Related by context. Frequent words. (Click for all words.) 63 active galactic nuclei 62 supernova remnants 60 galaxy formation 60 redshifts 60 planetary nebulae 59 dwarf galaxy 59 Type Ia supernovae 59 X ray emission 57 globular clusters 57 elliptical galaxies 56 globular cluster 56 Gamma ray bursts 56 quasars 56 galaxy clusters 56 Cepheids 56 GRBs 56 auroral 55 supernovae 55 galaxies 55 supernova remnant 55 brown dwarfs 55 spiral galaxies 55 supernova explosions 55 magnetar 55 Hubble observations 55 dwarf galaxies 55 galaxy cluster 55 Galaxy Evolution 54 morphologies 54 supernovas 54 magnetars 54 quasar 54 supermassive black holes 53 X ray Observatory 53 spectroscopic 53 photometry 53 rocky planets 53 accretion disk 53 supermassive black hole 53 redshift 53 radial velocity 53 XMM Newton 53 Kuiper belt 53 neutron stars 53 colliding galaxies 52 Large Magellanic Cloud 52 spectra 52 WASP #b 52 Jupiter Saturn Uranus 52 pulsars 52 Eta Carinae 52 planets circling 52 magnetic reconnection 52 astrophysical 51 solar nebula 51 distant galaxy 51 interstellar dust 51 Orion Nebula 51 solar corona 51 interferometry 51 super Earths 51 supernova 51 distant galaxies 51 Milky Way galaxy 51 electron density 51 supernova explosion 51 z = 51 brown dwarf 51 WMAP 51 galaxy 51 spectral signature 51 star Gliese 51 Andromeda galaxy 50 planetary nebula 50 AGN 50 polar vortex 50 terrestrial planets 50 microlensing 50 GRB # 50 planetesimals 50 gravitational waves 50 shorter wavelengths 50 planets orbiting 50 Crab Nebula 50 accreting 50 galactic 50 interstellar medium 50 NASA Chandra 50 anisotropy 49 oxygen isotopes 49 journal Astronomy 49 Andromeda Galaxy 49 Jupiter Saturn 49 astronomical objects 49 gamma ray bursts 49 nebulae 49 QDs 49 gravitational lensing 49 quark gluon plasma 49 planet orbits 49 gamma ray burst