NGC 4567 and NGC 4568 explained

NGC 4567 and NGC 4568
Epoch:J2000.0
Type:SA(rs)bc / SA(rs)bc
Dist Ly:19.1Mpc[1]
Appmag V:+10.9
Size V:4.6′ × 2.1′
Constellation Name:Virgo
Absmag V:-13.3
Notes:colliding galaxies
Names:NGC 4567/8, UGC 7776/7, PGC 42064/9, VV 219,[2] KPG 347,[3] Butterfly Galaxies,[4] Siamese Twin Galaxies, Siamese Twins Galaxies, Siamese Twins[5] [6]

NGC 4567 and NGC 4568 (nicknamed the Butterfly Galaxies[4] or Siamese Twins[6] [5]) are a set of unbarred spiral galaxies about 60 million light-years away[1] in the constellation Virgo. They were both discovered by William Herschel in 1784. They are part of the Virgo Cluster of galaxies.

These galaxies are in the process of colliding and merging with each other, as studies of their distributions of neutral and molecular hydrogen show, with the highest star-formation activity in the part where they overlap. However, the system is still in an early phase of interaction.[7] In about 500 million years the galaxies will coalesce into a single elliptical galaxy.[8]

Four supernovae have been observed in the Butterfly Galaxies: SN 1990B (type Ib, mag. 16),[9] SN 2004cc (type Ic, mag. 17.5),[10] SN 2020fqv (type IIb, mag. 19),[11] and SN 2023ijd (type II, mag. 16.8).[12]

Naming controversy

The two galaxies were nicknamed "Siamese Twins" because they appear to be connected. On August 5, 2020, NASA announced that they would not use that nickname in an effort to avoid systemic discrimination in their terminology.[13]

See also

External links

Notes and References

  1. Web site: Distance Results for NGC 4568. NASA/IPAC Extragalactic Database. 2010-05-01.
  2. Web site: VV 219 -- Interacting Galaxies . SIMBAD .
  3. Web site: KPG 347 -- Pair of Galaxies . SIMBAD .
  4. Mapping IR Enhancements in Closely Interacting Spiral-Spiral Pairs. I. IS0 CAM and IS0 SWS Observations . Cong Xu . Yu Gao . Joseph Mazzarella . Nanyao Lu . Jack W. Sulentic . Donovan L. Domingue . 2000 . 10.1.1.317.8256 .
  5. Book: 10.1007/978-1-4419-6757-2_4 . Cudnik B. . Faint Objects and How to Observe Them . The Nature of Galaxies and Galaxy Clusters . 2013 . Astronomers' Observing Guides . 2013 . 71–91 . Springer . 978-1-4419-6756-5 .
  6. NASA no longer uses the "Siamese Twins" terms due to perceived discriminatory naming
  7. Molecular Gas in the Early Stage of Interacting Galaxies: The NGC 4567/8 Pair . Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies . 423 . 26 . 2010ASPC..423...26K . Kaneko . H. . Kuno . N. . Iono . D. . Tosaki . T. . Sawada . T. . Nakanishi . H. . Hirota . A. . 2010 .
  8. Web site: The merging galaxy pair NGC 4568 and NGC 4567 .
  9. https://www.wis-tns.org/object/1990B Transient Name Server entry for SN 1990B.
  10. https://www.wis-tns.org/object/2004cc Transient Name Server entry for SN 2004cc.
  11. Web site: SN 2020fqv . Transient Name Server .
  12. https://www.wis-tns.org/object/2023ijd Transient Name Server entry for SN 2023ijd.
  13. Web site: NASA to Reexamine Nicknames for Cosmic Objects - NASA . 5 August 2020 .

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