Search Publications
Broadband X-ray Spectrum of the Intermediate Polar V2400 Oph
Sunyaev, R. A.; Lutovinov, A. A.; Revnivtsev, M. G. +2 more
We present the results of our analysis of the observations of the intermediate polar V2400 Oph by the INTEGRAL and RXTE observatories. We reconstructed the spectrum of the source over a wide (3-100 keV) energy range. The spectrum obtained can be fitted by a computed theoretical model of the post-shock emitting region with Tmax ~ 22 keV.…
Cluster observations of ULF waves with pulsating electron beams above the high latitude dusk-side auroral region
Winningham, J. D.; Balogh, A.; Dandouras, I. +8 more
We report observations by the four Cluster satellites of particle acceleration associated with ULF (Alfvén) waves at an altitude of 6RE above the dusk-side auroral region. All satellites observed upward accelerated ions and upgoing electron beams, which coincided with the upward field-aligned current around the plasmasheet boundary regi…
Jovian satellite positions from Hubble Space Telescope images
Mallama, Anthony; Aelion, Halley M.; Mallama, Celeste A.
An accurate technique has been developed for measuring planetocentric positions of Jupiter's satellites from Wide Field/Planetary Camera images. Our method of finding the centers of the satellites and planet is based upon established limb-fitting techniques, but we have adapted those techniques to astrometry. We compare our limb-fitting results wi…
Keck Adaptive Optics Imaging of 0.5 < z < 1 Field Galaxies from the Hubble Space Telescope Archive
Faber, S. M.; Koo, D. C.; Larkin, J. E. +6 more
We have employed natural guide star adaptive optics (AO) on the Keck II telescope to obtain near-infrared (H and K') images of three field galaxies, each of redshift greater than 0.5. These are among the highest-redshift non-active disk galaxies to be imaged with AO. Each of the galaxies was chosen because it had been observed previously with the …
Multi-object near-infrared Hα spectroscopy of z~ 1 star-forming galaxies in the Hubble Deep Field North
Wolf, Christian; Hippelein, Hans; Bunker, Andrew +6 more
We present preliminary results from a programme to obtain multi-object near-infrared spectroscopy of galaxies at redshifts 0.7 < z < 1.5. We are using the instrument CIRPASS (the Cambridge Infra-Red PAnoramic Survey Spectrograph), in multi-object mode, to survey Hα in galaxies at z~ 1. We aim to address the true star formation history of the…
New and Confirmed Triple Systems with Luminous Cool Primaries and Hot Companions
Parsons, Sidney B.
In the course of comparing parameters of evolved cool star plus hot main-sequence star binaries with theoretical isochrones, some discrepancies are found between implied stellar masses and the spectroscopic binary mass function or the measured angular separation. These are naturally explained if there is a third star in the system. Multiplicity is…
Suprathermal ions ahead of interplanetary shocks: New observations and critical instrumentation required for future space weather monitoring
Galvin, A. B.; McComas, D. J.; Schwadron, N. A. +2 more
We report new findings on the low-energy ion population associated with interplanetary (IP) shocks based on Wind/Suprathermal Ion Composition Spectrometer (STICS) observations. Suprathermal ions (6-200 keV) are present in the upstream region of most (86%) IP shocks at 1 AU. These foreshock ions are characterized by (1) median energy >25 keV, th…
M Dwarfs from Hubble Space Telescope Star Counts. V. The I-Band Luminosity Function
Gould, Andrew; Salim, Samir; Bahcall, John N. +2 more
We derive the disk I-band luminosity function from the Zheng et al. sample of ~1400 disk M dwarfs observed with the Hubble Space Telescope. We adopt a Galactic-height-dependent color-magnitude relation to account for the metallicity gradient above the Galactic plane. The resultant I-band luminosity function peaks at MI~9.5 and drops sha…
XMM-Newton observations of the eclipsing polar EP Dra
Cropper, Mark; Ramsay, Gavin; Priedhorsky, W. +3 more
We present XMM-Newton observations of the eclipsing polar EP Dra that cover nearly three binary orbital cycles. The X-ray and ultraviolet data show evidence for a prominent dip before the eclipse, which is due to the accretion stream obscuring the accretion region. The dip ingress is rapid in hard X-rays, suggesting that there is a highly collimat…
An Ion-Cyclotron Resonance-driven Three-Fluid Model of the Slow Wind near the Sun
Chen, Y.; Li, X.
A three-fluid slow wind consisting of electrons, protons, and O+5 ions is constructed to account for a recent UVCS/SOHO observation. In this model, ion-cyclotron waves, which are assumed to be generated by a Kolmogorov turbulent cascade, are assumed to play a key role in driving the slow solar wind. By reproducing recent measurements on…