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How Important Are Electron Beams in Driving Chromospheric Evaporation in the 2014 March 29 Flare?
Krucker, Säm; Kleint, Lucia; Battaglia, Marina +1 more
We present high spatial resolution observations of chromospheric evaporation in the flare SOL2014-03-29T17:48. Interface Region Imaging Spectrograph observations of the Fe xxi λ 1354.1 line indicate evaporating plasma at a temperature of 10 MK along the flare ribbon during the flare peak and several minutes into the decay phase with upflow velocit…
A Radio-Polarisation and Rotation Measure Study of the Gum Nebula and Its Environment
Gaensler, B. M.; Carretti, E.; Bernardi, G. +7 more
The Gum Nebula is 36°-wide shell-like emission nebula at a distance of only ∼450 pc. It has been hypothesized to be an old supernova remnant, fossil H ii region, wind-blown bubble, or combination of multiple objects. Here we investigate the magneto-ionic properties of the nebula using data from recent surveys: radio-continuum data from the NRAO VL…
Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity
Guenther, E. W.; Zechmeister, M.; Hatzes, A. P. +14 more
Aims: We investigate the nature of the long-period radial velocity variations in α Tau first reported over 20 yr ago.
Methods: We analyzed precise stellar radial velocity measurements for α Tau spanning over 30 yr. An examination of the Hα and Ca II λ8662 spectral lines, and Hipparcos photometry was also done to help discern the nature o…
On the triple peaks of SNHunt248 in NGC 5806
Sollerman, J.; Jerkstrand, A.; Smartt, S. J. +19 more
We present our findings on a supernova (SN) impostor, SNHunt248, based on optical and near-IR data spanning ~15 yr before discovery, to ~1 yr post-discovery. The light curve displays three distinct peaks, the brightest of which is at MR ~ -15.0 mag. The post-discovery evolution is consistent with the ejecta from the outburst interacting…
Gamma-Ray Flaring Activity from the Gravitationally Lensed Blazar PKS 1830-211 Observed by Fermi LAT
Troja, E.; Caraveo, P. A.; Bechtol, K. +125 more
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope routinely detects the MeV-peaked flat-spectrum radio quasar PKS 1830-211 (z = 2.507). Its apparent isotropic γ-ray luminosity (E > 100 MeV), averaged over ~3 years of observations and peaking on 2010 October 14/15 at 2.9 × 1050 erg s-1, makes it am…
A Statistical Study of the Solar Wind Turbulence at Ion Kinetic Scales Using the k-filtering Technique and Cluster Data
Li, X.; Roberts, O. W.; Jeska, L.
Plasma turbulence at ion kinetic scales in the solar wind is investigated using the multi-point magnetometer data from the Cluster spacecraft. By applying the k-filtering method, we are able to estimate the full three-dimensional power spectral density P(ωsc, k) at a certain spacecraft frequency ωsc in wavevector (k) space. B…
Morphometry of small recent impact craters on Mars: Size and terrain dependence, short-term modification
Watters, W. A.; Geiger, L. M.; Fendrock, M. +1 more
Most recent studies of crater morphometry on Mars have addressed large craters (D>5 km) using elevation models derived from laser altimetry. In the present work, we examine a global population of small (25 m ≤D≤5 km), relatively well-preserved simple impact craters using HiRISE stereo-derived elevation models. We find that scaling laws from pri…
Grain size limits derived from 3.6 µm and 4.5 µm coreshine
Juvela, M.; Paladini, R.; Henning, Th. +8 more
Context. Recently discovered scattered light from molecular cloud cores in the wavelength range 3-5 µm (called "coreshine") seems to indicate the presence of grains with sizes above 0.5 µm.
Aims: We aim to analyze 3.6 and 4.5 µm coreshine from molecular cloud cores to probe the largest grains in the size distribution.
M…
A morpho-kinematic and spectroscopic study of the bipolar nebulae: M 2-9, Mz 3, and Hen 2-104
Akras, S.; Steffen, W.; Harvey, E. +3 more
Context. Complex bipolar shapes can be generated either as a planetary nebula or a symbiotic system. The origin of the material ionised by the white dwarf is very different in these two scenarios, and it complicates the understanding of the morphologies of planetary nebulae.
Aims: The physical properties, structure, and dynamics of the bipola…
X-ray spectral variability of Seyfert 2 galaxies
González-Martín, O.; Márquez, I.; Masegosa, J. +1 more
Context. Variability across the electromagnetic spectrum is a property of active galactic nuclei (AGN) that can help constrain the physical properties of these galaxies. Nonetheless, the way in which the changes happen and whether they occur in the same way in every AGN are still open questions.
Aims: This is the third in a series of papers w…