Search Publications
Observations and Modeling of an Explosive Coronal Mass Ejection as Observed by LASCO
Wu, S. T.; Andrews, M. D.; Wang, A. -H.
We present a qualitative and quantitative comparison of a single coronal mass ejection (CME) as observed by LASCO on 5 October 1996 with the results of a two-dimensional magnetohydrodynamic (MHD) model. This event was selected as a clear example of a CME that is not caused by the disruption of a helmet streamer. This CME occurs against the backgro…
Different spatial structures between network regions and active regions indicated by TRACE 171 Å observation
Zhang, H. Q.; Zhang, M.; Wang, H. N. +1 more
By comparing TRACE 171 Å observations with photospheric magnetograms, we find that the root of TRACE 171 Å emission is centered in magnetic elements in simultaneous Huairou photospheric magnetogram and the luminosity of TRACE 171 Å emission is not always in proportion to the strength of the corresponding photospheric magnetic field. While TRACE em…
Evidence for a Population of Numerous Binaries with Comparably Bright Components among HIPPARCOS ``Single'' F Stars
McMaster, M.; Suchkov, A. A.
We find evidence for the presence of a population of numerous binaries with comparably bright components (C binaries) among Hipparcos F stars that are flagged in the Hipparcos catalog as single. We propose a criterion that identifies such binaries. The criterion is based on comparison of absolute magnitude MV obtained from the Hipparcos…
A Study of the Time-dependent Background and Continuum Flux Levels in IUE High-Dispersion SWP Images
Smith, Myron A.
The extraction of net spectral fluxes from echellogram images for the creation of the final International Ultraviolet Explorer (IUE) archive was accomplished by the processing system NEWSIPS computing a background surface from unilluminated pixels over a wide area of the image for any given echellogram order. Although this technique facilitates th…
The HIPPARCOS transit data: What, why and how?
Lindegren, L.; Quist, C. F.
The Hipparcos Transit Data are a collection of partially reduced, fully calibrated observations of (mostly) double and multiple stars obtained with the ESA Hipparcos astrometry satellite. The data are publicly available, as part of the CD-ROM set distributed with the Hipparcos and Tycho Catalogues \cite[(ESA SP-1200, 1997)]{hip}, for about a third…
The Second Cape Photographic Catalogue on the HIPPARCOS System
Zacharias, N.; Zacharias, M. I.; de Vegt, C.
The Second Cape Photographic Catalogue (CPC2) is an astrometric, photographic catalog covering the entire Southern Hemisphere to a limiting magnitude of about 10.5. The Hipparcos Catalogue has been used for a new, plate-by-plate, rigorous reduction. A significant improvement over the release 1 version of the data was achieved. With an average accu…
The widths of the unidentified infrared bands (UIBs). Molecular or solid-state carriers?
Papoular, Renaud
The molecular and solid-state models of the UIB widths are confronted with observations from ground-based telescopes and the ISO satellite. The PAH (Polycyclic Aromatic Hydrocarbons) model requires that free-flying molecules be excited by vacuum UV radiation. However, recent laboratory measurements of vibrational emission reveal that, in this case…
Galactic Extinction from Colors and Counts of Field Galaxies in WFPC2 Frames: An Application to GRB 970228
Fruchter, Andrew S.; González, Rosa A.; Dirsch, Boris
We develop the ``simulated extinction method'' to measure average foreground Galactic extinction from field galaxy number counts and colors. The method comprises simulating extinction in suitable reference fields by changing the isophotal detection limit. This procedure takes into account selection effects; in particular, the change in the isophot…
Plasma and Warm Dust in the Collisional Ring Galaxy VII ZW 466 from VLA and ISO Observations
Appleton, P. N.; Charmandaris, V.; Ghigo, F. +4 more
We present the first mid-infrared (mid-IR) (5-15 µm) and radio continuum (λ=20, 6, and 3.6 cm) observations of the star-forming collisional ring galaxy VII Zw 466 and its host group made with the Infrared Space Observatory (ISO) and the NRAO Very Large Array. A search was also made for CO line emission in two of the galaxies with the Onsala …
UGC 3995: A Close Pair of Spiral Galaxies
Marziani, P.; D'Onofrio, M.; Sulentic, J. W. +1 more
UGC 3995 is a close pair of spiral galaxies whose eastern component hosts a Seyfert 2 nucleus. The object was selected for observation because a bright filamentary structure that apparently connects the nuclei of the two galaxies made it a good candidate to investigate a possible connection between galaxy interactions and active galactic nuclei. W…