Search Publications
MG II Observed in the Local Interstellar Medium: The Local Cloud
Molaro, P.; Beckman, J. E.; Vladilo, G. +1 more
Observations of interstellar absorptions superposed on the chromospheric Mg II emissions of nearby cool stars have been used to explore the structure of the local interstellar medium along many lines of sight. The interstellar cloud in which the sun is immersed (the 'local cloud', hereafter LC) has not previously been detected using this technique…
Ultraviolet Interstellar Absorption toward HD 163522, a Halo Star at 9 Kiloparsecs in the Direction L = 350 and B = -9
Savage, Blair D.; Sembach, Kenneth; Massa, Derck
UV interstellar absorption line measurements obtained by the IUE satellite toward HD 163522 in the direction l = 349.6 deg and b = -9 deg are analyzed. The UV stellar spectrum of HD 163522 places the star beyond the Galactic center at a distance away from the Galactic plane of z = -1.5 kpc. An absorption-line spectrum with S/N approximately equal …
The Mass of the Classical Cepheid SU Cygni
Bolton, C. T.; Evans, Nancy Remage
Velocities of the companion of the classical Cepheid SU Cyg have been measured from 13 IUE high-dispersion spectra. Because the companion is itself a member of a short-period binary system, its short-period orbit and the orbital amplitude of the center of mass in the long-period system are determined from a triple system solution. The velocity amp…
Ionization in Nearby Interstellar Gas
Frisch, P. C.; York, D. G.; Fowler, J. R. +1 more
Due to dielectric recombination, neutral magnesium represents an important tracer for the warm low-density gas around the solar system. New Mg I 2852 absorption-line data from IUE are presented, including detections in a few stars within 40 pc of the sun. The absence of detectable Mg I in Alpha CMa and other stars sets limits on the combined size …
On the Spectrum and Field Strength of the Magnetic White Dwarf GD 229
Foltz, Craig B.; Schmidt, Gary D.; Latter, William B.
The broad-coverage optical spectrum obtained for the strongly polarized magnetic white dwarf GD 229 reveals additional as well as apparent changes in the locations of known absorption features; the latter are ostensibly due to star rotation in the decade since the last published spectrum. Since (1) the spectrum of magnetized hydrogen is not consis…
Ultraviolet and Optical Spectroscopy of NGC 5548 and the Nature of the Broad-Line Region
Peterson, Bradley M.; Reichert, Gail A.; Korista, Kirk T. +1 more
The structure of the broad-line region in NGC 5548 is investigated by analysis of the integrated flux and profile variations observed in optical and ultraviolet emission lines. It is shown that the observations do not appear to be consistent with models which identify the variable part of the emission lines with a simple rotating disk structure. T…
IUE Observations of Rapidly Rotating Low-Mass Stars in Young Clusters: The Relation between Chromospheric Activity and Rotation
Simon, Theodore
If the rapid spindown of low-mass stars immediately following their arrival on the ZAMS results from magnetic braking by coronal winds, an equally sharp decline in their chromospheric emission may be expected. To search for evidence of this effect, the IUE spacecraft was used to observe the chromospheric Mg II emission lines of G-M dwarfs in the n…
Ultraviolet Fe VII Absorption Lines in Planetary Nebula Nuclei, Hot Subdwarfs, and Hot Degenerate Objects
Feibelman, Walter A.; Bruhweiler, Frederick C.
Results are reported from a search for Fe VII absorption lines in data from high-dispersion IUE-SWP observations of PN nuclei (PNN), hot subdwarfs (HSDs), and hot white dwarfs (HWDs). The data-reduction techniques employed are outlined, and the results are presented in extensive tables and sample spectra and characterized in detail. Absorption in …
The Identification of H 3S + with the Ion of Mass per Charge (m/q) 35 Observed in the Coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
A sharp peak in the mass spectrum at 35 amu is observed by the heavy ion analyzer on board the Giotto spacecraft just inside the ionopause. This peak is identified with H3S(+) and it is argued that the dominant source of its likely parent molecule (H2S) is the observed distributed source of circumnuclear dust, rather than the central nucleus. In t…
Ultraviolet and Infrared Monitoring of FG Sagittae during 1982--1989: Evolutionary Status
Fernandez-Castro, Telmo; Cassatella, Angelo; Eiroa, Carlos +3 more
Ultraviolet IUE spectra and infrared JHKL photometry of FG Sge obtained over the period 1982-1989 indicate that the cooling rate of the star observed until about 1980 seems to have stopped and that an increase of the effective temperature may have occurred, this being a significant change in the evolutionary path traced so far. The current spectra…