The Antennae Galaxies, also known as the Ringtail Galaxy or Arp 244, are a pair of colliding galaxies located in Corvus constellation. The interacting spiral galaxies have the designations NGC 4038 and NGC 4039 in the New General Catalogue.
The galaxy collision resembles an insect’s antennae, which is how the pair got the name. The “antennae” are formed by two long tails of stars, dust and gas expelled from the galaxies as a result of their interaction.
The colliding galaxies reveal a likely future of the Milky Way when it collides with the neighbouring Andromeda Galaxy (Messier 31) in several billion years.
The NASA/ESA Hubble Space Telescope has snapped the best ever image of the Antennae Galaxies. Hubble has released images of these stunning galaxies twice before, once using observations from its Wide Field and Planetary Camera 2 (WFPC2) in 1997, and again in 2006 from the Advanced Camera for Surveys (ACS). Each of Hubble’s images of the Antennae Galaxies has been better than the last, due to upgrades made during the famous servicing missions, the last of which took place in 2009.
The galaxies — also known as NGC 4038 and NGC 4039 — are locked in a deadly embrace. Once normal, sedate spiral galaxies like the Milky Way, the pair have spent the past few hundred million years sparring with one another. This clash is so violent that stars have been ripped from their host galaxies to form a streaming arc between the two. In wide-field images of the pair the reason for their name becomes clear — far-flung stars and streamers of gas stretch out into space, creating long tidal tails reminiscent of antennae. This new image of the Antennae Galaxies shows obvious signs of chaos. Clouds of gas are seen in bright pink and red, surrounding the bright flashes of blue star-forming regions — some of which are partially obscured by dark patches of dust. The rate of star formation is so high that the Antennae Galaxies are said to be in a state of starburst, a period in which all of the gas within the galaxies is being used to form stars. This cannot last forever and neither can the separate galaxies; eventually the nuclei will coalesce, and the galaxies will begin their retirement together as one large elliptical galaxy. This image uses visible and near-infrared observations from Hubble’s Wide Field Camera 3 (WFC3), along with some of the previously-released observations from Hubble’s Advanced Camera for Surveys (ACS). Image: ESA/Hubble & NASA
The Antennae Galaxies are one of the youngest examples of colliding galaxies, as well as one of the nearest pairs of interacting galaxies to Earth.
The Antennae Galaxies are going through a phase of intense starburst activity as their colliding clouds of dust and gas compress massive molecular clouds and cause rapid formation of millions of new stars. Some of the newly formed stars are gravitationally bound and form massive clusters.
More than a thousand bright clusters consisting of newly formed stars have recently been discovered in the Ringtail Galaxy by astronomers. The brightest and most compact starburst regions contain super star clusters. Billions of stars will be formed before the galactic collision is over.
The Antennae Galaxies’ nuclei are in the process of joining to form a single giant galaxy. This will happen within the next 400 million years. Simulations of the galactic collision indicate that as the galaxies’ nuclei join to form a single core, the two galaxies will eventually form a single giant elliptical galaxy.
The Antennae Galaxies lie at a distance of 45 million light years from Earth.
NGC 4038 and NGC 4039 were two separate galaxies some 1.2 billion years ago. NGC 4039 was a spiral galaxy and the larger of the two, while NGC 4038 was a barred spiral galaxy.
The two galaxies started approaching each other roughly 900 million years ago. At this point, the pair appeared similar to the colliding spiral galaxies NGC 2207 and IC 2163, located in Canis Major constellation.
The Antennae Galaxies are believed to have passed through each other about 600 million years ago, when they may have appeared similar to the Mice Galaxies (NGC 4676), a pair of interacting spiral galaxies lying in the direction of the constellation Coma Berenices.
300 million years later, the stars in both galaxies started being released into intergalactic space. As a result, there are now two streamers of expelled stars extending far beyond NGC 4038 and NGC 4039, giving the pair the appearance of the antennae.
The Antennae Galaxies were discovered by William Herschel in 1785.
NGC 4038 and NGC 4039 are passing through each other at a very high speed, at hundreds of kilometres per second. The reason why the galactic merger is taking hundreds of millions of years to complete is the enormous size of the galaxies.
The galaxies’ tidal tails that have earned them the name Antennae were formed 200 to 300 million years ago, during the galaxies’ first encounter. As the galaxies collided and passed through each other, some of their stars, dust and gas were drawn out into long tails of material. The two streamers will eventually either fall back into the newly formed elliptical galaxy or be lost to space.
