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Simultaneous multi-scale and multi-instrument observations of Saturn's aurorae during the 2013 observing campaign
Baines, K. H.; Johnson, R. E.; Badman, S. V. +14 more
On 21 April 2013, during a co-ordinated Saturn auroral observing campaign, the northern and southern poles of the planet were observed from the Earth using the NASA Infrared Telescope Facility (IRTF), Keck, and Hubble Space Telescope (HST) simultaneously with the Cassini infrared, visible, and ultraviolet remote sensing instruments. We present sim…
Homologous Solar Events on 2011 January 27: Build-up and Propagation in a Complex Coronal Environment
Pick, M.; Démoulin, P.; Zucca, P. +2 more
In spite of the wealth of imaging observations at the extreme-ultraviolet (EUV), X-ray, and radio wavelengths, there are still relatively few cases where all of the imagery is available to study the full development of a coronal mass ejection (CME) event and its associated shock. The aim of this study is to contribute to the understanding of the r…
FK Comae Berenices, King of Spin: The COCOA-PUFS Project
Granzer, T.; Ayres, Thomas R.; Korhonen, H. +8 more
COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast spinning, heavily spotted, yellow giant FK Comae Berenices (FK Com: HD117555; G4 III). This single star is thought to be a recent binary merger, and is exceptionally active by measure of its intense ultraviolet (UV) and X-ray emissions, and proclivity to flare. COCOA-PUFS was car…
Substructures within a dipolarization front revealed by high-temporal resolution Cluster observations
Fazakerley, A. N.; Owen, C. J.; Guo, R. L. +8 more
The dipolarization front (DF), usually observed near the leading edge of a bursty bulk flow (BBF), is thought to carry an intense current sufficient to modify the large-scale near-Earth magnetotail current system. However, the physical mechanism of the current generation associated with DFs is poorly understood. This is primarily due to the limita…
3D Direct Simulation Monte Carlo Modelling of the Inner Gas Coma of Comet 67P/Churyumov–Gerasimenko: A Parameter Study
Kührt, E.; Keller, H. U.; Knollenberg, J. +9 more
Direct Simulation Monte Carlo (DSMC) is a powerful numerical method to study rarefied gas flows such as cometary comae and has been used by several authors over the past decade to study cometary outflow. However, the investigation of the parameter space in simulations can be time consuming since 3D DSMC is computationally highly intensive. For the…
Cool Subdwarf Investigations. III. Dynamical Masses of Low-metallicity Subdwarfs
Nelan, Edmund P.; Henry, Todd J.; Wasserman, Lawrence H. +2 more
We report dynamical mass measurements for the components of the previously known double-lined spectroscopic subdwarfs G 006-026 B and C using the Fine Guidance Sensors on the Hubble Space Telescope. To build the empirical mass-luminosity relation for low-metallicity subdwarfs, we collect four other subdwarf systems with dynamical masses that we co…
Exploring the crowded central region of ten Galactic globular clusters using EMCCDs. Variable star searches and new discoveries
Surdej, J.; Snodgrass, C.; Horne, K. +30 more
Aims: We aim to obtain time-series photometry of the very crowded central regions of Galactic globular clusters; to obtain better angular resolution thanhas been previously achieved with conventional CCDs on ground-based telescopes; and to complete, or improve, the census of the variable star population in those stellar systems.
Methods:…
Characteristics of field-aligned currents associated with magnetic flux ropes in the magnetotail: A statistical study
Zhao, Yan; Wang, Rongsheng; Du, Aimin
We present an investigation of 35 magnetic flux ropes encountered by Cluster in the Earth's magnetotail during the years between 2001 and 2004. The study shows that the parallel current dominates inside 86% of the identified flux ropes and 71% of the flux ropes are surrounded by the draping regions where the parallel current is comparable to the p…
Spectroscopic Confirmation of the Dwarf Spheroidal Galaxy d0994+71 as a Member of the M81 Group of Galaxies
Simon, Joshua D.; Chiboucas, Kristin; Guhathakurta, Puragra +3 more
We use Keck/DEIMOS spectroscopy to measure the first velocity and metallicity of a dwarf spheroidal (dSph) galaxy beyond the Local Group using resolved stars. Our target, d0944+71, is a faint dSph found in the halo of the massive spiral galaxy M81 by Chiboucas et al. We coadd the spectra of 27 individual stars and measure a heliocentric radial vel…
Asteroid orbits with Gaia using random-walk statistical ranging
Muinonen, Karri; Fedorets, Grigori; Pentikäinen, Hanna +10 more
We describe statistical inverse methods for the computation of initial asteroid orbits within the data processing and analysis pipeline of the ESA Gaia space mission. Given small numbers of astrometric observations across short time intervals, we put forward a random-walk ranging method, in which the orbital-element phase space is uniformly sample…