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…
The first broad-band X-ray images and spectra of the 30 Doradus region in the LMC
Pietsch, W.; Haberl, F.; Hasinger, G. +25 more
We present the XMM-Newton first light image, taken in January 2000 with the EPIC pn camera during the instrument's commissioning phase, when XMM-Newton was pointing towards the Large Magellanic Cloud (
Host Galaxies, Obscuration, and Nuclear Structure of Three Nearby Compact Symmetric Objects
Perlman, Eric S.; Stocke, John T.; Conway, John +1 more
We present three-band Hubble Space Telescope imaging of three nearby (z<=0.1) compact symmetric objects: 4C 31.04, 1946+708, and 1146+596. These objects were chosen on the basis of proximity to Earth as well as H I 21 cm line absorption. The inner H-band isophotes of these galaxies are well fitted by Nuker models, typical of nearby elliptical g…
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…
A new galaxy near the Local Group in Draco
Sarajedini, A.; Dolphin, A. E.; Grebel, E. K. +7 more
We present HST WFPC2 and ground-based images of the low surface brightness dwarf Irr/Sph galaxy KKR 25 in Draco. Its colour-magnitude diagram shows red giant branch stars with the tip at I= 22fm32 , and the presence of some blue stars. The derived true distance modulus, 26fm35 +/- 0fm14 , corresponds to linear distances of KKR 25 from the Milky Wa…
A Detailed Analysis of a Cygnus Loop Shock-Cloud Interaction
Blair, William P.; Danforth, Charles W.; Raymond, John C.
The XA region of the Cygnus Loop is a complex zone of radiative and nonradiatve shocks interacting with interstellar clouds. We combine five far ultraviolet spectral observations from the Hopkins Ultraviolet Telescope (HUT), a grid of 24 IUE spectra, and a high-resolution long-slit Hα spectrum to study the spatial emission line variations across t…
Stellar models and Hyades: the Hipparcos test
Prada Moroni, P. G.; Degl'Innocenti, S.; Castellani, V.
We compare theoretical stellar models for main sequence (MS) stars with the Hipparcos data base for the Hyades cluster to give a warning against the uncritical use of available theoretical scenarios and to show how formal MS fittings can be fortuitous if not fictitious. Moreover, we find that none of the current theoretical scenarios appears able …
Chemical abundances of planetary nebulae from optical recombination lines - II. The neon abundance of NGC 7009
Barlow, M. J.; Liu, X. -W.; Luo, S. -G.
We present high-quality observations of Neii optical recombination lines (ORLs) for the bright Saturn Nebula NGC 7009. The measured line fluxes are used to determine Ne2+/H+ abundance ratios. The results derived from individual multiplets of the 3s-3p and 3p-3d configurations agree reasonably well, although values derived fro…
The infrared continuum radiation of NGC 1808. A PAH and polarisation study
Siebenmorgen, R.; Laureijs, R. J.; Krügel, E.
The paper is devoted to the understanding of the infrared emission of nuclear regions in galaxies. a) ISO data of NGC 1808 are presented: spectro-photometry from 5.1 to 16.4 mu m; a 25''x 25'' map at 6 mu m and 170 mu m photometry. b) The data are complemented by a polarisation measurement at 170 mu m (2.5+/-0.4% at position angle 94degr +/-5degr …