NGC 3660

NGC 3660
SDSS image of NGC 3660.
Observation data (J2000 epoch)
ConstellationCrater
Right ascension11h 23m 32.27s[1]
Declination−08° 39′ 30.62″[1]
Redshift0.012285[1]
Heliocentric radial velocity3,683 km/s ± 2[1]
Distance206 Mly (63.27 Mpc)[1]
Apparent magnitude (V)12.2[2]
Characteristics
TypeSB(r)bc;HII Sy2[1]
Size~165,000 ly (50.7 kpc) (estimated)[1]
Other designations
2MASX J11233229-0839308, 6dF J1123322-083931, CGS 367, PGC 34980, IRAS 11210-0823, MCG -01-29-016, MRK 1291, NSA 139324[1]

NGC 3660 is a barred spiral galaxy[3] located in the constellation of Crater. The redshift of the galaxy is (z) 0.012[1] (roughly 200 million light-years away) and it was first discovered in February 1787 by the German-British astronomer by the name of William Herschel who described it as a large faint object with an irregular appearance and a bright center.[4] It is also an active Seyfert galaxy, specifically of Type 2.[5][6][7]

Description

NGC 3660 is described as a barred spiral galaxy of type SBbc with a measured optical magnitude of 11.9 in V-band.[8][3] The galaxy is also depicted as isolated and it has a strong bar feature with a barely resolved ring based on K-band imaging. The bar feature is shown to be extending outwards until around 16 arcseconds at the position angle of 116°. A smooth structure is seen to be more redder when inching towards the central region with a redder bar region. Color mapping also showed there is a possibility of a small circumnuclear region.[9]

The nucleus of the galaxy is active and it has been depicted to have a compact appearance. There are about 59 H II regions that are distributed around the ring feature and also along the direction of its spiral arms. On the outskirt regions, these regions are highly excited when compared to those located in the ring, especially in tow of the regions located in the direction of northeast by 40 and 50 arcseconds from its nucleus. Some faint regions are present to the southeast, forming a shell feature.[10]

A weak hydrogen alpha component has been detected with a full width at half maximum (FWHM) of 1,950 kilometers per seconds.[11] A study also found the galaxy is indeed variable when detected in both soft and hard X-rays.[12] There are also molecular gas detections in the galaxy with the total mass estimated to be 0.80 x 109 Mʘ based on CO 1-0 observations.[13]

Supernovae

Three supernovae have been observed in NGC 3660:

  • SN 2017byz (Type II, mag. 16.46) was discovered by ATLAS on 4 March 2017.[14]
  • SN 2018jlp (Type II, mag. 18.732) was discovered by ATLAS on 4 December 2018.[15]
  • SN 2026cff (Type II, mag. 17.0032) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 6 February 2026.[16]. This supernova (ZTF26aaffpvx) is part of the Unistellar "cosmic cataclysms" smart telescope tracking project.[17]

