Cycles of Matter
How Do Galaxies Evolve?
- To understand how galaxies evolve we must understand the cycle of star
formation and destruction. These processes include the generation and distribution
of cosmic rays, the distribution of the material between the stars, how
this material moves, and how stars explode and redistribute material leaving
pulsing, collapsed stars (pulsars). These processes are well probed by
observations in the new window gamma-ray, X-ray and radio bands.
- From the Earth's surface low frequency radio observations are blocked
by the obscuring veil of the atmosphere. However, such observations can
be made from space. Also, greater precision can be achieved by placing
several radio-wave telescopes in space at great distances from one another
relative to the limited separation size available on the Earth's surface.
Working "as a team" these telescopes can probe deep into the
center of our Milky Way galaxy and into hearts of other galaxies. The as-yet
unexplored band at radio frequencies below 30 MHz in particular has great
potential as a new tool for investigating a wide range of galactic phenomena.
- Observations in the EUV (extreme ultra-violet) and soft X-ray bands
provide unique access to some key expected spectral features of the local
hot (~million degree) interstellar medium (ISM). This plasma is a lasting
imprint of past explosive events in our region of the Galaxy. Detailed
high resolution spectroscopy of the spectral line dominated thermal emission
by the hot plasma of the ISM has now begun and holds the promise of determining
all principal constituents.
Missions: ALFA, ARISE,
Astro-E, AXAF, FIRST, GLAST, HIMS, HTXS, HUBE, SIRTF, SOFIA, XMM