A5049425566- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Atmospheric and Environmental Gas Dynamics
- SAS software applications and methods
- Radio Astronomy Observations and Technology
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Superconducting Materials and Applications
- Spacecraft Design and Technology
- Ionosphere and magnetosphere dynamics
- Magnetic confinement fusion research
- History and Developments in Astronomy
- Scientific Measurement and Uncertainty Evaluation
- Galaxies: Formation, Evolution, Phenomena
- Optical Systems and Laser Technology
Armagh Observatory & Planetarium
2016-2025
University of Manchester
2024
Western Sydney University
2021
University College London
1999-2011
UCL Australia
1997-2004
Utrecht University
1995-1998
Astronomical Institute of the Slovak Academy of Sciences
1997
Ultracompact binaries with orbital periods less than a few hours will dominate the gravitational wave signal in mHz regime. Until recently, 10 systems were expected have predicted strong enough to be detectable by Laser Interferometer Space Antenna (LISA), so-called `verification binaries'. System parameters, including distances, are needed provide an accurate prediction of strength measured LISA. Using parallaxes from {\sl Gaia} Data Release 2 we calculate signal-to-noise ratios (SNR) for...
Abstract Galactic compact binaries with orbital periods shorter than a few hours emit detectable gravitational waves (GWs) at low frequencies. Their GW signals can be detected the future Laser Interferometer Space Antenna (LISA). Crucially, they may useful in early months of mission operation helping to validate LISA's performance comparison prelaunch expectations. We present an updated list 55 candidate LISA-detectable measured properties, for which we derive distances based on Gaia Data...
Abstract We present volume-limited samples of cataclysmic variables (CVs) and AM CVn binaries jointly selected from SRG/eROSITA eRASS1 Gaia DR3 using an X-ray + optical color–color diagram (the “X-ray Main Sequence”). This tool identifies all CV subtypes, including magnetic low-accretion rate systems, in contrast to most previous surveys. find 23 CVs, 3 which are CVns, out 150 pc the Western Galactic Hemisphere. Our sample is spectroscopically verified complete down L X = 1.3 × 10 29 erg s...
ABSTRACT We report the results of optical follow-up observations 29 gravitational-wave (GW) triggers during first half LIGO–Virgo Collaboration (LVC) O3 run with Gravitational-wave Optical Transient Observer (GOTO) in its prototype 4-telescope configuration (GOTO-4). While no viable electromagnetic (EM) counterpart candidate was identified, we estimate our 3D (volumetric) coverage using test light curves on- and off-axis gamma-ray bursts kilonovae. In cases where source region observable...
ABSTRACT The Gravitational-wave Optical Transient Observer (GOTO) is an array of wide-field optical telescopes, designed to exploit new discoveries from the next generation gravitational wave detectors (LIGO, Virgo, and KAGRA), study rapidly evolving transients, multimessenger opportunities arising neutrino very high energy gamma-ray triggers. In addition a rapid response mode, will also perform sensitive, all-sky transient survey with few day cadence. facility features novel, modular design...
PLAnetary Transits and Oscillations of stars (PLATO) is an ESA M-class mission to be launched by the end 2026 discover characterize transiting planets around bright nearby stars, in particular habitable rocky hosted solar-like stars. Over lifetime, average 8% science data rate will allocated Guest Observer programs selected through public calls. Hence, it essential for community know advance where observing fields located. In a previous paper, we identified two preliminary long-pointing...
We present new high-speed, multi-observatory, multi-instrument photometry of the eclipsing polar UZ For in order to measure precise mid-eclipse times with aim detecting any orbital period variations. When combined published eclipse and archival data spanning ~27 years, we detect departures from a linear quadratic trend ~60 s. The are strongly suggestive two cyclic variations 16(3) 5.25(25) years. favoured mechanisms drive periodicities either giant extrasolar planets as companions binary...
We present phase resolved optical spectroscopy and photometry of V4580 Sagittarii, the counterpart to accretion powered millisecond pulsar SAX J1808.4−3658, obtained during 2008 September/October outburst. Doppler tomography N iiiλ4640.64 Bowen blend emission line reveals a focused spot at location consistent with secondary star. The velocity this occurs 324 ± 15 km s−1; applying 'K-correction', we find star projected on sight be 370 40 s−1. Based existing pulse timing measurements,...
AM CVn binaries are hydrogen deficient compact with an orbital period in the 5-65 min range and predicted to be strong sources of persistent gravitational wave radiation. Using Gaia Data Release 2, we present parallaxes proper motions 41 out 56 known systems. Compared parallax determined using HST Fine Guidance Sensor find that archetype star, CVn, is significantly closer than previously thought. This resolves high luminosity mass accretion rate which models had difficulty explaining....
Context. The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission will search for terrestrial planets in the habitable zone solar-type stars. Because telemetry limitations, PLATO targets need to be pre-selected. Aims. In this paper, we present an all sky catalogue that fundamental selecting best fields most promising target stars, deriving their basic parameters, analysing instrumental performances, then planing optimising follow-up observations. This also represents a valuable...
We calculate the temperature and density structure of hot post-shock plasma in magnetically confined accretion flows, including gravitational potential. This avoids inconsistency previous calculations which assume that height shock is negligible. a stratified column with 1D flow along symmetry axis. find predict lower than calculations, flatter profile height. revise determinations masses white dwarf primary stars, for higher mass dwarfs there general reduction derived when potential...
