Subject
- x-ray sources8
- galactic and extragalactic astronomy7
- solar system astronomy7
- stellar astronomy7
- stellar spectral types7
- pre-main sequence stars6
- radial velocity6
- stellar associations6
- astronomical object identification5
- galaxy classification systems5
- millimeter astronomy5
- submillimeter astronomy5
- variable stars5
- wide-band photometry5
- apparent magnitude4
- chemical abundances4
- diffuse molecular clouds4
- line intensities4
- milky way galaxy4
- stellar distance4
