Viewing Galaxies - Articles - Zimbio

You Name the Cosmos

Mon, 22 Jul 2008 07:06:00 GMT

posted by starling

Many of the recent discoveries by the Hubble Space Telescope have been "named" with numbers. Gone are the poetic, mythic names like Milky Way or Andromeda or Pegasus.

Let's have some fun and help NASA out and create names for these awesome celestial objects.

We'll select your best submissions and send them off to NASA headquarters.

What's your name for: Spiral galaxies NGC 5426 and NGC 5427, which are passing perilously close to each other, but each is likely to survive the collision.

Most frequently when galaxies collide, according to NASA experts, a large galaxy eats a much smaller galaxy. In this case, however, the two galaxies are quite similar, each being a sprawling spiral with expansive arms and a compact core. Close inspection of the above image taken by the 8-meter Gemini-South Telescope in Chile shows a bridge of material momentarily connecting the two giants. Known collectively as Arp 271, the interacting pair spans about 130,000 light years and lies about 90 million light-years away toward the constellation of Virgo. Credit & Copyright: Gemini Observatory, GMOS-South, NSF

The Atacama Desert -World's Space-Observatory Headquarters

Wed, 3 Jul 2008 07:22:00 GMT

posted by starling

The lunar landscapes of Chile's Atacama Desert, which stretches for about 650 miles along the Pacific Ocean to the Peruvian Border, is generally considered the driest place on earth, wedged between the rain shadows of the Andes to the east and the coast ranges to the west, while the cold Humboldt Current off the coast suppresses evaporation from the ocean. There are places in the Atacama where there has been no recorded or observed rainfall in the 400+ years since the Spaniards first arrived.

The Atacama Desert's dry climate and 5,600-meter (about 3.5 miles) altitude make it a unique and ideal mecca for both ground-based reflector and far-infrared astronomy. The southern hemisphere skies were opened with the construction of the Carnegie 100-inch DuPont telescope at Las Campanas in 1977.

Thirty years later, Cornell and Caltech have announced the "Atacama Telescope Project To Revolutionize Astronomy," a proposed 25-meter aperture telescope that will be the largest, most precise and highest astronomical facility in the world.

The $100 million Cornell Caltech telescope, to be built in the Cerro Chajnantor in the Atacama Desert region in Chile, will take advantage of the rapid development in bolometer array technology (instruments that measures radiant energy) to answer some of the most fundamental questions of cosmology. Radiation at submillimeter wavelengths (longer than visible light but shorter than radio waves) is normally difficult to detect from the ground because it is easily absorbed by water in the Earth's atmosphere. Situating the telescope in the dry Atacama Desert eliminates this problem.

Planners hope to begin construction this year and to see first light in 2013 under the guidance of Riccardo Giovanelli, Cornell professor of astronomy.

"CCAT is designed to optimize our ability to study the genesis of structures in the universe," said Giovanelli. "It will allow us to explore the process of formation of galaxies, which saw its heyday about a billion years after the big bang, some 13 billion years ago; to peek into the interior of the dusty molecular clouds within which stars and planets form; and to survey the pristine chunks of material left intact for billions of years on the outskirts of our solar system."

The telescope will also be a powerful survey tool, working 30 times faster than current facilities and with much greater sensitivity. Large-scale surveys of extremely distant galaxies could give scientists a better understanding of how galaxies were distributed as they formed and how their clustering properties evolved.

Nearby, on the Atacama's 5000 meter-high plateau of Chajnantor the European Southern Observatory's ALMA (Atacama Large Millimeter/submillimeter Array) Observatory project is a giant, international observatory currently in construction on the high-altitude Chajnantor site, and composed initially of 66 high-precision telescopes, operating at wavelengths of 0.3 to 9.6 mm.

The ALMA antennas will be electronically combined and provide astronomical observations which are equivalent to a single large telescope of tremendous size and resolution, able to probe the Universe at millimeter and submillimeter wavelengths with unprecedented sensitivity and resolution, with an accuracy up to ten times better than the Hubble Space Telescope.

ALMA will be the forefront instrument for studying the cool universe - the relic radiation of the Big Bang, and the molecular gas and dust that constitute the very building blocks of stars, planetary systems, galaxies, and life itself.

Because ALMA will observe in the millimeter and submillimeter wavelengths the atmosphere above the telescope must be transparent. This requires a site that is high and dry. ALMA is thus installed at the 5000m high plateau of Chajnantor in the Atacama Desert -the next best location to outer space for these high-accuracy astronomical observations.

ESO is the intergovernmental European Organization for Astronomical Research in the Southern Hemisphere. On behalf of its thirteen member states ESO operates a suite of the world's most advanced ground-based astronomical telescopes located at the La Silla Paranal Observatory in the Atacama desert in Chile.

