D
Glossary and Acronyms
Background radiation (cosmic)—
The radiation left over from the Big Bang explosion at the beginning of the universe. As the universe expanded, the temperature of the fireball cooled to its present level of 2.7 degrees above absolute zero.
Brown Dwarf—
A star-like object that contains less than about 0.08 the mass of the Sun and is thus too small to ignite nuclear fuels and become a normal star. Brown dwarfs emit small amounts of infrared radiation due to the slow release of gravitational energy.
Dark energy—
An as yet unknown form of energy that pervades the universe. Its presence was inferred from the discovery that the expansion of the universe is accelerating, and these observations suggest that about 70 percent of the total density of matter plus energy is in this form. One explanation for dark energy is Einstein’s cosmological constant.
Flat universe—
Cosmological concept that states that the universe will expand forever at a decelerating rate, and will never pass an outer limit.
Gamma-ray bursts—
A sudden burst of gamma rays coming from a source usually in deep space. The burst may last from a fraction of a second to several minutes.
Gravitational microlensing—
Gravitational lensing due to a stellar mass object. This lensing phenomenon is termed “microlensing” because the mass of the lens is so small compared with that of a galaxy.
Microlensing of distant stars by intervening faint stars can reveal planets in orbit around the lensing star.
Interferometry—
The main technique used by astronomers to map sources at high resolution and to measure their positions with high precision.
Kuiper Belt objects (KBOs)—
Icy planetesimals distributed in a roughly circular disk in the outer regions of our solar system, 50 to 100 AU from the Sun.
Redshift—
Radiation from an approaching object is shifted to higher frequencies (to the blue), while radiation from a receding object is shifted to lower frequencies (to the red). A similar effect raises the pitch of an ambulance siren as it approaches. The expansion of the universe makes objects recede so that the light from distant galaxies is redshifted. The redshift is often denoted by z, where z=v/c and v is the velocity and c the speed of light.
AAPB
Astronomy and Astrophysics Planning Board
AASC
NRC Astronomy and Astrophysics Survey Committee
ACAST
Advisory Committee for AST (NSF Astronomical Sciences Division)
ACCORD
AURA Coordinating Council of Observatory Research Directors
ALMA
Atacama Large Millimeter Array
ARISE
Advanced Radio Interferometry between Space and Earth
AST
Advanced Solar Telescope (now called the Advanced Technology Solar Telescope, or ATST); NSF Astronomical Sciences Division
ATM
NSF Division of Atmospheric Sciences
AURA
Associated Universities for Research in Astronomy, Inc.
CAA
NRC Committee on Astronomy and Astrophysics
CARMA
Combined Array for Research in Millimeter-wave Astronomy
CGRO
Compton Gamma-Ray Observatory
COMRAA
Committee on the Organization and Management of Research in Astronomy and Astrophysics
DOE
U.S. Department of Energy
EVLA
Expanded Very Large Array
EXIST
Energetic X-ray Imaging Survey Telescope
FASR
Frequency Agile Solar Radio telescope
GBT
Green Bank Telescope (now named after Senator Robert C. Byrd)
GLAST
Gamma-ray Large Area Space Telescope
GSMT
Giant Segmented Mirror Telescope
HENP
DOE Office of High Energy and Nuclear Physics
HEP
DOE Division of High Energy Physics
HEPAP
High Energy Physics Advisory Panel
HST
Hubble Space Telescope
LIGO
Laser Interferometer Gravitational-Wave Observatory
LISA
Laser Interferometer Space Antenna
LSST
Large-aperture Synoptic Survey Telescope
MPS
NSF Mathematical and Physical Sciences Directorate
MPSAC
MPS Advisory Committee
MRE
NSF Major Research Equipment line
NASA
National Aeronautics and Space Administration
NGST
Next Generation Space Telescope
NOAO
National Optical Astronomy Observatory
NRAO
National Radio Astronomy Observatory
NRC
National Research Council
NRL
Naval Research Laboratory
NSAC
Nuclear Science Advisory Committee
NSF
National Science Foundation
NSO
National Solar Observatory
NVO
National Virtual Observatory
OMA
NSF Office of Multidisciplinary Affairs
OMB
Office of Management and Budget
OPP
NSF Office of Polar Programs
OSS
NASA Office of Space Science
OSTP
Office of Science and Technology Policy
ROTSE
Robotic Optical Transient Search Experiment
SAFIR
Single Aperture Far Infrared observatory
SAGENAP
Science Assessment Group for Experiments in Non-Accelerator Physics
SDO
Solar Dynamics Observatory
SKA
Square Kilometer Array
SPST
South Pole Submillimeter-wave Telescope
