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NGC 1316 (Elliptical Galaxy), Arp 154


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NGC 1316
Elliptical Galaxy (楕円銀河)
Gx SB0


別名 (Other names)
Arp 154, PGC 12651, Fornax A

明るさ (Brightness)
8.4等級

星座 (Constellation)
ろ座 (For) (Fornax)

距離 (Distance)
7,500万光年 (75 million light-years)

NGC 1316 (Arp 154) is an elliptical galaxy located 75 million light years from the Earth in the constellation Fornax.

NGC 1316 (Elliptical Galaxy) : Picture

NGC 1316
NGC 1316: After Galaxies Collide
(C) P. Goudfrooij (STScI), Hubble Heritage Team, (STScI/AURA), ESA, NASA
How did this strange-looking galaxy form? Astronomers turn detectives when trying to figure out the cause of unusual jumbles of stars, gas, and dust like NGC 1316. A preliminary inspection indicates that NGC 1316 is an enormous elliptical galaxy that includes dark dust lanes usually found in a spiral. The above image taken by the Hubble Space Telescope shows details, however, that help in reconstructing the history of this gigantic jumble. Close inspection finds fewer low mass globular clusters of stars toward NGC 1316's center. Such an effect is expected in galaxies that have undergone collisions or merging with other galaxies in the past few billion years. After such collisions, many star clusters would be destroyed in the dense galactic center. The dark knots and lanes of dust indicate that one or more of the devoured galaxies were spiral galaxies. NGC 1316 spans about 60,000 light years and lies about 75 million light years away toward the constellation of the Furnace.

Fornax A
The Giant Radio Lobes of Fornax A
(C) Ed Fomalont (NRAO) et al., VLA, NRAO, AUI, NSF
Together, the radio lobes span over one million light years -- what caused them? In the center is a large but peculiar elliptical galaxy dubbed NGC 1316. Detailed inspection of the NGC 1316 system indicates that it began absorbing a small neighboring galaxy about 100 million years ago. Gas from the galactic collision has fallen inward toward the massive central black hole, with friction heating the gas to 10 million degrees. For reasons not yet well understood, two oppositely pointed fast moving jets of particles then developed, eventually smashing into the ambient material on either side of the giant elliptical galaxy. The result is a huge reservoir of hot gas that emits radio waves, observed as the orange (false-color) radio lobes in the above image. The radio image is superposed on an optical survey image of the same part of the sky. Strange patterns in the radio lobes likely indicate slight changes in the directions of the jets.

NGC 1316
Unusual Giant Galaxy NGC 1316
(C) FORS1, VLT ANTU, ESO

NGC 1316
NGC 1316: After Galaxies Collide
(C) C. Grillmair (IPAC/Caltech) et al., WFPC2, HST, NASA

NGC 1316
Twin Star Explosions Fascinate Astronomers
(C) NASA/Swift/Stefan Immler
Scientists using NASA's Swift satellite stumbled upon a rare sight, two supernovae side by side in one galaxy. Large galaxies typically play host to three supernovae per century. Galaxy NGC 1316 has had two supernovae in less than five months, and a total of four supernova in 26 years, as far back as the records go. This makes NGC 1316 the most prodigious known producer of supernovae.

The first supernova, still visible on the "right" in the image, was detected on June 19, 2006, and was named SN 2006dd. The second supernova, on the immediate "left" in the image, was detected on November 5 and has been named SN 2006mr. (The central bright spot is the galaxy core, and the bright object to the far left, like an earring, is a foreground star.)

NGC 1316, a massive elliptical galaxy about 80 million light years way, has recently merged with a spiral galaxy. Mergers do indeed spawn supernovae by forcing the creation of new, massive stars, which quickly die and explode. Yet all four supernovae in NGC 1316 appear to be Type Ia, a variety previously not associated with galaxy mergers and massive star formation. Scientists are intrigued and are investigating whether the high supernova rate is a coincidence or a result of the merger. Swift was launched on this date, November 20, in 2004.

NGC 1316 Fornax A
NGC 1316
(C) NASA/ESA
The Giant Radio Lobes of Fornax A
(C) VLA, NRAO, AUI, NSF
NGC 1316 NGC 1316
NGC 1316
(C) ESO
NGC 1316
(C) NASA
NGC 1316
NGC 1316
(C) NASA/JPL-Caltech/CTIO
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NGC 1316 (Elliptical Galaxy) : Movie

Zooming in on the galaxies NGC 1316 and 1317
This zoom starts with a wide spread of sky, including the familiar constellation of Orion at the upper right and the Large Magellanic Cloud at the upper left. We then close in on the less dramatic constellation of Fornax and see two galaxies close together. These are the contrasting pair of galaxies NGC 1316 and the smaller 1317. Although NGC 1317 appears to be relative unperturbed, its larger neighbour bears the scars of a turbulent history during which it has engulfed smaller galaxies.

Panning across the galaxies NGC 1316 and 1317
This pan video gives a close look at a new image from the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile. It shows a pair of contrasting galaxies: NGC 1316, and its smaller companion NGC 1317 (right). NGC 1317 seems to be relatively unperturbed and has a clear spiral structure. But its larger neighbour bears the scars of several past violent events when it has swallowed other galaxies.
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