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در مرکز کهکشان راه شیری . . .
#1
[تصویر:  13602148041.jpg]




WASHINGTON -- Researchers using the Stratospheric Observatory for
Infrared Astronomy (SOFIA) have captured new images of a ring of gas and
dust seven light-years in diameter surrounding the supermassive black
hole at the center of the Milky Way, and of a neighboring cluster of
extremely luminous young stars embedded in dust cocoons.

The
images of our galaxy's circumnuclear ring (CNR) and its neighboring
quintuplet cluster (QC) are the subjects of two posters presented this
week during the American Astronomical Society's meeting in Long Beach,
Calif. Ryan Lau of Cornell University and his collaborators studied the
CNR. Matt Hankins of the University of Central Arkansas in Conway is
lead author of the other paper, regarding the QC.

SOFIA is a
highly modified Boeing 747SP aircraft carrying a telescope with an
effective diameter of 100 inches (2.54 meters) to altitudes as high as
45,000 feet (13.7 kilometers).

The images were obtained during
SOFIA flights in 2011 with the Faint Object Infrared Camera for the
SOFIA Telescope (FORCAST) instrument built by a team with principal
investigator Terry Herter of Cornell



[تصویر:  13602149691.png]


FORCAST offered astronomers the ability to see the CNR and QC regions
and other exotic cosmic features whose light is obscured by water vapor
in Earth's atmosphere and interstellar dust clouds in the mid-plane of
the Milky Way. Neither ground-based observatories on tall mountain peaks
nor NASA's orbiting Hubble and Spitzer space telescopes can see them.

The images may be seen by visiting:

Each image is a combination of multiple exposures at wavelengths of 20, 32, and 37 microns.


Figure 1a shows the CNR and Figure 2a shows the QC. The CNR and other
exotic features revealed by SOFIA's FORCAST camera are invisible to
Hubble's near-infrared camera, as shown for comparison in figures 1b and
2b. Figure 3 shows the two fields studied in these papers as square
insets on a large-scale image of the galactic center made by the Spitzer
Space Telescope at a wavelength of 8 microns



[تصویر:  13602150931.jpg]




The focus of our study has been to determine the structure of the
circumnuclear ring with the unprecedented precision possible with SOFIA"
said Lau. "Using these data we can learn about the processes that
accelerate and heat the ring."

The nucleus of the Milky Way is
inhabited by a black hole with 4 million times the mass of the sun and
is orbited by a large disk of gas and dust. The ring seen in Figure 1a
is the inner edge of that disk. The galactic center also hosts several
exceptionally large star clusters containing some of the most luminous
young stars in the galaxy, one of which is the Quintuplet Cluster seen
in Figure 2. The combination of SOFIA's airborne telescope with the
FORCAST camera produced the sharpest images of those regions ever
obtained at mid-infrared wavelengths, allowing discernment of new clues
about what is happening near the central black hole.

"Something
big happened in the Milky Way's center within the past 4 million to 6
million years which resulted in several bursts of star formation,
creating the Quintuplet Cluster, the Central Cluster, and one other
massive star cluster." said Hankins, lead author of the QC paper. "Many
other galaxies also have so-called 'starbursts' in their central
regions, some associated with central black holes, some not. The Milky
Way's center is much nearer than other galaxies, making it easier for us
to explore possible connections between the starbursts and the black
hole



[تصویر:  13602155321.png]



SOFIA Chief Scientific Advisor Eric Becklin, who is working with the CNR
group, determined the location of the galaxy's nucleus as a graduate
student in the 1960s by laboriously scanning a single-pixel infrared
detector to map the central region.

"The resolution and spatial
coverage of these images is astounding, showing what modern infrared
detector arrays can do when flown on SOFIA," Becklin said. "We hope to
use these data to substantially advance our understanding of the
environment near a supermassive black hole."

SOFIA is a joint
project of NASA and the German Aerospace Center. SOFIA is based and
managed at NASA's Dryden Aircraft Operations Facility in Palmdale,
Calif. NASA's Ames Research Center in Moffett Field, Calif., manages the
SOFIA science and mission operations in cooperation with the
Universities Space Research Association headquartered in Columbia, Md.,
and the German SOFIA Institute at the University of Stuttgart.
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