Search Publications
Discovery of the `missing' mode in HR1217 by the Whole Earth Telescope
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +35 more
HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6µHz, with a sixth mode at a problematic spacing of 50.0µHz (which equals to the high-frequency side. As…
Crystalline silicates in the envelopes and discs around oxygen-rich asymptotic giant branch stars
Suh, Kyung-Won
We have modelled dust envelopes and discs around oxygen-rich asymptotic giant branch (AGB) stars using optical properties of amorphous and crystalline silicate dust grains, paying close attention to the infrared observations of the stars including the Infrared Space Observatory (ISO ) data. Using the opacity functions for various mixtures of amorp…
Observations of the Hubble Deep Field South with the Infrared Space Observatory - I. Observations, data reduction and mid-infrared source counts
Oliver, Seb; Elbaz, David; Franceschini, Alberto +14 more
We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15µm with the ISOCAM instrument on board the Infrared Space Observatory (ISO ). The final map in each band was constructed by the co-addition of four independent rasters, registered using bright sources securely detected in a…
On the detectability of distant Compton-thick obscured quasars
Fabian, A. C.; Crawford, C. S.; Wilman, R. J.
Chandra and XMM-Newton have resolved the 2-8keV X-ray background (XRB) into point sources. Many of the fainter sources are obscured active galactic nuclei (AGN) with column densities in the range of 1022-1023cm-2, some of which have quasar-like luminosities. According to obscuration models, the XRB above 8keV is do…
Multiple X-ray reflection from ionized slabs
Fabian, A. C.; Ross, R. R.; Ballantyne, D. R.
Multiple reflection of X-rays may be important when an accretion disc and its hot corona have a complicated geometry, or if returning radiation due to gravitational light bending is important, or in emission from a funnel such as proposed in some γ-ray burst models. We simulate the effects of multiple reflection by modifying the boundary condition…
The 69-µm forsterite band as a dust temperature indicator
Waters, L. B. F. M.; Ade, P. A. R.; Barlow, M. J. +6 more
A band of pure crystalline forsterite (100 per cent Mg2SiO4) occurs at 69.67µm at room temperature (295K) for olivines with >~10 per cent Fe the corresponding feature is at >~73µm. The Mg-rich forsterite feature is observed in a variety of ISO LWS spectra, but the corresponding Fe-rich olivine feature is not…
Chandra HRC and HST observations of NGC 6240: resolving the active galactic nucleus and starburst
Zezas, A.; Murray, S. S.; Lira, P. +1 more
We present high spatial resolution X-ray Chandra HRC and HST WFPC2 Hα observations of the prototypical infrared-luminous galaxy NGC 6240. The central region of this system shows a remarkably complex morphology, with filaments and loops observed in the optical and X-rays. The total X-ray luminosity is dominated by the extended emission. Both nuclei…
Hipparcos open clusters and stellar evolution
Prada Moroni, P. G.; Degl'Innocenti, S.; Castellani, V. +1 more
By relying on recently improved Hipparcos parallaxes for the Hyades, Pleiades and Ursa Major clusters we find that stellar models with updated physical inputs reproduce nicely the location in the colour-magnitude diagram of main-sequence stars of different metallicities. Stars in the helium-burning phase are also discussed, showing that the lumino…
XMM-Newton Reflection Grating Spectrometer observations of the prototypical starburst galaxy M82
Stevens, Ian R.; Read, Andrew M.
We present results from XMM-Newton Reflection Grating Spectrometer observations of the prototypical starburst galaxy M82. These high-resolution spectra represent the best X-ray spectra to date of a starburst galaxy. A complex array of lines from species over a wide range of temperatures is seen, the most prominent being due to Lyman α emission fro…
UBV(RI)C photometry of Hipparcos red stars
Kilkenny, D.; Marang, F.; Koen, C. +2 more
We present homogeneous and standardized UBV(RI)C photometry for nearly 550 M stars selected from the Hipparcos satellite data base using the following selection criteria: lack of obvious variability (no Hipparcos variability flag); δ<+10°(V-I)>1.7 and V magnitude fainter than about 7.6. Comparisons are made between the current pho…