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Energetic proton observations at 1 and 5 AU: 2. Rising phase of the solar cycle 23
Plunkett, S. P.; Lario, D.; Balogh, A. +7 more
The increasing level of solar activity at the end of 1997 coincides with the observation of solar energetic particle (SEP) events by the Wind and Ulysses spacecraft. The proximity of Ulysses to the ecliptic plane during this period allows us to study the effects of the solar activity at two different heliolongitudinal and heliocentric distances bu…
Age, Evolution, and Dispersion of the Loose Groups of Blue Stars in the Northeast Radio Lobe of Centaurus A
Fassett, Caleb I.; Graham, John A.
The association of shocked gas and loose groups of young stars in the northeast radio lobe of Centaurus A (NGC 5128) provides direct evidence for shock-induced star formation. In this paper, we present UBV photometry of the blue stars based on observations made with the 2.5 m du Pont Telescope at Las Campanas Observatory. In a field covering 8.8‧×…
ISO observations of a sample of 60 mu m peaker galaxies
Hanlon, L.; McBreen, B.; Clavel, J. +9 more
The sample of IRAS galaxies with spectral energy distributions that peak near 60 mu m are called Sixty Micron Peakers (SMPs or 60PKs). Their generally peculiar and amorphous morphologies, hot dust and lack of a cirrus component have been interpreted as being indicative of a recent interaction/merger event. Mid-infrared spectra of eight SMPs, obtai…
Coronal X-Ray Brightness and Photospheric Magnetic Field: A Study in Correlations
Weber, Mark A.; Sturrock, P. A.; Wolfson, Richard +1 more
We have examined correlations between coronal X-ray emission from the Yohkoh Soft X-Ray Telescope (SXT) and photospheric magnetic field measurements from the Michelson Doppler Imager (MDI) on SOHO. Our data sets span a 521 day period beginning 1996 July 25, and we have averaged the data temporally into one bin per day and spatially into nine latit…
Polaris: astrometric orbit, position, and proper motion
Wielen, R.; Dettbarn, C.; Jahreiß, H. +2 more
We derive the astrometric orbit of the photo- center of the close pair α UMi AP (= α UMi Aa) of the Polaris multiple stellar system. The orbit is based on the spectroscopic orbit of the Cepheid α UMi A (orbital period of AP: 29.59 years), and on the difference Δµ between the quasi-instantaneously measured HIPPARCOS proper motion of Polaris a…
Ulysses observations of the magnetic field structure within CIRs
Forsyth, R. J.; Dunlop, M. W.; Clack, D.
Ulysses encountered two separate sequences of corotating interaction regions (CIRs) in 1992-3 and 1996-7 when the spacecraft was in the southern and northern solar hemispheres, respectively. We have examined magnetometer data from one event observed in each hemisphere. Using two separate analytical methods we provide evidence for the magnetic fiel…
Model for the mass fractionation in the January 6, 1997, coronal mass ejection
Bochsler, Peter; Wurz, Peter; Lee, Martin A.
For the coronal mass ejection (CME) of January 6, 1997, strong element fractionation of the heavy ions was observed at 1 AU with the Mass Time-of-Flight (MTOF) sensor of the Charge, Element, and Isotope Analysis System (CELIAS) on the Solar and Heliospheric Observatory (SOHO). During the passage of the CME plasma and the passage of the erupted fil…
Long-term behavior of Jovian bKOM and nKOM radio emissions observed during the Ulysses-Jupiter encounter
Kaiser, M. L.; Desch, M. D.; Reiner, M. J.
We present observational evidence that the long-term behavior of Jovian bKOM and nKOM radio emissions observed during the Ulysses-Jupiter encounter was controlled by the sector structure of the solar wind. Specifically, we found brightenings in the Jovian bKOM emission, followed by a sudden cessation of the bKOM emission and an onset of an nKOM “e…
Galactic Rotation Derived from OB Stars Using Hipparcos Proper Motions and Radial Velocities
Uemura, Makoto; Kato, Taichi; Hirata, Ryuko +3 more
We have examined the systematic velocity field of the solar neighborhood, based on Hipparcos (HIgh Precision PARallax COllecting Satellite) proper motions and ground-based radial velocities of about 240 O-B5 stars. The distances of these stars were derived from either Hipparcos parallaxes or the SKYMAP compilation of the spectroscopic parallaxes. …
Merging Process and Tidal-induced Star Formation in the Ultraluminous Infrared Galaxy IRAS 08572+3915
Arribas, Santiago; Colina, Luis; Borne, Kirk D.
Integral field optical spectroscopy using the INTEGRAL system, complemented with HST imaging, has been used to characterize the merging process giving rise to the ultraluminous infrared galaxy IRAS 08572+3915, the star formation along the tidal tails of the galaxy, and the nature of the nuclear ionizing sources deep within the galaxy. The overall …