Search Publications
Proper motions of open clusters based on the TYCHO2 Catalogue. II. Clusters farther than 1 kpc
Dias, W. S.; Lépine, J. R. D.; Alessi, B. S.
We determined the mean absolute proper motion of 94 open clusters situated farther than 1 kpc from the Sun. The results are derived from the stellar proper motion data given in the Tycho2 Catalogue. The mean proper motion of the clusters and membership probability of individual stars were obtained from the proper motion data by applying the statis…
Off-limb EUV line profiles and the search for wave activity in the low corona
Harrison, R. A.; Hood, A. W.; Pike, C. D.
Two extreme-ultraviolet (EUV) observations are used to examine the off-limb characteristics of emission line widths of the million K Mg X 625 Å line. To obtain sufficient statistical accuracy, the observations were made over long periods of time and a pixel summing technique is used. The observations are made above the western limb, for quiet coro…
The Eagle's EGGs: Fertile or sterile?
Andersen, M.; McCaughrean, M. J.
We present a deep, high spatial resolution (0.35 arcsec FWHM), near-infrared (1-2.5 mu m) imaging survey of the Eagle Nebula, M 16, made with the VLT, centred on the famous elephant trunks. We compare these data with the existing HST optical images to search for evidence of ongoing or recent star formation in the trunks, and in particular in the 7…
Wind variability of B supergiants. IV. A survey of IUE time-series data of 11 B0 to B3 stars
Massa, D.; Prinja, R. K.; Fullerton, A. W.
We present the most suitable data sets available in the International Ultraviolet Explorer (IUE) archive for the study of time-dependent stellar winds in early B supergiants. The UV line profile variability in 11 B0 to B3 stars is analysed, compared and discussed, based on 16 separate data sets comprising over 600 homogeneously reduced high-resolu…
Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton
Parmar, A. N.; Boirin, L.; Oosterbroek, T. +1 more
We report the discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X1624-490 during an XMM-Newton observation in 2001 February. The features are identified with the Kalpha absorption lines of Fe XXV and Fe XXVI and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV and equivalent widths (EWs) of -7.5 +1.7…
HST observations of the protoplanetary nebula OH 231.8+4.2: The structure of the jets and shocks
Sahai, R.; Sánchez Contreras, C.; Alcolea, J. +1 more
We present high-resolution images obtained with the WFPC2, on board the HST, of the protoplanetary nebula (PPN) OH 231.8+4.2. Hα and NII line emission and scattered light in the continuum at 6750 and 7910 Å were observed. We also discuss NIR NICMOS images from the HST archive. The images show with high accuracy the shape and excitation state of th…
ISO ammonia line absorption reveals a layer of hot gas veiling Sgr B2
Prusti, T.; Ceccarelli, C.; Caux, E. +7 more
We report the first results of the unbiased spectral high resolution survey obtained towards Sgr B2 with the Long Wavelength Spectrometer on board ISO. The survey detected more than one hundreds lines from several molecules. Ammonia is the molecule with the largest number (21) of detected lines in the survey. We detected NH3 transitions…
On electron acceleration at CIR related shock waves
Mann, G.; Keppler, E.; Roelof, E. C. +1 more
The interaction of fast and slow speed solar wind streams leads to the formation of so-called corotating interaction regions (CIRs) in the heliosphere. These CIRs are often associated with shock waves, at which electrons are accelerated as observed by the Ulysses spacecraft. A correlation between the ratio of energetic electron fluxes at the cross…
Probing the mass loss history of carbon stars using CO line and dust continuum emission
Ryde, N.; Olofsson, H.; Schöier, F. L.
An extensive modelling of CO line emission from the circumstellar envelopes around a number of carbon stars is performed. By combining radio observations and infrared observations obtained by ISO the circumstellar envelope characteristics are probed over a large radial range. In the radiative transfer analysis the observational data are consistent…
On the absence of wind bow-shocks around OB-runaway stars: Probing the physical conditions of the interstellar medium
Kaper, L.; Huthoff, F.
High-resolution IRAS maps are used to search for the presence of stellar-wind bow-shocks around high-mass X-ray binaries (HMXBs). Their high space velocities, recently confirmed with Hipparcos observations, combined with their strong stellar winds should result in the formation of wind bow-shocks. Except for the already known bow-shock around Vela…