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Echoes from an irradiated disc in GRO J1655-40
Horne, Keith; O'Brien, K.; Chen, W. +2 more
We demonstrate correlated rapid variability between the optical/UV and X-ray emission for the first time in a soft X-ray transient, GRO J1655-40: Hubble Space Telescope (HST) light curves show similar features to those seen by the Rossi X-ray Timing Explorer (RXTE), but with mean delay of up to 10-20s. We interpret the correlations as the result o…
Power-Law Decays in the Optical Counterparts of GRB 970228 and GRB 970508
Kouveliotou, C.; van Paradijs, J.; McClintock, J. E. +7 more
We report on RC- and K-band observations of the optical counterpart to GRB 970508 with the Fred Lawrence Whipple Observatory (FLWO) 1.2 m telescope. Eleven RC-band observations were obtained on 1997 May 12, and three on May 14. The counterpart clearly faded between the two nights. On May 12 there was no evidence for variabili…
Origin and production of C(^1D) atoms in cometary comae
Feldman, P. D.; Festou, M. C.; Tozzi, G. P.
The abundance of carbon atoms in the metastable (1) D state near the cometary nucleus provides an important diagnostic of one of the principal sources of carbon in the cometary coma. This quantity may be determined in two independent ways: measurement of (1) D -(1) P fluorescence at 1931 Angstroms and by prompt emission of the (1) D -(3) P doublet…
New study of the quasi-molecular Lyman alpha satellites due to H-H and H-H(+) collisions
Gerbaldi, M.; Allard, N. F.; Kielkopf, J. +2 more
We present new theoretical calculations of the total profile of the atomic hydrogen Lyman alpha spectral line perturbed by collisions with neutral hydrogen atoms and protons. The variation of the radiative dipole moment during the collision is taken into account. This leads to an increase in the amplitude of the main spectral line satellites and t…
Long-term variability of the Be/X-ray binary A0535+26 - I. Optical and UV spectroscopy
Coe, M. J.; Steele, I. A.; Buckley, D. A. H. +11 more
The results of a 7-yr optical and UV spectroscopic study of the high-mass X-ray binary A0535+26 are presented. It was found that throughout the period of the observations the line profile of Hα showed considerable variability. A correlation between the equivalent width of Hα and both V-band magnitude and (B-V) colour excess was observed, albeit wi…
Cosmic-Ray Transport Coefficients
Giacalone, Joe
A review of cosmic-ray transport coefficients, based on historic and recent observations and theoretical insights, is presented. Particular emphasis is on the transport of cosmic rays across the magnetic field, which is of foremost importance, and is presently poorly understood and widely debated.
Detection of Far-Infrared Water Vapor, Hydroxyl, and Carbon Monoxide Emissions from the Supernova Remnant 3C 391
Reach, William T.; Rho, Jeonghee
We report the detection of shock-excited far-infrared emission of H2O, OH, and CO from the supernova remnant 3C 391, using the Infrared Space Observatory Long-Wavelength Spectrometer. This is the first detection of thermal H2O and OH emission from a supernova remnant. For two other remnants, W28 and W44, CO emission was detec…
The Lensing Cluster MS 0440+0204 Seen by HST, ROSAT, and ASCA. I. Cluster Properties
Le Fèvre, O.; Hammer, F.; Falco, E. E. +3 more
We present an analysis of the properties of the lensing cluster MS 0440+0204 at z = 0.1965. MS 0440+0204 has been observed with a variety of telescopes at diverse wavelengths: from the ground with the Canada-France-Hawaii Telescope, the Multiple Mirror Telescope, and the Keck Telescope, and from the Earth orbit with HST, ROSAT, and ASCA. Mass dete…
Energetic (∼ 1 to 50 MeV) protons associated with Earth-directed coronal mass ejections
Laitinen, T.; Vainio, R.; Valtonen, E. +7 more
During the period from January through mid-May, 1997, four large Earth-directed CMEs were observed by the Large Angle Spectroscopic Coronograph (LASCO). These CMEs were associated with long-lasting fluxes of >1.6 MeV protons detected by the Energetic and Relativistic Nuclei and Electron instrument (ERNE). However, the magnitudes of energetic pr…
Evidence for low-level AGN activity in the nucleus of the LINER galaxy NGC4594
Filippenko, A. V.; Ho, L. C.; Reichert, G. A. +4 more
We investigate the properties of the low-ionization nuclear emission-line region (LINER) galaxy, NGC4594, using data taken with the Faint Object Spectrograph on the Hubble Space Telescope (HST) and with the ASCA X-ray observatory. The ultraviolet spectrum shows only narrow-line emission (FWHM ~800-1000 km s^-1) with no evidence for broad emission-…