Search Publications
A Giant Flare from a Soft Gamma Repeater in the Andromeda Galaxy (M31)
Hurley, K.; von Kienlin, A.; Frederiks, D. D. +6 more
The light curve, energy spectra, energetics, and IPN localization of an exceedingly intense, short-duration, hard-spectrum burst, GRB 070201, obtained from Konus-Wind, INTEGRAL (SPI-ACS), and MESSENGER data are presented. The total fluence of the burst and the peak flux are S = 2.00+ 0.10-0.26 × 10-5 erg cm-2<…
The role of AGN in the colour transformation of galaxies at redshifts z ~ 1
Barmby, P.; Cooper, M. C.; Georgakakis, A. +10 more
We explore the role of active galactic nuclei (AGN) in establishing and/or maintaining the bimodal colour distribution of galaxies by quenching their star formation and hence, causing their transition from the blue to the red cloud. Important tests for this scenario include (i) the X-ray properties of galaxies in the transition zone between the tw…
Evidence of an extended electron current sheet and its neighboring magnetic island during magnetotail reconnection
Khotyaintsev, Y.; Vaivads, A.; Runov, A. +9 more
We have identified a spatially extended electron current sheet (ECS) and its adjacent magnetic island during a magnetotail reconnection event with no appreciable guide field. This finding is based on data from the four Cluster spacecraft and is enabled by detailed maps of electron distribution functions and DC electric fields within the diffusion …
Temperature and Composition of Saturn’s Polar Hot Spots and Hexagon
Fletcher, L. N.; Irwin, P. G. J.; Teanby, N. A. +11 more
Saturn’s poles exhibit an unexpected symmetry in hot, cyclonic polar vortices, despite huge seasonal differences in solar flux. The cores of both vortices are depleted in phosphine gas, probably resulting from subsidence of air into the troposphere. The warm cores are present throughout the upper troposphere and stratosphere at both poles. The the…
Outer edges of debris discs. How sharp is sharp?
Thébault, P.; Wu, Y.
Context: Rings or annulus-like features have been observed in most imaged debris discs. Outside the main ring, while some systems (e.g., β Pictoris and AU Mic) exhibit smooth surface brightness profiles (SB) that fall off roughly as ~r-3.5, others (e.g. HR 4796A and HD 139664) display large drops in luminosity at the ring's outer edge a…
Evolution of Kelvin-Helmholtz activity on the dusk flank magnetopause
Farrugia, C. J.; Fazakerley, A. N.; Owen, C. J. +3 more
Our purpose is to characterize the evolution of the magnetopause Kelvin-Helmholtz (KH) wave activity with changes in thickness of the adjacent boundary layer, geomagnetic latitude and interplanetary magnetic field (IMF) orientation. As the IMF turns northward, wave activity may be generated at the dayside before propagating down the tail, where th…
The Horizontal Internetwork Magnetic Field: Numerical Simulations in Comparison to Observations with Hinode
Rezaei, R.; Wedemeyer-Böhm, S.; Steiner, O. +1 more
Observations with the Hinode space observatory led to the discovery of predominantly horizontal magnetic fields in the photosphere of the quiet internetwork region. Here we investigate realistic numerical simulations of the surface layers of the Sun with respect to horizontal magnetic fields and compute the corresponding polarimetric response in t…
A comet-like escape of ionospheric plasma from Mars
Barabash, S.; Lundin, R.; Holmström, M. +4 more
New measurements of the ion escape from Mars display a mantle of low-energy ionospheric ions swept from the dayside over the terminator, expanding into the tail in a comet-like fashion. The finding is based on data obtained with new energy settings for the ASPERA-3 ion mass analyzer (IMA), enabling us to also measure cold ionospheric ions. By incl…
Electron densities in the upper ionosphere of Mars from the excitation of electron plasma oscillations
Gurnett, D. A.; Morgan, D. D.; Modolo, R. +3 more
In addition to remote radio sounding of the ionosphere of Mars, the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument on the Mars Express spacecraft is also able to measure the in situ electron density from the excitation of local electron plasma oscillations. This paper presents an investigation of the electron densi…
The Hα-based Star Formation Rate Density of the Universe at z = 0.84
Barro, Guillermo; Pérez-González, Pablo G.; Koo, David C. +5 more
We present the results of an Hα near-infrared narrowband survey searching for star-forming galaxies at redshift z = 0.84. This work is an extension of our previous narrowband studies in the optical at lower redshifts. After removal of stars and redshift interlopers (using spectroscopic and photometric redshifts), we build a complete sample of 165 …