Search Publications
VLBI Observations of Symmetric Parsec-Scale Twin Jets in the Narrow-Angle-Tail Radio Galaxy NGC 1265 (3C 83.1B)
O'Dea, Christopher P.; Xu, Chun; Biretta, John A.
We present global VLBI observations of the nucleus of the narrow-angle-tail radio galaxy NGC 1265. We report the discovery of symmetric parsec-scale twin jets which are well aligned with the kiloparsec-scale jets. We also present an archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) image of the galaxy, showing an apparently alm…
Near Infrared Photometry of the Jovian Ring and Adrastea
Terrile, Richard J.; Smith, Bradford A.; Owen, Tobias C. +2 more
The near IR spectral reflectance of the Jupiter dust ring is poorly known because of problems with scattered light from the planet. Here we report colors for the jovian ring and one of the two ring satellites, Adrastea, using observations from the near-IR camera NICMOS on the Hubble Space Telescope. Near the time when the Earth crossed the jovian …
The Compact UV Nucleus of M33
Long, Knox S.; Dubus, Guillaume; Charles, Philip A.
The most luminous X-ray source in the Local Group is associated with the nucleus of M33. This source, M33 X-8, appears modulated by ~20% over a ~106 day period, making it unlikely that the combined emission from unresolved sources could explain the otherwise persistent ~1039 ergs s-1 X-ray flux. We present here high-resolutio…
The Gaseous Extent of Galaxies and the Origin of Lyα Absorption Systems. IV. Lyα Absorbers Arising in a Galaxy Group
Barcons, X.; Fernández-Soto, A.; Webb, J. K. +2 more
We present new Goddard High Resolution Spectrograph observations of Lyα absorption lines associated with a group of galaxies toward the QSO 1545+2101. We have identified eight distinct Lyα absorption features in the spectrum of QSO 1545+2101 at a mean redshift of =0.2648 with a velocity dispersion of 163 km s-1. A group of galaxies is d…
Sinusoidal variables from the Tycho Epoch Photometry Annex
Koen, Chris; Schumann, Robert
The Tycho Epoch Photometry Annex A, a data base of photometry of more than 34 000 bright stars, has been searched for periodic variable stars with approximately sinusoidal light curves. Advantage was taken of special properties of the observing programme (photometry in two wavebands, availability of repeated measurements) to use simple but efficie…
A comparison of different spectral classification systems for early type stars using HIPPARCOS parallaxes
Paunzen, Ernst
An ``inventory'' of different classification systems were made. Two different surveys for B9 to F2 type stars were chosen in oder to get an unbiased sample of ``normal'' stars. Jaschek & Valbousquet (1997) and Jaschek & Gómez (1998) already investigated the intrinsic consistency of the MK spectral classification systems. But interesting en…
Wavelength shifts of emission line profiles due to velocity fields in the solar corona
Spadaro, D.; Ventura, R.
We have investigated the dependence of the wavelength shift of the coronal emission line profiles on the line of sight velocity of the emitting plasma. The results of our numerical calculations point out that, while the wavelength shift of the collisionally excited component of the line is related to the line of sight velocity by the usual formula…
Identification of lambda Bootis stars using IUE spectra. II. High resolution data
Solano, E.; Paunzen, E.
Stars included in the catalogue of lambda Bootis stars by Paunzen et al. (\cite{Paunzen97}) with high resolution spectra (FWHM: 0.10-0.25 Ä) in the INES Archive of the International Ultraviolet Explorer satellite (IUE) are analyzed here in order to establish membership criteria for the lambda Bootis group. Line-ratios of carbon to heavier elements…
Variation of Thermal Structure with Height of a Solar Active Region Derived from SOHO CDS and YOHKOH BCS Observations
Antiochos, Spiro K.; Watanabe, Tetsuya; Sterling, Alphonse C. +2 more
We present observations of NOAA solar Active Region 7999 when it was near the west solar limb on 1996 December 2 and 3, using data from the Coronal Diagnostic Spectrometer (CDS) experiment on the SOHO satellite. Ratios of intensities of 2 MK material (as observed in CDS Fe XVI images) to 1 MK material (from CDS Mg IX images) indicate that there is…
ISOPHOT Polarization Measurements of the Asteroids (6) Hebe and (9) Metis at 25 µm
Erikson, A.; Müller, T. G.; Klaas, U. +1 more
The subsurface thermal IR emission of asteroids becomes linearly polarized when scattered across the surface. The disk integrated mid-IR Stokes parameters are computed by extending the new thermophysical model by Lagerros (1996, Astron. Astrophys.315, 625-632; 1998, Astron. Astrophys.332, 1123-1132). The small scale surface roughness is approximat…