Cannabaceae

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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]

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]

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[edit]

  1. ^ "Elegant spiral hides a hungry monster". Hubble Space Telescope. ESA. Retrieved 13 October 2015.
  2. ^ a b 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. ^ a b c 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. ^ a b c "NASA/IPAC Extragalactic Database". Results for NGC 4639. Retrieved 2007-04-01.
  5. ^ a b 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. ^ a b 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. ^ a b 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.

External links[edit]

  • Media related to NGC 4639 at Wikimedia Commons
source: https://en.wikipedia.org/wiki/SN_1990N

One thought on “Cannabaceae”

  1. Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
    View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction

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