Search Publications
On the Wolf-Rayet counterpart to IC 10 X-1
Crowther, P. A.; Clark, J. S.
Recent CHANDRA observations of the starburst galaxy
Studies of Microflares in RHESSI Hard X-Ray, Big Bear Solar Observatory Hα, and Michelson Doppler Imager Magnetograms
Krucker, Säm; Liu, Chang; Qiu, Jiong +2 more
In this paper, we present a study of the morphology of 12 microflares jointly observed by RHESSI in the energy range from 3 to 15 keV and by Big Bear Solar Observatory (BBSO) at the Hα line. They are A2-B3 events in GOES classification. From their time profiles, we find that all of these microflares are seen in soft X-ray, hard X-ray, and Hα wavel…
Long-lived triaxiality in the dynamically old elliptical galaxy NGC 4365: a limit on chaos and black hole mass
Bacon, Roland; Emsellem, Eric; Peletier, Reynier F. +1 more
Supermassive black holes in the centres of giant elliptical galaxies are thought to be capable of inducing chaos and eliminating or preventing triaxiality in their hosts if they are sufficiently massive. We address whether this process operates in real systems, by modelling the stellar kinematics of the old elliptical NGC 4365. This galaxy has a m…
Spectral evolution of weak bursts from SGR 1806-20 observed with INTEGRAL
Hurley, K.; Götz, D.; Mereghetti, S. +1 more
We report on bursts from the Soft Gamma-Ray Repeater SGR 1806-20 detected with INTEGRAL in October 2003, during a period of moderate activity of the source. The spectral and temporal properties of 21 short bursts are consistent with those found in previous observations, even if these bursts are among the faintest observed in the 15-200 keV range f…
A Period and a Prediction for the Of?p Spectrum Alternator HD 191612
Corcoran, Michael F.; Walborn, Nolan R.; Bond, Howard E. +7 more
The observational picture of the enigmatic O-type spectrum variable HD 191612 has been sharpened substantially. A symmetrical, low-amplitude light curve with a period near 540 days has recently been reported from Hipparcos photometry. This period satisfies all of the spectroscopy since at least 1982, including extensive new observations during 200…
Hubble Space Telescope NICMOS Variability Study of Massive Stars in the Young Dense Galactic Starburst NGC 3603
Bergeron, E.; Moffat, A. F. J.; Marchenko, S. V. +4 more
We have used the relatively long data string of the 1997-1999 NICMOS focus tests on NGC 3603 to extract ~J-band light curves for several hundred stars in the cluster core. Given the relatively modest photometric precision [σ(J)>=0.05 mag], we were able to isolate only a half-dozen variable candidates with peak-to-valley amplitudes above ~0.2 ma…
Central Stars of Planetary Nebulae in the Large Magellanic Cloud: A Far-Ultraviolet Spectroscopic Analysis
Bianchi, L.; Herald, J. E.
We observed seven central stars of planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) with the Far Ultraviolet Spectroscopic Explorer and performed a model-based analysis of these spectra in conjunction with Hubble Space Telescope spectra in the UV and optical range to determine the stellar and nebular parameters. Most of the objects show…
Studies of orbital parameters and pulse profile of the accreting millisecond pulsar XTE J1807-294
Freyberg, M. J.; Kendziorra, E.; Smith, M. J. S. +4 more
The accreting millisecond pulsar XTE J1807-294 was observed as a Target of Opportunity (ToO) by XMM-Newton on March 22, 2003 after its discovery on February 21, 2003 by RXTE. The source was detected in its bright phase with an observed average count rate of 33.3 cts s-1 in the EPIC-pn camera in the 0.5-10 keV energy band (3.7 mCrab). Us…
Resolving the Nature of the Large Magellanic Cloud Microlensing Event MACHO-LMC-5
Cook, K. H.; Drake, A. J.; Keller, S. C.
We present the results from an analysis of Hubble Space Telescope high-resolution camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object, we find that the lens is an M dwarf star at a distance of 578+65-53 pc with a proper motion of 21.39+/-0.04 …
Orientation and motion of a discontinuity from Cluster curlometer capability: Minimum variance of current density
Klecker, B.; Vaivads, A.; Dunlop, M. W. +4 more
A new technique to derive magnetopause key parameters such as orientation, velocity and thickness from multi-spacecraft observations is presented. The method is based on four-spacecraft determination of the current density, variance analysis to estimate the orientation and thereafter integration of the current density across the magnetopause to fi…