Search Publications
Stellar Populations in Three Outer Fields of the Large Magellanic Cloud
Cole, Andrew A.; Ballester, Gilda E.; Crisp, David +15 more
We present Hubble Space Telescope photometry for three fields in the outer disk of the Large Magellanic Cloud (LMC) extending approximately 4 mag below the faintest main-sequence turnoff. We cannot detect any strongly significant differences in the stellar populations of the three fields based on the morphologies of the color-magnitude diagrams, t…
Shock and Discontinuity Normals, Mach Numbers, and Related Parameters
Schwartz, Steven J.
Observational Properties of the Orion Nebula Proplyds
O'Dell, C. R.
Hubble Space Telescope Planetary Camera images have been used to quantitatively determine key parameters characterizing emission-line proplyds in the Orion Nebula. A previous conclusion that the objects are radiation-bounded ionization fronts is confirmed and found to be in excellent agreement with the observations. Only a very loose correlation o…
Cross-helicity and residual energy in solar wind turbulence: Radial evolution and latitudinal dependence in the region from 1 to 5 AU
Bavassano, B.; Pietropaolo, E.; Bruno, R.
Solar wind plasma and magnetic field measurements by Ulysses have been used to study magnetohydrodynamic turbulence in different heliospheric regions. Four intervals of six solar rotations have been analyzed. Two of them are on the ecliptic around 2 and 5 AU, respectively, one is at midlatitude near 5 AU, and the last one is at high latitude aroun…
Navy Prototype Optical Interferometer Observations of the Double Stars Mizar A and Matar
Hajian, Arsen R.; Hutter, D. J.; Hummel, C. A. +3 more
We present a detailed analysis of two spectroscopic binaries based on new observations obtained with the Navy Prototype Optical Interferometer (NPOI). While the data calibration needs refinement, first results show the impressive potential of NPOI, both in terms of speed and precision, for imaging and modeling the orbits of spectroscopic binaries.…
A Radio Study of the Seyfert Galaxy IC 5063: Evidence for Fast Gas Outflow
Tsvetanov, Z.; Morganti, R.; Oosterloo, T.
We present new radio continuum (8 and 1.4 GHz) and H i 21 cm line observations of the Seyfert 2 galaxy IC 5063 (PKS 2048-572), obtained with the Australia Telescope Compact Array. The high-resolution 8 GHz image reveals a linear triple structure ~4" (1.3 kpc) in size. This small-scale radio emission shows a strong morphological association with th…
Stellar radii of M giants
Schild, H.; Dumm, T.
We determine the stellar radii of the M giant stars in the Hipparcos catalogue3 that have a parallax measured to better than 20% accuracy. This is done with the help of a relation between a visual surface brightness parameter and the Cousins ( V - I) colour index, which we calibrate with M giants with published angular diameters. The ra…
Are Seyfert Narrow-Line Regions Powered by Radio Jets?
Dopita, Michael A.; Sutherland, Ralph S.; Tsvetanov, Zlatan I. +1 more
We argue that the narrow-line regions (NLRs) of Seyfert galaxies are powered by the transport of energy and momentum by the radio-emitting jets. This implies that the ratio of the radio power to jet energy flux is much smaller than is usually assumed for radio galaxies. This can be partially attributed to the smaller ages (~106 yr) of S…
The sun's shape and brightness
Kuhn, J. R.; Bush, R. I.; Scherrer, P. +1 more
We present satellite data that show that the sun's shape and temperature vary with latitude in an unexpectedly complex way. Although the solar oblateness shows no evidence of varying with the solar cycle, we find a significant hexadecapole shape term which may vary. We also see a variation of about 1.5 K in the surface temperature with latitude. B…
A Study of Nine High-Redshift Clusters of Galaxies. II. Photometry, Spectra, and Ages of Clusters 0023+0423 and 1604+4304
Postman, Marc; Lubin, Lori M.; Oke, J. B.
We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10 m telescopes and the Hubble Space Telescope. The clusters Cl 0023+0423 (z = 0.84) and Cl 1604+4304 (z = 0.90) are part of a multiwavelength program of Oke, Postman & Lubin to study nine candidate cluster…