Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.arcetri.astro.it/~palla/ANDREAIMMAGINI/ISM/Reflection.txt Дата изменения: Tue Jan 30 13:51:59 2001 Дата индексирования: Sat Dec 22 08:24:30 2007 Кодировка: Поисковые слова: saturn's moon

EMBARGOED UNTIL: 1:00 a.m. (EST) March 2, 2000

PHOTO NO.: STScI-PRC00-10

"HUBBLE TAKES A CLOSE-UP VIEW OF A REFLECTION NEBULA IN ORION"

Just weeks after NASA astronauts repaired the Hubble Space
Telescope in December 1999, the Hubble Heritage Project snapped
this picture of NGC 1999, a nebula in the constellation Orion.
The Heritage astronomers, in collaboration with scientists in
Texas and Ireland, used Hubble's Wide Field Planetary Camera 2
(WFPC2) to obtain the color image.

NGC 1999 is an example of a reflection nebula. Like fog around
a street lamp, a reflection nebula shines only because the light
from an embedded source illuminates its dust; the nebula does not
emit any visible light of its own. NGC 1999 lies close to the
famous Orion Nebula, about 1,500 light-years from Earth, in a
region of our Milky Way galaxy where new stars are being formed
actively. The nebula is famous in astronomical history because
the first Herbig-Haro object was discovered immediately adjacent
to it (it lies just outside the new Hubble image). Herbig-Haro
objects are now known to be jets of gas ejected from very young
stars.

The NGC 1999 nebula is illuminated by a bright, recently formed
star, visible in the Hubble photo just to the left of center. This
star is cataloged as V380 Orionis, and its white color is due
to its high surface temperature of about 10,000 degrees Celsius
(nearly twice that of our own Sun). Its mass is estimated to be
3.5 times that of the Sun. The star is so young that it is still
surrounded by a cloud of material left over from its formation,
here seen as the NGC 1999 reflection nebula.

The WFPC2 image of NGC 1999 shows a remarkable jet-black cloud
near its center, resembling a letter T tilted on its side,
located just to the right and lower right of the bright
star. This dark cloud is an example of a "Bok globule," named
after the late University of Arizona astronomer Bart Bok. The
globule is a cold cloud of gas, molecules, and cosmic dust, which
is so dense it blocks all of the light behind it. In the
Hubble image, the globule is seen silhouetted against the
reflection nebula illuminated by V380 Orionis. Astronomers
believe that new stars may be forming inside Bok globules,
through the contraction of the dust and molecular gas under their
own gravity.

NGC 1999 was discovered some two centuries ago by Sir William
Herschel and his sister Caroline, and was cataloged later in the
19th century as object 1999 in the New General Catalogue.

These data were collected in January 2000 by the Hubble Heritage
Team with the collaboration of star-formation experts C. Robert
O'Dell (Rice University), Thomas P. Ray (Dublin Institute for
Advanced Study), and David Corcoran (University of Limerick).

Image Credit: NASA and the Hubble Heritage Team (STScI)

NOTE TO EDITORS -- For additional information, please contact:
Professor C. R. O'Dell, Rice University, MS 108, PO Box 1892,
Houston, Texas 77251-1892, (phone) 713-348-3633, (fax) 713-348-5143,
(e-mail) cro@rice.edu or

Professor T.P. Ray, School Of Cosmic Physics, Dublin Institute for
Advanced Studies, 5 Merrion Square, Dublin 2, Ireland, (phone)
+353 1 6621333, (fax) +353 1 6621477, (e-mail) tr@cp.dias.ie or

Keith Noll, Space Telescope Science Institute, 3700 San Martin
Drive, Baltimore, MD 21218, (e-mail) noll@stsci.edu.

Image files are available on the Internet at:
http://heritage.stsci.edu
http://oposite.stsci.edu/pubinfo/pr/2000/10 or via links in
http://oposite.stsci.edu/pubinfo/latest.html and
http://oposite.stsci.edu/pubinfo/pictures.html

Higher resolution digital versions (300 dpi JPEG and TIFF) are
available at:
http://oposite.stsci.edu/pubinfo/pr/2000/10/pr-photos.html

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