The European Southern Observatory (ESO) operates two additional observational sites in the Chilean Atacama. The Very Large Telescope (VLT) is located on Paranal, a 2600 meter high mountain south of Antofagasta. At La Silla, 600 kilometers north of Santiago at 2400 meter altitude, ESO operates several medium-sized optical telescopes.

The Swiss, French and Portuguese astronomers manning the La Silla 3.6m telescope were responsible for the recent discovery of Gliese 581c, an exo-planet that revolves around the star known as Gliese 581, a red dwarf in the Libra constellation. It is older than our solar system and its year lasts only 13 days, since it is 14 times closer to its star than the Earth is to the our Sun. Astronomers also say—based on initial high-tech models and density-mass calculations—this quasi-Earth’s surface is either rocky or ocean-covered—both Earth-like geographical qualities.

Posted by Casey Kazan.

In the Heart of the Virgo Cluster

Tue, 9 Jul 2008 00:10:16 GMT

posted by thefifthlord

In the Heart of the Virgo Cluster
Credit & Copyright: Günter Kerschhuber (Gahberg Observatory)

Explanation: The Virgo Cluster of Galaxies is the closest cluster of galaxies to our Milky Way Galaxy. The Virgo Cluster is so close that it spans more than 5 degrees on the sky - about 10 times the angle made by a full Moon. With its heart lying about 70 million light years distant, the Virgo Cluster is the nearest cluster of galaxies, contains over 2,000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy. The cluster contains not only galaxies filled with stars but also gas so hot it glows in X-rays. Motions of galaxies in and around clusters indicate that they contain more dark matter than any visible matter we can see. Pictured above, the heart of the Virgo Cluster includes bright Messier galaxies such as Markarian’s Eyes on the upper left, M86 just to the upper right of center, M84 on the far right, as well as spiral galaxy NGC 4388 at the bottom right.

Inside the Coma Cluster of Galaxies

Sun, 16 Jun 2008 20:40:39 GMT

posted by thefifthlord

Credit: NASA, ESA, Hubble Heritage (STScI/AURA);
Acknowledgment: D. Carter (LJMU) et al. and the Coma HST ACS Treasury Team

Explanation: Almost every object in the above photograph is a galaxy. The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies. Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does. Although nearby when compared to most other clusters, light from the Coma Cluster still takes hundreds of millions of years to reach us. In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other! The above mosaic of images of a small portion of Coma was taken in unprecedented detail by the Hubble Space Telescope to investigate how galaxies in rich clusters form and evolve. Most galaxies in Coma and other clusters are ellipticals, although some imaged here are clearly spirals. The spiral galaxy on the upper left of the above image can also be found as one of the bluer galaxies on the upper left of this wider field image. In the background thousands of unrelated galaxies are visible far across the universe.

Hubble Captures Gargantuan Fossil Galaxy

Tue, 6 Feb 2008 08:02:00 GMT

posted by starling

The Hubble Space Telescope has captured a new image of a galaxy located approximately 320 million light-years away in the constellation of Eridanus, the River, which is, most likely, a cosmic fossil – the aftermath of an enormous multi-galactic pile-up, where the carnage of collision after collision has built up a brilliant giant elliptical galaxy far outshining typical galaxies.

Scientists have found that NGC 1132 resides in an enormous halo of dark matter, comparable to the amount of dark matter usually found in an entire group of tens or hundreds of galaxies.

Galaxy NGC 1132, seen in this latest image from Hubble, belongs to a category of galaxies called giant ellipticals. NGC 1132, together with the small dwarf galaxies surrounding it, are dubbed a “fossil group” as they are most likely the remains of a group of galaxies that merged together in the recent past.

The origin of fossil group systems remains a puzzle. The most likely explanation is that they are the end-products of a cosmic feeding frenzy in which a large cannibal galaxy devours all of its neighbors. A less likely explanation is that they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.

There is strong evidence that the Milky Way is one such cannibal that has snacked on numerous smaller galaxies during its lifetime, inheriting their stars in the process. Scientists are keenly studying the environment surrounding galaxies such as NGC 1132 using space telescopes like Hubble, and they try to trace the history of the formation these galaxies by analysing their properties.

In this Hubble image, NGC 1132 is seen surrounded by thousands of ancient globular clusters, swarming around the galaxy like bees around a hive. These globular clusters are likely to be the survivors of the disruption of their cannibalized parent galaxies that have been eaten by NGC 1132 and may reveal its merger history. In the background, there is a stunning tapestry of numerous galaxies that are much further away.

Elliptical galaxies are smooth and featureless. They contain hundreds of millions to trillions of stars, and their shapes range from nearly spherical to very elongated in shape. Their overall yellowish colour is a telltale sign of their great age. Because elliptical galaxies do not contain much cool gas they can no longer make new stars.

Posted by Casey Kazan.

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