(2005-06-15)
Cambridge, MA - Meeting this week in Cambridge, Mass., astronomers using the Submillimeter Array (SMA) on Mauna Kea, Hawaii, confirmed, for the first time, that many of the objects termed "proplyds" found in the Orion Nebula do have sufficient material to form new planetary systems like our own.
"The SMA is the only telescope that can measure the dust within the Orion
proplyds, and thereby assess their true potential for forming planets. This
is critical in our understanding of how solar systems form in hostile regions
of space," said Jonathan Williams of the University of Hawaii Institute for
Astronomy, lead author on a paper submitted to The Astrophysical Journal.
Surviving in the chaotic regions within the Orion Nebula where stellar
winds can reach a staggering two million miles per hour and temperatures
exceed a searing 18,000 degrees Fahrenheit, the question remained - would
enough material endure to form a new solar system or would it be eroded away
into space like wind and sand eroding away desert cliffs? It now appears
that these protoplanetary disks are quite tenacious, bringing new grounds
for optimism in the search for planetary systems.
Imaged by the Hubble Space Telescope back in the early 1990s as misshapen
silhouettes against the nebular background, the most spectacular proplyds
appear bright. Their surrounding ionized cocoons glow due to their close
proximity to a nearby hot star formation called the Trapezium. The Trapezium
is a star cluster consisting of more than 1,000 young, hot stars that are
only 1 million years old. They condensed out of the original cold, dark cloud
of gas that now glows from their ionizing light. They are crowded into a
space about 4 light-years in diameter, the same as the distance between the
Sun and Proxima Centauri, the next closest star in space.
Blasted by the solar winds of the Trapezium, the proplyds are the next
generation of smaller stars to arise in Orion, this time with visible discs
that may be forming planets. It has remained unclear, however, whether they
contained enough material to form stable planetary systems. Using the SMA,
astronomers now have been able to probe deep inside these disks to measure
their mass and to unravel the formation process presented by these potential
infant solar systems.
"While the Hubble pictures were spectacular, they revealed only disk-like
shapes that did not tell us the amount of material present," said David Wilner,
of the Harvard-Smithsonian Center for Astrophysics (CfA). Since some of the
discs appear to be comparable in size and mass to our own solar system, this
strengthens the connection between the Orion proplyds and our origins.
Since most Sun-like stars in the Galaxy eventually form in environments
like the Orion Nebula, the SMA results suggest that the formation of solar
systems like our own is common and a continuing event in the Galaxy.
"The same cycle of birth, life and death we experience here on Earth
is repeated in the stars overhead. Now, the SMA provides us with a front-row
seat in unraveling the wonder of these cosmic events," reflected Wilner.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical
Observatory and the Harvard College Observatory. CfA scientists, organized
into six research divisions, study the origin, evolution and ultimate fate
of the universe.