FOR RELEASE: 9:20 a.m. EST, January 14, 2000.

Press Release NO: MAP 1 for CGPS pr_14012000 (CGPS pr_14012000.map1)

EXPOSING THE STUFF BETWEEN STARS: A Panorama
Canadian Galactic Plane Survey Mapping Our Milky Way Galaxy

 
Map 1 displays the stuff between stars in the Perseus Spiral Arm
of our Milky Way Galaxy by assigning different colours to
radiation not detected by the human eye. Invisible to optical
telescopes, hydrogen gas can only be revealed by observations of
faint radio waves emitted at a wavelength of 21
centimetres. Besides radio data showing this gas, from the
National Research Council of Canada's Dominion Radio
Astrophysical Observatory (and assigned colour combinations of
blue, orange, yellow, and green), this composite image includes
Infrared Astronomical Satellite (IRAS) data (coloured pale pink),
and data (grey-blue) from the Westerbork Synthesis Radio
Telescope (WRST) in the Netherlands.

The location on the night sky of this panoramic strip (2000
light-years across) is displayed in Diagram 1 while its position
in the Milky Way relative to our Sun is presented in the ``top
view'' schematic in Diagram 2. (Diagrams are included in press
release CGPS pr_14012000.)

The diffuse nebulosity that fills the Map 1 panorama from left to
right is hydrogen gas, which is distributed along the mid-plane
of the Galactic disk and runs across the middle of the
image. However Canadian Galactic Plane Survey astronomers used
the DRAO array to isolate the gas in the Perseus Arm, 6500
light-years distant, from the rest of the gas in the disk.
Overlaid on these hydrogen data are IRAS images of the dust that
intersects our line of sight through the disk. The point-like
sources (WRST) are mainly distant galaxies that have very
energetic cores called Active Galactic Nuclei.

Far from a homogeneous environment, the interstellar medium in the
Perseus Arm shows a highly disturbed and seemingly chaotic
appearance.  This region has been shaped partly by the ongoing
formation of massive, hot stars near the hot dusty clouds
(appearing pink) of the W3, W4 and W5 regions right of centre, and
perhaps also by the passage of a large scale spiral shock wave as
the matter in the Perseus Arm orbits around the centre of the
Galaxy.

MAP CREDIT:

Jayanne English (CGPS/STScI) using data acquired by the Canadian
Galactic Plane Survey (NRC/NSERC) and produced with the support
of Russ Taylor (U. of Calgary).

SCIENCE CONTACT INFORMATION:

A. Russ Taylor, University of Calgary, Department of Physics
and Astronomy, 2500 University Drive, N.W., Calgary, Alberta Canada
T2N 1N4; PHONE: 403-220-5385; FAX: 403 289-3331,
EMAIL: russ@ras.ucalgary.ca

INTERNET ACCESS: 

On January 14, 2000 full resolution tiffs of this image, plus 2
other images and 2 diagrams from CGPS pr_14012000, along with
other images from the CGPS will be available at
      http://www.stsci.edu/~jenglish/cgps/pr/

(Note that since Map 1 is 3204 x 1764 pixels, it is well-suited
 to 2 page spreads.)

IMAGE CONTACT INFORMATION:
Jayanne English, Space Telescope Science Institute, 3700 San Martin
Dr., Baltimore Maryland USA 21211; PHONE: 410-338-4352;
FAX: 410-338-5090; EMAIL: jenglish@stsci.edu