Subject
- planetary nebulae4
- star forming regions4
- stellar evolutionary tracks4
- stellar flares4
- stellar mass loss4
- catalogs3
- galaxy classification systems3
- h ii regions3
- interstellar medium3
- morgan-keenan classification3
- standard stars3
- ultraviolet astronomy3
- accretion2
- am stars2
- emission line stars2
- millimeter astronomy2
- nebulae2
- orbits2
- parallax2
- photographic photometry2