NGC 1097: Coiled Creature of the Night

[bystander]

http://www.nasa.gov/mission_pages/spitz ... 90723.html

NASA's Spitzer Space Telescope has imaged a wild creature of the dark -- a coiled galaxy with an eye-like object at its center.

The galaxy, called NGC 1097, is located 50 million light-years away. It is spiral-shaped like our Milky Way, with long, spindly arms of stars. The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars. In this color-coded infrared view from Spitzer, the area around the invisible black hole is blue and the ring of stars, white.

The black hole is huge, about 100 million times the mass of our sun, and is feeding off gas and dust along with the occasional unlucky star. Our Milky Way's central black hole is tame in comparison, with a mass of a few million suns.

The ring around the black hole is bursting with new star formation. An inflow of material toward the central bar of the galaxy is causing the ring to light up with new stars.

[neufer]

http://www.nasa.gov/mission_pages/spitz ... 90723.html

NASA's Spitzer Space Telescope has imaged a wild creature of the dark -- a coiled galaxy with an eye-like object at its center.

The galaxy, called NGC 1097, is located 50 million light-years away. It is spiral-shaped like our Milky Way, with long, spindly arms of stars. The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars. In this color-coded infrared view from Spitzer, the area around the invisible black hole is blue and the ring of stars, white.

The black hole is huge, about 100 million times the mass of our sun, and is feeding off gas and dust along with the occasional unlucky star. Our Milky Way's central black hole is tame in comparison, with a mass of a few million suns.

The ring around the black hole is bursting with new star formation. An inflow of material toward the central bar of the galaxy is causing the ring to light up with new stars.

Coiled Creature of the Night: An earwig?
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Explanation: A smaller companion seems wrapped in the spiral arms of enigmatic galaxy NGC 1097. The faint details revealed include hints of a mysterious jet emerging toward the top of the view. Seen to be about 42,000 light-years from the larger galaxy's center, the companion galaxy is gravitationally interacting with the spiral and will ultimately merge with it. NGC 1097's center also harbors a massive black hole. NGC 1097 is located about 45 million light-years away in the chemical constellation Fornax.

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<<NGC 1097 is a barred spiral galaxy about 45 million light-years away in the constellation Fornax. Three supernovae (SN 1992bd, SN 1999eu, & SN 2003B) have been observed in NGC 1097 (as of 2006). NGC 1097 is also a Seyfert galaxy, with jets shooting from the core. Like most galaxies, NGC 1097 has a supermassive black hole at its center. Around the central black hole is a ring of star-forming regions with a network of gas and dust that spirals from the ring to the black hole.>>

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NGC 1097 - The Galaxy with the Longest known Optical Jets

<<In 1974, astronomer Halton Arp was sitting at a viewing machine scanning some deep plates in the southern sky when R.D. Wolstencroft walked up to him with a long exposure plate taken with the United Kingdom’s 48” Schmidt reflector of the barred spiral galaxy NGC 1097. Arp was asked what he thought of a faint luminous smear pointing away from the galaxy’s northern edge. He replied that it must be a plate defect since he had never seen anything like it. Later plates by Wolstencroft continued to show this “jet-like” feature emerging from the galaxy.

In 1975 about 1 year later, Dr. Arp had a 2 week night run on the new 4-meter reflector at Cerro Tololo in Chile. Arp’s main target was NGC 1097 and he took many photos of it. A total of 4 optical jets showed up all pointing away from the host galaxy, thanks to the masterful image processing by Arp’s colleague Jean Lorre. The jets are identified as JET 1, JET 2, JET 3, and JET 4. Traced backwards, all the jets intersected at the nucleus of NGC 1097. From direct examination of the high resolution photographs, Arp was able to estimate a) the age of the jets, b) their ejection velocity, and c) frequency of ejection. Figure 2 shows NGC 1097 with many H II regions dotting the spiral arms.

The southern spiral arm shows a section of the H II regions “missing” at the point of where JET 3 interacts. JET 1 seems to have separated the northern spiral arm. As the galaxy has rotated since the “ejection” Arp concluded from the 15° disruption angle of the northern spiral arm, that JET 1 is approximately 10 million years old.

The assumed distance of NGC 1097 is 20 Mpc (based upon a Hubble Constant of 65 km/sec/Mpc). JET 2’s extent of 9’ from the galaxy center has a linear amplitude of 52 kpc. Assuming a 10 million year lifetime, the ejection velocity must be on the order of 5,200 km/sec. The jets also exhibit a very low surface brightness as they are only seen on deep exposures. Dr. Arp has suggested that being so faint at an early age (10 million years) makes them transient, and probably a short lived phenomena similar to planetary nebula. Which is presumably why we don’t see many jets in other galaxies. Some other galaxies that have optical jets are M87, NGC 5128 (also known as Centaurus A) and quasar 3c 273.