References

  1. ^ a b c d e f g h i "NED Search results for NGC 3660". NASA/IPAC Extragalactic Database. Retrieved 2026-01-22.
  2. ^ "Revised NGC Data for NGC 3660". spider.seds.org. Retrieved 30 March 2024.
  3. ^ a b Kollatschny, W.; Biermann, P.; Fricke, K. J.; Huchtmeier, W.; Witzel, A. (March 1983). "Nuclear activity in the barred spiral galaxy NGC 3660 from radio, optical and X-ray observations". Astronomy and Astrophysics. 119: 80–84. Bibcode:1983A&A...119...80K. ISSN 0004-6361.
  4. ^ "New General Catalog Objects: NGC 3650 - 3699". cseligman.com. Retrieved 2026-01-22.
  5. ^ Rivers, Elizabeth; Brightman, Murray; Bianchi, Stefano; Matt, Giorgio; Nandra, Kirpal; Ueda, Yoshihiro (2016-02-01). "Suzaku confirms NGC 3660 is an unabsorbed Seyfert 2". Publications of the Astronomical Society of Japan. 68 (SP1) S24. arXiv:1601.02702. doi:10.1093/pasj/psv137. ISSN 2053-051X.
  6. ^ Gu, Q.; Melnick, J.; Cid Fernandes, R.; Kunth, D.; Terlevich, E.; Terlevich, R. (February 2006). "Emission-line properties of Seyfert 2 nuclei". Monthly Notices of the Royal Astronomical Society. 366 (2): 480–490. arXiv:astro-ph/0510742. Bibcode:2006MNRAS.366..480G. doi:10.1111/j.1365-2966.2005.09872.x. ISSN 0035-8711.
  7. ^ Condon, J. J.; Yin, Q. F.; Thuan, T. X.; Boller, Th (December 1998). "The ROSAT/IRAS Galaxy Sample Revisited". The Astronomical Journal. 116 (6): 2682–2716. Bibcode:1998AJ....116.2682C. doi:10.1086/300624. ISSN 0004-6256.
  8. ^ Kinney, A. L.; Bohlin, R. C.; Calzetti, D.; Panagia, N.; Wyse, Rosemary F. G. (May 1993). "An Atlas of Ultraviolet Spectra of Star-forming Galaxies". The Astrophysical Journal Supplement Series. 86: 5. Bibcode:1993ApJS...86....5K. doi:10.1086/191771. ISSN 0067-0049.
  9. ^ Marquez, I.; Durret, F.; Delgado, R. M. Gonzalez; Marrero, I.; Masegosa, J.; Maza, J.; Moles, M.; Perez, E.; Roth, M. (1999-09-21). "Near-infrared photometry of isolated spirals with and without an AGN". Astronomy and Astrophysics Supplement Series. 140: 1–14. arXiv:astro-ph/9909351. doi:10.1051/aas:1999516.
  10. ^ Gonzalez Delgado, Rosa M.; Perez, Enrique; Tadhunter, Clive; Vilchez, Jose M.; Rodriguez-Espinosa, Jose Miguel (January 1997). "H II Region Population in a Sample of Nearby Galaxies with Nuclear Activity. I. Data and General Results". The Astrophysical Journal Supplement Series. 108 (1): 155–198. Bibcode:1997ApJS..108..155G. doi:10.1086/312951. ISSN 0067-0049.
  11. ^ Gonçalves, A. C.; Véron-Cetty, M.-P.; Véron, P. (March 1999). "AGNs with composite spectra. II. Additional data". Astronomy and Astrophysics Supplement Series. 135 (3): 437–466. arXiv:astro-ph/9811342. Bibcode:1999A&AS..135..437G. doi:10.1051/aas:1999183. ISSN 0365-0138.
  12. ^ Bianchi, Stefano; Panessa, Francesca; Barcons, Xavier; Carrera, Francisco J.; La Franca, Fabio; Matt, Giorgio; Onori, Francesca; Wolter, Anna; Corral, Amalia; Monaco, Lorenzo; Ruiz, Ángel; Brightman, Murray (2012-10-17). "Simultaneous X-ray and optical observations of true type 2 Seyfert galaxies". Monthly Notices of the Royal Astronomical Society. 426 (4): 3225–3240. arXiv:1209.0274. Bibcode:2012MNRAS.426.3225B. doi:10.1111/j.1365-2966.2012.21959.x. ISSN 0035-8711.
  13. ^ Strong, Matt; Pedlar, Alan; Aalto, Susanne; Beswick, Rob J.; Curran, Stephen; Booth, Roy (October 2004). "Molecular gas properties of 12-μm Seyfert galaxies - I. The southern sample". Monthly Notices of the Royal Astronomical Society. 353 (4): 1151–1160. Bibcode:2004MNRAS.353.1151S. doi:10.1111/j.1365-2966.2004.08139.x. ISSN 0035-8711.
  14. ^ "SN 2017byz". Transient Name Server. IAU. Retrieved 6 February 2026.
  15. ^ "SN 2018jlp". Transient Name Server. IAU. Retrieved 6 February 2026.
  16. ^ "SN 2026cff". Transient Name Server. IAU. Retrieved 9 February 2026.
  17. ^ "ZTF26aaffpvx". Unistellar. Retrieved 2026-03-15.
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