Search Publications
The Evidence for Clumpy Accretion in the Herbig AE Star HR 5999
Grady, C. A.; Perez, M. R.; The, P. S.
Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978–1992 has revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 Å) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Lyα, OI and CIV emission lines, which are co…
Observations and analyses of the S VI λ1975, λ1993A lines in the IUE ultraviolet spectra of WN stars.
Willis, A. J.; Nugis, T.
From a detailed study of high resolution IUE ultraviolet spectra we identify strong emission lines near ~λ1990A as the S VI (4p^2^P^0^-4d^2^D) transitions at λ1975.21A, λ1992.56, 1993.24A in HD 187282 (WN4), HD 50896 (WN5), HD 191765 (WN6) and HD 192163 (WN6). These S VI emissions may also be weakly present in HD 151932 (WN7). Additional S VI (4s …
β1 Monocerotis: oscillations and chromospheric structure
Ringuelet, A. E.; Colombo, E.; Maranon di Leo, C.
β1 Monocerotis is a Be star with a V/R cycle of 12.5 years. We observed the star from CTIO (Chile) and with the IUE satellite and found that the star undergoes photospheric oscillations of 1.7 hours and presents a chromospheric structure in the extended atmosphere. Infall velocities and ejection of material are discussed.
Detection of Accreting Circumstellar Gas around Weak Emission-Line Herbig Ae/Be Stars
Grady, C. A.; Perez, M. R.; The, P. S.
We present archival and recent IUE high dispersion spectra of late B stars which reveal the presence of accreting gas with velocities as high as 350 km s‑1, collisional ionization of the accreting gas to temperatures above the stellar Teff, and column densities intermediate between those observed toward classical Herbig Ae/Be…
2800 MG II Emission in the Most Active Radio Stars
Gurzadyan, G. A.; Rustambekyan, S. S.
Spectral recordings in the region near 2800 Å are examined from the IUE archives for the twenty most active radio stars, which are also close binary systems. In all of these spectra, the doublet k and h Mg II is seen in strong emission. We find that the observed fluxes of the magnesium doublet emission are directly proportional to the mean fluxes …
Proper motions in the field of the globular cluster NGC 6934.
Tucholke, H. -J.
We measured relative proper motions with a typical accuracy of 1.0 millarcsec/year (mas/a) for 2000 stars in a 1.4 deg x 1.4 deg field around the low-latitude globular cluster NGC 6934. Four plates taken with the Bonn double refractor, spanning an epoch difference of 62 years, were digitized completely. Within the tidal radius of the cluster, we f…
The establishment of a continuous declination system with photoelectric astrolabe Mark I—An international cooperation between Lintong and Irkutsk
Xu, Jia-yan; Wang, Zheng-ming
We propose a cooperative observational project of using the photo-electric astrolabe Mark I of Shaanxi Observatory in Irkutsk. As the instrument will be equipped with a Z = 45° angle prism, it will have no blind zone when used at latitude ( φ = 52°. Important contribution can be expected to the establishing of fundamental reference system and the …
Seeing the Nuclei of Active Galaxies
Kinney, Anne L.
The Ultraviolet Spectrum of Triton from HST: First Results
Stern, S. Alan; Trafton, Laurence M.
We report on the first Hubble Space Telescope (HST) spectra of Neptune's largest satellite, Triton. The spectra were taken on 16-17 May 1992 by the HST Faint Object Spectrograph. They span the region 2220-3278 Å. This overlaps IUE spectra of Triton we obtained, 2700-3100 Å, and penetrates the region from 2220 to 2550 A for the first time. The deri…
Structural Parameters of Globular Clusters in the Fornax Cluster
Elson, Rebecca A. W.; Schade, David J.
We present measurements of the structural parameters of 24 globular cluster candidates with 19 < I < 22, ~4' from NGC 1399, the central giant elliptical galaxy in the Fornax cluster (distance modulus ~31). The data were obtained with the Hubble Space Telescope's Wide Field Camera prior to refurbishment. We use a two-dimensional model-fitting…