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EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf
Fossati, L.; Zejda, M.; Paunzen, E. +7 more
Context. Very precise satellite photometry has revealed a large number of variable stars whose variability is caused either by surface spots or by binarity. Detailed studies of such variables provide insights into the physics of these objects.
Aims: We study the nature of the periodic light variability of the white dwarf EPIC 206197016 that w…
Disentangling the nature of the prototype radio weak BL Lac. Contemporaneous multifrequency observations of WISE J141046.00+740511.2
Masetti, N.; Chavushyan, V.; Acosta-Pulido, J. A. +13 more
Context. The γ-ray emitting source WISE J141046.00+740511.2 has been associated with a Fermi-LAT detection by crossmatching with Swift/XRT data. It has shown all the canonical observational characteristics of a BL Lac source, including a power-law, featureless optical spectrum. However, it was only recently detected at radio frequencies and its ra…
A new method to determine X-ray luminosity functions of AGN and their evolution with redshift
Page, Mat J.; Alqasim, Ahlam
Almost all massive galaxies today are understood to contain supermassive black holes (SMBH) at their centres. SMBHs grew by accreting material from their surroundings, emitting X-rays as they did so. X-ray luminosity functions (XLFs) of active galactic nuclei (AGN) have been extensively studied in order to understand the AGN population's cosmologi…
Abundance analysis of a nitrogen-rich extreme-helium hot subdwarf from the SALT survey
Dorsch, M.; Jeffery, C. S.; Scott, L. J. A. +2 more
We have performed a detailed spectral analysis of the helium-rich hot subdwarf EC 20187-4939, using data obtained in the SALT survey of helium-rich hot subdwarfs. We have measured its effective temperature, surface gravity, and chemical abundances from the spectrum. Its radius has also been determined by fitting the spectral energy distribution us…
Space Weather Disturbances in Non-Stormy Times: Occurrence of dB/dt Spikes During Three Solar Cycles
Gunell, H.; Hamrin, M.; Opgenoorth, H. +8 more
Spatio-temporal variations of ionospheric currents cause rapid magnetic field variations at ground level and Geomagnetically Induced Currents (GICs) that can be harmful for human infrastructure. The risk for large excursions in the magnetic field time derivative, "dB/dt spikes", is known to be high during geomagnetic storms and substorms. However,…
Statistical Signatures of Nanoflare Activity. III. Evidence of Enhanced Nanoflaring Rates in Fully Convective stars as Observed by the NGTS
Mathioudakis, M.; Wheatley, P. J.; Goad, M. R. +11 more
Previous examinations of fully convective M-dwarf stars have highlighted enhanced rates of nanoflare activity on these distant stellar sources. However, the specific role the convective boundary, which is believed to be present for spectral types earlier than M2.5V, plays on the observed nanoflare rates is not yet known. Here, we utilize a combina…
Looking ahead to the sky with the Square Kilometre Array: simulating flux densities and resolved radio morphologies of 0 < z < 2.5 star-forming galaxies
Daddi, Emanuele; Franco, Maximilien; Cibinel, Anna +4 more
SKA-MID surveys will be the first in the radio domain to achieve clearly sub-arcsecond resolution at high sensitivity over large areas, opening new science applications for galaxy evolution. To investigate the potential of these surveys, we create simulated SKA-MID images of a ~0.04 deg2 region of GOODS-North, constructed using multi-ba…
Characterizing CO Emitters in the SSA22-AzTEC26 Field
Tamura, Yoichi; Kohno, Kotaro; Kawabe, Ryohei +5 more
We report the physical characterization of four CO emitters detected near the bright submillimeter galaxy (SMG) SSA22-AzTEC26. We analyze the data from Atacama Large Millimeter/submillimeter Array band 3, 4, and 7 observations of the SSA22-AzTEC26 field. In addition to the targeted SMG, we detect four line emitters with signal-to-noise ratio >5…
X-Ray and UV Observations of the Contact Binary KIC 9832227
Pandel, Dirk; Molnar, Lawrence A.
We investigate the X-ray and UV emission from the contact binary star KIC 9832227, which was observed with XMM-Newton for one orbital cycle. The binary is detected with an average X-ray luminosity of 3.4 × 1030 erg s-1. The X-ray emission is restricted to energies below 3 keV and originates from a multitemperature plasma with…
Partially Erupted Prominence Material as a Diagnostic of Coronal Mass Ejection Trajectory
Thompson, B. J.; Mason, E. I.; Hovis-Afflerbach, B. A.
Coronal mass ejections (CMEs) are energetic releases of large-scale magnetic structures from the Sun. CMEs can have impacts on spacecraft and at Earth. This trajectory is typically assumed to be radial, but often the CME moves outward with some spatial offset from the source region where the eruption initially occurred. A CME is frequently accompa…