| Antennae Galaxies | |
|---|---|
 Hubble Space Telescope image of NGC 4038 (top) and NGC 4039 (bottom) | |
| Observation data (J2000epoch) | |
| Constellation | Corvus[1] |
| Right ascension | 12h 01m 53.0s[2] /12h 01m 53.5s[3] |
| Declination | −18° 52′ 03″[2] / −18° 53′ 10″[3] |
| Redshift | 0.005417±0.000017[2] /0.005474±0.000030[3] |
| Heliocentric radial velocity | 1,624±5 km/s[2] /1,641±9 km/s[3] |
| Galactocentric velocity | 1,467±8 km/s[4][2] /1,484±11 km/s[4][3] |
| Distance | 71.75 ± 9.785 Mly (22 ± 3 Mpc)[5] |
| Apparent magnitude (V) | 11.2[2] / 11.08[3] |
| Characteristics | |
| Type | SB(s)m pec[2] / SA(s)m pecLINERSbrst[3] |
| Size | 634,410 ly × 456,780 ly (194.51 kpc × 140.05 kpc) (diameter; 27.0 B-mag arcsec−2)[2][a] / 258,320 ly × 118,820 ly (79.20 kpc × 36.43 kpc) (diameter; 25.5 B-mag arcsec−2)[3][a] |
| Apparent size (V) | 5.2′ × 3.1′[2] /3.1′ × 1.6′[3] |
| Notable features | Interacting galaxies |
| Other designations | |
| Ringtail Galaxy,[2][3]NGC 4038 / 4039,[2][3]PGC 37967 / 37969,[2][3]Arp 244,[2][3]Caldwell 60/61,[2][3]UGCA 264/265[2][3] | |
TheAntennae Galaxies (also known asNGC 4038/NGC 4039 orCaldwell 60/Caldwell 61) are a pair ofinteracting galaxies in theconstellationCorvus. They are currently going through astarburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation. They were discovered byWilliam Herschel in 1785.[6]
The Antennae Galaxies are undergoing a galactic collision. These interacting galaxies are located 0.25° north of31 Crateris and 3.25° southwest ofGamma Corvi.[7]
Located in theNGC 4038 group with five other galaxies, these two galaxies are known as the Antennae Galaxies because the two long tails ofstars,gas and dust ejected from the galaxies as a result of the collision resemble aninsect'santennae.
Thenuclei of the two galaxies are joining to become one giantgalaxy. Most galaxies probably undergo at least one significant collision in their lifetimes. This might be the future of ourMilky Way with a 50 percent chance ofcolliding with theAndromeda Galaxy.[8] This collision and merger sequence (theToomre sequence) for galaxy evolution was developed in part by successfully modeling the Antennae Galaxies' "antennae" in particular.
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.[9] 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.
NGC 4038 has manyCepheid variables, around 53 of them.[10]
Antennae Galaxies are widely accepted to be located at roughly 20megaparsecs (70 millionlight-years) fromEarth. However, a 2008 study stated that they are less remote from the Milky Way than previously thought—at 13.3 ± 1.0 megaparsec (43.4 ± 3.26 million light-years) based on photometry of the presumedtip of the red-giant branch,[11][12] but an immediate paper later found three major issues regarding this estimate and considered it to be a probable misidentification of the tip of the red-giant branch.[5] An average distance estimate of 22 ± 3 megaparsecs (71.8 ± 9.78 million light-years) has been also calculated based on observations of theType IaSN 2007sr in the southern tail usingLas Campanas Observatory, the large-scale flow model, reanalyzingHubble Space Telescope data in the Archive with an improved method, finding a fainter tip of the red-giant branch.[5]
Foursupernovae have been observed in NGC 4038.
Onesupernova has been found in NGC 4039.
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About 1.2 billion years ago, the Antennae were two separate galaxies.[23] NGC 4038 was abarred spiral galaxy and NGC 4039 was aspiral galaxy. 900 million years ago, the Antennae began to approach one another, looking similar toNGC 2207 and IC 2163. 600 million years ago, the Antennae passed through each other, looking like theMice 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.[24]
Within 400 million years, the Antennae's nuclei will collide and become a single core with stars, gas, and dust around it.[25] Observations and simulations of colliding galaxies (e.g., byAlar Toomre) suggest that the Antennae Galaxies will eventually form anelliptical galaxy.[23][page needed]
Areas containing large amounts ofneon (Ne),magnesium (Mg), andsilicon (Si) were found when theChandra X-ray Observatory analyzed the Antennae Galaxies.Heavy elements such as these are necessary in order for planets that may containlife (as we know it) to form. The clouds imaged contain 16 times as much magnesium and 24 times as much silicon as theSun.
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