http://www.noao.edu/outreach/press/pr03/pr0302.html
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For More Information:
Douglas Isbell
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National Optical Astronomy Observatory
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Kristi Phillips
Lowell Observatory
Phone: 928/774-3358, x232
E-mail: [EMAIL PROTECTED]
EMBARGOED FOR RELEASE: 2:00 a.m. PST, January 8, 2003
RELEASE NO: NOAO 03-02
First Neptune Trojan Discovered
Astronomers have discovered a small body orbiting the Sun
at the distance of Neptune whose orbit makes it the first
known member of a long-sought population of objects known
as Neptune Trojans.
This small body, known as 2001 QR322, leads Neptune around
its orbit in such a way as to maintain -- on average --
approximately equal distance from Neptune and the Sun. As
such, it mimics the Trojan asteroids of Jupiter, which
orbit the Sun in two clouds approximately 60 degrees
ahead of and behind Jupiter. The first Jovian Trojan was
discovered in 1906, and approximately 1,560 such objects
are known today. However, until the discovery of
2001 QR322, Trojan-like objects associated with other
giant planets had not been found.
2001 QR322 was discovered in the course of the Deep
Ecliptic Survey, a NASA-funded survey of the outer solar
system that uses the National Science Foundation's
telescopes at Kitt Peak National Observatory near Tucson,
AZ, and Cerro Tololo Inter-American Observatory in Chile.
Astronomers from Lowell Observatory, the Massachusetts
Institute of Technology, the University of California
at Berkeley, the University of Hawaii, the University
of Pennsylvania, and the Large Binocular Telescope
Observatory comprise the Deep Ecliptic Survey team.
The team first detected 2001 QR322 on August 21, 2001,
in deep digital images taken with the 4-meter Blanco
Telescope at Cerro Tololo by Marc Buie, Robert Millis,
and Lawrence Wasserman of Lowell Observatory. However,
several subsequent observations, made with a variety
of telescopes over the past 16 months, coupled with
numerical orbit integrations of the trajectory of the
asteroid, were required to prove that 2001 QR322 is
indeed a Neptune Trojan. The object is estimated to be
approximately 230 kilometers (140 miles) in diameter
and, like Neptune, requires about 166 years to complete
each circuit of its orbit.
"Neptunian Trojans were long suspected to exist and it
is gratifying to finally know that they do," says team
member Eugene Chiang of the University of California at
Berkeley. "The orbit of 2001 QR322 is remarkably stable;
projections of its trajectory into the future reveal
that it can co-orbit with Neptune for at least billions
of years. It is likely that 2001 QR322 is a dynamically
pristine object whose orbital eccentricity and inclination
have been largely unaltered by processes that afflicted
the majority of bodies in the outer solar system."
A graphic that describes the orbit of 2001 QR322 is
available.
Kitt Peak and Cerro Tololo Inter-American Observatory are
part of the National Optical Astronomy Observatory (NOAO),
which is operated by the Association of Universities for
Research in Astronomy (AURA), Inc., under a cooperative
agreement with the National Science Foundation.
The survey team's research is supported in part by the
NASA Planetary Astronomy Program through grants to Lowell
Observatory, the Massachusetts Institute of Technology,
and the University of Hawaii; by the National Science
Foundation through a grant to the University of
California at Berkeley; by the Space Telescope Science
Institute through grants to University of Pennsylvania
and by the University of California at Berkeley; by the
University of California at Berkeley through a Faculty
Research Award; and by the Friends of Lowell Observatory.
NOTE: Marc Buie, Robert Millis, and Larry Wasserman can
be reached at 928/774-3358 or via email at:
[EMAIL PROTECTED], [EMAIL PROTECTED], and [EMAIL PROTECTED]
Eugene Chiang can be reached at 510/642-2131 or via email
at: [EMAIL PROTECTED]
For more information about the Deep Ecliptic Survey, see:
http://www.lowell.edu/Research/DES/
IMAGE CAPTION:
The left-hand panel displays a bird's-eye view of the
outer solar system, with the orbits of Jupiter (J),
Saturn (S), Uranus (U), and Neptune (N) about the Sun
shown schematically. The dark tube of points lying on
Neptune's orbit marks the path of the newly discovered
Trojan object 2001 QR322, relative to Neptune. The
Trojan shuttles back and forth along Neptune's orbit
as indicated by the red and green curved arrows. Each
full shuttling takes about 10,000 years to complete.
The small inset rectangle at left is magnified in the
right-hand panel. When plotted over time, 2001 QR322
traces a local corkscrew pattern. The red curve traces
the path of the Trojan as it travels away from Neptune,
as indicated by the red arrows. The green curve traces
the trajectory of the Trojan as it approaches Neptune.
Each full twist of the corkscrew takes about the same
time as Neptune takes to revolve around the Sun (166
years).
Image Credit: Deep Ecliptic Survey Team/NOAO/AURA/NSF
Download:
* 800 x 411 GIF [56 KB]
http://www.noao.edu/outreach/press/pr03/images/trojan_med.gif
* 1969 x 1011 GIF [96 KB]
http://www.noao.edu/outreach/press/pr03/images/trojan.gif
* 1969 x 1011 TIF [1.6 MB]
http://www.noao.edu/outreach/press/pr03/images/trojan.tif";
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