A beautiful new image of two colliding galaxies has been released by NASA’s Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red). The Antennae galaxies take their name from the long antenna-like “arms,” seen in wide-angle views of the system. These features were produced by tidal forces generated in the collision. The collision, which began more than 100 million years ago and is still occurring, has triggered the formation of millions of stars in clouds of dust and gas in the galaxies. The most massive of these young stars have already sped through their evolution in a few million years and exploded as supernovas. The X-ray image from Chandra shows huge clouds of hot, interstellar gas that have been injected with rich deposits of elements from supernova explosions. This enriched gas, which includes elements such as oxygen, iron, magnesium, and silicon, will be incorporated into new generations of stars and planets. The bright, point-like sources in the image are produced by material falling onto black holes and neutron stars that are remnants of the massive stars. Some of these black holes may have masses that are almost one hundred times that of the Sun.
The Spitzer data show infrared light from warm dust clouds that have been heated by newborn stars, with the brightest clouds lying in the overlapping region between the two galaxies. The Hubble data reveal old stars and star-forming regions in gold and white, while filaments of dust appear in brown. Many of the fainter objects in the optical image are clusters containing thousands of stars.
The Chandra image was taken in December 1999. The Spitzer image was taken in December 2003. The Hubble image was taken in July 2004 and February 2005. Image: NASA, ESA, SAO, CXC, JPL-Caltech, and STScI
The Antennae Galaxies are members of the NGC 4038 Group along with five other galaxies.
Two supernovae were discovered in the Antennae Galaxies in the last decade: SN 2004GT in 2004 and SN 2007sr in 2007.
Most of the super star clusters formed in the Antennae will disperse within the first 10 million years. Astronomers have predicted that only 10 percent of these clusters will last longer. Roughly a hundred of the most massive ones will survive to eventually form regular globular clusters, similar to those found in our galaxy, the Milky Way.
A Chandra X-ray Observatory study of the Antennae Galaxies revealed that they contain considerable amounts of elements necessary for the formation of habitable planets, including magnesium, neon, and silicon.
The distance between the galaxies’ centres is estimated to be around 30,000 light years. The nuclei of NGC 4038 and NGC 4039 are believed to contain mostly old stars.
Antennae Galaxies – NGC 4038 and NGC 4039
Antennae Galaxies location. Image: Roberto Mura
Type: SB(s)m pec (NGC 4038), SA(s)m pec (NGC 4039)
NGC 4038 – 12h 01m 53s (right ascension), -18°52’10” (declination)
NGC 4039 – 12h 01m 53.6s (right ascension), -18°53’11” (declination)
Distance: 45 million light years
Apparent magnitude: 11.2 (NGC 4038), 11.1 (NGC 4039)
Apparent dimensions: 5′.2 × 3′.1 (NGC 4038), 3′.1 × 1′.6 (NGC 4039)
Designations: Antennae Galaxies, Ringtail Galaxy, Arp 244, NGC 2038, NGC 2039, Caldwell 60, Caldwell 61, PCG 37967, PGC 37969
Galaxy collision simulation
Antennae Galaxies – The two spiral galaxies started to interact a few hundred million years ago, making the Antennae galaxies one of the nearest and youngest examples of a pair of colliding galaxies. Nearly half of the faint objects in the Antennae image are young clusters containing tens of thousands of stars. The orange blobs to the left and right of image center are the two cores of the original galaxies and consist mainly of old stars criss-crossed by filaments of dust, which appear brown in the image. The two galaxies are dotted with brilliant blue star-forming regions surrounded by glowing hydrogen gas, appearing in the image in pink. Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration
The Antennae Galaxies (also known as NGC 4038 and 4039) are a pair of distorted colliding spiral galaxies about 70 million light-years away, in the constellation of Corvus (The Crow). This view combines ALMA observations, made in two different wavelength ranges during the observatory’s early testing phase, with visible-light observations from the NASA/ESA Hubble Space Telescope. The Hubble image is the sharpest view of this object ever taken and serves as the ultimate benchmark in terms of resolution. ALMA observes at much longer wavelengths which makes it much harder to obtain comparably sharp images. However, when the full ALMA array is completed its vision will be up to ten times sharper than Hubble. Most of the ALMA test observations used to create this image were made using only twelve antennas working together — far fewer than will be used for the first science observations — and much closer together as well. Both of these factors make the new image just a taster of what is to come. As