Search Publications
Detection of Low-velocity Collisions in Saturn's F Ring
Cooper, N. J.; Murray, C. D.; Williams, G. A. +1 more
Jets of material extending several hundred kilometers from Saturn's F ring are thought to be caused by collisions at speeds of several tens of ms-1 between ~10 km diameter objects such as S/2004 S 6 and the core of the ring. The subsequent effects of Keplerian shear give rise to the multi-stranded nature of the F ring. Observations of t…
The Low-Mass End of the MBH/Mhost Relation in Quasars
Uslenghi, Michela; Decarli, Roberto; Treves, Aldo +3 more
The Mbh-Mhost relation in quasars has been probed only in a limited parameter space, namely at Mbh~10^9 Msun and Mhost~10^12 Msun. Here we present a study of 26 quasars lying in the low-mass end of the relation, down to Mbh~10^7 Msun. We selected quasars from the SDSS and HST-FOS archives, requiring modest Mbh (as derived through the virial paradi…
First ever in situ observations of Venus' polar upper atmosphere density using the tracking data of the Venus Express Atmospheric Drag Experiment (VExADE)
Rosenblatt, P.; Häusler, B.; Svedhem, H. +3 more
On its highly elliptical 24 h orbit around Venus, the Venus Express (VEX) spacecraft briefly reaches a periapsis altitude of nominally 250 km. Recently, however, dedicated and intense radio tracking campaigns have taken place in August 2008, October 2009, February and April 2010, for which the periapsis altitude was lowered to the 186-176 km altit…
The detection of energetic electrons with the Cassini Langmuir probe at Saturn
Schippers, P.; Gurnett, D. A.; Krupp, N. +10 more
The Cassini Langmuir probe, part of the Radio and Plasma Wave Science (RPWS) instrument, has provided a wealth of information about the cold and dense plasma in the Saturnian system. The analysis of the ion side current (current for negative potentials) measured by the probe from 2005 to 2008 reveals also a strong sensitivity to energetic electron…
Oxygen-rich dust production in IC 10
Lebouteiller, V.; Groenewegen, M. A. T.; Bernard-Salas, J. +6 more
Context. We report the detection of oxygen-rich circumstellar envelopes in stars of the nearby (700 kpc) starburst galaxy IC 10. The star-formation history and the chemical environment of this galaxy make it an ideal target to observe dust production by massive stars in a metal-poor environment.
Aims: The goal of this study is to identify oxy…
XMM-Newton Observations of Five INTEGRAL Sources Located Towards the Scutum Arm
Tomsick, J. A.; Rodriguez, J.; Bodaghee, A.
Results are presented for XMM-Newton observations of five hard X-ray sources discovered by INTEGRAL in the direction of the Scutum Arm. Each source received gsim20 ks of effective exposure time. We provide refined X-ray positions for all five targets enabling us to pinpoint the most likely counterpart in optical/infrared archives. Spectral and tim…
Observations of upper tropospheric acetylene on Saturn: No apparent correlation with 2000 km-sized thunderstorms
Fletcher, L. N.; Irwin, P. G. J.; Moses, J. I. +4 more
Thunderstorm activity has been observed on Saturn via radio emissions from lightning discharges and optical detections of the lightning flashes on the planet's nightside. Thunderstorms provide extreme environments in which specific atmospheric chemistry can be induced-namely through energy release via lightning discharges, and fast vertical transp…
Stability valley for strange dwarfs
Vartanyan, Yu. L.; Hajyan, G. S.; Grigoryan, A. K. +1 more
This is a study of the stability of strange dwarfs, superdense stars with a small self-confining core (Mcore < 0.02 M⊙) containing strange quark matter and an extended crust consisting of atomic nuclei and degenerate electron gas. The mass and radius of these stars are of the same orders as those of ordinary white dwarfs. …
A Coronal Jet Ejection from a Sunspot Light Bridge
Liu, S.
Chromospheric brightening and Hα surges are evident and common phenomena along sunspot light bridges. In this paper, a coronal jet ejection from a sunspot light bridge is presented. Using data from the Solar Dynamics Observatory and Hinode satellites, it is confirmed that the jet has its root near the light bridge. This suggests that the jet may b…
Variation of solar oscillation frequencies in solar cycle 23 and their relation to sunspot area and number
Hill, F.; Fletcher, L.; Jain, K. +3 more
Aims: Studying the long term evolution of the solar acoustic oscillations is necessary for understanding how the large-scale solar dynamo operates. In particular, an understanding of the solar cycle variation in the frequencies of solar oscillations can provide a powerful diagnostic tool for constraining various dynamo models. In this work, w…