Astronomers discover a nearby star system just like
our own Solar System
8 July 1998
HILO, HAWAII -- An international team of astronomers from the Joint
Astronomy Centre (JAC) in Hawaii, the University of California at Los
Angeles (UCLA) and the Royal Observatory in Edinburgh announced today
the discovery of a ring of dust particles around a nearby star,
Epsilon Eridani, that appears to signify a Solar System very similar
to our own.
Submillimetre wavelength view of a ring of
dust particles around Epsilon Eridani, taken with the SCUBA camera at
the James Clerk Maxwell Telescope. The false-colour scale is brightest
where there is more dust. Epsilon Eridani is marked by the star
symbol, although the star itself is not seen at submillimetre
wavelengths. Pluto's orbit (marking the edge of our Solar System) is
shown at the same scale.
The ring is "strikingly similar" to the outer comet zone in our Solar
System, and shows an intriguing bright region that may be particles
trapped around a young planet, said JAC astronomer Jane Greaves, who
led the research team.
"What we see looks just like the comet belt on the outskirts of our
Solar System, only younger," said Greaves, who presented the findings
today at the "Protostars and Planets" Conference in Santa
Barbara. "It's the first time we've seen anything like this around a
star similar to our Sun. In addition, we were amazed to see a bright
spot in the ring, which may be dust trapped in orbit around a planet."
Why is Epsilon Eridani so interesting?
Greaves was a member of the international team that reported new
images of dusty disks around the hotter stars Fomalhaut and Vega in
April. However, the new image of Epsilon Eridani is even more exciting
for several reasons:
"Epsilon Eridani is far more similar to our Sun than either Vega or
Fomalhaut." she said. "This star system is a strong candidate for
planets, but if there are planets, it's unlikely there could be life
yet. When the Earth was this young, it was still being very heavily
bombarded by comets and other debris."
"It is also a star in our local neighbourhood, being only about 10
light years away, which is why we can see so much detail in the new
Epsilon Eridani is clearly visible to the naked eye, in the
constellation Eridanus (the River), which stretches from the foot of
Orion (near the bright star Rigel) to the 9th brightest star in the
sky, the southerly Achernar (barely visible from the USA and
Europe). Epsilon Eridani is among the 10 closest star systems to the
"If an astronomer could have seen what our Solar System looked like
four billion years ago, it would have been very much as Epsilon
Eridani looks today," said Benjamin Zuckerman, UCLA professor of
physics and astronomy. "This is a star system very like our own, and
the first time anyone has found something that truly resembles our
Solar System; it's one thing to suspect that it exists, but another to
actually see it, and this is the first observational evidence."
The research team -- which also includes astronomers from the
University of Arizona, University College London, and the Rutherford
Appleton Laboratory -- has submitted its findings to the Astrophysical
Journal Letters, the most widely-read scholarly journal in astronomy.
More about the discovery:
Sketch of how our Solar System would look at
the same scale as the Epsilon Eridani image. On the outskirts of the
Solar System, vast numbers of comets beyond the orbit of Pluto make up
the Kuiper Belt. The giant planets - Jupiter, Saturn, Uranus and
Neptune - orbit inside this belt. The location of the "belt" is
remarkably similar to the ring around Epsilon Eridani.
Beyond Pluto in our Solar System is a region containing more than
70,000 large comets, and hundreds of millions of smaller ones, called
the "Kuiper belt". The image obtained by Greaves' team shows dust
particles that the astronomers believe are analogous to our Kuiper
belt at the same distance from Epsilon Eridani as the Kuiper belt is
from our Sun. Although the image cannot reveal comets directly, the
dust that is revealed is believed to be debris from comets, Greaves
Epsilon Eridani's inner region contains about 1,000 times more dust
than our Solar System's inner region, which may mean it has about
1,000 times more comets, the astronomers said. Epsilon Eridani is
believed to be only 500 million years to 1 billion years old; our Sun
is estimated to be 4.5 billion years old, and its inner region is
believed to have looked very similar at that age.
In our Solar System, the first 600 million years was a time of "heavy
bombardment" when the planets were assaulted by massive meteorites and
other celestial objects until the gravitation of Jupiter and Saturn
cleaned out these destructive objects. Life on Earth probably did not
start until after the era of heavy bombardment, said JAC astronomer
How was the new image obtained?
The 15-m wide James Clerk Maxwell
Telescope (JCMT) on Mauna Kea
The new image -- which is from short-radio wavelengths, and is not an
optical picture -- was obtained using the 15-meter James Clerk Maxwell
Telescope at the Mauna Kea Observatory in Hilo, Hawaii. The JCMT is
the world's largest telescope dedicated to the study of light at
"submillimeter" wavelengths. The team of astronomers used a
revolutionary new camera called SCUBA (Submillimeter Common User
Bolometer Array), which was built by the Royal Observatory in
Edinburgh (which is now the UK Astronomical Technology Centre). SCUBA
uses detectors cooled to a tenth of a degree above absolute zero (-273
degrees Celsius) to measure the tiny amounts of heat emission from
small dust particles at a wavelength close to one-millimeter.
Implications and mysteries of the new discovery
What is the significance of the similarity between Epsilon Eridani
and our own Solar System?
"The implication is that if there is one system similar to ours at
such a close star, presumably there are many others," Zuckerman
said. "In the search for life elsewhere in the universe, we have never
known where to look before. Now, we are closing in on the right
candidates in the search for life."
Epsilon Eridani is probably too young to support even primitive life,
the astronomers said, but there may be other similar star systems that
are billions of years older, and are good candidates to search for
life. Although astronomers have not yet located a star system that is
the right age with the right atmosphere to support life, they are
A region near the star that is partially evacuated indicates that
planets may have formed, the astronomers said; the presence of planets
is the most likely explanation for the absence of dust in this region
because planets absorb the dust when they form.
What is the bizarre bright spot in the image obtained by the
"There may be a planet stirring up the dust in the ring and causing
the bright spot," said Bill Dent of the Royal Observatory, Edinburgh,
"or it could be the remnants of a massive collision between comets."
Epsilon Eridani is about three-quarters as massive as the sun, but
only one-third as luminous. When astronomer Frank Drake conducted the
first serious search for radio signals from other civilizations in the
late 1950s, Epsilon Eridani was one of the first two stars he
studied. Today, researchers know something Drake did not: Epsilon
Eridani is much too young to have intelligent life. However, the new
image shows there may be at least one planet, and perhaps life in the
In addition to Greaves, Holland, Zuckerman and Dent, the astronomers
on the project are Gerald Moriarty-Schieven and Tim Jenness at JAC;
Harold Butner at the University of Arizona, Tucson; Walter Gear at
University College London; Helen Walker at the Rutherford Appleton
Laboratory; and UCLA graduate students Richard Webb and Chris
The JCMT is operated by the Joint Astronomy Centre, on behalf of the
UK Particle Physics and Astronomy Research Council, the Netherlands
Organisation for Scientific Research, and the National Research
Council of Canada. This work was also supported, in part, by NSF and
NASA grants to UCLA.