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Molecular gas and dust in NGC 4550. A galaxy with two counterrotating stellar disks
Henkel, C.; Wiklind, T.
We report the detection of 1 x 107 Msun of molecular gas in the central region of the S0/E7 galaxy NGC 4550, inferred from observations of CO(1-0) emission. Dust is detected in HST WFPC2 images and found to be asymmetrically distributed around the nucleus, only extending to a galactocentric distance of 7'' (600 pc). The shape…
The distance to Supernova 1998aq in NGC 3982
Gibson, Brad K.; Stetson, Peter B.
The distance to NGC 3982, host galaxy to the Type Ia supernova SN 1998aq, is derived using 32 Cepheids discovered in archival multi-epoch Hubble Space Telescope observations. Employing recent Large Magellanic Cloud Cepheid period-luminosity relations and absolute zero-point, we find a distance to NGC 3982 of [formmu3]20.5+/-0.8 (r) +/-1.7 (s)Mpc, …
The transport of interstellar pickup ions
Zank, G. P.; Lu, J. Y.
A new approach to the time-dependent anisotropic propagation of interstellar pickup ions in the interplanetary medium is presented. The model includes the effects of adiabatic focusing in a radial magnetic field, adiabatic deceleration, anisotropic pitch angle scattering, convection in the solar wind, and the continual injection of newly ionized p…
The European Large Area ISO Survey - VI. Discovery of a new hyperluminous infrared galaxy
Pérez-Fournon, I.; Pozzi, F.; Alexander, D. M. +20 more
We report the discovery of the first hyperluminous infrared galaxy (HyLIG) in the course of the European Large Area ISO Survey (ELAIS). This object has been detected by ISO at 6.7, 15 and 90µm, and is found to be a broad-line, radio-quiet quasar at a redshift [formmu4]z=1.099. From a detailed multicomponent model fit of the spectral energy d…
Time-Dependent 2d Model Compared with Observations During the 1974 Mini Cycle
Wibberenz, G.; Ferreira, S. E. S.; Potgieter, M. S. +1 more
The 1974 mini-cycle is a medium term cosmic ray modulation event with about one year duration. It occurred in an A>0 epoch of solar magnetic polarity during conditions of low activity, but with an increase in the latitudinal extent of the heliospheric current sheet (tilt angle α) and the magnitude B of the heliospheric magnetic field. This cosm…
Ionization, Extinction, and Spiral Structure in the Inner Disk of NGC 1068
Smith, A. M.; Landsman, Wayne; Bruhweiler, Fred C. +2 more
We present our analysis of Hubble Space Telescope/Planetary Camera narrow-bandpass and broadband imagery of the inner 3 kpc region of NGC 1068. Our analysis of F160BW and F547M broadband continuum imagery suggests that roughly 40% of the scattered active galactic nucleus (AGN) continuum emission originates from an unobscured single cloud complex l…
The Interstellar Medium Interactions of a Runaway Luminous Blue Variable Nebula in the Large Magellanic Cloud
Danforth, Charles W.; Chu, You-Hua
New observations of the Magellanic Cloud luminous blue variable candidate S119 (HD 269687) show the relationship of the star to its environs. Echelle spectroscopy and high-resolution Hubble Space Telescope imagery reveal an expanding bubble centered on the star. This bubble appears in both Hα and [N II] and is noticeably brighter on the near (blue…
Ion-Sound Model of Microwave Spikes with Fast Shocks in the Reconnection Region
Fu, Q. J.; Chernov, G. P.; Hanaoka, Y. +1 more
A new model for solar spike bursts is considered based on the interaction of Langmuir waves with ion-sound waves: l+s→t. Such a mechanism can operate in shock fronts, propagating from a magnetic reconnection region. New observations of microwave millisecond spikes are discussed. They have been observed in two events: 4 November 1997 between 05:52-…
Far-ultraviolet spectroscopy of the hot DA white dwarf WD 2218+706 (DeHt5) with STIS
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +3 more
We report a study of the photospheric composition of the hot DAQ3 white dwarf WD 2218+706, which is also the central star of the old planetary nebula DeHt5. Helium is detected in the far-UV spectrumQ4. In addition, the star clearly contains significant quantities of elements heavier than He at abundances generally a factor of 2 to 10 higher than t…
Active Region Transient Events Observed with TRACE
Reeves, Katharine K.; Golub, Leon; Winebarger, Amy R. +3 more
Nearly all active region observations made by the Transition Region and Coronal Explorer (TRACE) contain seemingly spontaneous, short-lived brightenings in small-scale loops. In this paper, we present an analysis of these brightenings using high-cadence TRACE observations of Active Region 9506 on 2001 June 21 from 15:17:00 to 15:46:00 UT. During t…