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Overexpanding coronal mass ejections at high heliographic latitudes: Observations and simulations
McComas, D. J.; Riley, Pete; Gosling, J. T. +1 more
Ulysses observations reveal that most coronal mass ejections (CMEs) observed in the solar wind far from the Sun at high heliographic latitudes have large radial widths and are still expanding as they pass the spacecraft. CME radial widths ranging between 0.5 and 2.5 AU have been observed at heliocentric distances between 1.4 and 4.6 AU and at lati…
A model of solar total and spectral irradiance variations
Solanki, S. K.; Unruh, Y. C.; Fligge, M. +2 more
We model solar spectral irradiance variations under the assumption that they are produced by sunspots and faculae alone. The model is based on three components, i.e. quiet Sun, assumed to be temporally invariant, sunspots and faculae whose temporal variations are mimicked using time series of sunspot areas and Mg II core-to-wing ratios. The detail…
Emission Features and Source Counts of Galaxies in the Mid-Infrared
Xu, Cong; Ashby, Matthew L. N.; Shupe, David L. +6 more
In this work we incorporate the newest Infrared Space Observatory (ISO) results on the mid-infrared spectral energy distributions (MIR SEDs) of galaxies into models for the number counts and redshift distributions of MIR surveys. A three-component model, with empirically determined MIR SED templates of (1) a cirrus/photodissociation region compone…
Optical Structure and Colors of Faint Compact Narrow Emission-Line Galaxies
Bershady, Matthew A.; Koo, David C.; Simard, Luc +2 more
We present the results of Hubble Space Telescope Wide Field Planetary Camera imaging in V606 and I814 of five compact narrow emission line galaxies (CNELGs) and four slightly more extended faint blue galaxies (FBGs) with 20.3<=B<=22.4 and redshifts z~0.22-0.66. Half-light radii are measured to span from 0.14" to 0.67", …
An analysis of DA white dwarfs from the Hamburg Quasar Survey
Reimers, D.; Dreizler, S.; Heber, U. +5 more
Follow-up spectroscopy of several hundred hot stars detected by the Hamburg Quasar Survey (HQS) has been carried out between 1989 and 1996. We present the analysis of 80 DA white dwarfs using model atmospheres and theoretical cooling tracks to derive the atmospheric parameters T_eff and log g, masses and absolute magnitudes. The HQS turned out to …
A reliable transformation of HIPPARCOS H_p magnitudes into Johnson V and B magnitudes
Harmanec, P.
A comparison of accurate UBV magnitudes, derived from numerous observations at Hvar and SkalnatePleso, and of the mean Hipparcos \hp magnitudes for a number of constant stars showed a very good mutual correspondence of these two data sets. Simple transformation formul\ae\ are presented which allow calculating Johnson V and B magnitudes from the \h…
A Search for Ultraviolet Emission from LINERs
Filippenko, Alexei V.; Ho, Luis C.; Barth, Aaron J. +1 more
We have obtained Hubble Space Telescope Wide Field and Planetary Camera 2 ultraviolet (UV) 2200 Å and optical V-band images of 20 low-luminosity active galactic nuclei, most of which are spectroscopically classified as LINERs, in order to search for a possible photoionizing continuum. Six (30%) of the galaxies are detected in the UV. Two of the de…
Comparison of two different extinction laws with HIPPARCOS observations
Carraro, G.; Vergely, J. L.; Chen, B. +1 more
Interstellar absorption in the galactic plane is highly variable from one direction to another. In this paper colour excesses and distances from a new open cluster sample are used to investigate the spatial distribution of the interstellar extinction. An inverse method (Tarantola & Valette, 1982) is used to construct the extinction map in the …
On the Far-Infrared Emission of Quasars
Haas, Martin; Meisenheimer, Klaus; Chini, Rolf +4 more
Infrared spectral energy distributions between 4.8 and 200 µm are presented for a subsample of 10 quasars and radio galaxies from the European Central Quasar Programme observed with the Infrared Space Observatory. For three of the sources, this represents the first far-infrared detection. The spectral energy distributions (SEDs) reveal signa…
On the relationship between coronal mass ejections and magnetic clouds
Thompson, B. J.; Nitta, N.; Steinberg, J. T. +9 more
We compare the substructures of the 1997 February 07 coronal mass ejection (CME) observed near the Sun with a corresponding event in the interplanetary medium to determine the origin of magnetic clouds (MCs). We find that the eruptive prominence core of the CME observed near the Sun may not directly become a magnetic cloud as suggested by some aut…