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Resolved stellar populations of super-metal-rich star clusters in the bulge of M 31
Magain, P.; Jablonka, P.; Sarajedini, A. +3 more
We have applied the MCS image deconvolution algorithm (Magain et al. 1998) to HST/WFPC2 V, I data of three M 31 bulge globular clusters (G170, G177, and G198) and control fields near each cluster. All three clusters are clearly detected, with an increase in stellar density with decreasing radius from the cluster centers; this is the first time tha…
The Asymmetric Coma of Comets. I. Asymmetric Outgassing from the Nucleus of Comet 2P/Encke
Festou, M. C.; Barale, O.
Very little is known about how outgassing regions are distributed over the nucleus of comets. In periodic comets, active regions are believed to be few and of small extent. Since periodic comets are notorious for their lack of (small) solid particles that efficiently scatter sunlight, we try to find traces of the existence of production sites by e…
UV light curves of thermonuclear supernovae
Sorokina, E. I.; Blinnikov, S. I.
Ultraviolet light curves are calculated for several thermonuclear supernova models using a multifrequency radiation hydrodynamic code. It is found that Chandrasekhar-mass models produce very similar light curves both for detonation and deflagration. Sub-Chandrasekhar-mass models essentially differ from ``normal'' Chandrasekhar ones regarding behav…
High-Resolution Study of Associated C IV Absorption Systems in NGC 5548
Srianand, R.
We present the results of a careful analysis of associated absorption systems toward NGC 5548. Most of the well-resolved narrow components in the associated system, defined by the Lyα, C IV, and N V profiles, show velocity separation similar (to within 10 km s-1) to the C IV doublet splitting. We estimate the chance probability of the o…
Recent Observations of the Heliospheric Magnetic Field at Ulysses: Return to Low Latitude
Balogh, A.; Tsurutani, B. T.; Smith, E. J. +2 more
Ulysses recently completed a second slow latitude scan of the northern heliosphere, a descent from 80.2°N in July 1995 to the solar equator in December 1997. These recent magnetic field observations complement those from the south hemisphere and reveal new features as well as the effect of the changing solar cycle. Five topics are emphasized in th…
RX J1313.2-3259, a missing link in CV evolution?
Gänsicke, B. T.; Beuermann, K.; de Martino, D. +1 more
We present low-state IUE spectroscopy of the ROSAT-discovered polar RX J1313.2-3259. The SWP spectrum displays a broad Lyalpha absorption profile, which can be fitted with a two-temperature model of a white dwarf of T_wd=15 000 K with a hot spot of T_spot=34 000 K which covers f ~ 0.01 of the white dwarf surface. The white dwarf temperature is aty…
The potential of solar high-degree modes for structure inversion
Christensen-Dalsgaard, J.; Basu, Sarbani; Rabello-Soares, M. C. +1 more
It is likely that precise and reliable frequencies of high-degree modes will soon be available from the SOI/MDI experiment. Here we examine the ability of such modes (with l>300) to resolve the solar structure in the near-surface region. In particular, we investigate inversions to determine the adiabatic exponent Γ1 as a test of the …
Shock excited far-infrared molecular emission around T Tau
White, G. J.; Palla, F.; Pezzuto, S. +9 more
The first complete far-infrared spectrum of T Tau has been obtained with the LWS spectrometer on-board the Infrared Space Observatory (ISO), which detected strong emission from high-J (J=14-25) CO, para- and ortho-H_2O and OH transitions over the wavelength range from 40 to 190 mu m. In addition the [OI]63mu m, [OI]145mu m and [CII]158mu m atomic …
SUMER observations of transition region fine structures
Mason, H. E.; Landini, M.; Lemaire, P. +1 more
The SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on SOHO (Solar and Heliospheric Observatory) provides an opportunity to observe and study the solar transition region with high spatial and spectral resolution. We present new evidence to confirm that the emission from the quiet Sun at 2x 105 K is dominated by co…
On measuring low-degree p-mode frequency splitting with full-disc integrated data
Appourchaux, T.; Gough, D. O.; Sekii, T. +1 more
The standard method of measuring rotational splitting from solar full-disc oscillation data, based on maximum-likelihood fitting of multi-Lorentzian profiles to oscillation power spectra, systematically overestimates the splitting. One of the reasons is that the maximum likelihood estimators (MLE) become unbiased only asymptotically as the number …