...76..457H. doi:10.1098/rstl.1786.0027
4. ^ Seligman, Courtney. "New General Catalogue Objects: NGC 718". Celestial Atlas. Retrieved 27 December 2025.
5. ^ Asmus, D.; Greenwell, C. L.; Gandhi, P.; Boorman, P. G.; Aird, J.; Alexander, D. M.; Assef, R. J.; Baldi, R. D.; Davies, R. I.; Hönig, S. F.; Ricci, C.; Rosario, D. J.; Salvato, M.; Shankar, F.; Stern, D. (2020). "Local AGN survey (LASr): I. Galaxy sample, infrared colour selection, and predictions for AGN within 100 MPC". Monthly Notices of the Royal Astronomical Society. 494 (2): 1784. arXiv:2003.05959. Bibcode:2020MNRAS.494.1784A. doi:10.1093/mnras/staa766
6. ^ "NGC 718". Retrieved 27 December 2025.
7. ^ Comerón, S.; Knapen, J. H.; Beckman, J. E.; Laurikainen, E.; Salo, H.; Martínez-Valpuesta, I.; Buta, R. J. (2010). "AINUR: Atlas of Images of NUclear Rings". Monthly Notices of the Royal Astronomical Society. 402 (4): 2462. arXiv:0908.0272. Bibcode:2010MNRAS.402.2462C. doi:10.1111/j.1365-2966.2009.16057.x
8. ^ Dong, X. Y. & De Robertis, M. M. (2006). "Low-Luminosity Active Galaxies and Their Central Black Holes". The Astronomical Journal. 131 (3): 1236. arXiv:astro-ph/0510694. Bibcode:2006AJ....131.1236D. doi:10.1086/499334
9. ^ Mahtessian, A. P. (1998). "Groups of galaxies. III. Some empirical characteristics". Astrophysics. 41 (3): 308–321. Bibcode:1998Ap.....41..308M. doi:10.1007/BF03036100
10. ^ Valerin, G. et al. (2025). "A study in scarlet: I. Photometric properties of a sample of intermediate-luminosity red transients". Astronomy and Astrophysics. 695. arXiv:2407.21671. Bibcode:2025A&A...695A..42V. doi:10.1051/0004-6361/202451733
11. ^ "AT 2019udc". Transient Name Server. IAU. Retrieved 27 December 2025.
12. ^ Siebert, M. R.; Dimitriadis, G.; Kilpatrick, C. D.; Foley, R. J.; Nunez, R.; McKinnon, K.; Guhathakurta, P. (2019). "Spectroscopic Classification of AT2019udc with the Lick Shane telescope". The Astronomer's Telegram. 13263: 1. Bibcode:2019ATel13263....1S