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A Chinese Dragon and a Knotted Galactic Embrace

September 5, 2005

The Gemini Observatory released a pair of images today that capture the dynamics of two very different interactions in space. One is a cold, dark dust cloud that resembles an ethereal-looking Chinese dragon. The other shows a distant duo of galaxies locked in a knot-like embrace that could portend the long-term future of our own Milky Way galaxy.

The processes shown in these views occur on a tremendous range of size scales. NGC 6559 is a relatively small, nearby dust cloud in our Milky Way galaxy that measures about seven light-years across, while NGC 520 features two completely entwined galaxies that stretch across 150,000 light-years.

While both images hint at how dynamic and active these objects can be, their evolution occurs on astronomical timescales. According to Ian Robson, Director of the UK’s Astronomy Technology Center, “If we could see either of these objects as an extreme time-lapse movie made over millions of years, the galaxy pair would dance in a graceful orbital embrace that is likely similar to the fate between our Milky Way and the great Andromeda Galaxy, while the dusty cloud would probably resemble waving smoke from an extinguished candle.”

Together, these Gemini images illustrate another point about the universe: it’s dusty. The main features of NGC 6559 that lend this nebula its Chinese dragon appearance are dark clouds of backlit dust. The merging galaxies also show a prominent dust lane running diagonally across the image. In both cases this dust is visible because it blocks the light from behind it much like a cloud obscures sunlight here on Earth.

The two images were selected based on observations made during the first half of 2005 at each of the twin Gemini telescopes.

“I coordinated observations in Chile when the dragon-like images of NGC 6559 were obtained,” said Gemini South Astronomer Rodrigo Carrasco. “I could tell this was going to make a fantastic color image with lots of details never resolved before in this cloud of dust. Other astronomers will appreciate this data now that it is in the Gemini Data Archive.”

Gemini North on Mauna Kea captured the image of NGC 520, showing two interacting galaxies against a backdrop of dimmer much more distant galaxies. Gemini Astronomer Kathy Roth oversaw the observations and shared her reactions. “Watching images like these come off the telescope is always a thrill. It is very satisfying to have everything working perfectly and to be able to take advantage of the great conditions on Mauna Kea,” she said. “This particular image not only makes a pretty picture but I expect it will be useful to astronomers who model interacting galaxies and how these interactions trigger star formation.”

The pair of images were obtained using the Gemini Multi-Object Spectrograph (GMOS). It provides high-resolution imaging on both of the twin Gemini 8-meter telescopes. The observations are part of the ongoing Gemini Legacy Imaging program that shares striking views of the universe made possible with the new generation of large ground- based telescopes. Travis Rector of the University of Alaska combined the raw data to create the color images.

Additional technical and background information and full-resolution image downloads are provided from a link at: www.gemini.edu

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located at Mauna Kea, Hawai’i (Gemini North) and the other telescope at Cerro Pach³n in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in each partner country with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comisi³n Nacional de Investigaci³n Cientifica y Tecnol³gica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Científicas y T©cnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnol³gico (CNPq).

The Observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.


A Chinese Dragon and a Knotted Galactic Embrace


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