The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun

摘要: Based on the Hipparcos and Tycho-2 astrometric catalogs ROSAT surveys, a sample of 100 stars most luminous in X-rays within or around distance 50 pc is culled. The smallest X-ray luminosity sample, units 1029 ergs s-1, LX = 9.8; strongest source solar neighborhood II Peg, RS CVn star, at 175.8. With respect to origin emission, divided into partly overlapping classes pre–main-sequence, post–T Tauri, very young ZAMS objects (type XY), CVn–type binary RS), other active short-period binaries, including BY Dra–type XO), apparently single long-period evolved XG), contact binaries WU UMa kind WU), variable Dra BY), unknown nature X?). Chromospherically active, (RS XO) make up 40% brightest emitters, followed by (XY) 30% sources (X?) 15%. fraction spectroscopically emitters spectral IV III quite large (10%). identified as (RS, 23 objects) are considerably stronger than XY-objects (XO WU, 20 objects). Seven have > 100, all except one XY, viz., BO Mic. Only five (22%) 25. Formally, limit 25 could serve statistical criterion differentiate XY stars. However, (including eclipsing Algol β Lyr type) distribution similar objects. (WU) appear be much weaker their detached counterparts type, but former too small (three reach firm conclusion. Sources matched with giants (either binaries) found significantly harder, only 7% hardness ratios below 0, subgiants (66% HR1 < 0) dwarfs (59% 0). Almost multiple stars; components (FC), defined total number systems sum stars, least 0.90. FC for reaches 0.81, type 0.89. About 70% also visual companions, which makes them hierarchical systems. (mostly old, stars) different kinematics. While move considerable velocities random directions local standard rest, smaller orderly tend comprise expanding mini-associations such Pic Tucana groups. majority belong Pleiades stream mean heliocentric velocity (U, V, W) (-9.6, -21.8, -7.7) km s-1.