Search Publications
Two Böhm-Vitense Gaps in the Main Sequence of the Hyades
de Bruijne, J. H. J.; de Zeeuw, P. T.; Hoogerwerf, R.
Hipparcos proper motions and trigonometric parallaxes allow the derivation of secular parallaxes that fix the distances to individual stars in the Hyades to an accuracy of ~2%. The resulting color-absolute magnitude diagram for 92 high-fidelity single members of the cluster displays a very narrow main sequence, with two turnoffs and associated gap…
Mira's Wind Explored in Scattering Infrared CO Lines
Ryde, N.; Eriksson, K.; Gustafsson, B. +1 more
We have observed the intermediate regions of the circumstellar envelope of Mira (ο Ceti) in photospheric light scattered by three vibration-rotation transitions of the fundamental band of CO, from low-excited rotational levels of the ground vibrational state, at an angular distance of β~2''-7" away from the star. The data were obtained …
Modeling the 1994 April 14 Polar Crown SXR Arcade Using Three-Dimensional Magnetohydrostatic Equilibrium Solutions
Hoeksema, J. T.; Scherrer, P. H.; Zhao, X. P.
The coronal magnetic field in the polar crown soft X-ray (SXR) arcade of 1994 April 14 has been computed using the global photospheric magnetic field distribution constructed for the time of interest and the three-dimensional magnetohydrostatic equilibrium solutions. In the solutions there are two free parameters, α and a, respectively, characteri…
The Caltech Faint Galaxy Redshift Survey. XII. Clustering of Galaxies
Hogg, David W.; Cohen, Judith G.; Blandford, Roger
A clustering analysis is performed on two samples of ~600 faint galaxies each, in two widely separated regions of the sky, including the Hubble Deep Field. One of the survey regions is configured so that some galaxy pairs span angular separations of up to 1°. The median redshift is zmed~0.55. Strong clustering is obvious, with every pen…
Knots in the Outer Shells of the Planetary Nebulae IC 2553 and NGC 5882
Corradi, Romano L. M.; Gonçalves, Denise R.; Villaver, Eva +2 more
We present images and high-resolution spectra of the planetary nebulae IC 2553 and NGC 5882. Spatiokinematic modeling of the nebulae shows that they are composed of a markedly elongated inner shell and of a less aspherical outer shell expanding at a considerably higher velocity than the inner one. Embedded in the outer shells of both nebulae are f…
On the Ongoing Multiple Blowout in NGC 604
Maíz-Apellániz, Jesús; Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana +2 more
Several facts regarding the structure of NGC 604 are examined here. The three main cavities produced by the mechanical energy from massive stars, which in NGC 604 are spread over a volume of 106 pc3, are shown here to be undergoing blowout into the halo of M33. High-resolution long-slit spectroscopy is used to track the impac…
The Physical Conditions in a Polar Coronal Hole and Nearby Regions from Norikura and SOHO Observations
Ichimoto, K.; Singh, Jagdev; Raju, K. P. +1 more
The distribution of emission-line intensities, Doppler velocities, and line widths in a polar coronal hole and nearby regions are obtained from the spectroscopic observations carried out on 1998 November 3 at the Norikura Solar Observatory, Japan. The coronal red line [Fe X] λ6374 that is prominent at coronal hole temperatures is used for the stud…
Gamma-Ray Burst Arrival-Time Localizations: Simultaneous Observations by Ulysses, Pioneer Venus Orbiter, SIGMA, WATCH, and PHEBUS
Cline, T.; Hurley, K.; Sunyaev, R. +15 more
Between the launch of the Ulysses spacecraft in 1990 October and the entry of Pioneer Venus Orbiter (PVO) into the atmosphere of Venus in 1992 October, concurrent coverage by Ulysses, PVO, the WATCH experiments aboard the Granat and Eureca spacecraft, and the SIGMA and PHEBUS experiments aboard the Granat spacecraft was obtained for numerous gamma…
Ultraviolet Spectroscopy of Polar Coronal Jets
Raymond, J. C.; Dobrzycka, D.; Cranmer, S. R.
We have observed a total of five UVCS/SOHO polar jets that correlate with the Extreme-Ultraviolet Imaging Telescope (EIT) and Large Angle Spectrometric Coronagraph (LASCO) jet events. We analyzed spectroscopic observations of these jets and found that they typically undergo two phases: at the first phase the O VI lines show a brief intensity enhan…
The Ionization Source in the Nucleus of M84
Nelson, C.; Green, R. F.; Kaiser, M. E. +9 more
We have obtained new Hubble Space Telescope observations of M84, a nearby massive elliptical galaxy whose nucleus contains a ~1.5×109 Msolar dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph spectrum provides the first clear detection of emission lines in the blue (e.…