Search Publications
Hot Stars: Old-Fashioned or Trendy? (With 24 Figures)
Pauldrach, A. W. A.
Spectroscopic analyses with the intention of the interpretation of the UV-spectra of the brightest stars as individuals - supernovae - or as components of star-forming regions - massive O stars - provide a powerful tool with great astrophysical potential for the determination of extragalactic distances and of the chemical composition of star-formi…
First evidence of IMF control of Jovian magnetospheric boundary locations: Cassini and Galileo magnetic field measurements compared
Kivelson, Margaret G.; Southwood, David J.
The Cassini spacecraft, en route to Saturn, passed close to Jupiter while the Galileo spacecraft was completing its 28th and 29th orbits of Jupiter, thus offering a unique opportunity for direct study of the solar wind-Jovian interaction. Here evidence is given of response of the Jovian magnetopause and bow shock positions to changes of the north-…
Hubble Space Telescope NICMOS Observations of the Embedded Cluster in NGC 2024: Constraints on the Initial Mass Function and Binary Fraction
Young, Erick T.; Meyer, Michael R.; Cotera, Angela S. +1 more
We present an analysis of NICMOS observations of the embedded cluster associated with NGC 2024. An analysis of the cluster color-magnitude diagram (CMD) using the models of D'Antona & Mazzitelli and Baraffe et al. (published in 1997 and 1998, respectively) indicates that the ratio of intermediate-mass (1.0-10.0 Msolar) to low-mass (…
On the Origin of the High-Ionization Intermediate-Velocity Gas toward HD 14434
Sembach, Kenneth R.; Meyer, David M.; Lauroesch, James T. +2 more
We present Far-Ultraviolet Spectroscopic Explorer and Space Telescope Imaging Spectrograph observations of high-ionization interstellar absorption toward HD 14434 (l=135.1d, b=-3.8d d~2.3 kpc), an O5.5 V star in the Perseus OB1 association. Intermediate-velocity interstellar Si IV and C IV absorption is present at VLSR=-67 km s-1
Status of the Integral/IBIS telescope modeling and of the response matrices generation
Goldoni, P.; Malaguti, G.; Bird, A. J. +8 more
The main objective of the IBIS modeling activities is the generation of the IBIS spectral response matrices. This generation has been done step by step by firstly constructing a ``calibrated model" of each IBIS sub-system. A ``calibrated model" is defined as a GEANT Monte-Carlo model, further checked by intensive corresponding calibration. These c…
The nature of X-ray selected extremely red objects
Ivison, R. J.; Smail, Ian; Page, M. J. +4 more
We report on the X-ray, optical, near-infrared, submillimetre and radio properties of five extremely red objects (EROs) selected at X-ray wavelengths by XMM-Newton in the Lockman Hole field. They all have enough counts in the X-ray band to allow spectral fitting: four are most probably obscured, Compton-thin active galactic nuclei (AGNs) with reds…
Cooling out the radiation damage on the XMM-Newton EPIC MOS CCDs
Altieri, B.; Bennie, P. J.; Turner, M. J. L. +2 more
The X-ray astronomy satellite XMM-Newton has been in an orbit taking it through the trapped radiation belts and direct solar proton flux during the peak of the current solar cycle for over two and a half years. The MOS CCD detectors (E2V CCD22's) have degraded in charge transfer efficiency (CTE) as a result of damage created by high energy protons…
Observation of GRB 030131 with the INTEGRAL satellite
Pian, E.; Frontera, F.; Hurley, K. +13 more
A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted ~ 150 s, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS ins…
Hyades dynamics from N-body simulations: Accuracy of astrometric radial velocities from Hipparcos
Madsen, Søren
The internal velocity structure in the Hyades cluster as seen by Hipparcos is compared with realistic N-body simulations using the NBODY6 code, which includes binary interaction, stellar evolution and the Galactic tidal field. The model allows to estimate reliably the accuracy of astrometric radial velocities in the Hyades as derived by Lindegren …
New Identifications of Mn VI and Fe VII Vacuum Ultraviolet Lines
Feldman, U.; Ekberg, J. O.
The Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer aboard the Solar and Heliospheric Observatory (SOHO) recorded a large number of spectra in the 500-1600 Å region. Although many of the detected lines have already been identified, the origins of a substantial fraction of the lines remain unknown. In this paper we report o…