Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.arcetri.astro.it/~palla/ANDREAIMMAGINI/Galassie/tagliate/NGC1365a-b.txt Дата изменения: Sun Mar 4 19:58:22 2001 Дата индексирования: Sat Dec 22 12:14:11 2007 Кодировка: Поисковые слова: annular solar eclipse

EMBARGOED UNTIL: 1:00 p.m. (EDT) October 6, 1999

PHOTO NO.: STScI-PRC99-34a


GETTING TO THE HEART OF A GALAXY

This collage of images in visible and infrared light reveals how the
barred spiral galaxy NGC 1365 is feeding material into its central
region, igniting massive star birth and probably causing its bulge of
stars to grow. The material also is fueling a black hole in the galaxy's
core. A galaxy's bulge is a central, football-shaped structure composed
of stars, gas, and dust.

The black-and-white image in the center, taken by a ground-based
telescope, displays the entire galaxy. But the telescope's resolution is
not powerful enough to reveal the flurry of activity in the galaxy's
hub. The blue box in the galaxy's central region outlines the area
observed by the NASA Hubble Space Telescope's visible-light camera, the
Wide Field and Planetary Camera 2 (WFPC2). The red box pinpoints a
narrower view taken by the Hubble telescope's infrared camera, the Near
Infrared Camera and Multi-Object Spectrometer (NICMOS).

A barred spiral is characterized by a lane of stars, gas, and dust
slashing across a galaxy's central region. It has a small bulge that is
dominated by a disk of material. The spiral arms begin at both ends of
the bar. The bar is funneling material into the hub, which triggers star
formation and feeds the bulge.

The visible-light picture at upper left is a close-up view of the
galaxy's hub. The bright yellow orb is the nucleus. The dark material
surrounding the orb is gas and dust that is being funneled into the
central region by the bar. The blue regions pinpoint young star
clusters.

In the infrared image at lower right, the Hubble telescope penetrates
the dust seen in the WFPC2 picture to reveal more clusters of young
stars. The bright blue dots represent young star clusters; the brightest
of the red dots are young star clusters enshrouded in dust and visible
only in the infrared image. The fainter red dots are older star
clusters.

The WFPC2 image is a composite of three filters: near-ultraviolet (3327
Angstroms), visible (5552 Angstroms), and near-infrared (8269
Angstroms). The NICMOS image, taken at a wavelength of 16,000 Angstroms,
was combined with the visible and near-infrared wavelengths taken by
WFPC2.

The WFPC2 image was taken in January 1996; the NICMOS data were taken in
April 1998.

Credits for the ground-based image: Allan Sandage (The Observatories of
the Carnegie Institution of Washington) and John Bedke (Computer
Sciences Corporation and the Space Telescope Science Institute)


Credits for the WFPC2 image: NASA and John Trauger (Jet Propulsion
Laboratory)

Credits for the NICMOS image: NASA, ESA, and C. Marcella Carollo
(Columbia University)