The Milky Way Galaxy is the only galaxy close enough to see the details of the Galactic “Ecosystem”.
Challenges• The Galaxy is very big. Because we are inside it, it completely
encircles the earth. – A large area of sky must be observed.
• The Galaxy is a 3-dimensional object.– Must untangle the third dimension
• High Angular resolution is need to see the details in the context of the larger picture– A very large data base
• A large range of wavelengths must be covered to see all major components of the ISM– Several telescopes will be required.
The Canadian Galactic Plane ConsortiumCanadian Universities
• University of Calgary• University of Alberta • University of British Columbia• University of Toronto• University of Montreal• University of Waterloo• Queen’s University• Université Laval
National Research Council of Canada
• Dominion Radio Astrophysical Observatory• Canadian Astronomical Data Centre
International Organizations
• California Institute of Technology • University of California, Berkeley • University of Massachusetts • University of New Mexico • Space Telescope Science Institute • Cambridge University • Hamburger Sternwarte
Objectives of the CGPS
Science Goals:
• How does the interstellar medium evolve?Explore the evolutionary relationship between the phases and states
of the interstellar medium. How due galaxies convert diffuse primordial hydrogen to stars and the building blocks of life?
• What energizes and shapes the medium?Characterize the energy sources and modes of energy transport
• Is the Milky Way a closed system?Explore the vertical structure out of the disk. Is there mass and
energy exchange between the disk and extragalactic space?
Observing Goals:
• Create a high-resolution, 3-dimensional map of the interstellar medium of the Milky Way
• Construct a Galactic Plane Survey Data base of the distribution of major constituents of the interstellar medium.
Atomic Hydrogen Image from a Single Antenna Radio Telescope
25-m Radio Telescope, DwingelooNetherlands Foundation for Radio Astronomy
Atomic Hydrogen Image from a Radio Interferometer
7-element Interferometer, PentictonDominion Radio Astrophysical Observatory
equivalent diameter equals 600m
Slicing up the Milky Way Galaxy
Sun
Galactic Centre
Velocity changes systematically with distance along the line of sight.
Optical Image Stars and Ionized gas (Thanks to Alan Dyer)
Radio 21cm image Neutral Hydrogen gas (Perseus Spiral Arm)
Cold Hydrogen Clouds
Clouds of very cold, dense hydrogen are seen silhouetted against a bright hydrogen gas.
Where did these clouds come from?
Temperature < 50 K (-220 C)
Are they related to molecular clouds?
In some cases CO molecules are found. But in most cases there is no association.
Evidence of Large Scale Shocks
A “spur” of dust and gas emerging from the galactic plane.
All components of the interstellar medium merge in this spur.
What caused it?
A Chimney to the Galactic halo
The chimney is blown out by a cluster of massive hot stars at the bottom
Intense ultra-violet radiation “leaks” out of the galaxy
Only a very small fraction of the Galaxy has been surveyed so far.
• The missing link between diffuse hydrogen gas and molecular clouds
• Evidence of transfer (leakage) of radiation and matter to extragalactic space (chimney and mushroom cloud)
• Examples of large scale shocks that energize the matter between the stars.
• …
In this small fraction we have found:
A Global Galactic Plane Survey Dominion Radio Astrophysical ObservatoryNational Research Council of Canada
Australia Telescope Compact Array Commonwealth Science and Industrial Research Organisation
Very Large ArrayU.S. National Radio Astronomy Observatory
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