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…
Mapping Jupiter's Latitudinal Bands and Great Red Spot Using HST/WFPC2 Far-Ultraviolet Imaging
West, Robert A.; Ballester, Gilda E.; Crisp, David +16 more
Jupiter's low and mid-latitudes are examined using ultraviolet (UV) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994-1997. Effective atmospheric pressures probed by the F160W, F218W, and F255W are estimated at 100, 165, and 370 mbar, respectively, at low latitudes. Far-ultraviolet images of …
C32: A Young Star Cluster in IC 1613
Hodge, Paul W.; Wyder, Ted K.; Cole, Andrew
The Local Group irregular galaxy IC 1613 has remained an enigma for many years because of its apparent lack of star clusters. We report the successful search for clusters among several of the candidate objects identified many years ago on photographic plates. We have used a single Hubble Space Telescope WFPC2 pointing and a series of images obtain…
Supernova Remnants in the Fossil Starburst in M82
Chevalier, Roger A.; de Grijs, Richard; O'Connell, Robert W. +2 more
We report the discovery of 10 compact Hα-bright sources in the poststarburst region northeast of the center of M82, called M82 B. These objects have Hα luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same Hα surface brightness-diameter relation (Σ-D) defined by SNRs in other nearby star-forming galaxies, …
New astrometric binaries among HIPPARCOS stars
Gontcharov, G. A.; Andronova, A. A.; Titov, O. A.
A new realization of the International Celestial Reference System (ICRS) is built upon the data of the HIPPARCOS catalogue and astrometric ground-based catalogues of the 20th century reduced to the HIPPARCOS system. Non-linear motion of some stars has been detected with this realization of the ICRS. This motion is separated into the pro…
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 …
Influence of electrophilic species on the lower ionosphere of Titan
Rodrigo, R.; López-Moreno, J. J.; Molina-Cuberos, G. J.
The galactic cosmic rays induced ionosphere of Titan is studied from 0 to 70 km. We resent here a new model developed for calculating the concentration of cations, anions, and electrons depending on the mixing ratio of electrophilic species present in the atmosphere of Titan. The existence of neutral species in which electrons can be attached by t…
Hubble Space Telescope Wide Field Planetary Camera 2 Imaging of Shocks in Superbubbles
Chu, You-Hua; Gruendl, Robert A.; Chen, C. -H. Rosie +1 more
Bright X-ray emission has been detected in superbubbles in the Large Magellanic Cloud (LMC), and it is suggested that supernova remnants (SNRs) near the inner-shell walls are responsible for this X-ray emission. To identify SNR shocks in superbubble interiors, we have obtained Hubble Space Telescope Wide Field Planetary Camera 2 emission-line imag…
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…