Search Publications
Modelling the orbital modulation of ultraviolet resonance lines in high-mass X-ray binaries
van Loon, J. Th.; Hammerschlag-Hensberge, G.; Kaper, L.
The stellar-wind structure in high-mass X-ray binaries (HMXBs) is investigated through modelling of their ultraviolet (UV) resonance lines. For the OB supergiants in two systems, Vela X-1 and 4U1700-37, high-resolution UV spectra are available; for Cyg X-1, SMC X-1, and LMC X-4 low-resolution spectra are used. In order to account for the non-monot…
Early Chandra X-Ray Observations of η Carinae
Karovska, M.; Butt, Y. M.; Schlegel, E. M. +3 more
Subarcsecond-resolution Chandra observations of η Carinae reveal a 40''×70'' ring or partial shell of X-ray emission surrounding an unresolved bright central source. The spectrum of the central source is strongly absorbed and can be fitted with a high-temperature thermal continuum and emission lines. The surrounding shell is …
Trigonometric Parallaxes and a Kinematically Adjusted Distance Scale for OB Associations
Dambis, A. K.; Rastorguev, A. S.; Mel'Nik, A. M.
By directly comparing the photometric distances of Blaha and Humphreys (1989) (BH) to OB associations and field stars with the corresponding Hipparcos trigonometric parallaxes, we show that the BH distance scale is overestimated, on average, by 10-20%. This result is independently corroborated by applying the rigorous statistical-parallax method a…
On the metal abundance in the core of M 87
Molendi, S.; Gastaldello, F.
We revisit the XMM-Newton observation of M 87 to make a new and more detailed measurement of the metal abundance profile. After having verified that spectral fits with single temperature models show a dramatic abundance drop within 1 arcmin of the cluster core, we show that more appropriate models, which include a multi-temperature component to ac…
First results from the Cluster wideband plasma wave investigation
Gurnett, D. A.; Persoon, A. M.; Pickett, J. S. +9 more
In this report we present the first results from the Cluster wideband plasma wave investigation. The four Cluster spacecraft were successfully placed in closely spaced, high-inclination eccentric orbits around the Earth during two separate launches in July August 2000. Each spacecraft includes a wideband plasma wave instrument designed to provide …
Reconciliation of the Surface Brightness Fluctuation and Type Ia Supernova Distance Scales
Riess, Adam G.; Ajhar, Edward A.; Schmidt, Brian P. +2 more
We present Hubble Space Telescope measurements of surface brightness fluctuation (SBF) distances to early-type galaxies that have hosted Type Ia supernovae (SNe Ia). The agreement in the relative SBF and SN Ia multicolor light-curve shape and delta-m15 distances is excellent. There is no systematic scale error with distance, and previou…
New Measurements of the Winds of Uranus
Karkoschka, E.; Hammel, H. B.; de Pater, I. +2 more
Hubble Space Telescope imaging of Uranus in 1994, 1997, 1998, and 2000 revealed 13 cloud features, allowing the first measurements of wind velocities at northern latitudes not accessible to the Voyager cameras and new measurements of southern-latitude wind velocities determined during the 1986 Voyager encounter. Images acquired with the Keck 10-me…
The Abundances of Solid N2 and Gaseous CO2 in Interstellar Dense Molecular Clouds
Allamandola, L. J.; Sandford, S. A.; Bernstein, M. P. +2 more
We present 2338-2322 cm-1 (4.277-4.307 µm) infrared spectra of a number of N2-containing mixed molecular ices and demonstrate that the strength of the infrared ``forbidden'' band due to the NN stretch near 2328 cm-1 (4.295 µm) is extremely sensitive to the composition of the ice. The strength of the 232…
Interferometric Astrometry with Hubble Space Telescope Fine Guidance Sensor 3: The Parallax of the Cataclysmic Variable TV Columbae
McArthur, B. E.; Benedict, G. F.; Franz, O. G. +14 more
TV Col is a 13th magnitude intermediate polar cataclysmic variable with multiple periods found in the light curves. Past estimates predicted a distance of 400 pc to greater than 500 pc. Recently completed Hubble Space Telescope fine guidance sensor interferometric observations allow us to determine the first trigonometric parallax to TV Col. This …
A Search for Early Optical Emission from Short- and Long-Duration Gamma-Ray Bursts
Hurley, Kevin; McKay, Tim; Kehoe, Robert +16 more
Gamma-ray bursts of short duration may harbor vital clues to the range of phenomena producing bursts. However, recent progress from the observation of optical counterparts has not benefited the study of short bursts. We have searched for early optical emission from six gamma-ray bursts using the telephoto array on the Robotic Optical Transient Sea…