Search Publications
A Search for High-Velocity Be Stars
Gies, D. R.; Berger, D. H.
We present an analysis of the kinematics of Be stars based upon Hipparcos proper motions and published radial velocities. We find approximately 23 of the 344 stars in our sample have peculiar space motions greater than 40 km s-1 and up to 102 km s-1. We argue that these high-velocity stars are the result of either a supernova…
Differential Flow Speeds of Ions of the Same Element: Effects on Solar Wind Ionization Fractions
Esser, Ruth; Edgar, Richard J.
In previous studies of solar wind ion fractions it has always been assumed that ions of the same element flow with the same flow speed. In the present paper, we investigate the effects of differential flow speeds between different ionization states of the same element on the formation of O, C, Mg, Si, and Fe ions. We show that if the difference in…
Keck LWS Images of the Compact Nebula around RY Scuti in the Thermal Infrared
Smith, Nathan; Gehrz, Robert D.; Yahil, Amos +2 more
We report new 3 to 20 µm Keck Telescope images of the massive eclipsing binary RY Scuti with ~0.25" spatial resolution. These images show complex structure near the diffraction limit of the 10 m telescope in a nebula less than 2" across. The limb-brightened structure is consistent with optically thin emission from a circumstellar torus. At 3…
Optical Spectrum of the Compact Planetary Nebula IC 5117
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H. +1 more
High-resolution spectroscopic data of the very compact planetary nebula IC 5117 were obtained in optical wavelengths of 3700-10050 Å with the Hamilton Echelle Spectrograph at the Lick Observatory and have been analyzed along with the International Ultraviolet Explorer UV archive data. Although a diagnostic diagram shows significant density and tem…
RR Lyrae Variables in the Globular Clusters of M31: A First Detection of Likely Candidates
Clementini, G.; Cacciari, C.; Bellazzini, M. +3 more
The purpose of this Letter is to show that RR Lyrae variables exist and can be detected in M31 globular clusters. We report on the first tentative identification of RR Lyrae candidates in four globular clusters of the Andromeda galaxy, i.e., G11, G33, G64, and G322. Based on Hubble Space Telescope Wide Field Planetary Camera 2 archive observations…
The Infrared Continuum Spectrum of VY Canis Majoris
Decin, Leen; Feuchtgruber, Helmut; Melnick, Gary J. +3 more
We combine spectra of VY CMa obtained with the short- and long-wavelength spectrometers, SWS and LWS, on the Infrared Space Observatory3 to provide a first detailed continuum spectrum of this highly luminous star. The circumstellar dust cloud through which the star is observed is partially self-absorbing, which makes for complex computational mode…
The European Large-Area Infrared Space Observatory Survey V: A BeppoSAX Hard X-Ray Survey of the S1 Region
Danese, L.; Alexander, D. M.; Perola, G. C. +18 more
We present BeppoSAX observations of the southern S1 region in the European Large-Area Infrared Space Observatory (ISO) Survey (ELAIS). These observations cover an area of ~1.7 deg2 and reach an on-axis (~0.7 deg2) 2-10 keV (hard X-ray, or HX) sensitivity of ~10-13 ergs s-1 cm-2. This is the fi…
Analysis of Type IIn SN 1998S: Effects of Circumstellar Interaction on Observed Spectra
Filippenko, Alexei V.; Kirshner, R. P.; McCray, R. +20 more
We present spectral analysis of early observations of the Type IIn supernova 1998S using the general non-local thermodynamic equilibrium atmosphere code PHOENIX. We model both the underlying supernova spectrum and the overlying circumstellar interaction region and produce spectra in good agreement with observations. The early spectra are well fitt…
Kinematics of 1200 Kilometer per Second Jets in HE 3-1475
Borkowski, Kazimierz J.; Harrington, J. Patrick
Spectroscopic observations of a proto-planetary nebula He 3-1475 with the Space Telescope Imaging Spectrograph reveal the kinematics of its high-velocity (1200 km s-1) jets. The jets are formed at a large (0.15 pc) distance from its central star by collimation of an asymmetric stellar wind in a pair of conical shocks seen in Wide Field …
Observations of the Interstellar Medium in the Magellanic Bridge
Sembach, K. R.; Dufton, P. L.; Keenan, F. P. +2 more
We present ultraviolet and optical spectra of DI 1388, a young star in the Magellanic Bridge, a region of gas between the Small and Large Magellanic Clouds. The data have signal-to-noise ratios of 20-45 and a spectral resolution of 6.5 km s-1. Interstellar absorption by the Magellanic Bridge at vLSR~200 km s-1 is v…