SMA confirms proto-planetary systems are common in the galaxy

University of Hawaiʻi
Posted: Jun 14, 2005

HONOLULU - Astronomers using Mauna Kea's newest telescope -- the Submillimeter Array (SMA) -- confirmed for the first time that many young stars in the Orion Nebula are surrounded by enough orbiting material to form new planetary systems like our own.

"The SMA is the only telescope that can measure the dust around these stars, and thereby assess their true potential for forming planets. This is critical to 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 in collaboration with David Wilner of the Harvard-Smithsonian Center for Astrophysics.

The objects were first seen by the Hubble Space Telescope back in the early 1990s as misshapen silhouettes against the nebular background. They were given the name "proplyds," standing for "protoplanetary disks," on the assumption that they consisted of a newly formed star surrounded by a disk of matter out of which new planets are forming. They are found in the "Trapezium" star cluster of the Orion Nebula, a group of more than 1,000 stars crowded into a space only 4 light-years in diameter. They are among the youngest stars in the Galaxy, having been born out of the original cold, dark cloud of gas about a million years ago.

"The Hubble telescope showed us the size of the disks, but not how much material they contained," said University of Hawaii graduate student and co-author Sean Andrews. 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.

Since some of the disks 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 our Milky Way 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 exceptional skies and the unique, cutting-edge telescopes of Mauna Kea made these observations possible, and allow us to continue the quest to understand our origins," added Williams.

For more information, visit the following websites:
- Submillimeter Array:
- Harvard-Smithsonian Center for Astrophysics:
- More about "Proplyds" (from Hubble Space Telescope Science Institute):
- Preprint of scientific paper submitted to Astrophysical Journal:

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