the observatory grows, the sharpness, speed, and quality of its observations will increase dramatically as more antennas become available and the array grows in size. This is nevertheless the best submillimetre-wavelength image ever taken of the Antennae Galaxies and opens a new window on the submillimetre Universe. While visible light — shown here mainly in blue — reveals the newborn stars in the galaxies, ALMA’s view shows us something that cannot be seen at those wavelengths: the clouds of dense cold gas from which new stars form. The ALMA observations — shown here in red, pink and yellow — were made at specific wavelengths of millimetre and submillimetre light (ALMA bands 3 and 7), tuned to detect carbon monoxide molecules in the otherwise invisible hydrogen clouds, where new stars are forming. Massive concentrations of gas are found not only in the hearts of the two galaxies but also in the chaotic region where they are colliding. Here, the total amount of gas is billions of times the mass of the Sun — a rich reservoir of material for future generations of stars. Observations like these will be vital in helping us understand how galaxy collisions can trigger the birth of new stars. This is just one example of how ALMA reveals parts of the Universe that cannot be seen with visible-light and infrared telescopes. Image: ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope
One of the first images from the new VIMOS facility, obtained right after the moment of “first light” on Ferbruary 26, 2002. It shows the famous “Antennae Galaxies” (NGC 4038/9), the result of a recent collision between two galaxies. Image: ESO
A new Very Large Telescope (VLT) image of the Antennae Galaxies gives us what may be the second-best visible-light view yet of this striking pair of colliding galaxies with dramatically distorted shapes. This amazing object takes its name from the long antenna-like “arms” extending far out from the nuclei of the two galaxies, best seen in wider-field images by ground-based telescopes such as the one at this link. This VLT view focuses instead on the galaxies’ nuclei, where the real action is taking place as the two galaxies merge into a single giant galaxy. Spurred by shock waves created by their gravitational wrestling, the two galaxies have become dotted with brilliant blue hot young stars in star-forming regions, surrounded by glowing hydrogen gas, shown here in pink. The two pale yellow blobs are the cores of the original galaxies, shining with the light of old stars and picked out by delicate lanes of dust. The Antennae Galaxies were immortalised in 2006 by one of the NASA/ESA Hubble Space Telescope’s most famous images (composed by ESA’s Hubble group residing at ESO). Image: ESO
This false-color image from NASA’s Spitzer Space Telescope reveals hidden populations of newborn stars at the heart of the colliding “Antennae” galaxies. These two galaxies, known individually as NGC 4038 and 4039, are located around 68 million light-years away and have been merging together for about the last 800 million years. The latest Spitzer observations provide a snapshot of the tremendous burst of star formation triggered in the process of this collision, particularly at the site where the two galaxies overlap. The main image is a false-color composite of infrared data from Spitzer and visible-light data from Kitt Peak National Observatory, Tucson, Ariz. Visible light from stars in the galaxies (blue and green) is shown together with infrared light from warm dust clouds heated by newborn stars (red). The two nuclei, or centers, of the merging galaxies show up as yellow-white areas, one above the other. The brightest clouds of forming stars lie in the overlap region between and left of the nuclei. The upper right panel shows the Spitzer image by itself. This picture was taken by the infrared array camera and is a combination of infrared light ranging from 3.6 microns (shown in blue) to 8.0 microns (shown in red). The dust emission (red) is by far the strongest feature in this image. Starlight was systematically subtracted from the longer wavelength data (red) to enhance dust features. The lower right panel shows the true-color, visible-light image by itself. Here, we find a strikingly different view, with the bright star-forming features seen in the Spitzer image buried within dark clouds of dust. Throughout the sky, astronomers have identified many of these so-called “interacting” galaxies, whose spiral discs have been stretched and distorted by their mutual gravity as they pass close to one another. The distances involved are so large that the interactions evolve on timescales comparable to geologic changes on Earth. Observations of such galaxies, combined with computer models of these collisions, show that the galaxies often become forever bound to one another, eventually merging into a single, spheroidal-shaped galaxy. Image: NASA/JPL-Caltech/Z. Wang (Harvard-Smithsonian CfA); Visible: M. Rushing/NOAO