Search Publications
Solar latitudinal distortions: From observations to theory
Lefebvre, S.; Rozelot, J. P.
Solar diameters have been measured from different ground-based instruments on different sites all around the world. There are values dating back to three centuries ago, but the revival of interest began in the 1970s when it was claimed that a temporal periodic modulation had been found. The interest of such measurements, pinpointed from only two d…
Soft X-ray heating of the solar chromosphere during the gradual phase of two solar flares
Heinzel, P.; Berlicki, A.
In this paper we perform an analysis of the energetics of the solar flaring chromosphere irradiated by soft X-rays (SXR) emitted from overlying hot flare loops. To study an expected SXR heating we used the observations of two solar flares obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph attached to the Large Coronagraph o…
Is the giant elliptical galaxy NGC 5018 a post-merger remnant?
Bressan, A.; Buson, L. M.; Burstein, D. +2 more
NGC 5018, one of the weakest UV emitters among giant ellipticals (gE) observed with IUE, appears to consist of an optical stellar population very similar to that of the compact, dwarf elliptical M 32, which is several magnitudes fainter in luminosity than NGC 5018 and whose stellar population is known to be ∼3 Gyr old. Here we show that the mid-UV…
Astrometric monitoring of the binary brown dwarf DENIS-P J1228.2-1547
Martín, E. L.; Bouy, H.; Brandner, W. +4 more
We present astrometric monitoring data of the binary brown dwarf DENIS-P J1228.2-1547. The data have been obtained with the Hubble Space Telescope over a time span of 5.5 yr, and confirm that DENIS-P J1228.2-1547 is indeed a common proper motion, i.e., physical, binary. The data cover about 1/8th of the binary orbit, indicating an orbital period o…
Acceleration of electrons by interacting CMEs
Odstrcil, D.; Vandas, M.
There is growing observational evidence that interaction of coronal mass ejections (CMEs) near the Sun is a common phenomenon, particularly during the solar cycle's maximum years. Recently, we performed 2.5-D MHD simulations of the interaction between two magnetic flux ropes. The aim was to provide some qualitative picture of the shock-cloud and c…
The tidally disturbed luminous compact blue galaxy Mkn 1087 and its surroundings
Esteban, C.; López-Sánchez, Á. R.; Rodríguez, M.
We present new broad-band optical and near-infrared CCD imaging together with deep optical intermediate-resolution spectroscopy of Mkn 1087 and its surrounding objects. We analyze the morphology and colors of the stellar populations of the brightest objects, some of them star-formation areas, as well as the kinematics, physical conditions and chem…
Gamma-ray all-sky imaging with the Burst and Transient Source Experiment
Hill, A. B.; Knödlseder, J.; Bird, A. J. +6 more
The BATSE mission aboard CGRO monitored the whole sky in the 20 keV-1 MeV energy band continuously from April 1991 until June 2000. Although BATSE had very poor intrinsic angular resolution, the data can be used to survey the entire soft gamma-ray sky with <1° angular resolution and ∼mCrab sensitivity by using the Earth occultation m…
The XMM-Newton observation of GRB 040106: Evidence for an afterglow in a wind environment
Piro, L.; De Pasquale, M.; Gendre, B.
We present the XMM-Newton observation of GRB 040106. From the X-ray spectral index and temporal decay, we argue that the afterglow is consistent with a fireball expanding in a wind environment. A constant density environment is excluded by the data. This is one of the very few cases in which this conclusion can be drawn.
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…
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…