TYPES OF STAR A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z           HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site YY Orionis star An extremely young star, preceding even the T Tauri stage. YY Orionis stars are very young, late-type, low-mass stars, still contracting gravitationally and accreting matter from the protostellar cloud. They show inverse P Cygni profiles corresponding to an infall of material at 300–400 km/s directly onto the star. Related entry    • variable stars Related category    • TYPES OF STAR Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP