Search Publications
Missions
Journals
Publication Years
Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares (Invited Review)
Milligan, Ryan O.
The extreme ultra-violet (EUV) portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature- and density-sensitive line ratios, Doppler-shifted emission lines, nonthermal broadening…
Suprathermal electron environment of comet 67P/Churyumov-Gerasimenko: Observations from the Rosetta Ion and Electron Sensor
Frahm, R. A.; Goldstein, R.; Mokashi, P. +9 more
Context. The Rosetta spacecraft is currently escorting comet 67P/Churyumov-Gerasimenko until its perihelion approach at 1.2 AU. This mission has provided unprecedented views into the interaction of the solar wind and the comet as a function of heliocentric distance.
Aims: We study the interaction of the solar wind and comet at large heliocent…
Control of the topside Martian ionosphere by crustal magnetic fields
Gurnett, D. A.; Edberg, N. J. T.; Němec, F. +4 more
We present observations from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument onboard Mars Express of the thermal electron plasma density of the Martian ionosphere and investigate the extent to which it is influenced by the presence of Mars's remnant crustal magnetic fields. We use locally measured electron densi…
Mixtures of clays and sulfates within deposits in western Melas Chasma, Mars
Wray, James J.; Weitz, Catherine M.; Noe Dobrea, Eldar
We have utilized several data sets from multiple spacecraft that have been acquired over a continuous observation campaign across the southwestern Melas Chasma region of Mars. The blocky deposit observed on the chasma floor and on portions of the southern wallrock consists of mixtures of light- and medium-toned materials that exhibit displacement …
THOR: The H i, OH, Recombination line survey of the Milky Way. The pilot study: H i observations of the giant molecular cloud W43
Menten, K. M.; Hill, T.; Henning, T. +30 more
To study the atomic, molecular, and ionized emission of giant molecular clouds (GMCs) in the Milky Way, we initiated a large program with the Karl G. Jansky Very Large Array (VLA): "THOR: The H i, OH, Recombination line survey of the Milky Way". We map the 21 cm H i line, 4 OH lines, up to 19 Hα recombination lines and thecontinuum from 1 to 2 GHz…
What Are Little Worlds Made Of? Stellar Abundances and the Building Blocks of Planets
Gaidos, Eric
If the photospheres of solar-type stars represent the composition of circumstellar disks from which any planets formed, spectroscopic determinations of stellar elemental abundances offer information on the composition of those planets, including smaller, rocky planets. In particular, the C/O ratio is proposed to be a key determinant of the composi…
MRK 1216 and NGC 1277 - an orbit-based dynamical analysis of compact, high-velocity dispersion galaxies
Gebhardt, Karl; van de Ven, Glenn; Husemann, Bernd +5 more
We present a dynamical analysis to infer the structural parameters and properties of the two nearby, compact, high-velocity dispersion galaxies MRK 1216 and NGC 1277. Combining deep Hubble Space Telescope imaging, wide-field integral field unit stellar kinematics, and complementary long-slit spectroscopic data out to three effective radii, we cons…
Excitation of Chirping Whistler Waves in a Laboratory Plasma
Bortnik, J.; Thorne, R. M.; Van Compernolle, B. +3 more
Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibit…
New binaries among UV-selected, hot subdwarf stars and population properties
Buckley, D. A. H.; Vennes, S.; Németh, P. +4 more
We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ∼0.17 to 3 d. One new system, GALEX J2205-3141, shows reflection on an M dwarf companion. Three other objects show significant short-period variations…
Modelling the extreme X-ray spectrum of IRAS 13224-3809
Fabian, A. C.; Gallo, L. C.; Wilkins, D. R. +2 more
The extreme narrow-line Seyfert 1 galaxy IRAS 13224-3809 shows significant variability, frequency-dependent time lags, and strong Fe K line and Fe L features in the long 2011 XMM-Newton observation. In this work, we study the spectral properties of IRAS 13224-3809 in detail, and carry out a series of analyses to probe the nature of the source, foc…