NGC 4639

NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast".[7] This is a relatively nearby galaxy,[8] lying approximately 72 million light-years away from the Milky Way.[3] It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago.[9] NGC 4639 is a member of the Virgo Cluster.[10]

NGC 4639
A Hubble Space Telescope (HST) image of NGC 4639.[1]
Observation data (J2000 epoch)
ConstellationVirgo
Right ascension12h 42m 52.37814s[2]
Declination+13° 15′ 26.7129″[2]
Heliocentric radial velocity989 km/s[3]
Distance72.02 ± 0.23 Mly (22.08 ± 0.07 Mpc)[3]
Group or clusterVirgo Cluster
Apparent magnitude (V)12.2[4]
Characteristics
TypeSAB(rs)bc[5]
Apparent size (V)2′.8 × 1′.9[4]
Notable featuresSeyfert type 1
Other designations
IRAS 12403+1331, LEDA 42741, MCG+02-32-189, NGC 4639, UGC 7884, VCC 1943,[6] PGC 42741[4]

The morphological classification of this galaxy is SAB(rs)bc,[5] indicating a spiral galaxy with a weak bar (SAB), an incomplete ring around the bar (rs), and moderate to loosely-wound spiral arms (bc). NGC 4639 has a mildly active galactic nucleus of the Seyfert type 1; one of the weakest known. The compact central source has been detected by its X-ray emission, and is variable on timescales of months to years.[8] There is a supermassive black hole at the core[11] with an estimated mass of 7.9×106 M☉.[12]

Two supernovae have been observed in NGC 4639. The classical Type Ia Supernova SN 1990N was discovered in this galaxy on June 22, 1990, two weeks before reaching peak brightness.[13] It was positioned 63.2″ east and 1.8″ south of the galaxy core.[14] The brightness and proximity of this supernova event has allowed it to be used as a standard candle.[13] SN 2018imf (type IIP, mag. 15.7) was discovered on 14 November, 2018.[15]

References
  1. "Elegant spiral hides a hungry monster". Hubble Space Telescope. ESA. Retrieved 13 October 2015.
  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. Tully, R. Brent; et al. (October 2013), "Cosmicflows-2: The Data", The Astronomical Journal, 146 (4): 25, arXiv:1307.7213, Bibcode:2013AJ....146...86T, doi:10.1088/0004-6256/146/4/86, S2CID 118494842, 86
  4. "NASA/IPAC Extragalactic Database". Results for NGC 4639. Retrieved 2007-04-01.
  5. Graham, Alister W.; et al. (March 2019). "Expected intermediate-mass black holes in the Virgo cluster - II. Late-type galaxies". Monthly Notices of the Royal Astronomical Society. 484 (1): 814–831. arXiv:1811.03232. Bibcode:2019MNRAS.484..814G. doi:10.1093/mnras/sty3068. S2CID 119303249.
  6. "NGC 4639". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-09-21.
  7. Seligman, Courtney. "New General Catalogue objects: NGC 4600 - 4649". cseligman.com. Retrieved 2020-09-19.
  8. Ho, Luis C.; et al. (November 1999). "X-Ray Properties of the Weak Seyfert 1 Nucleus in NGC 4639". The Astrophysical Journal. 525 (1): 168–175. arXiv:astro-ph/9905013. Bibcode:1999ApJ...525..168H. doi:10.1086/307898. S2CID 14517224.
  9. Vollmer, B. (February 2003). "NGC 4654: Gravitational interaction or ram pressure stripping?". Astronomy and Astrophysics. 398 (2): 525–539. arXiv:astro-ph/0211321. Bibcode:2003A&A...398..525V. doi:10.1051/0004-6361:20021729. S2CID 7265130.
  10. "Detailed Object Classifications". ned.ipac.caltech.edu. Retrieved 2017-08-29.
  11. Botkin-Kowacki, Eva (13 October 2015). "Spectacular Hubble photo: A bright galaxy holds a hidden secret". The Christian Science Monitor. Retrieved 14 October 2015.
  12. 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.
  13. Saha, A.; et al. (September 1997). "Cepheid Calibration of the Peak Brightness of Type Ia Supernovae. VIII. SN 1990N in NGC 4639". The Astrophysical Journal. 486 (1): 1–20. Bibcode:1997ApJ...486....1S. doi:10.1086/304507.
  14. Maury, A.; et al. (June 1990). Green, D. W. E. (ed.). "Supernova 1990N in NGC 4639". IAU Circular. 5039: 1. Bibcode:1990IAUC.5039....1M.
  15. Transient Name Server entry for SN 2018imf. Retrieved 23 March 2023.
  • Media related to NGC 4639 at Wikimedia Commons
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