We present an analysis of K2 short cadence data 34 M dwarfs which have spectral types in the range M0–L1. Of these stars, 31 showed flares with a duration between ∼10 and 90min. Using distances obtained from Gaia DR2 parallaxes, we determined energy to be ∼1.2 × 1029–6 1034 erg. In agreement previous studies find rapidly rotating stars tend show more flares, evidence for decline activity rotation periods longer than d. The rotational modulation seen dwarf is widely considered result starspot...
Superflares on solar-type stars has been a rapidly developing field ever since the launch of $\it Kepler$. Over years, there have several studies investigating statistics these explosive events. In this study, we present statistical analysis stellar flares made using photometric data in 2-min cadence from TESS$ whole southern hemisphere (sectors 1 - 13). We derive rotational periods for all our sample modulations lightcurve as result large starspot(s) surface. identify 1980 209 with energies...
Detailed studies of the Sun have shown that sunspots and solar flares are closely correlated. Photometric data from Kepler/K2 has allowed similar to be carried out on other stars. Here, we utilise TESS photometric 2-min cadence 167 low mass stars Sectors 1 - 3 investigate relationship between starspots stellar flares. From our sample, 90 percent show clear rotational modulation likely due presence a large, dominant starspot use this determine period for each star. Additionally, star shows...
PLATO (PLAnetary Transits and Oscillations of stars) is an ESA M-class satellite planned for launch by end 2026 dedicated to the wide-field search transiting planets around bright nearby stars, with a strong focus on discovering habitable rocky hosted solar-like stars. The choice fields be pointed at crucial task since it has direct impact scientific return mission. In this paper we describe discuss formal requirements key prioritization criteria that have taken into account in Long-duration...
Abstract The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable transient radio sources timescales from 5 s $\sim\!5$ yr. In this paper, we present survey description, observation strategy initial results VAST Phase I Pilot Survey. This pilot consists of $\sim\!162$ h observations conducted at a central frequency 888 MHz between 2019 August 2020 August, with typical rms sensitivity $0.24\ \mathrm{mJy\...
We report the discovery of a dark companion to 2MASS J15274848+3536572 with an orbital period 6.14 hr. Combining radial velocity from LAMOST observations and modelling multiband light curve, one obtains mass function $\simeq 0.131~\rm M_{\odot}$, inclination $45.20^\circ{}^{+0.13^{\circ}}_{-0.20^{\circ}}$, ratio $0.631^{+0.014}_{-0.003}$, which demonstrate binary nature $0.98 \pm 0.03\rm M_{\odot}$ main-sequence K9-M0 star $0.62 0.01~\rm M_{\odot}$. optical spectra at range phases reveal...
One method of obtaining the mass white dwarf in magnetic cataclysmic variables (mCVs) is through their hard X-ray spectra. However, previous estimates using this give lower limits because temperature plasma post-shock region (where X-rays are emitted) than shock itself. In AM Her systems, additional cooling by cyclotron emission will further derived mass. Here we present masses 13 mCVs Ginga data and a model which emitted from multi-temperature with appropriate density profile. We include...
We present a detailed analysis of Jupiter's X-ray (0.2-10 keV) auroral emissions as observed over two XMM-Newton revolutions in Nov. 2003 and compare it with that an earlier observation Apr.2003.We discover the existence electron bremsstrahlung component aurorae, which accounts for essentially all flux above 2 keV: its presence had been predicted but never detected lack sensitivity previous missions.This varied significantly strength spectral shape 3.5 days covered by observation, displaying...
We present the results of a high-cadence photometric survey an 11 arcmin × field centred on globular cluster M71, with Near-Infrared Transiting ExoplanetS Telescope. The aim our is to search for stellar variability and giant transiting exoplanets. This differs from previous surveys M71 in that it more sensitive lower amplitude (ΔM ≤ 0.02 mag) longer period (P > 2 d) than work this cluster. have discovered 17 new variable stars towards confirm nature 13 previously known objects, which orbital...
ABSTRACT Large-scale sky surveys have played a transformative role in our understanding of astrophysical transients, only made possible by increasingly powerful machine learning-based filtering to accurately sift through the vast quantities incoming data generated. In this paper, we present new real-bogus classifier based on Bayesian convolutional neural network that provides nuanced, uncertainty-aware classification transient candidates difference imaging, and demonstrate its application...
ABSTRACT We report the discovery of a brown dwarf orbiting M1 host star. first identified within Next Generation Transit Survey data, with supporting observations found in TESS sectors 11 and 38. confirmed follow-up photometry from South African Astronomical Observatory, SPECULOOS-S, TRAPPIST-S, radial velocity measurements HARPS, which allowed us to characterize system. find an orbital period ∼1.25 d, mass $69.0^{+5.3}_{-4.8}$ MJ, close hydrogen burning limit, radius 0.95 ± 0.05 RJ....
PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect characterise extrasolar planets perform asteroseismic monitoring a large number stars. will small (down <2 R_(Earth)) around bright stars (<11 mag), including terrestrial in the habitable zone solar-like With complement radial velocity observations from ground, be characterised for their radius, mass, age with high accuracy (5 %, 10 % an Earth-Sun combination respectively). provide us large-scale...
We present the results of ROSAT pointed observations AM Her stars AN UMa and MR Ser. was in a high-brightness state. examine its soft X-ray light curve, fit spectrum with two-component model consisting an absorbed blackbody harder thermal bremsstrahlung distribution. Ser found to be low-brightness state, had which well fitted single-component, model.