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Processing of silicate dust grains in Herbig Ae/Be systems
Waters, L. B. F. M.; Hony, S.; Dominik, C. +3 more
We have analysed the 10 mu m spectral region of a sample of Herbig Ae/Be (HAEBE) stars. The spectra are dominated by a broad emission feature caused by warm amorphous silicates, and by polycyclic aromatic hydrocarbons. In HD 163296 we find aliphatic carbonaceous dust, the first detection of this material in a HAEBE star. The silicate band shows a …
A Possible Cepheid-like Luminosity Estimator for the Long Gamma-Ray Bursts
Ramirez-Ruiz, Enrico; Hurley, Kevin; Reichart, Daniel E. +3 more
We present a possible Cepheid-like luminosity estimator for the long gamma-ray bursts based on the variability of their light curves. To construct the luminosity estimator, we use CGRO/BATSE data for 13 bursts, Wind/Konus data for five bursts, Ulysses/GRB data for one burst, and NEAR/XGRS data for one burst. Spectroscopic redshifts, peak fluxes, a…
The black hole masses of Seyfert galaxies and quasars
McLure, R. J.; Dunlop, J. S.
The central black hole masses of a sample of 30 luminous quasars are estimated using Hβ full width half-maximum (FWHM) measurements from a combination of new and previously published nuclear spectra. The quasar black hole mass estimates are combined with reverberation-mapping measurements for a sample of Seyfert galaxies in order to study active g…
The SUMER spectral atlas of solar-disk features
Dwivedi, B. N.; Wilhelm, K.; Curdt, W. +4 more
A far-ultraviolet and extreme-ultraviolet (FUV, EUV) spectral atlas of the Sun between 670 Å and 1609 Å in the first order of diffraction has been derived from observations obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory). The atlas contains spect…
Population effects on the red giant clump absolute magnitude, and distance determinations to nearby galaxies
Salaris, Maurizio; Girardi, Léo
The red giant clump has been recently argued to be a reliable distance indicator for the galaxies in the Local Group. The accuracy of distance determinations based on this method, however, depends on the possible presence of systematic magnitude differences (ΔMIRC) between the local clump revealed by the Hipparcos colour-magnitude diagram (CMD), a…
ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
Prusti, T.; Olofsson, G.; Boulanger, F. +19 more
We present the results of the first extensive mid-infrared (IR) imaging survey of the rho Ophiuchi embedded cluster, performed with the ISOCAM camera on board the ISO satellite. The main rho Ophiuchi molecular cloud L1688, as well as the two secondary clouds L1689N and L1689S, have been completely surveyed for point sources at 6.7 mu m and 14.3 mu…
First results of electric field and density observations by Cluster EFW based on initial months of operation
Wahlund, J. -E.; André, M.; Khotyaintsev, Y. +22 more
Highlights are presented from studies of the electric field data from various regions along the Cluster orbit. They all point towards a very high coherence for phenomena recorded on four spacecraft that are separated by a few hundred kilometers for structures over the whole range of apparent frequencies from 1 mHz to 9 kHz. This presents completel…
M33: A Galaxy with No Supermassive Black Hole
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +9 more
Galaxies that contain bulges appear to contain central black holes whose masses correlate with the velocity dispersion of the bulge. We show that no corresponding relationship applies in the pure disk galaxy M33. Three-integral dynamical models fit Hubble Space Telescope WFPC2 photometry and Space Telescope Imaging Spectrograph spectroscopy best i…
The correlation between solar energetic particle peak intensities and speeds of coronal mass ejections: Effects of ambient particle intensities and energy spectra
Kahler, S. W.
The correlation of peak intensities of solar energetic particle (SEP) events with the speeds of the associated coronal mass ejections (CMEs) is understood to be a result of SEP acceleration at shocks driven by the CMEs. However, the peak SEP intensities associated with CMEs of a given speed vary over ~ 4 orders of magnitude. We examine a database …
Observational Determination of the Rate of Magnetic Helicity Transport through the Solar Surface via the Horizontal Motion of Field Line Footpoints
Chae, Jongchul
Magnetic helicity may be transported to the solar corona through the solar surface either via the passage of helical magnetic field lines from below or via the shuffling of footpoints of preexisting coronal field lines. In this Letter, we show how to observationally determine the rate of magnetic helicity transport via photospheric footpoint shuff…