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T. Montmerle L. Koch-Miramond E. Falgarone J.E. Grindlay 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(9):95-98
The Rho Ophiuchi dark cloud region has been the subject of an extensive guest investigation using the Observatory. The set of observations comprise 14 IPC fields and 3 HRI fields. The densest part of the cloud has been observed 6 times. Forty seven sources were detected at a level > 3.5 σ and twenty more above 2 σ. The majority of these sources have optical, IR, or even radio continuum counterparts; nine are identified with known T Tauri stars, while several others are identified with stars showing H α in emission. All show a high degree of time variability; flux variations reach factors of 5 in a few hours, or 25 in a day. Apparent luminosities are in the range 10(30) – 10(31)(1) erg.s?1. The possibility that the X-ray variability is due to flares is examined. If this interpretation is correct, one source has been the seat of the largest stellar flare ever recorded in X rays [Lx = 10(32) erg.s?1, Ex ?10(36) ergs-]. 相似文献
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E. D. Feigelson S. Casanova T. Montmerle J. Guibert 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):311-314
Two soft X-ray images of the Chamaeleon I star forming cloud obtained with the ROSAT Position Sensitive Proportional Counter are presented. Seventy reliable, and perhaps 19 additional, X-ray sources are found. Up to Ninety percent of these sources are certainly or probably identified with T Tauri stars formed in the cloud. Twenty to 35 are probably previously unrecognized ‘weak’ T Tauri (WTT) stars. T Tauri X-ray luminosities range from log
, or 102 – 104 times solar levels, with mean
in the 0.2–2.5 keV band. The X-ray luminosities of well-studied Chamaeleon cloud members are correlated with a complex of four stellar properties: effective temperature, mass, radius and bolometric luminosity. The spatial distribution, H-R diagram locations of the stars indicate WTT and CTT are coeval. The total premain sequence population of the cloud is likely to be > 100 stars, with WTT stars outnumbering ‘classical’ T Tauri (CTT) stars by 2:1. 相似文献
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Space Science Reviews - Recent studies of the solar wind-magnetosphere interaction are reviewed in terms of the input-output relationship. We show that the magnetosphere is primarily a directly... 相似文献
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