electromagnetic spectrum, electromagnetic radiationÕs>2023  
emissions, >2032
light>2054
galaxy>2040,2058
wavelengths, wavelength of light>2114
neutral hydrogen, Radio, radio light emission, radio photons, radio radiation, radio wavelengths, radio waves, radio emission, Radio emission, radio emissions, >2028
galaxies, Galaxies, galaxyÕs, galaxy, mixed spiral galaxy, ellipticals, Ellipticals, Spiral galaxies, spiral galaxies, spiral galaxy, Spiral galaxy, spiral, spirals, barred galaxies, Barred galaxy, barred spiral galaxy, barred spirals, elliptical, galaxyÑcolli, elliptical galaxies, elliptical galaxy,  Elliptical galaxy, E2 elliptical, >2036 
optical light, optical wavelengths, optical, wavelengths: visible light, visible, visible light, Visible light, ultraviolet, ultraviolet-bright, ultraviolet emission, ultraviolet light, ultraviolet radiation, ultraviolet radiation, Ultraviolet radiation, >2025
gamma ray emission, gamma, gamma rays, x-rays, x-ray emis- sion, x-ray emissionÑabout, x-ray emission, x-ray radiation, x-ray wavelengths, x-ray, >2024
photons, >2072
spectra, spectral line, spectral lines, >2094  
absolute zero,Kel- vin,Kelvin>2053
absorption lines>2001
accretion disks>2002
active galaxies,active galactic nuclei,active nucleus>2003
angstroms>2004
arc minutes,arc seconds,minutes,seconds>2005
spiral arms>2099
asteroidlike,asteroids>2006
aurora, >2007
background radiation>2009
Big Bang>2010
star>2066,2081
star>2113,2083
binaries,binary star systems,binary system>2012
black holes>2013
black dwarf,white dwarfs>2115
black- body radiation, blackbody radiation, emission: thermal, Thermal emission, thermal radiation>2110
blueshifted,redshifted>2020
brems- strahlung,bremsstrahlung radiation>2014
carbon monoxide>2016
cD galaxies,S(B)c,S0 galaxies, Sa, SABb spiral galaxy, Sb galaxy, Sb spiral galaxy, SBb galaxy, SBb spiral galaxy, SBcd, Sc type galaxy, Sc, Sd type spiral galaxy, type ÒcÓ spiral>2037
Cepheid variables>2015
Cluster of galaxies, cluster,galaxy clusters, irregular clusters >2040
cometÕs, comets>2019
wind>2093,151
interstellar winds, wind, stellar wind, stellar wind?, stellar winds-, >2102
corona,Solar winds>2093
cosmic rays>2017
disk galaxies, galactic disk, Milky WayÕs galactic disk, >2035
Doppler shifts, Doppler, Doppler shifted, shift, >2020
doubly ionized, ionization, ionizes, singly ionized, un-ionized, >2051
dust lane, dust lanes, dusty, >2022
dwarf irregular galaxy, Irregular barred,Irregular spiral,peculiar galaxy, >2038
Lenticular galaxies,Lenticular galaxy,>2039
electrons, >2030
emission lines, >2031
emission nebulae, nebulaÕs>2064
supernova remnants, >2106,2074
explosions like the one that created Cas A liberate these elements from stellar interiors and seed them throughout space, Type II supernova, thermal bremsstrahlung, supernova, supernovaÕs, Supernova, supernovae, >2104
false color image, false color infrared, false color radio, false color visible light, false color x-ray, False colors, false-color radio, >2033
far infrared light, far-infrared, wave background radiation, near infrared, millimeter, micro-, microwaves>2027
frequencies, Frequency >2034
clusters, globular clusters, star cluster, open cluster, globular cluster, star clusters, globular clusterÕs, Globular cluster, globular clusters (spherical, Globular clusters, globular clusters, globular clusters, >2101
H alpha emission, H alpha light, H alpha spectral line, H alpha transition, H alpha, >2041
H I, >2042
H II region, ultraviolet radiation, H II region, H II regions, II, >2043
heavier elements, heavy elements, >2044
helium>2045
hydrogen emission, hydrogen gasÑthe, hydrogen gas, hydrogen, >2046
infrared emission, infrared light, infrared radiation, Infrared radiation, infrared wavelengths, Infrared, infrared-sensitive, infrared wavelengths, infrared, >2026
intercluster medium, intergalactic gas, intergalactic gases, intergalactic medium, intergalactic medium, >2047
interstellar dust, interstellar gas, interstellar gases, interstellar material, interstellar matter, interstellar mediumÑa, interstellar medium, >2048
inverse Compton emission, >2049
lightÑshowed, light, Light, >2054
light curveÑa, light curve, >2055
light year, light yearsÑand, light yearsÑit, light yearsÑroughly, light  years, years, >2056
Local Group, >2057
Local Supercluster, Local, Supercluster, superclusters, >2058
luminosity, >2059
magnetic field, magnetic fields, >2060
magnitudes, >2061 
mass, massÑover, Mass,     masses, >2063
supernova rem-, remnant, supernova remnant, Supernova remnant, supernova remnantsÑoften, supernova remnants, >2106
neutron star, neutron stars, >2066
nonthermal emission, nonthermal emissions, >2067
nova, novae, >2068
nuclear fusion, thermonuclear fusion, >2069 
nuclei>2003,100
nucleus>2003,111
nucleus>2003,112
nucleus>2003,121
nucleus>2003,122
nucleus>2003,175
nuclei,nucleus>2070
plasma, >2073
polarized, >2075
Position, >2076
progenitor star, progenitor stars, >2078
proton, protons, Protons, >2079
protostar, protostars, >2080
pul- sar, pulsars, >2081
plerion>2074
Quasar, quasars, >2082
radiation pressure, >2084
radio galaxies, Radio galaxy, >2085
radio jets>2052
Red giant stars, red giant, red giants, red supergiant, >2088
RR Lyrae variables, >2083
Seyfert galaxies, Seyfert galaxy, >2089
shock front, supernovaÕs shock front, >2090
S0 Galaxy, S0 Galaxies>2037
solar masses >2091
solar systemÑ, Solar systems, >2092
spectrographic analysis, spectroscopic analysis, spectroscopy, spectrum, >2096
speed of light, >2098
Starbursts, >2100
supergiant stars, supergiant, supergiantsÑamong, >2103
surface brightness, >2107
synchrotron emission, synchrotron ra- diation, synchrotron radiation, Synchrotron radiation, synchrotron, >2108
T Tauri stars, >2109
Type I supernova, >2104
ultraviolet>2023
Van Allen belts, >2112
variable stars, >2113