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The distances to star clusters hosting Red Supergiants: χ Per, NGC 7419, and Westerlund 1
Beasor, Emma R.; Davies, Ben
Galactic, young massive star clusters are approximately coeval aggregates of stars, close enough to resolve the individual stars, massive enough to have produced large numbers of massive stars, and young enough for these stars to be in a pre-supernova state. As such these objects represent powerful natural laboratories in which to study the evolut…
Stellar disc streams as probes of the Galactic potential and satellite impacts
Laporte, Chervin F. P.; Johnston, Kathryn V.; Tzanidakis, Anastasios
Stars aligned in thin stream-like features (feathers), with widths of δ ∼ 1-10° and lengths as large as Δl ∼ 180°, have been observed towards the Anticentre of our Galaxy and their properties mapped in abundances and phase-space. We study their origin by analysing similar features arising in an N-body simulation of a Galactic disc interacting with…
Filament Eruption and Its Reformation Caused by Emerging Magnetic Flux
Yang, Bo; Chen, Huadong
We present observations of the eruption and then reformation of a filament caused by its nearby emerging magnetic flux. Driven by the emerging magnetic flux, the emerging positive fluxes moved toward and canceled with their nearby negative fluxes, where the negative ends of a filament channel beneath the filament and a bundle of left-skewed corona…
From solar to stellar flare characteristics. On a new peak size distribution for G-, K-, and M-dwarf star flares
Heber, Bernd; Papaioannou, Athanasios; Herbst, Konstantin +1 more
Context. The connection between solar energetic proton events and X-ray flares has been the focus of many studies over the past 13 yr. In the course of these investigations several peak size distribution functions based on Geostationary Operational Environmental Satellite (GOES) measurements of both quantities have been developed. In more recent s…
Formation Imprints in the Kinematics of the Milky Way Globular Cluster System
Piatti, Andrés E.
We report results on the kinematics of Milky Way (MW) globular clusters (GCs) based on updated space velocities for nearly the entire GC population. We found that a 3D space with the semimajor axis, the eccentricity, and the inclination of the orbit with respect to the MW plane as its axes, is helpful in order to dig into the formation of the GC s…
Robust identification of active galactic nuclei through HST optical variability in GOODS-S: comparison with the X-ray and mid-IR-selected samples★
Hatzidimitriou, D.; Georgantopoulos, I.; Gavras, P. +9 more
Identifying active galactic nuclei (AGNs) through their X-ray emission is efficient, but necessarily biased against X-ray-faint objects. We aim to characterize this bias by comparing X-ray-selected AGNs to the ones identified through optical variability and mid-infrared (mid-IR) colours. We present a catalogue of AGNs selected through optical vari…
The Galactic Disk Phase Spirals at Different Galactic Positions Revealed by Gaia and LAMOST Data
Wang, H. -F.; Huang, Y.; Chen, B. -Q. +9 more
We have investigated the distributions of stellar azimuthal and radial velocity components V Φ and V R in the vertical position-velocity plane Z-V Z across the Galactic disk of 6.34 ≲ R ≲ 12.34 kpc and | {{Φ }}| ≲ 7\buildrel{\circ}\over{.} 5 using a Gaia and Gaia-LAMOST sample of stars. As found in previous wor…
Numerical integration of stochastic differential equations: A parallel cosmic ray modulation implementation on Africa's fastest computer
Moeketsi, D. M.; Engelbrecht, N. E.; Strauss, R. D. +2 more
Three-dimensional studies of the transport and modulation of cosmic ray particles in turbulent astrospheres require large-scale simulations using specialized scientific codes. Essentially, a multi-dimensional Fokker-Planck type equation (a parabolic diffusion equation) must be integrated numerically. One such approach is to convert the relevant tr…
Indications of non-conservative mass transfer in AMXPs
Sanna, A.; Papitto, A.; Di Salvo, T. +7 more
Context. Since the discovery of the first accreting millisecond X-ray pulsar (AMXP) SAX J1808.4-3658 in 1998, the family of these sources has kept growing. Currently, it has 22 members. All AMXPs are transients with usually very long quiescence periods, implying that the mass accretion rate in these systems is quite low and not constant. Moreover,…
Understanding Cassini RPWS Antenna Signals Triggered by Dust Impacts
Hospodarsky, G. B.; Kurth, W. S.; Zaslavsky, A. +11 more
Electric field antennas are capable of detecting dust impacts in different space environment. We analyze the dust impact signals detected by the Cassini Radio and Plasma Wave Science instrument at different locations around Saturn and compare them with dust impact signals simulated in laboratory conditions and numerically. The spacecraft potential…