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Cumulants and symmetries in a trivariate normal mixture. A qualitative study of the local velocity distribution
Cubarsi, R.; Alcobé, S.
An alternative parameterization of a trivariate normal mixture for the stellar velocity distribution provides a set of constraint equations between global cumulants that are used to estimate characteristic constants of the mixture and population parameters. Under particular distribution symmetries these relationships become simpler and easy to eva…
Discovery of a new INTEGRAL source: IGR J19140+0951
Rodriguez, J.; Henri, G.; Petrucci, P. O. +5 more
IGR J19140+0951 (formerly known as IGR J19140+098) was discovered with the INTEGRAL satellite in March 2003. We report the details of the discovery, using an improved position for the analysis. We have performed a simultaneous study of the 5-100 keV JEM-X and ISGRI spectra from which we can distinguish two different states. From the results of our…
The Counterstreaming Instability in Dwarf Elliptical Galaxies with Off-Center Nuclei
Debattista, Victor P.; De Rijcke, Sven
In many nucleated dwarf elliptical galaxies (dE,N's), the nucleus is offset by a significant fraction of the scale radius with respect to the center of the outer isophotes. Using a high-resolution N-body simulation, we demonstrate that the nucleus can be driven off-center by the m=1 counterstreaming instability, which is strong in flattened stella…
Wolf-Rayet stars in M33 - I. Optical spectroscopy using CFHT-MOS
Drissen, Laurent; Crowther, Paul A.; Dessart, Luc +3 more
We have obtained spectroscopy of a large sample of Wolf-Rayet stars in M33 with the Canada-France-Hawaii Telescope Multi-Object Spectrograph (CFHT-MOS), including 26 WC stars, 15 WN stars and a WN/C star. In general, spectral types are merely refined, although the spectral type of X9 from Massey & Johnson is revised from WNL?+abs to WC4+abs, w…
The Orbits of the Inner Neptunian Satellites from Voyager, Earth-based, and Hubble Space Telescope Observations
Jacobson, R. A.; Owen, W. M., Jr.
We present revised orbital elements for the six small Neptunian satellites discovered by Voyager 2. The elements have been determined from a fit to imaging data acquired by the Voyager 2 spacecraft and astrometric observations made at Earth-based observatories and by the Hubble Space Telescope. An assessment of the accuracy of the elements is prov…
The dependence of Langmuir wave amplitudes on position in Earth's foreshock
Gurnett, D. A.; Balogh, A.; Pickett, J. S. +3 more
We present the first results of Langmuir wave observations in the foreshock from the Cluster WBD Plasma Wave Receiver. When the data were binned by distance to the foreshock boundary, the Langmuir wave amplitude probability distributions followed the log-normal statistics predicted by stochastic growth theory for all regions of the foreshock. The …
Stellar activity and magnetism studied by optical interferometry
Jankov, S.; Kilbinger, M.; Lanz, T. +5 more
By means of numerical simulations, we investigate the ability of optical interferometry, via the fringe phase observable, to address stellar activity and magnetism. To derive abundance maps and stellar rotation axes, we use color differential interferometry which couples high angular resolution to high spectral resolution. To constrain magnetic fi…
Optical and infrared spectroscopic analysis of the post-AGB star candidate IRAS 19386+0155
Pereira, C. B.; Lorenz-Martins, S.; Machado, M.
This work reports high-resolution spectroscopic stellar parameters and abundance analysis of the post-AGB star IRAS 19386+0155. The analysis of the high resolution spectrum shows that it has an effective temperature of Teff=6800±100 K and a surface gravity of log g = 1.4±0.2. The abundance analysis reveals IRAS 19386+0155 to be a metal-…
The circumstellar environment of IRAS 16293-2422. ISO-LWS and SCUBA observations
Griffin, M.; Saraceno, P.; Correia, J. C.
We present far-infrared (FIR) continuum observations of the deeply embedded source IRAS 16293-2422 performed with the Long Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). We also report 450 and 850 µm mapping observations done with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell T…
Dual Flows with Supersonic Velocities in the Sunspot Transition Region
Wilhelm, K.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more
Observations of sunspot transition region lines that deviate significantly from a Gaussian shape are presented. Attention is given to ``dual flows,'' a line profile phenomenon in which two distinct velocities are observed within the same spatial resolution element. In 5 out of 12 sunspots we observe dual flows. Several emission line profiles are w…