This color panorama of the center the Orion nebula is one of the largest pictures ever assembled from individual images taken with NASA's Hubble Space Telescope. Seamlessly composited from a mosaic of 15 separate fields, it covers an area about five percent that covered by the full Moon.

The seemingly infinite tapestry of rich detail revealed by Hubble shows a churning turbulent star factory set within a maelstrom of flowing, luminescent gas. Though this 2.5 light-years wide view is still a small portion of the entire nebula, it includes almost all of the light from the bright glowing clouds of gas and a star cluster associated with the nebula. Hubble reveals details as small as 4.1 billion miles across (less than the distance of Neptune from the Sun).

Hubble Space Telescope observing time was devoted to making this panorama because the nebula is a vast laboratory for studying the processes which gave birth to our own Sun and solar system 4.5 billion years ago. Many of the nebula's details can't be captured in a single picture - any more than one snapshot of the Grand Canyon yields clues to its formation and history. Like the Grand Canyon, the Orion nebula has a dramatic surface topography -- of glowing gasses instead of rock -- with peaks, valleys and walls. They are illuminated and heated by a torrent of energetic ultraviolet light from its four hottest and most massive stars, called the Trapezium, which lie near the center of the image.

In addition to the Trapezium, this stellar cavern contains 700 hundred other young stars at various stages of formation. High-speed jets of hot gas spewed by some of the infant stars send supersonic shock waves tearing into the nebula at 100,000 miles per hour. These shock waves appear as thin curved loops, sometimes with bright knots on their end (the brightest examples are near the bright star at the lower left).

The mosaic reveals at least 153 glowing protoplanetary disks (first discovered with the Hubble in 1992, and dubbed "proplyds") that are believed to be embryonic solar systems that will eventually form planets. (Our solar system has long been considered the relic of just such a disk that formed around the newborn Sun). The abundance of such objects in the Orion nebula strengthens the argument that planet formation is a common occurrence in the universe. The proplyds that are closest to the Trapezium stars (image center) are shedding some of their gas and dust. The pressure of starlight from the hottest stars forms "tails" which act like wind vanes pointing away from the Trapezium. These tails result from the light from the star pushing the dust and gas away from the outside layers of the proplyds. In addition to the luminescent proplyds, seven disks are silhouetted against the bright background of the nebula. These dark objects allow Hubble astronomers to estimate the masses of the disks as at least 0.1 to 730 times the mass of our Earth.

Located 1,500 light-years away, along our spiral arm of the Milky Way, the Orion nebula is located in the middle of the sword region of the constellation Orion the Hunter, which dominates the early winter evening sky, at northern latitudes. The stars have formed from collapsing clouds of interstellar gas within the last million years. The most massive clouds have formed the brightest stars near the center and these are so hot that they illuminate the gas left behind after the period of star formation was complete. The more numerous faint stars are still in the process of collapsing under their own gravity, but have become hot enough in their centers to be self luminous bodies.

Technical information: To create this color mosaic, 45 separate images of the Orion nebula were taken in blue, green and red between January 1994 and March 1995. Light emitted by oxygen is shown as blue, hydrogen emission is shown as green, and nitrogen emission as red light. The overall color balance is close to that which an observer living near the Orion nebula would see. The irregular borders produced by the HST images have been smoothed out by the addition of images from the European Southern Observatory in Chile obtained by Bo Reipurth and John Bally, these being about 2% of the area shown here and lying at the top left corner.

Credit: C.R. O'Dell (Rice University), and NASA

Original press release

Planetary Systems in the Making

These are HST images of four newly discovered protoplanetary disks around young stars in the Orion nebula, located 1,500 light-years away. Gas and dust disks, long suspected by astronomers to be an early stage of planetary formation, can be directly seen in visible light by Hubble.

Disks around young stars (also known as circumstellar or protoplanetary disks) are thought to be made up of 99% gas and 1% dust. Even that small amount of dust is enough to make the disks opaque and dark at visible wavelengths. The dark disks are seen in these images because they are silhouetted against the bright backdrop of the hot gas of the Orion nebula.

The red glow in the center of each disk is a young, newly formed star, roughly one million years old (compared to the 4.5 billion year age of the Sun). The stars range in mass from 30% to 150% of the mass of our own Sun. As they evolve, the disks may go on to form planetary systems like our own. While only a handful of these dark silhouette disks have been discovered so far, they seem to belong to a much larger family of similar objects, and current indications are that protoplanetary disks are common in the Orion nebula.

Mark McCaughrean of the Max-Planck-Institute for Astronomy, Heidelberg, Germany, and his collaborator C. Robert O'Dell from Rice University, Houston, Texas, spotted the new disks in large-scale survey images of the Orion nebula that O'Dell had taken with Hubble between January 1994 and March 1995. A detailed study of the disk images has been submitted for publication to the Astronomical Journal.

Each image is 167 billion miles, or 257 billion kilometers across (30 times the diameter of our own solar system). The disks range in size from two to eight times the diameter of our solar system. The researchers explain the different circular or elliptical shapes as being due to the fact that each disk is tilted toward Earth by different degrees.

Each picture is a composite of three images taken with Hubble's Wide Field and Planetary Camera 2, through narrow-band filters which admit the light of emission lines of ionized oxygen (represented here by blue), hydrogen (green), and nitrogen (red). The hot gas of the background Orion nebula emits strongly at each of these wavelengths, providing a strong backdrop for the disks to be silhouetted against. In each case, the central star is also clearly visible.

Credit: Mark McCaughrean (Max-Planck-Institute for Astronomy), C. Robert O'Dell (Rice University), and NASA

Original Press Release

Edge-on protoplanetary disk in the Orion nebula

Resembling an interstellar Frisbee, this is a disk of dust seen edge-on around a newborn star in the Orion nebula, located 1,500 light-years away. Because the disk is edge-on, the star is largely hidden inside, in this striking Hubble Space Telescope picture. The disk may be an embryonic planetary system in the making. Our solar system probably formed out of just such a disk 4.5 billion years ago. At 17 times the diameter of our own solar system, this disk is the largest of several recently discovered in the Orion nebula.

The left image is a three-color composite, taken in blue, green, and red emission lines from glowing gas in the nebula. The right image was taken through a different filter, which blocks any bright spectral emission lines from the nebula, and hence the disk itself is less distinctly silhouetted against the background. However, clearly visible in this image are nebulosities above and below the plane of the disk; these betray the presence of the otherwise invisible central star, which cannot be seen directly due to dust in the edge-on disk.

The images were taken between January 1994 and March 1995, and a study of their characteristics has been submitted for publication to the Astronomical Journal.

Credit: Mark McCaughrean (Max-Planck-Institute for Astronomy), C. Robert O'Dell (Rice University), and NASA

Original Press Release

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Hartmut Frommert (spider@seds.org)
Christine Kronberg (smil@lrz.uni-muenchen.de)

Last Modification: 24 May 1998, 15:55 MET