NGC 4435 (top) and NGC 4438 (bottom) taken by the FORS2 instrument of the Very Large Telescope in 2011 (Credit: ESO)
|Observation data (J2000.0 epoch)|
|Right ascension||12h 27m 45.6s(J2000)|
|Declination||+13° 00' 31" (J2000)|
|Distance||52 million ly|
|Apparent dimensions (V)||?|
|Apparent magnitude (V)||+10|
|Absolute magnitude (V)||12|
|NGC 4435-8, Arp 120. VV 188|
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. This galaxy takes its name from its ring structure which made it popular.
NGC 4435 is a barred lenticular galaxy with a relatively young (age of 190 million years) stellar population on its central regions that has been discovered by the Spitzer Space Telescope and whose origin may be the interaction with NGC 4438. It also has a long tidal tail possibly caused by the interaction with the mentioned galaxy; however other studies suggest that tail is actually a galactic cirrus in the Milky Way totally unrelated to NGC 4435.
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 of the hypotheses are still being investigated.
This galaxy shows a highly distorted disk with long tidal tails due to interactions with other galaxies, that explain why sources differ to classify it as a lenticular or spiral galaxy. It also shows signs of a past extended -but modest- starburst, a considerable deficience 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, which suggests both a tidal interaction with the latter and the effects of ram-pressure stripping as NGC 4438 moves at high speed through Virgo's intracluster medium, increased by the encounter between both galaxies.
As interacting galaxies
While as described above there is evidence to suggest that the environmental damage to the interstellar medium of NGC 4438 may have been caused by an encounter (off-center collision) with NGC 4435, millions of years ago, the discover of several filaments of ionized gas that link NGC 4438 with its large neighbor the galaxy Messier 86 and the discover on the latter of gas and dust that may have been stripped of the former also shows a past interaction between the two systems, so given the high density of galaxies in the center of galaxy clusters it's possible the three galaxies mentioned (NGC 4435, NGC 4438, and M86) had interacted.
NGC 4435 and dust ring around its nucleus by HST, 1.8′ view
Hubble Space Telescope (HST) image of NGC 4438.
- NGC 4438
- The Eyes Galaxies on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- 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.
- The Tail of NGC 4435
- 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.
- 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.
- 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.
- 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. Bibcode:2005A&A...441..473V. doi:10.1051/0004-6361:20041389.
- 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.
- 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. arXiv:1005.1597. Bibcode:2010A&A...518L..45G. doi:10.1051/0004-6361/201014530. L45.
- "Big Galaxy Collisions Can Stunt Star Formation" (Press release). National Optical Astronomy Observatory. October 7, 2008.
- David Darling. "The Eyes (NGC 4435 and 4438)". Encyclopedia of Science.
- "VLT Looks into The Eyes of the Virgin". ESO Photo Release. 24 August 2011. Retrieved 31 August 2011.