Astronomy:Antennae Galaxies

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Short description: Interacting galaxies in the constellation Corvus
Antennae Galaxies
Antennae Galaxies reloaded.jpg
Hubble Space Telescope image of NGC 4038 (top) and NGC 4039 (bottom)
Observation data (J2000 epoch)
ConstellationCorvus[1]
Right ascension 12h 01m 53.0s /  12h 01m 53.6s[2]
Declination−18° 52′ 10″ / −18° 53′ 11″[2]
Redshift1642 ± 12 / 1641 ± 9 km/s[2]
Distance45 Mly / 65 Mly
Apparent magnitude (V)11.2 / 11.1[2]
Characteristics
TypeSB(s)m pec / SA(s)m pec[2]
Size500,000 ly (150 kpc)[3][lower-alpha 1]
Apparent size (V)5.2′ × 3.1′ / 3.1′ × 1.6′[2]
Notable featuresInteracting galaxies
Other designations
Ringtail Galaxy,[2] NGC 4038 / 4039,[2]
PGC 37967 / 37969, Arp 244,[2] Caldwell 60/61, UGCA 264/265[2]

The Antennae Galaxies (also known as NGC 4038/NGC 4039 or Caldwell 60/Caldwell 61) are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation. They were discovered by William Herschel in 1785.[4]

General information

Visible light Hubble image (blue) showing newly formed young stars overlaid with a radio image from the Atacama Large Millimeter Array showing the clouds of dense cold gas from which new stars form (red, pink and yellow)
Streams of stars and dust, resembling insect antennae, being ejected from both galaxies. The name Antennae Galaxies comes from this resemblance.

The Antennae Galaxies are undergoing a galactic collision. Located in the NGC 4038 group with five other galaxies, these two galaxies are known as the Antennae Galaxies because the two long tails of stars, gas and dust ejected from the galaxies as a result of the collision resemble an insect's antennae.

The nuclei of the two galaxies are joining to become one giant galaxy. Most galaxies probably undergo at least one significant collision in their lifetimes. This is likely the future of our Milky Way when it collides with the Andromeda Galaxy. This collision and merger sequence (the Toomre sequence) for galaxy evolution was developed in part by successfully modeling the Antennae Galaxies' "antennae" in particular.

Five supernovae have been discovered in NGC 4038: SN 1921A, SN 1974E, SN 2004GT, SN 2007sr and SN 2013dk.[5]

A recent study finds that these interacting galaxies are less remote from the Milky Way than previously thought—at 45 million light-years instead of 65 million light-years.[6]

They are located 0.25° north of 31 Crateris and 3.25° southwest of Gamma Corvi.[7]

The Antennae galaxies also contain a relatively young collection of massive globular clusters that were possibly formed as a result of the collision between the two galaxies.[8] The young age of these clusters is in contrast to the average age of most known globular clusters (which are around 12 billion years old), with the formation of the globulars likely originating from shockwaves, generated by the collision of the galaxies, compressing large, massive molecular clouds. The densest regions of the collapsing and compressing clouds are believed to be the birthplace of the clusters.

Timeline

About 1.2 billion years ago, the Antennae were two separate galaxies.[9] NGC 4038 was a barred spiral galaxy and NGC 4039 was a spiral galaxy. 900 million years ago, the Antennae began to approach one another, looking similar to NGC 2207 and IC 2163. 600 million years ago, the Antennae passed through each other, looking like the Mice Galaxies. 300 million years ago, the Antennae's stars began to be released from both galaxies. Today the two streamers of ejected stars extend far beyond the original galaxies, resulting in the antennae shape.[10]

Within 400 million years, the Antennae's nuclei will collide and become a single core with stars, gas, and dust around it.[11] Observations and simulations of colliding galaxies (e.g., by Alar Toomre) suggest that the Antennae Galaxies will eventually form an elliptical galaxy.[9][page needed]

X-ray source

Areas containing large amounts of neon (Ne), magnesium (Mg), and silicon (Si) were found when the Chandra X-ray Observatory analyzed the Antennae Galaxies. Heavy elements such as these are necessary in order for planets that may contain life (as we know it) to form. The clouds imaged contain 16 times as much magnesium and 24 times as much silicon as the Sun.

See also

References

  1. ↑ R. W. Sinnott, ed (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN 978-0-933346-51-2. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 "NASA/IPAC Extragalactic Database". Results for NGC 4038 / 4039. http://nedwww.ipac.caltech.edu/. 
  3. ↑ Astronomy Picture of the Day Archive (28 April 2017). "Exploring the Antennae". https://apod.nasa.gov/apod/ap170428.html. 
  4. ↑ "Corvus". Universe Today. http://www.universetoday.com/guide-to-space/constellations/corvus/. 
  5. ↑ "List of Supernovae". IAU Central Bureau for Astronomical Telegrams. http://www.cbat.eps.harvard.edu/lists/Supernovae.html. 
  6. ↑ "The Antennae Galaxies Found To Be Closer To Us". Space Daily. 2008-05-12. http://www.spacedaily.com/reports/The_Antennae_Galaxies_Found_To_Be_Closer_To_Us_999.html. 
  7. ↑ O'Meara, Stephen James (2002). The Caldwell Objects. Cambridge University Press. pp. 240–43. ISBN 978-0-521-82796-6. https://books.google.com/books?id=3Hg6YHgx9nAC&pg=PA242. 
  8. ↑ Van Den Bergh, Sidney (2001). "van den Bergh, How Did Globular Clusters Form?". The Astrophysical Journal 559 (2): L113–L114. doi:10.1086/323754. Bibcode: 2001ApJ...559L.113V. 
  9. ↑ 9.0 9.1 J. E. Barnes; L. Hernquist (1992). "Dynamics of interacting galaxies". Annual Review of Astronomy and Astrophysics 30 (1): 705–742. doi:10.1146/annurev.aa.30.090192.003421. Bibcode: 1992ARA&A..30..705B. 
  10. ↑ Henderson, Edward (2019-12-18). "Caldwell 60/61". NASA. https://nasa.gov/feature/goddard/caldwell-60-61. 
  11. ↑ Wilkins, Alasdair (2010-08-05). "Antennae Galaxies are slowly colliding in beautiful chaos of black holes". Gizmodo. https://gizmodo.com/antennae-galaxies-are-slowly-colliding-in-beautiful-cha-5605407. 

Notes

  1. ↑ The quoted size is based on an assumed distance around 60 million ly although a more recent study gives a less remote distance of 45 million ly, giving consequently smaller values for the size.

External links

Coordinates: Sky map 12h 01m 53s, −18° 52′ 10″



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