title: X-ray and molecular emission from the nearest region of recent star formation.
abstract: The isolated, young, sunlike star TW Hya and four other young stars in its vicinity are strong x-ray sources. Their similar x-ray and optical properties indicate that the stars make up a physical association that is on the order of 20 million years old and that lies between about 40 and 60 parsecs (between about 130 and 200 light years) from Earth. TW Hya itself displays circumstellar CO, HCN, CN, and HCO+ emission. These molecules probably orbit the star in a solar-system-sized disk viewed more or less face-on, whereas the star is likely viewed pole-on. Being at least three times closer to Earth than any well-studied region of star formation, the TW Hya Association serves as a test-bed for the study of x-ray emission from young stars and the formation of planetary systems around sunlike stars.
authors.affiliation: Center for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Building 37-667a, Cambridge, MA 02139, USA. jhk@space.mit.edu
authors.forename: J H
authors.initials: JH
authors.lastname: Kastner
authors.forename: B
authors.initials: B
authors.lastname: Zuckerman
authors.forename: D A
authors.initials: DA
authors.lastname: Weintraub
authors.forename: T
authors.initials: T
authors.lastname: Forveille
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002248:Carbon Monoxide; D003486:Cyanides; D019419:Evolution, Planetary; D005118:Extraterrestrial Environment; D005561:Formates; D006856:Hydrogen Cyanide; D013052:Spectrometry, X-Ray Emission; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D003486:Cyanides; D005561:Formates; C106724:oxomethylium; D006856:Hydrogen Cyanide; D002248:Carbon Monoxide