Search Publications
Self-consistent nanoflare heating in model active regions: MHD avalanches
Hood, A. W.; Threlfall, J.; Reid, J.
Straightened cylindrical models of coronal loops have been standard for decades, and shown to support nanoflare-like heating, but the influence of geometric curvature in models upon the heating produced has not been discussed in depth. Heating, its spatiotemporal distributions, and the associated mechanisms responsible are discussed, and compared …
A study of the rapid rotator ζ Aql: differential surface rotation?
Bailey, Jeremy; Cotton, Daniel V.; Howarth, Ian D. +1 more
We report new, extremely precise photopolarimetry of the rapidly-rotating A0 main-sequence star ζ Aql, covering the wavelength range ~400-900 nm, which reveals a rotationally-induced signal. We model the polarimetry, together with the flux distribution and line profiles, in the framework of Roche geometry with ω-model gravity darkening, to establi…
Discovery of inverse-Compton X-ray emission and estimate of the volume-averaged magnetic field in a galaxy group
Simionescu, A.; Mernier, F.; Shimwell, T. W. +6 more
Observed in a significant fraction of clusters and groups of galaxies, diffuse radio synchrotron emission reveals the presence of relativistic electrons and magnetic fields permeating large scale systems of galaxies. Although, these non-thermal electrons are expected to upscatter cosmic microwave background photons up to hard X-ray energies, such …
The role of magnetic fields in the formation of the filamentary infrared dark cloud G11.11-0.12
Chen, Zhiwei; Su, Yang; Zhang, Shaobo +4 more
We report on the near-infrared polarimetric observations of G11.11-0.12 (hereafter G11) obtained with SIRPOL on the 1.4 m IRSF telescope. The starlight polarisation of the background stars reveals the on-sky component of magnetic fields in G11, and these are consistent with the field orientation observed from polarised dust emission at $850\, \mu$…
Prevalence of non-stationarity in quasi-periodic pulsations (QPPs) associated with M- and X-class solar flares
Hayes, L. A.; Broomhall, A. -M.; Mehta, T.
Quasi-periodic pulsations (QPPs) are frequently observed in solar and stellar flare emission, with recent studies suggesting that an increasing instantaneous period is a common characteristic of QPPs. Determining the prevalence of non-stationarity in QPPs contributes to a better understanding of which mechanism(s) is (are) responsible in QPP gener…
Impact of M-dwarf stellar wind and photoevaporation on the atmospheric evolution of small planets
Estrela, Raissa; Valio, Adriana; Modi, Ashini
The evolution of a planet's atmosphere depends strongly on its host star's properties. When their host stars are younger, planets can experience stronger winds and extreme ultraviolet radiation (EUV) emissions. This is particularly true for planets orbiting M dwarfs due to their close proximity to the host star. To determine if these planets retai…
A precise blue-optical transmission spectrum from the ground: evidence for haze in the atmosphere of WASP-74b
Madhusudhan, Nikku; Constantinou, Savvas; Mancini, Luigi +5 more
We report transmission spectroscopy of the bloated hot Jupiter WASP-74b in the wavelength range from 4000 to 6200 Å. We observe two transit events with the Very Large Telescope (VLT) Focal Reducer and Spectrograph and present a new method to measure the exoplanet transit depth as a function of wavelength. The new method removes the need for a refe…
On the anticorrelation between pericentric distance and inner dark matter density of Milky Way's dwarf spheroidal galaxies
Battaglia, Giuseppina; Nipoti, Carlo; Di Cintio, Arianna +1 more
An anticorrelation between the central density of the dark matter (DM) halo (ρ150, DM) and the pericentric distances (rp) of the Milky Way's (MW's) dwarf spheroidal galaxies (dSphs) has been reported in the literature. The existence and origin of such anticorrelation are, however, controversial, one possibility being that onl…
Hemispheric distribution of coronal mass ejections from 1996 to 2020
Li, C.; Deng, L. H.; Zhang, X. J. +3 more
Solar magnetic structures are known to be asymmetrically distributed between the two hemispheres. To date, the hemispheric variations of the coronal mass ejections (CMEs) at different latitudes, in different cycles, and for different types (regular and specific events) are still unclear. From the list of white-light CMEs in the Coordinated Data An…
Kinematics of stellar substructures in the small magellanic cloud
de Grijs, Richard; Kacharov, Nikolay; Cioni, Maria-Rosa L. +6 more
We present a kinematic analysis of the Small Magellanic Cloud using 3700 spectra extracted from the European Southern Observatory archive. We used data from Gaia and near-infrared photometry to select stellar populations and discard Galactic foreground stars. The sample includes main-sequence red giant branch and red clump stars, observed with Fib…