Search Publications
A multi-periodic oscillatory event in a solar flare
Nakariakov, V. M.; Inglis, A. R.
Aims: Ratios of different significant periods found in the light curves of a solar flare exhibiting quasi-periodic pulsations (QPP) are used to distinguish between the possible physical mechanisms responsible for such periodic behaviour.
Methods: Time series data of the flaring event of 2002 July 3, observed via the Nobeyama Radioheliograph, N…
Optical polarization of the Crab pulsar: precision measurements and comparison to the radio emission
Kramer, M.; Kanbach, G.; Słowikowska, A. +1 more
The linear polarization of the Crab pulsar and its close environment was derived from observations with the high-speed photopolarimeter Optical Pulsar TIMing Analyser at the 2.56-m Nordic Optical Telescope in the optical spectral range (400-750 nm). Time resolution as short as 11 µs, which corresponds to a phase interval of 1/3000 of the pul…
The End of the White Dwarf Cooling Sequence in M4: An Efficient Approach
Anderson, Jay; Salaris, Maurizio; Bedin, Luigi R. +3 more
We use 14 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf cooling sequence in the globular cluster M4. Our photometry and completeness tests show that the end is located at magnitude m F606W = 28.5 ± 0.1, which implies an age of 11.6 ± 0.6 Gyr (internal errors only). This is consistent with the age…
FUSE Measurements of Far-Ultraviolet Extinction. III. The Dependence on R(V) and Discrete Feature Limits from 75 Galactic Sightlines
Gordon, Karl D.; Clayton, Geoffrey C.; Cartledge, Stefan
We present a sample of 75 extinction curves derived from Far Ultraviolet Spectroscopic Explorer (FUSE) far-ultraviolet spectra supplemented by existing International Ultraviolet Explorer (IUE) spectra. The extinction curves were created using the standard pair method based on a new set of dereddened FUSE+IUE comparison stars. Molecular hydrogen ab…
The structure of blue supergiant winds and the accretion in supergiant high-mass X-ray binaries
Mereghetti, S.; Sidoli, L.; Ducci, L. +2 more
We have developed a stellar wind model for OB supergiants to investigate the effects of accretion from a clumpy wind on the luminosity and variability properties of high-mass X-ray binaries. Assuming that the clumps are confined by ram pressure of the ambient gas and exploring different distributions for their mass and radii, we computed the expec…
STIS Imaging of the HR 4796A Circumstellar Debris Ring
Schneider, G.; Becklin, E. E.; Weinberger, A. J. +2 more
We have obtained high spatial resolution imaging observations of the HR 4796A circumstellar debris dust ring using the broad optical response of the Hubble Space Telescope Imaging Spectrograph (STIS) in coronagraphic mode. We use our visual wavelength observations to improve upon the earlier measured geometrical parameters of the ring-like disk. T…
A Relationship Between Supermassive Black Hole Mass and the Total Gravitational Mass of the Host Galaxy
Crampton, David; Simard, Luc; Bandara, Kaushala
We investigate the correlation between the mass of a central supermassive black hole (SMBH) and the total gravitational mass of the host galaxy (M tot). The results are based on 43 galaxy-scale strong gravitational lenses from the Sloan Lens ACS Surveys (SLACS) Survey whose black hole masses were estimated through two scaling relations:…
XMM-Newton detects a relativistically broadened iron line in the spectrum of the ms X-ray pulsar SAX J1808.4-3658
Robba, N. R.; Papitto, A.; Di Salvo, T. +5 more
We report on a 63-ks long XMM-Newton observation of the accreting millisecond pulsar SAX J1808.4-3658 during the latest X-ray outburst which started on September 21st 2008. The pn spectrum shows a highly significant emission line in the energy band where the iron K-α line is expected, and which we identify as emission from neutral (or mildly ioniz…
Titan's surface at 2.2-cm wavelength imaged by the Cassini RADAR radiometer: Calibration and first results
Lorenz, R. D.; Janssen, M. A.; Stiles, B. +16 more
The first comprehensive calibration and mapping of the thermal microwave emission from Titan's surface is reported based on radiometric data obtained at 2.2-cm wavelength by the passive radiometer included in the Cassini Radar instrument. The data reported were accumulated from 69 separate observational segments in Titan passes from Ta (October 20…
The Galactic Positron Annihilation Radiation and the Propagation of Positrons in the Interstellar Medium
Rothschild, R. E.; Higdon, J. C.; Lingenfelter, R. E.
The ratio of the luminosity of diffuse 511 keV positron annihilation radiation, measured by INTEGRAL in its four years, from a Galactic "positron bulge" (<1.5 kpc) compared to that of the disk is ~1.4. This ratio is roughly 4 times larger than that expected simply from the stellar bulge-to-disk ratio of ~0.33 of the Galactic supernovae (SNe), w…