In 1979 follow up observations of NGC 1097 was observed by the Einstein X-Ray satellite. A lot of X-Ray emission was evident on the north side of the galaxy. An object of m = +18 coincided with one bright patch of X-Ray emission - and this object turned out to be a quasar. Follow up observations in 1983 by Arp et. al. showed an even higher quasar density. Thirty-four quasars to m = +20 were discovered within 80 arc minutes of NGC 1097, far too many to be accounted for by random chance. (There are only 1000 quasars known across the entire sky!) And most of these quasars appear to be on the north side of the galaxy along the lines of the two northern jets! The redshifts of the quasars ranged from z = 0.34 to z = 3.09. Despite the overwhelming evidence of the association of these quasars with Arp’s ejection theories, the quasar density paper was almost rejected by the Astrophysical Journal. After a year and a half delay, it was published in the October 1984 issue.

The nature of the optical jets still remains a mystery as no conclusive observational proof (other than the unusually high quasar density) exists that the quasars (or some other material) have been ejected from NGC 1097. A recent paper by Ann Wherle, et. al. (Astronomical Journal) entitled “The Nature of the Optical “JETS” in the Spiral Galaxy NGC 1097” studied the colors of the optical jets. Although Wherle, et. al could not identify the composition of the jets by examining the B-V colors, their conclusions in the paper were based upon the process of elimination. Their observations were: 1) the jets showed no radio emission at certain frequencies, 2) that their colors were very blue, (indicating these colors are consistent with starburst formation seen in other galaxies) and 3) optically, the jets are inconsistent with the jet in the galaxy M87 in which something appears to have been ejected (The M87 jet is not continuous, but shows several knots). Wherle, et. al described that the jets in NGC 1097 were the result of some previous gravitational encounter with the companion galaxy NGC 1097A. The jets are thus merely tidal plumes from such an encounter, and the “X” pattern of these jets is due to the viewing angle. Wherle, et. al also mentioned in their 1997 paper that they have conducted a survey of other bright galaxies for similar “X” pattern jets. They have found none to date and thus the interacting galaxy “NGC 1097 with four optical jets is still a rara avis in the celestial menagerie.” Would any CCD imagers be willing to try and image the jets?>>

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The Activities of NGC 1097


<<This image from the European Southern Observatory shows the inner 5500-light-year region of the barred spiral galaxy NGC 1097. According to the press release, it shows a “ring of dust and gas” surrounding a “super-massive black hole” at the center and a “filamentary structure spiralling down” into the black hole. The press release notes that this Active Galactic Nucleus (AGN) at the center is fainter than most, indicating that “only a small amount of gas and stars” are falling into the black hole. This galaxy is famous for its “dogleg” jet—a narrow filament that ends with a right-angle turn into an arc. Another fainter jet extends from the nucleus in the opposite direction. Still another jet and counter-jet extend through the nucleus with a 20-degree-or-so angle of rotation from the dogleg. The dogleg is not unique. NGC 4651 has a “tangential arc” at the end of a jet. Several x-ray clusters have similar features. Often these are called “gravitational lensing”. But ejecting stars show the same feature It is a feature seen frequently in lab plasma discharges

X-ray and radio images of NGC 1097 show lobes of emission in line with the jets. Especially to the north, the lobes resolve into strings of bright sources. Many of these have been identified as quasars and galaxy clusters, objects considered (by standard theory) to be far beyond the galaxy. A plot of all quasar and cluster locations in the area around the galaxy shows that their numbers increase toward the galaxy and that they, too, are aligned with the jets. For distant objects that have no connection to the galaxy, this is strange behavior.

But to look outside the narrow field of view of modern telescopes is to look outside the narrow field of explanation of modern theories. What if the rings of material around AGNs are composed not of gas and dust but of plasma? What if the filamentary structure is not gas and stars falling into a black hole but Birkeland currents driving a plasma focus? What if quasars and galaxy clusters are ejected from AGNs? The properties of plasma can be investigated in laboratories on Earth. The properties of black holes can only be deduced from the malleable mathematics of conjecture. Active Galactic Nuclei stand in contrast to the ossified idealism of a science that has lost touch with its empirical roots.>>

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[bystander]

APOD: 2009 July 27 - NGC 1097: Spiral Galaxy with a Central Eye
http://apod.nasa.gov/apod/ap090727.html
http://asterisk.apod.com/vie ... =9&t=17148