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Quasar hosts: differences between radio-loud and radio-quiet galaxies
Kukula, Marek J.
Strong evidence exists that radio-loud quasars and FR II radio galaxies differ only in the orientation of their central AGN, and HST studies of quasar hosts have confirmed that there are no significant differences between radio galaxies and the massive elliptical galaxies which host RLQs. Detailed studies of radio-quiet quasars show that these pow…
Shock acceleration of energetic particles in wave heated corona
Laitinen, T.; Vainio, R.
The solar wind wave heating models require substantial amount of wave power in order to efficiently heat and accelerate solar wind. The level of fluctuations is however limited by energetic particle observations. The simplest cyclotron sweep models result in convection-dominated transport, contradicting observations. However, models incorporating …
Estimating the Interstellar Extinction and the Contribution from an Accretion Shock to the Formation of Emission Continuum in DS Tau and DG Tau
Kravtsova, A. S.
We analyze the UV spectra of the young stars DG Tau and DS Tau taken with the STIS spectrograph from the Hubble Space Telescope. For these stars, we found the upper limits of the interstellar extinction A_V. Their values proved to be lower than those obtained by other authors from optical observations. For DS Tau, DG Tau, and TW Hya, we also deter…
Calculated atmospheric color refraction and observed stellar positions
Langhans, R.; Malyuto, V.; Potthoff, H.
Astrometric observations at different zenith distances have been performed in Dresden in an area centered at NGC 6791 where there are some stars with reliable color information (widely dispersed spectral types in the MK system and color indices BT-VT) as well as with accurate positions from Tycho-2 catalog. The results are us…
Radio galaxy host properties spanning three dex in radio luminosity
Willott, Chris J.; Rawlings, Steve; Jarvis, Matt J. +4 more
We describe a major study of radio source host galaxies being carried out with the HST and ground-based facilities. Our sample is selected from 4 complete samples with different radio flux-density limits, giving a range of three orders of magnitude in radio luminosity at a fixed epoch ( z=0.5). High-resolution HST WFPC2 imaging shows that all 44 r…
Identifying Compact Moving Groups Based on Stellar Kinematics Data
Flynn, C.; Orlov, V. V.; Myullyari, A. A.
We investigate the possibility of identifying substructures in velocity space in three well-known stellar streams (the Hyades, the Pleiades, and Ursa Major) using a cluster-analysis method (the maximum-density method). Only compact groups in velocity space with radii no greater than 5 km/s and containing at least 10 members were considered. As an …
Calibration of the Strömvil Photometric System
Sperauskas, J.; Straižys, V.; Boyle, R. P. +4 more
A calibration of color indices of the Strömvil photometric system in terms of physical parameters of stars is presented. The calibration is based on photoelectric photometry of about 1000 stars with known effective temperatures, distances, gravities and metallicities. The observations were accomplished in 2000--2003 with the 1.5 meter telescope of…
Solar radio emissions at solar maximum: Interplanetary perspective
Kaiser, M. L.
At frequencies below 10-15 MHz, radio astronomical observations of the sun are routinely performed in space because Earth's ionosphere effectively prohibits these low frequency emissions from reaching the ground. In terms of solar altitude, these frequencies correspond to about 2 Rs to 1 AU.At these low frequencies, a least four counterparts of th…
The CCD and readout electronics for the OMC instrument on Integral
Culhane, J. L.; Smith, A.; Jordan, B. +4 more
The Optical Monitoring Camera (OMC) on ESA's Integral gamma-ray astronomy satellite is devoted to optical wavelength observations simultaneously covering the same field-of-view as the gamma-ray and X-ray instruments. The OMC consists of a refracting telescope with a CCD as the imaging device in the focal plane. Here we describe the CCD and its ass…
Energetic ions in the high latitude boundary layer of the magnetosphere—Rapid/Cluster observation
Zong, Q. -G.; Daly, P.; Fritz, T. A. +1 more
The thrust of this paper concentrates on the energetic ion behaviour near the high latitude boundary layer of the magnetosphere during both IMF southward and northward conditions. On December 19, 2000, an energetic ion layer has been observed in the high latitude boundary region just outside the magnetosphere during IMF southward. However, on Janu…