Search Publications
Exploring the dynamical nature of the lower solar chromosphere
Doyle, J. G.; Banerjee, D.; O'Shea, E. +1 more
We examine spectral time-series of two lower-chromospheric lines (N i 1319 Ä and C ii 1335 Ä) observed with the SUMER instrument on the SOHO spacecraft. We point out differences between (intensity and velocity) power spectra of network and internetwork regions and argue that the behaviour resembles that of Ca ii power spectra. No significant phase…
Star-forming regions near GRB 990123
Hjorth, Jens; Holland, Stephen
We reduced the Hubble Space Telescope Space Telescope Imaging Spectrograph images of the gamma-ray burst
The stellar content of soft X-ray surveys. II. Cross-correlation of the ROSAT All-Sky Survey with the Tycho and Hipparcos catalogs
Schmitt, J. H. M. M.; Motch, C.; Guillout, P. +3 more
We present the result of the cross-correlation of the ROSAT All-Sky Survey with the Tycho and Hipparcos catalogs. The constructed RASS - Tycho (RasTyc) and RASS - Hipparcos (RasHip) samples respectively consist of 13 875 and 6 200 matches and represent the largest and most comprehensive samples of stellar X-ray sources constructed so far. The X-ra…
Globular clusters in NGC 5128
Côté, P.; Holland, S.; Hesser, J. E.
We used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to search for globular clusters in the inner regions of the nearby giant elliptical galaxy
A very cold disc of dust around the G0V star HD 207129
Kessler, M. F.; Siebenmorgen, R.; Bouchet, P. +9 more
We present ISO observations made between 2.5 and 180 mu m of the nearby G0V dwarf HD 207129 taken as part of a large survey of nearby main-sequence stars in search of debris discs. HD 207129 emits radiation in excess of the photospheric flux density between at least 60 and 180 mu m. The infrared excess is explained by a disc of cold dust particles…
Interstellar C_2 absorption lines towards CH+ forming regions
Gredel, R.
Interstellar C_2 absorption line observations towards the southern OB associations NGC 2439, Vela OB1, and Cen OB1 are used to infer gaskinetic temperatures Tkin and densities nc towards lines of sight with previously determined large CH and CH+ column densities. Towards NGC 2439, the material is characterised by t…
The effects of opacity in the transition region of YZ CMi
Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H. +2 more
It has generally been assumed that the emission from the upper atmosphere of late-type stars is optically thin. In the present paper we use the Si IV and C IV resonance lines to investigate this assumption for the active dMe star YZ CMi. The significant deviations of the line ratios from their optically thin values, demonstrate that opacity can be…
Mid-infrared and far-ultraviolet observations of the star-forming ring of M 31
Sauvage, M.; Pagani, L.; Lequeux, J. +4 more
We present mid-IR images of a 15\arcminx15' field in the south-west part of the Andromeda galaxy M 31 obtained with the ISOCAM camera (6'' pixels) on board ISO. These broad-band images complement spectro-imaging observations of smaller fields (Cesarsky et al. \cite{Cesarsky98}). We also present a 20'' resolution far-UV image of a larger field at 2…
Element mixing in the Cassiopeia A supernova
Lagage, P. O.; Cesarsky, C. J.; Douvion, T.
Thanks to mid-infrared observations, we provide new clues to the element mixing during a supernova explosion by probing the mixing between three adjacent layers: the oxygen burning products layer (sulfur, argon,...), the silicate layer and the neon layer. The silicate and neon layers are both contaminated by sulfur and argon in a macroscopic way, …
SW Ursae Majoris, CU Velorum and AH Mensae: three more accreting white dwarfs unveiled?
Gänsicke, B. T.; Koester, D.
We present IUE spectroscopy of the three cataclysmic variables SW UMa, CU Vel, and AH Men. In all three systems, a broad Lyalpha absorption profile is observed. In the two short-period dwarf novae SW UMa and CU Vel, the SWP flux is interpreted as photospheric emission from white dwarfs with effective temperatures of 16 000 K and 18 500 K, respecti…