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Monopole and dipole estimation for multi-frequency sky maps by linear regression
Banday, A. J.; Dickinson, C.; Eriksen, H. K. +9 more
We describe a simple but efficient method for deriving a consistent set of monopole and dipole corrections for multi-frequency sky map data sets, allowing robust parametric component separation with the same data set. The computational core of this method is linear regression between pairs of frequency maps, often called T-T plots. Individual cont…
ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm
Solanki, Sami K.; Shimojo, Masumi; White, Stephen M. +2 more
We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are among the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a λ = 3 mm (100 GHz) mosaic…
Expanding and Contracting Coronal Loops as Evidence of Vortex Flows Induced by Solar Eruptions
Aulanier, G.; Schmieder, B.; Démoulin, P. +2 more
Eruptive solar flares were predicted to generate large-scale vortex flows at both sides of the erupting magnetic flux rope. This process is analogous to a well-known hydrodynamic process creating vortex rings. The vortices lead to advection of closed coronal loops located at the peripheries of the flaring active region. Outward flows are expected …
Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius
Bonifacio, P.; Saviane, I.; Monaco, L. +1 more
We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/Magellan spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, α, proton- and neutron-capture elem…
Dynamic response of the Martian ionosphere to an interplanetary shock: Mars Express and MAVEN observations
Gurnett, D. A.; Halekas, J. S.; Kopf, A. J. +10 more
Multipoint observations from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission reveal a dynamic response of the Martian ionosphere to abrupt variations in the upstream solar wind plasma. On 2 February 2017, MAVEN, located upstream …
Long-Term Variability of Jupiter's Magnetodisk and Implications for the Aurora
Bunce, Emma J.; Clarke, John T.; Vogt, Marissa F. +2 more
Observations of Jupiter's UV auroral emissions collected over several years show that the ionospheric positions of the main emission and the Ganymede footprint can vary by as much as 3° in latitude. One explanation for this shift is a change of Jupiter's current sheet current density, which would alter the amount of field line stretching and displ…
AGN Activity in Nucleated Galaxies as Measured by Chandra
Baldassare, Vivienne F.; Gültekin, Kayhan; Gnedin, Oleg Y. +4 more
Motivated by theoretical expectations that nuclear star clusters (NSCs) in galactic centers may provide a favorable environment for supermassive black holes to form and/or efficiently grow, we set out to measure the fraction of nearby nucleated galaxies that also host an active galactic nucleus. We targeted a distance-limited sample of 98 objects …
Characterization of dust aggregates in the vicinity of the Rosetta spacecraft
Jorda, L.; Lamy, P. L.; Lara, L. M. +49 more
In a Rosetta/OSIRIS imaging activity in 2015 June, we have observed the dynamic motion of particles close to the spacecraft. Due to the focal setting of the OSIRIS wide angle camera, these particles were blurred, which can be used to measure their distances to the spacecraft. We detected 109 dust aggregates over a 130 min long sequence, and find t…
Dust in Clusters: Separating the Contribution of Galaxies and Intracluster Media
López-Corredoira, M.; Gutiérrez, C. M.
We have analyzed a sample of 327 clusters of galaxies, spanning the range of 0.06-0.70 in redshift. Strong constraints on their mean intracluster emission of dust have been obtained using maps and catalogs from the Herschel MerMES project; within a radius of 5 arcmin centered in each cluster, the 95% C.L. limits obtained are 86.6, 48.2, and 30.9 m…
A Heuristic Approach to Remove the Background Intensity on White-light Solar Images. I. STEREO/HI-1 Heliospheric Images
Stenborg, Guillermo; Howard, Russell A.
White-light coronal and heliospheric imagers observe scattering of photospheric light from both dust particles (the F-Corona) and free electrons in the corona (the K-corona). The separation of the two coronae is thus vitally important to reveal the faint K-coronal structures (e.g., streamers, co-rotating interaction regions, coronal mass ejections…