Eyes Galaxies

The Eyes Galaxies (NGC 4435-NGC 4438, also known as Arp 120) are a pair of galaxies about 52 million light-years away in the constellation Virgo. The pair are members of the string of galaxies known as Markarian's Chain.

Eyes Galaxies
NGC 4438 (top) and NGC 4435 (bottom) taken by the FORS2 instrument of the Very Large Telescope in 2011
Observation data (J2000.0 epoch)
ConstellationVirgo
Right ascension12h 27m 45.6s(J2000)
Declination+13° 00' 31" (J2000)
Redshift0.002638/0.000237
Distance52 million ly
Apparent magnitude (V)+10
Absolute magnitude (V)12
Characteristics
TypeSB0/SA(s)O/a pec
Apparent size (V)2.35 × 1.43/8.5 × 3.2
Notable featuresInteracting
Other designations
NGC 4435-8, Arp 120, VV 188 VCC 1030, VCC 1043

NGC 4435

NGC 4435 is a barred lenticular galaxy currently interacting with NGC 4438. Studies of the galaxy by the Spitzer Space Telescope revealed a relatively young (190 million years) stellar population within the galaxy's nucleus, which may have originated through the interaction with NGC 4438 compressing gas and dust in that region, triggering a starburst.[1] It also appears to have a long tidal tail possibly caused by the interaction;[2] however, other studies suggest the apparent tail is actually foreground galactic cirrus within the Milky Way unrelated to NGC 4435.[3]

NGC 4438

NGC 4438 is the most curious interacting galaxy in the Virgo Cluster, due to the uncertainty surrounding the energy mechanism that heats the nuclear source; this energy mechanism may be a starburst region, or a black hole-powered active galactic nucleus (AGN). Both hypotheses are currently under investigation by astronomers.

This galaxy shows a highly distorted disk, including long tidal tails due to the gravitational interactions with other galaxies in the cluster and its companion. The aforementioned features explain why sources differ as to its classification, defining it either as a lenticular or spiral galaxy. NGC 4438 also shows signs of a past, extended - but modest - starburst,[4] a considerable deficiency of neutral hydrogen, as well as a displacement of the components of its interstellar medium - atomic hydrogen, molecular hydrogen, interstellar dust, and hot gas - in the direction of NGC 4435. This observation suggests both a tidal interaction with NGC 4435 and the effects of ram-pressure stripping[5] as NGC 4438 moves at high speed through Virgo's intracluster medium, increased by the encounter between both galaxies.[6][7]

As interacting galaxies
NGC 4435-NGC 4438 in the Virgo Cluster of galaxies

While there is evidence to suggest that the environmental damage to the interstellar medium of NGC 4438 may have been caused by an off-center collision with NGC 4435 millions of years ago, a recent discovery of several filaments of ionized gas links NGC 4438 with the large neighboring elliptical galaxy Messier 86,[8] in addition to a discovery of gas and dust within M86 that may have been stripped from NGC 4438 during a past encounter between the two.[9][10] Given the high density of galaxies in the center of the Virgo galaxy cluster, it is possible that the three galaxies, NGC 4435, NGC 4438, and M86, have had past interactions.[11]

In the 2014 film Interstellar, "NGC 4438" along with specific observation data can be seen in Murphy Cooper (Jessica Chastain)'s notepad during the film's climactic sequence. As the presence of a supermassive black hole in the AGC of NGC 4438 is one of two leading theories, the galaxy is potentially that accessed by the wormhole in the film.

References
  1. Panuzzo, P.; Vega, O.; Bressan, A.; Buson, L.; et al. (2007). "The Star Formation History of the Virgo Early-Type Galaxy NGC 4435: The Spitzer Mid-Infrared View". The Astrophysical Journal. 656 (1): 206–216. arXiv:astro-ph/0610316. Bibcode:2007ApJ...656..206P. doi:10.1086/510147. S2CID 14509466.
  2. The Tail of NGC 4435
  3. Cortese, L.; Bendo, G. J.; Isaak, K. G.; Davies, J. I.; et al. (2010). "Diffuse far-infrared and ultraviolet emission in the NGC 4435/4438 system: tidal stream or Galactic cirrus?". Monthly Notices of the Royal Astronomical Society: Letters. 403 (1): L26–L30. arXiv:1001.0980. Bibcode:2010MNRAS.403L..26C. doi:10.1111/j.1745-3933.2009.00808.x. S2CID 118358744.
  4. Boselli, A.; Boissier, S.; Cortese, L.; Gil de Paz, A.; et al. (2005). "GALEX Ultraviolet Observations of the Interacting Galaxy NGC 4438 in the Virgo Cluster". The Astrophysical Journal. 623 (1): L13–L16. arXiv:astro-ph/0502040. Bibcode:2005ApJ...623L..13B. doi:10.1086/429377. S2CID 16771650.
  5. Vollmer, B.; Soida, M.; Chung, A.; Chemin, L.; et al. (2009). "Ram pressure stripping of the multiphase ISM in the Virgo cluster spiral galaxy NGC 4438". Astronomy & Astrophysics. 496 (3): 669–675. arXiv:0901.2770. Bibcode:2009A&A...496..669V. doi:10.1051/0004-6361/200811140. S2CID 15686123.
  6. Combes, F.; Dupraz, C.; Casoli, F.; Pagani, L. (1988). "CO emission in NGC 4438 - A case for tidal stripping?". Astronomy & Astrophysics. 203 (1): L9–L12. Bibcode:1988A&A...203L...9C.
  7. Vollmer, B.; Braine, J.; Combes, F.; Sofue, Y. (2005). "New CO observations and simulations of the NGC 4438/NGC 4435 system. Interaction diagnostics of the Virgo cluster galaxy NGC 4438". Astronomy & Astrophysics. 441 (2): 473–489. arXiv:astro-ph/0507252. Bibcode:2005A&A...441..473V. doi:10.1051/0004-6361:20041389. S2CID 8506380.
  8. Kenney, Jeffrey D. P.; Tal, Tomer; Crowl, Hugh H.; Feldmeier, John; et al. (2008). "A Spectacular Hα Complex in Virgo: Evidence for a Collision between M86 and NGC 4438 and Implications for the Collisional ISM Heating of Ellipticals". The Astrophysical Journal. 687 (2): L69–L94. arXiv:0810.0711. Bibcode:2008ApJ...687L..69K. doi:10.1086/593300. S2CID 14277489.
  9. Gomez, H. L.; Baes, M.; Cortese, L.; Smith, M. W. L.; et al. (2010). "A Spectacular Hα Complex in Virgo: Evidence for a Collision between M86 and NGC 4438 and Implications for the Collisional ISM Heating of Ellipticals". Astronomy and Astrophysics. 518: L45. arXiv:1005.1597. Bibcode:2010A&A...518L..45G. doi:10.1051/0004-6361/201014530. S2CID 14563125. L45.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. "Big Galaxy Collisions Can Stunt Star Formation" (Press release). National Optical Astronomy Observatory. October 7, 2008. Archived from the original on February 9, 2013. Retrieved August 8, 2012.
  11. David Darling. "The Eyes (NGC 4435 and 4438)". Encyclopedia of Science.
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