From: LARRY KLAES (ljk4_at_msn.com)
Date: Tue Jul 01 2003 - 17:06:59 PDT
----- Original Message -----
From: NASA Jet Propulsion Laboratory
Sent: Tuesday, July 01, 2003 6:39 PM
Subject: Hawaiian Telescope Team Makes Debut Discovery
Jane Platt (818) 354-0880
Jet Propulsion Laboratory, Pasadena, Calif.
Donald Savage (202) 358-1727
Headquarters, Washington. D.C.
Laura Kraft (808) 885-7887
W.M. Keck Observatory, Kamuela, Hawaii July 1, 2003
News Release: 2003-093
Hawaiian Telescope Team Makes Debut Discovery
Astronomers have observed a young star ringed by a swirling disc that
may spin off planets, marking the first published science observation
using two linked 10-meter (33-
foot) telescopes in Hawaii.
The linked telescopes at the W.M. Keck Observatory on Mauna Kea, known
as the Keck Interferometer, comprise the world's largest optical
telescope system. The observation was made of DG Tau, a young star
that has not yet begun to burn hydrogen in its core. Such stars are
called T-Tauri objects. Observations of DG Tau were made on October
23, 2002, and February 13, 2003, and the findings will appear in an
upcoming issue of the Astrophysical Journal Letters.
"We're trying to measure the size of the hot material in the dust disc
around DG Tau, where planets may form," said Dr. Rachel Akeson, leader
of the study team and an astronomer at the Michelson Science Center at
the California Institute of Technology in Pasadena. "Studies like this
teach us more about how stars form, either alone or in pairs, and how
planets eventually form in discs around stars."
The Keck Interferometer observations revealed a gap of nearly 29
million kilometers (18 million miles) between DG Tau and its orbiting
dust disc. Akeson notes that of the extra-solar planets -- planets
orbiting other stars -- discovered so far, roughly one in four lies
within 16 million kilometers (10 million miles) of the parent star.
Since planets are believed to form within a dust disc, either DG Tau's
disc has a larger-than-usual gap, or the close-in planets form farther
from the star and migrate inward.
Since 1995, astronomers have detected more than 100 extra-solar
planets, many considered too large and close to their hot, parent
stars to sustain life. By measuring the amount of dust around other
stars, where planets may form, the Keck Interferometer will pave the
way for NASA's Terrestrial Planet Finder mission. Terrestrial Planet
Finder will look for smaller, Earth-like planets that may harbor life.
The Keck Interferometer and Terrestrial Planet Finder are part of
NASA's Origins Program, which seeks to answer the questions: Where did
we come from? Are we alone?
"T-Tauri objects had been observed with other instruments, but only
the brightest ones were detectable until now," Akeson said. "With the
larger telescopes and greater
sensitivity of the Keck Interferometer, we can look at fainter T-Tauri
objects, like this one."
The Keck Interferometer gathers light waves with two telescopes and
then combines the waves so they interact, or "interfere" with each
other. It's like throwing a rock into a lake and watching the ripples,
or waves, and then throwing in a second rock. The second set of waves
either bumps against the first set and changes its pattern, or both
sets join together to form larger, more powerful waves. With
interferometry, the idea is to combine light waves from multiple
telescopes to simulate a much larger, more powerful telescope.
In its ability to resolve fine details, the Keck Interferometer is
equivalent to an 85-meter (279-foot) telescope. "The system transports
the light gathered by the two telescopes to an optical laboratory
located in the central building," said Dr. Mark Colavita of NASA's Jet
Propulsion Laboratory, Pasadena, interferometer system architect and
lead author of the paper. "In the lab, a beam combiner and infrared
camera combine and process the collected light to make the science
To make these measurements, the interferometer's optical system
adjusts the light paths to a fraction of a wavelength of light, and
adaptive optics on the telescopes remove the
distortion caused by Earth's atmosphere.
"This research represents the first scientific application of an
interferometer with telescopes that use adaptive optics," said Dr.
Peter Wizinowich, interferometer team lead for the W.M. Keck
Observatory and co-author of the paper.
The development of the Keck Interferometer is managed by JPL for
NASA's Office of Space Science, Washington. JPL is a division of the
California Institute of Technology in
Pasadena. The W.M. Keck Observatory is funded by Caltech, the
University of California and NASA, and is managed by the California
Association for Research in Astronomy, Kamuela, Hawaii.
Additional information and images are available on the Internet at
http://www.nasa.gov http://www.nasa.gov/ .
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