Search Publications
Torus models of the outer disc of the Milky Way using LAMOST survey data
Mao, Shude; Liu, Chao; Wang, Qiao +2 more
With a sample of 48 161 K giant stars selected from the LAMOST DR 2 catalogue, we construct torus models in a large volume extending, for the first time, from the solar vicinity to a Galactocentric distance of ∼20 kpc, reaching the outskirts of the Galactic disc. We show that the kinematics of the K giant stars match conventional models, e.g. as c…
Diurnal variation in martian dust devil activity
Lewis, S. R.; Chapman, R. M.; Balme, M. +1 more
We show that the dust devil parameterisation in use in most Mars Global Circulation Models (MGCMs) results in an unexpectedly high level of dust devil activity during morning hours.
Prior expectations of the diurnal variation of Martian dust devils are based mainly upon the observed behaviour of terrestrial dust devils: i.e. that the majority…CoRoT 223992193: Investigating the variability in a low-mass, pre-main sequence eclipsing binary with evidence of a circumbinary disk
Aigrain, S.; Gandolfi, D.; Bouvier, J. +10 more
CoRoT 223992193 is the only known low-mass, pre-main sequence eclipsing binary that shows evidence of a circumbinary disk. The system displays complex photometric and spectroscopic variability over a range of timescales and wavelengths. Using two optical CoRoT runs from 2008 and 2011/2012 (spanning 23 and 39 days), along with infrared Spitzer 3.6 …
A Suzaku View of Accretion-powered X-Ray Pulsar GX 1+4
Hoshino, Akio; Naik, Sachindra; Kitamoto, Shunji +3 more
We present results obtained from a Suzaku observation of the accretion-powered X-ray pulsar GX 1+4. A broadband continuum spectrum of the pulsar was found to be better described by a simple model consisting of a blackbody component and an exponential cutoff power law than the previously used compTT continuum model. Though the pulse profile had a s…
The Uncertainty of Local Background Magnetic Field Orientation in Anisotropic Plasma Turbulence
Saur, J.; Gerick, F.; von Papen, M.
In order to resolve and characterize anisotropy in turbulent plasma flows, a proper estimation of the background magnetic field is crucially important. Various approaches to calculating the background magnetic field, ranging from local to globally averaged fields, are commonly used in the analysis of turbulent data. We investigate how the uncertai…
First results from SAM-FP: Fabry-Perot observations with ground-layer adaptive optics - the structure and kinematics of the core of 30 Doradus
Mendes de Oliveira, C.; Barbá, R.; Amram, P. +3 more
The aim of this paper is to present the first data set obtained with SOAR Adaptive Module-Fabry-Parot (SAM-FP), a Fabry-Perot instrument mounted inside the SOAR telescope Adaptive-Optics Module. This is the only existing imaging Fabry-Perot interferometer using laser-assisted ground-layer adaptive optics. SAM-FP was used to observe the ionized gas…
The low-luminosity behaviour of the 4U 0115+63 Be/X-ray transient
Degenaar, N.; Wijnands, R.; Cavecchi, Y. +3 more
The Be/X-ray transient 4U 0115+63 exhibited a giant, type-II outburst in 2015 October. The source did not decay to its quiescent state but settled in a meta-stable plateau state (a factor ∼ 10 brighter than quiescence) in which its luminosity slowly decayed. We used XMM-Newton to observe the system during this phase and we found that its spectrum …
25 MeV solar proton events in Cycle 24 and previous cycles
Richardson, Ian G.; Cane, Hilary V.; von Rosenvinge, Tycho T.
We summarize observations of around a thousand solar energetic particle (SEP) events since 1967 that include ∼25 MeV protons, made by various near-Earth spacecraft (IMPs 4, 5, 7, 8, ISEE 3, SOHO), that encompass Solar Cycle 20 to the current cycle (24). We also discuss recent observations of similar SEP events in Cycle 24 made by the STEREO spacec…
Key Ground-Based and Space-Based Assets to Disentangle Magnetic Field Sources in the Earth's Environment
Milan, S. E.; Masson, A.; Matzka, J. +1 more
The magnetic field measured on the ground or in space is the addition of several sources: from flows within the Earth's core to electric currents in distant regions of the magnetosphere. Properly separating and characterizing these sources requires appropriate observations, both ground-based and space-based. In the present paper, we review the exi…
Running vacuum cosmological models: linear scalar perturbations
Perico, E. L. D.; Tamayo, D. A.
In cosmology, phenomenologically motivated expressions for running vacuum are commonly parameterized as linear functions typically denoted by Λ(H2) or Λ(R). Such models assume an equation of state for the vacuum given by bar PΛ = - bar rhoΛ, relating its background pressure bar PΛ with its mean energy de…