Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.arcetri.astro.it/~palla/ANDREAIMMAGINI/ISM/butterflyBW.txt Дата изменения: Tue Jan 30 14:44:13 2001 Дата индексирования: Sat Dec 22 08:31:30 2007 Кодировка: Поисковые слова: crab nebula

FOR RELEASE: 9:00 AM (EST) March 14, 1997

PHOTO RELEASE NO.: STScI-PRC97-07

Hubble Camera Resumes Science Operation With Picture Of
"Butterfly" In Space.

The Hubble Space Telescope's Wide Field and Planetary Camera 2
(WFPC2) is back at work, capturing this black-and-white image
of the "butterfly wing"-shaped nebula, NGC 2346. The nebula is
about 2,000 light-years away from Earth in the direction of
the constellation Monoceros. It represents the spectacular
"last gasp" of a binary star system at the nebula's center.

The image was taken on March 6, as part of the recommissioning
of the Hubble Space Telescope's previously installed scientific
instruments following the successful servicing of the HST by
NASA astronauts in February. WFPC2 was installed in HST during
the servicing mission in 1993.

At the center of the nebula lies a pair of stars that are so
close together that they orbit around each other every 16 days.
This is so close that, even with Hubble, the pair of stars cannot
be resolved into its two components. One component of this
binary is the hot core of a star that has ejected most of its
outer layers, producing the surrounding nebula. Astronomers
believe that this star, when it evolved and expanded to become a
red giant, actually swallowed its companion star in an act of
stellar cannibalism. The resulting interaction led to a
spiraling together of the two stars, culminating in ejection
of the outer layers of the red giant.

Most of the outer layers were ejected into a dense disk, which
can still be seen in the Hubble image, surrounding the central
star. Later the hot star developed a fast stellar wind. This
wind, blowing out into the surrounding disk, has inflated the
large, wispy hourglass-shaped wings perpendicular to the disk.
These wings produce the butterfly appearance when seen in
projection.

The total diameter of the nebula is about one-third of a light-year,
or 2 trillion miles.

Our own Sun will eject a nebula about 5 billion years from now.
However, the Sun is not a double star, so its nebula may well
be more spherical in shape.

The image was taken through a filter that shows the light of
glowing nitrogen atoms.

Scientists are still testing and calibrating the newly installed
instruments on Hubble , the Near Infrared Camera and Multi-Object
Spectrometer (NICMOS) and the Space Telescope Imaging
Spectrograph (STIS). These instruments will be ready to make
observations in a few weeks.

Credit: Massimo Stiavelli (STScI), and NASA

other team member: Inge Heyer (STScI)


Image files in GIF and JPEG format and captions may be accessed
on the Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.

GIF JPEG
PRC97-07 NGC 2346 gif/ngc2346.gif jpeg/ngc2346.jpg

A higher resolution digital version (300 dpi JPEG) of this
photograph is available in /pubinfo/hrtemp: 97-07bw.jpg.

GIF and JPEG images, captions and press release text are available via
World Wide Web at http://www.stsci.edu/pubinfo/PR/97/07.html and links in
http://www.stsci.edu/pubinfo/Pictures.html.

Space Telescope is operated by the Association of Universities for
Research in Astronomy, Inc. (AURA), for NASA, under contract with
the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space
Telescope is a project of international cooperation between NASA
and the European Space Agency (ESA).

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