Astronomy Picture of the Day 03-11-04

Explanation: Peering into a dusty nebula in nearby galaxy the Large Magellanic Cloud, infrared cameras on board the Spitzer Space Telescope recorded this detailed view of stellar nursery Henize 206 filled with newborn stars. The stars appear as white spots within the swirls of dust and gas in the false-color infrared image. Near the top, the sweeping telltale arcs of a supernova remnant are also visible, expanding debris from the final explosion of a massive star. The proximity of the ancient supernova indicates that the shockwave from that stellar death explosion itself likely triggered the formation of the new generation of emerging stars, compressing the gas and dust within Henize 206 and continuing the cosmic cycle of star death and star birth. At the distance of the Large Magellanic Cloud, about 163,000 light-years this image covers an area about 1,000 light-years across.

25-metre telescope planned for Chile
CALIFORNIA INSTITUTE OF TECHNOLOGY
Posted: March 9, 2004


Image credit: Caltech

The California Institute of Technology and Cornell University are in the planning stages for a new 25-metre telescope to be built in Chile. The submillimetre telescope will cost an estimated $60 million and will be nearly two times larger in diameter than the largest submillimetre telescope currently in existence.

The first step of the plan, which is being announced today jointly by Caltech and Cornell, commits the two institutions to a $2-million study, says Jonas Zmuidzinas, a physics professor at Caltech who is leading the Institute's part of the collaboration. The telescope is projected for a 2012 completion date on a high site in the Atacama Desert of northern Chile, and will significantly ramp up Caltech's research in submillimetre astronomy.

Scientists from Cornell, Caltech, and Caltech's Jet Propulsion Laboratory (JPL) will be participating in the telescope study, including Caltech faculty members Andrew Blain, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, and others.

"We are very much looking forward to working with our Cornell colleagues on this project," says Zmuidzinas.

At Cornell, the participants will include professors Riccardo Giovanelli, Terry Herter, Gordon Stacey, and Bob Brown.

Submillimetre wavelength astronomy allows the study of a number of astrophysical phenomena that do not emit much visible or infrared light. The new telescope will observe stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

"So far, we have gotten just a small taste of what there is to learn at submillimetre wavelengths," says Zmuidzinas. "This telescope will be a huge step forward for the field."

The new telescope is poised to take advantage of the rapid development of sensitive superconducting detectors, an area in which Zmuidzinas and his Caltech/JPL colleagues have been making important contributions. The new superconducting detectors enable large submillimetre cameras to be built, which will produce very sensitive panoramic images of the submillimetre sky.

The 25-metre telescope is a natural progression in Caltech and JPL's longstanding interest in submillimetre astronomy. Caltech already operates the Caltech Submillimetre Observatory (CSO), a 10.4-meter telescope constructed and operated with funding from the National Science Foundation, with Tom Phillips serving as director. The telescope is fitted with sensitive submillimetre detectors and cameras, many of which were developed in collaboration with JPL, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation.

The advantages of the new telescope will be fourfold. First, due to the larger size of its mirror and its more accurate surface, the 25-meter telescope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Second, the larger diameter and better surface will result in much sharper images of the sky. Third, the large new cameras will provide huge advantages over those currently available.

Finally, the 16,500-foot elevation of the Atacama Desert will provide an especially dry sky for maximum effectiveness. Submillimetre wavelengths (as short as two-tenths of a millimetre) are strongly absorbed by the water vapour in the atmosphere. For maximum effectiveness, a submillimetre telescope must be located at a very high, very dry altitude--the higher the better--or best of all, in space.

However, while the idea of a large (10-metre) submillimetre telescope in space is being considered by NASA and JPL, it is still more than a decade away. Meanwhile, existing space telescopes such as the Hubble and the Spitzer work at shorter wavelengths, in the visible and infrared, respectively.

In 2007, the European Space Agency plans to launch the 3.5-metre Herschel Space Observatory, which will be the first general-purpose submillimetre observatory in space. NASA is participating in this project, and scientists at JPL and Caltech are providing detectors and components for the science instruments.

"It is a very exciting time for submillimetre astronomy," says Zmuidzinas. "We are making rapid progress on all fronts--in detectors, instruments, and new facilities--and this is leading to important scientific discoveries."

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