Search Publications
A Synoptic Study of H alpha Line Profile Variability in the T Tauri Star SU Aurigae
Giampapa, Mark S.; Basri, Gibor S.; Johns, Christopher M. +1 more
We present a catalog of 106 high spectral resolution observations of the H-alpha line profile in the T Tauri star SU Aurigae, obtained during the period from 1986 October through 1990 November. The spectra were acquired during joint synoptic programs to observe selected T Tauri stars using the Hamilton Echelle Spectrometer of the Lick Observatory …
The First Detection of Ionized Helium in the Local ISM: EUVE and IUE Spectroscopy of the Hot DA Dwarf GD 246
Bowyer, Stuart; Vennes, Stephane; Chayer, Pierre +4 more
We report observations of the extreme ultraviolet spectrum of the hot degenerate star GD 246 obtained with the EUVE. Our initial attempt at modeling the photospheric emission from the white dwarf reveals a relatively uncontaminated pure H spectrum in the range above 200 A, allowing a study of interstellar continuum absorption features in the line …
Morphology and time variation of the Jovian far UV aurora: Hubble Space Telescope observations
Paresce, Francesco; Prange, Renee; Gerard, Jean-Claude +1 more
High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera on board the Hubble Space Telescope. The first set of two images collected 87 min apart in February 1992 shows a bright (≃180 kR) emission superimposed on the background in rotation with the planet. Both Ly α images show common regio…
Cyclotron and Zeeman spectroscopy of MR Serpentis in low and high states of accretion.
Beuermann, K.; Jordan, S.; Schwope, A. D. +1 more
Phase-resolved low-resolution spectrophotometry of the polar MR Ser obtained during states of low and high accretion reveals cyclotron line emission as well as Balmer line Zeeman absorption. At both occasions the cyclotron lines move with phase. The whole system of cyclotron lines appears wavelength- and phase-shifted when the system switches from…
HST Imaging of Hydrogen-poor Ejecta in Abell 30 and Abell 78: Wind-blown Cometary Structures
Harrington, J. P.; Borkowski, Kazimierz J.; Tsvetanov, Zlatan +1 more
HST Faint Object Camera images of hydrogen-poor gas in the planetary nebulae A30 and A78 have revealed remarkable 'cometary' structures in the O III 5007-A forbidden line. Most of these cometary structures, consisting of compact (0.15-0.5 arcsec) knots with radial tails several arcsec in length, are located in an equatorial plane in both nebulae. …
Evaluation of Emission Mechanisms at omega P E Using ULYSSES Observations of Type III Bursts
Goldstein, M. L.; Stone, R. G.; Lengyel-Frey, D. +1 more
We present the first observational tests of existing theories for the generation of type III radio bursts emitting at the fundamental plasma frequency, ωpe. This study is based on local radio emission and in situ wave phenomena associated with four interplanetary type III radio bursts observed by the unified radio and plasma wave experi…
High-Energy Spectrum of Cygnus X-1 Revisited
Done, C.; Fabian, A. C.; Matt, G. +1 more
The X-ray spectrum of Cyg X-1 is probably produced by thermal Comptonization in an accretion disk corona. Photons reflected from the disk are also Comptonized, so the predicted reflection spectrum is dependent on the optical depth and temperature of the scattering medium. Thus, observations of reflection in the 2-20 keV energy range can constrain …
Binary Star Orbits From Speckle Interferometry. V. A Combined Speckle/Spectroscopic Study of the O Star Binary 15 Monocertis
Gies, Douglas R.; Shara, Michael M.; Penny, Laura R. +7 more
We report on the discovery of a speckle binary companion to the O7 V (f) star 15 Monocerotis. A study of published radial velocities in conjunction with new measurements from Kitt Peak National Observatory (KPNO) and IUE suggests that the star is also a spectroscopic binary with a period of 25 years and a large eccentricity. Thus, 15 Mon is the fi…
New detections of Ly-alpha emission in young galaxies.
Terlevich, Roberto; Terlevich, Elena; Diaz, Angeles I. +1 more
We report IUE observations of two extremely low-metallicity H II galaxies. Ly α emission was detected in both galaxies. Our results confirm previous findings that young or unevolved galaxies exhibit weak or absent Ly α emission combined with a strong UV continuum, and that the Ly α/Hβ ratio and metal content are correlated in the sense that the lo…
The dusty ballerina skirt of Jupiter
Horanyi, M.; Gruen, E.; Morfill, G.
We suggest a model to explain the unexpected recurrent dust events that were observed during the Jupiter encounter by the dust detector on board the Ulysses spacecraft. This model is based on dust-magnetosphere interactions. Dust particles inside the Jovian magnetosphere collect electrostatic charges and their interaction with the magnetic and ele…