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The M81 Group Dwarf Irregular Galaxy DDO 165. I. High-velocity Neutral Gas in a Post-starburst System
Cannon, John M.; Dolphin, Andrew E.; Skillman, Evan D. +8 more
We present new multi-configuration Very Large Array H I spectral line observations of the M81 group dwarf irregular post-starburst galaxy DDO 165. The H I morphology is complex, with multiple column density peaks surrounding a large region of very low H I surface density that is offset from the center of the stellar distribution. The bulk of the n…
The ACS Nearby Galaxy Survey Treasury. VII. The NGC 4214 Starburst and the Effects of Star Formation History on Dwarf Morphology
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +4 more
We present deep Hubble Space Telescope WFPC2 optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury as well as early release Wide Field Camera 3 ultraviolet and infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our data provide a detailed example of how covering such a broad range in wavelength provide…
Monitoring the solar UV irradiance spectrum from the observation of a few passbands
Kretzschmar, M.; Dudok de Wit, T.; Cessateur, G. +3 more
Context. The solar irradiance in the UV is a key ingredient in space weather applications; however, because of the lack of continuous and long-term observations, various indices are still used today as surrogates for the solar spectral irradiance.
Aims: As an alternative to current spectrometers we use a few radiometers with properly chosen p…
Mercer 5: a probable new globular cluster in the Galactic bulge
Maccarone, T. J.; de Grijs, R.; Lucas, P. W. +6 more
We present a detailed study of a dust-obscured Galactic star cluster Mercer 5 ([MCM2005b] 5) in an extremely crowded field in the Milky Way. Near-infrared (near-IR) photometry from United Kingdom Infrared Digital Sky Surveys (UKIDSS) and the Son of ISAAC on the New Technology Telescope (SofI/NTT), combined with near-IR spectroscopy also from SofI,…
XMM-Newton Observations of NGC 247: X-Ray Population and a Supersoft Ultraluminous X-Ray Source
Feng, Hua; Kaaret, Philip; Zhang, Shuang-Nan +1 more
We report on a new XMM-Newton observation of NGC 247 from 2009 December. The galaxy contains a supersoft, ultraluminous X-ray source whose spectrum consists of a thermal component with a temperature about 0.1 keV and a power-law tail with a photon index around 2.5. The thermal emission is absolutely the dominant component, contributing 96% of the …
Analysis of ionospheric electrodynamic parameters on mesoscales - a review of selected techniques using data from ground-based observation networks and satellites
Amm, O.; Vanhamäki, H.
We present a review of selected data-analysis methods that are frequently applied in studies of ionospheric electrodynamics and magnetosphere-ionosphere coupling using ground-based and space-based data sets. Our focus is on methods that are data driven (not simulations or statistical models) and can be used in mesoscale studies, where the analysis…
Lunar mare single-scattering, porosity, and surface-roughness properties with SMART-1 AMIE
Koschny, D.; Foing, B.; Muinonen, K. +8 more
A novel shadowing and coherent-backscattering model is utilized in the analysis of the single-scattering albedos and phase functions, local surface roughness, and regolith porosity of specific lunar mare regions imaged by the AMIE camera (Advanced Moon micro-Imager Experiment) onboard ESA SMART-1 mission. Shadowing due to the regolith particles is…
Lateral Offset of the Coronal Mass Ejections from the X-flare of 2006 December 13 and Its Two Precursor Eruptions
Harra, Louise K.; Moore, Ronald L.; Sterling, Alphonse C.
Two GOES sub-C-class precursor eruptions occurred within ~10 hr prior to and from the same active region as the 2006 December 13 X4.3-class flare. Each eruption generated a coronal mass ejection (CME) with center laterally far offset (gsim 45°) from the co-produced bright flare. Explaining such CME-to-flare lateral offsets in terms of the standard…
The Response of A Three-dimensional Solar Atmosphere to Wave-driven Jets
Doyle, J. G.; Erdélyi, R.; Scullion, E. +1 more
Global oscillations from the solar interior are, mainly, pressure-driven (p-modes) oscillations with a peak power of a five-minute period. These oscillations are considered to manifest in many phenomena in the lower solar atmosphere, most notably, in spicules. These small-scale jets may provide the key to understanding the powering mechanisms of t…
Peak electron densities in Saturn's ionosphere derived from the low-frequency cutoff of Saturn lightning
Gurnett, D. A.; Fischer, G.; Zarka, P. +2 more
Radio bursts from Saturn lightning have been observed by the Cassini Radio and Plasma Wave Science instrument at frequencies of a few megahertz during several month-long storms since 2004. As the radio waves traverse Saturn's ionosphere on their way to the spacecraft, one can determine the peak electron density from the measurement of the low-freq…