Search Publications
Star formation in the centre of NGC 1808 as observed by ALMA
Chen, Guangwen; Kong, Xu; Bendo, George J. +2 more
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 85.69- and 99.02-GHz continuum emission and H42α and H40α lines emission from the central 1 kpc of NGC 1808. These forms of emission are tracers of photoionizing stars but unaffected by dust obscuration that we use to test the applicability of other commonly star format…
Smoke on the wind: dust nucleation in the archetype colliding-wind pinwheel WR 104
Millour, F.; Lau, R. M.; Soulain, A. +2 more
A handful of binary Wolf-Rayet stars are known to harbour spectacular spiral structures spanning a few hundred astronomical units. These systems host some of the highest dust production rates in the Universe and are therefore interesting candidates for addressing the origin of the enigmatic dust excess observed across galactic evolution. The subst…
No plateau observed in late-time near-infrared observations of the underluminous Type Ia supernova 2021qvv
Galbany, L.; Rest, A.; Howell, D. A. +23 more
Near-infrared (NIR) observations of normal Type Ia supernovae (SNe Ia) obtained between 150 and 500 d past maximum light reveal the existence of an extended plateau. Here, we present observations of the underluminous, 1991bg-like SN 2021qvv. Early, ground-based optical and NIR observations show that SN 2021qvv is similar to SN 2006mr, making it on…
Timing analysis of Swift J0243.6+6124 with NICER and Fermi/GBM during the decay phase of the 2017-2018 outburst
Santangelo, A.; Serim, M. M.; Baykal, A. +3 more
We present a timing and noise analysis of the Be/X-ray binary system Swift J0243.6+6124 during its 2017-2018 super-Eddington outburst using NICER/XTI observations. We apply a synthetic pulse timing analysis to enrich the Fermi/GBM spin frequency history of the source with the new measurements from NICER/XTI. We show that the pulse profiles switch …
A Hunting Expedition For High-Order Hierarchies
Kostov, Veselin B.; Powell, Brian P.; Tokovinin, Andrei
Stellar hierarchical systems of high order containing more than three stars are rare and fascinating objects; their discovery and study highlight still unknown aspects of star formation and early evolution. We matched eclipsing binaries discovered by Transiting Exoplanet Survey Satellite with a Gaia catalogue of wide binaries and selected candidat…
Exotic image formation in strong gravitational lensing by clusters of galaxies - IV. Elliptical NFW lenses and hyperbolic umbilics
Meena, Ashish Kumar; Bagla, Jasjeet Singh
A source lying near a hyperbolic umbilic (HU) singularity leads to a ring-like image formation, constituting four images with high magnification factors and lying in a small region of the lens plane. Since (based on our earlier work) the observed number of HU image formations in cluster lenses is expected to increase in the future, it is timely to…
The imprint of bursty star formation on alpha-element abundance patterns in Milky Way-like galaxies
Bailin, Jeremy; Stern, Jonathan; Faucher-Giguère, Claude-André +5 more
Milky Way-mass galaxies in the FIRE-2 simulations demonstrate two main modes of star formation. At high redshifts star formation occurs in a series of short and intense bursts, while at low redshifts star formation proceeds at a steady rate with a transition from one mode to another at times ranging from 3 to 7 Gyr ago for different galaxies. We a…
VLBI Astrometry of radio stars to link radio and optical celestial reference frames. I. HD 199178 & AR Lacertae
Wang, Min; Sun, Yan; Zhang, Bo +6 more
To accurately link the radio and optical Celestial Reference Frames (CRFs) at optical bright end, i.e. with GaiaG-band magnitude $\lesssim$13, increasing number and improving sky distribution of radio stars with accurate astrometric parameters from both Very Long Baseline Interferometry (VLBI) and Gaia measurements are mandatory. We selected two r…
Accretion disc evolution in GRO J1655-40 and LMC X-3 with relativistic and non-relativistic disc models
Grinberg, Victoria; Dovčiak, Michal; Boorman, Peter G. +3 more
Black hole X-ray binaries are ideal environments to study the accretion phenomena in strong gravitational potentials. These systems undergo dramatic accretion state transitions and analysis of the X-ray spectra is used to probe the properties of the accretion disc and its evolution. In this work, we present a systematic investigation of ~1800 spec…
Multi-wavelength aperture polarimetry of debris disc host stars
Bailey, Jeremy; Cotton, Daniel V.; Kedziora-Chudczer, Lucyna +3 more
Debris discs around main sequence stars have been extensively characterized from infrared to millimetre wavelengths through imaging, spectroscopic, and total intensity (scattered light and/or thermal emission) measurements. Polarimetric observations have only been used sparingly to interpret the composition, structure, and size of dust grains in t…