The search for secrets of newborn stars

Astronomer Antony Schinckel drives his SUV up a final rise and into a dale just shy of this dormant volcano's 13,600-foot summit, the world capital of ground-based astronomy.

His pride and joy sprouts from the dale's floor: An apparently haphazard arrangement of eight antennas that look like satellite-TV dishes on steroids.

In fact, these antennas are linked and their arrangement carefully planned. This array is now subjecting some of the most hidden areas of the universe to the kind of scrutiny currently afforded only to astronomers who use optical and radio telescopes.

Known as the Submillimeter Array (SMA), this group of dishes is named for the tiny wavelengths of radiation it detects - a no man's land in the electromagnetic spectrum between the lowest infrared wavelengths and the highest radio wavelengths (roughly between 0.25 and 1.3 millimeters).

Through this window, Dr. Schinckel and his colleagues hope to gain access to some of the coldest, darkest, and youngest regions of the cosmos - and make those observations in unprecedented detail.

The way signals received by the antennas are combined and the wavelengths at which the array operates will allow scientists to pierce more deeply than ever through the dust and gas in the Milky Way that hides the birth of stars and solar systems. This will allow researchers to track such processes from their earliest stages.

The array, which can yield information about temperatures and pressures, is expected to help scientists unravel the complex chemistry hidden in molecular clouds that can spawn organic molecules, seen as the precursors of life. It also is expected to help shed light on processes inside galaxies currently blocked from view at optical and infrared wavelengths by gas and dust, or at distances so great that the expansion of the universe stretches their light from optical or ultraviolet wavelengths within the galaxy to submillimeter wavelengths on Earth.

Of four ground-based observatories designed exclusively for submillimeter operations, the SMA is the first dedicated to interferometry - a technique that turns several antennas into one super- antenna. The result substantially improves an observatory's ability to distinguish two tightly spaced cosmic objects or regions that a single dish or telescope might see as one oddly-shaped blob.

Peering into cold regions of dust and gas sounds boring, says Schinckel, operations director for the array, "but it's potentially so interesting because it's in areas that are initially cool" that stars and planets begin to form, whether in the universe's earliest epochs or in nearby galaxies. Cold and dark, he maintains, is "where the excitement is."

Beyond its immediate scientific importance, the new array holds symbolic importance for a once-obscure and still technically demanding field of astronomy, researchers say. In short, submillimeter astronomy has come of age. From humble beginnings with single-dish telescopes, research groups are now building large-scale ground arrays and sending submillimeter observatories into orbit.

"We're taking a quantum step" in exploring a relatively new band of wavelength for astronomers, says Schinckel. "Despite what we think we're going to be doing, in five years' time we may be doing something quite different - looking at exciting regimes and topics that we just don't know about today."

Dedicated last November, the SMA was built by the Smithsonian Astrophysical Observatories (SAO) with help from Taiwan's Academia Sinica Institute of Astronomy and Astrophysics. Astronomers at the observatory have started working on a few experiments and plan to fully utilize the array by year's end.

So far, their telescope has taken detailed images of a number of objects, including Mars and its atmosphere, says Paul Ho, an astronomer from the SAO offices in Cambridge, Mass.

In images, the Martian atmosphere stands out as a thin layer above the planet itself. The images yield information on the atmosphere's structure, composition, temperature, and pressure, says Dr. Ho.

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