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Modelling of dust scattering toward the Coalsack
Shalima, P.; Murthy, Jayant
Murthy, Henry & Holberg discovered intense far-ultraviolet (FUV) (λλ912-1600) emission from the direction of the Coalsack molecular cloud 10 years ago. We have used their results in conjunction with a Monte Carlo model for the scattering in the region to show that the scattering is from dust in the foreground of the Coalsack. The albedo of the…
The Zeeman-sensitive Emission Lines of Mg I at 12 Microns in Procyon
Ryde, N.; Ryde, F.; Korn, A. J. +1 more
Emission lines of magnesium at 12 µm have been observed in the spectrum of Procyon. We reproduce the observed disk-averaged line flux from Procyon (as well as the observed intensity profiles from the Sun) by calculating the line formation and relaxing the assumption of local thermodynamic equilibrium. We find that the lines in Procyon are fo…
Analysis of a Solar Eruptive Event on November 4, 2001, Using CORONAS-F/SPIRIT Data
Grechnev, V. V.; Chertok, I. M.; Kuzin, S. V. +5 more
We analyze large-scale solar activity following the eruption of a very powerful, geoeffective coronal mass ejection in the 23rd solar cycle, observed at 175, 284, and 304 Å on November 4, 2001, using data from the CORONAS-F/SPIRIT telescope. In particular, we have shown that the restructuring of the magnetic field above the eruption center was acc…
Continuous and burst-like accretion on to substellar companions in Mira winds
Struck, Curtis; Cohanim, Babak E.; Willson, Lee Anne
We present numerical hydrodynamical modelling of the effects of a giant planet or brown-dwarf companion orbiting within the extended atmosphere and wind formation zone of an approximately solar-mass Mira variable star. The large-scale, time-dependent accretion flows within the radially oscillating and outflowing circumstellar gas around Miras are …
A model of the stellar radiation field in the UV.
Henry, R. C.; Murthy, Jayant; Sujatha, N. V. +1 more
This work is the first step in a systematic effort to understand and predict the different components of the UV (912 A - 3000 A) radiation field over the entire sky. We have developed a model to predict the ISRF in the UV within a few hundred parsecs of the Sun using the Hipparcos star catalog. We have checked the model through a comparison with t…
Mid-infrared sources in the ELAIS Deep X-ray Survey
Franceschini, A.; Vaccari, M.; Serjeant, S. +9 more
We present a cross-correlation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep X-ray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15-µm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five …
Limits on the Optical Brightness of the ɛ Eridani Dust Ring
Calzetti, Daniela; Livio, Mario; Gull, Theodore R. +10 more
The STIS CCD camera on the Hubble Space Telescope (HST) was used to take deep optical images near the K2 V main-sequence star ɛ Eridani in an attempt to find an optical counterpart of the dust ring previously imaged by submillimeter observations. Upper limits for the optical brightness of the dust ring are determined and discussed in the context o…
VLT FORS-1 observations of NGC 6397: Evidence for mass segregation
Testa, V.; Marconi, G.; Buonanno, R. +3 more
We present (V, V-I) VLT-FORS1 observations of the Galactic Globular Cluster NGC 6397. We derive accurate color-magnitude diagrams and luminosity functions (LFs) of the cluster Main Sequence (MS) for two fields extending from a region near the centre of the cluster out to ≃10 arcmin. The photometry of these fields produces a narrow MS extending dow…
The Enigmatic Radio Source T Tauri S
Hummel, C. A.; Thomasson, P.; Johnston, K. J. +4 more
We have observed the T Tau multiple star system using the Multielement Radio-linked Interferometer Network at a frequency of 5 GHz. The compact centimeter wavelength radio emission from T Tau S has been found to consist of at least two components separated by approximately 70 mas in right ascension at Julian epoch 2001.89. Using this data and that…
Inference of hot star density stream properties from data on rotationally recurrent DACs
Owocki, S. P.; Kaper, L.; Hamann, W. -R. +5 more
The information content of data on rotationally periodic recurrent discrete absorption components (DACs) in hot star wind emission lines is discussed. The data comprise optical depths τ(w,φ) as a function of dimensionless Doppler velocity w=(Δλ/λ0)(c/v&infy) and of time expressed in terms of stellar rotation angle φ. This…