The Universe Revealed by Subaru Telescope Ⅱ

The Births of Stars and Planetary Systems

Throughout the universe, stars like our Sun are born in stellar nurseries. These are places of extremely high-density gas and dust. Infrared wavelengths are critical when observing these regions, since they often cannot be probed any other way. The high-resolution infrared capability of the Subaru Telescope continues to unveil how stars are created. The telescope's capability also allows precise observation of a star's motion that may reveal the presence of any planetary systems in orbit around it.

S106:A Cradle of Stars -A Region Where Many Stars Are Being Born-

This infrared image shows Sharpless 106, a star-forming region of about 2 light years across that lies about 2,000 light-years away from Earth. There is a young high-mass star near its bright center. The hourglass-shaped structure appears to be expanding toward the top and the bottom of the image and is thought to be a nebula created by the flow of matter erupting from the star. The center of this nebula could be so narrow because a massive disk made up of gas and dust surrounds the high-mass star. This image also shows that there are many sub-stellar-mass objects in the region of S106. (The infrared CISCO camera used for this observation has since been retired.)

The Silhouette of a Protostellar Envelope

New stars are being born in the region of Swan Nebula (M17), another star-formation region that appears in this image as a bright nebula. Subaru Telescope looked at this region in infrared light and clearly captured the envelope of clouds covering the forming stars as a "silhouette." Further observation has led to a new discovery: the envelope has a complex, multi-layered structure. This study has contributed to a deeper understanding of the disk that formed around the star at the time of its birth.

Disks Surrounding Protostars Can Assume Different Shapes

The infrared pictures of AB Aurigae (left) and HD142527 (right) taken by the Coronagraphic Imager with Adaptive Optics (CIAO). The bright center star is hidden. The distance to the object is approximately 470 light years and 650 light years respectively. The width of the image has a scale about equal to 1,000 astronomical units (a distance out from the star about 10 times greater than the orbit of Pluto around the Sun).

When a star with relatively low mass is born (one like our Sun, for example), material surrounding the protostar falls toward the center of mass. At the same time, a spinning disk of gas and dust forms along a plane orbiting the newly forming star. Astronomers think that planets may be born within this orbiting disk. Observations of this region may hold the key to a better understanding of the formation of stars and their companion planets. The Subaru's observation of protostars illustrates that disks around protostars can actually take a number of complex forms. This spiral-shaped object was found around AB Aurigae (down left). The disk of HD142527 (lower right) has two banana-shaped arcs that seem to face each other from either side of the star. Subaru's image provided the first discovery of this kind of object. It now appears possible that other planetary systems may be formed in a way quite different from our solar system.

Commentary from Dr. Motohide Tamura, Associate Professor at NAOJ :

We can see the process of stellar and planetary formation from both the macro and micro points of view using the wide view and sharp imaging that Subaru Telescope provides. These observations may answer many important questions about how a planet is formed or how various stars are being born with masses that can be as low as that of a planet or 100 times greater than our Sun. Also it is hoped that these observations may lead to the first photographs of a young massive extrasolar planet.

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Universe Revealed by Subaru Telescope