Search Publications
The Star-grazing Extrasolar Comets in the HD 100546 System
Sitko, M. L.; Grady, C. A.; Bjorkman, Karen S. +4 more
Redshifted absorption profiles that resemble the high-velocity circumstellar gas features in the spectrum of β Pictoris have been detected in IUE data for the 10 Myr old Herbig Be star, HD 100546, on 1995 March 7. In addition to Mg II, Si II, and other refractory species similar to those seen in β Pic, the HD 100546 spectra are rich in accreting g…
A Hubble Space Telescope Faint Object Spectrograph Survey for Broad Absorption Lines in a Sample of Low-redshift Weak [O III] Quasi-stellar Objects
Turnshek, David A.; Espey, Brian R.; Monier, Eric M. +1 more
The study by Boroson & Meyers led to the suggestion that radio-quiet QSOs with weak [O III] and strong Fe II emission spectra form a class of QSOs that has a high probability of exhibiting broad absorption lines (BALs) in their spectra. Furthermore, they argued that since narrow-line [O III] emission is almost certainly emitted isotropically, …
Mars surface mineralogy from Hubble Space Telescope imaging during 1994-1995: Observations, calibration, and initial results
Bell, James F.; Wolff, Michael J.; Clancy, R. Todd +3 more
Visible to near-infrared observations of Mars were made with the Hubble Space Telescope (HST) during 1994-1995 with the goals of monitoring seasonal variability of the surface and atmosphere and mapping specific spectral units to constrain the planet's surface mineralogy. This paper presents the details of the collection and calibration of the dat…
Evidence for an outflow from the Seyfert galaxy NGC 4051
Steffen, W.; Mundell, C. G.; Meaburn, J. +5 more
New observations using narrow-band imaging, long-slit spectroscopy and MERLIN observations of the nuclear region of the Seyfert galaxy NGC 4051 have been made. An edge-brightened, triangular region of ionized gas extending 420 pc from the centre of the galaxy has been detected. Long-slit spectra of this ionized gas, taken at 1.5 arcsec from the co…
SUMER Observations of the Quiet Solar Atmosphere: The Network Chromosphere and Lower Transition Region
Wilhelm, Klaus; Carlsson, Mats; Judge, Philip
We examine spectral properties of the network chromosphere and lower transition region from the SUMER instrument on the SOHO spacecraft, using time-series data sets discussed in an accompanying Letter by Carlsson, Judge, & Wilhelm. The data were obtained early in the mission with no tracking of solar features and so cannot generally be used to…
The Ultraviolet Imaging Telescope: Instrument and Data Characteristics
O'Connell, R. W.; Bohlin, R. C.; Stecher, T. P. +16 more
The Ultraviolet Imaging Telescope (\UIT) was flown as part of the \AstroMiss\ observatory on the Space Shuttle Columbia in December 1990 and again on the Space Shuttle Endeavor in March 1995. Ultraviolet (1200-3300\AA) images of a variety of astronomical objects, with a 40\arcmin\ field of view and a resolution of about 3\arcsec, were recorded on …
Detailed Non-LTE Model Atmospheres for Novae during Outburst. I. New Theoretical Results
Baron, E.; Shore, Steven N.; Hauschildt, Peter H. +3 more
We present new, detailed non-LTE (NLTE) calculations for model atmospheres of novae during outburst. This fully self-consistent NLTE treatment for a number of model atoms includes 3922 NLTE levels and 47,061 NLTE primary transitions. We discuss the implication of departures from LTE for the strengths of the lines in nova spectra. The new results s…
GHRS Monitoring of the Outflowing Material in NGC 4151
Morris, Simon L.; Hutchings, John B.; Weymann, Ray J. +1 more
We present the results of a program to monitor the absorption lines in the spectrum of the Seyfert 1 galaxy NGC 4151 caused by outflowing gas from the nucleus. Spectral observations were taken in the UV with the GHRS and FOS of HST. GHRS G160M and G270M exposures were taken of the wavelength regions centered on C IV and Mg II, respectively, extend…
Quantitative analysis of the FUV, UV and optical spectrum of the O3 star HD 93129A.
Butler, K.; Lennon, D. J.; Kudritzki, R. P. +6 more
A quantitative analysis of the extremely hot and massive galactic O3If^*^ supergiant HD 93129A is carried out using stellar wind and pseudo photospheric lines observed in the FUV, UV and optical spectrum together with hydrodynamical NLTE model atmospheres. The analysis in the FUV is combined with spectrum synthesis of the molecular and atomic/ioni…
The Mg/Ne abundance ratio in a recently emerged flux region observed by CDS
Young, P. R.; Mason, H. E.
Evidence for the existence of the FIP-effect in the transition region is presented here based on recent observations from the Coronal Diagnostic Spectrometer (CDS) on-board the Solar and Heliospheric Observatory (SOHO). Observations of an emerging flux region in lines of Mgv-vii and Nevi-vii reveal differences in the relative Mg/Ne abundance of a …