protoplanetary disk

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protoplanetary disk

[‚prōd·ō‚plan·ä‚ter·ē ′disk]
(astronomy)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Certainly, Orion proplyds are unique targets to investigate the metallicity content and its role in the evolution of circumstellar disks.
The chemical composition of Orion proplyds has, however, remained unknown for a long time.
The speaker remarked that the more distant of the two jets appeared anomalously faint and explained that this seemed to provide evidence for the presence of a proto-planetary disc, or proplyd, of solid material around the star, absorbing the X-rays from the jet behind it.
"Their energetic photons can quickly deplete a nearby protoplanetary disk by heating up its gas, breaking it up, and sweeping it away." Earlier observations with the Hubble Space Telescope revealed striking images of proplyds in Orion.
In contrast to the Orion proplyds and the TW Hydrae disk, the disk that originally surrounded the nearby 1st-magnitude star Fomalhaut has been swept away over the star's estimated 200-million-year life.
Projected mass-loss rates suggest that the proplyds in Orion lose about an Earth mass a year, says Shuping.
The four images seen at right are of newly discovered proplyds buried deep inside the Carina Nebula.
Jeff Hester and a team of colleagues used HST to take a detailed look at proplyds and jets in the well-known Trifid Nebula (), which lies about 9,000 light-years away in the constellation Sagittarius.
The small cloudlets seen in Orion - dubbed proplyds, for protoplanetary disks - are believed to contain forming stars, just like M16's EGGs.
Early evidence that proplyds exist in Orion includes some narrow-band images of the Trapezium from 1979 that show six unresolved stars with only emission lines.
The true nature of proplyds became clear after Hubble first observed this region in August 1991, and follow-up observations were made immediately after the telescope's refurbishment in December 1993.
From their HST images O'Dell and Wen have determined that 56 of 110 stars they surveyed have protoplanetary disks -- which the astronomers dubbed "proplyds" when they first spotted them on prerepair images made in 1992.