Search Publications
The recurrent nova U Scorpii from the 2010.1 to 2022.4 eruptions; the missed eruption of 2016.78 ± 0.10 and the critical complex period changes
Schaefer, Bradley E.
U Sco is a recurrent nova with 11 observed eruptions, most recently in 2010.1 and 2022.4. I report on my program (running since 1989) of measuring eclipse times and brightnesses of U Sco in quiescence, from 2010 to 2022. The orbital period suddenly increased by +22.4 ± 1.0 parts-per-million across the 2010.1 eruption. This period change is greater…
Quantifying kinematic substructure in star-forming regions with statistical tests of spatial autocorrelation
Parker, Richard J.; Wright, Nicholas J.; Arnold, Becky
We investigate whether spatial-kinematic substructure in young star-forming regions can be quantified using Moran's I statistic. Its presence in young star clusters would provide an indication that the system formed from initially substructured conditions, as expected by the hierarchical model of star cluster formation, even if the cluster were sp…
A detailed study of the bridge of excess X-ray emission between the galaxy clusters Abell 2029 and Abell 2033
Walker, S. A.; Mirakhor, M. S.; Runge, J.
We examine Suzaku, XMM-Newton, and Chandra observations of the Abell 2029/2033 system to investigate the nature of a bridge of X-ray emission joining the two galaxy clusters. By modelling the contributions from the outskirts of the two clusters, and excluding the emission from the southern infalling group and the background group LOS9, we find a s…
Catching a grown-up starfish planetary nebula - II. Plasma analysis and central star properties of PC 22
Morisset, C.; Guerrero, M. A.; Todt, H. +4 more
After performing the morpho-kinematic analysis of the planetary nebula (PN) PC 22, we now present its nebular and stellar analysis. The plasma investigation relies on the novel use of a Monte Carlo analysis associated with the PYNEB code for the uncertainty propagation. The innermost region of the nebula shows electronic temperatures Te…
Investigating the nature of the ultraluminous X-ray sources in the galaxy NGC 925
Salvaterra, R.; Wolter, A.; Belfiore, A. +7 more
Variability is a powerful tool to investigate properties of X-ray binaries (XRB), in particular for Ultraluminous X-ray sources (ULXs) that are mainly detected in the X-ray band. For most ULXs the nature of the accretor is unknown, although a few ULXs have been confirmed to be accreting at super-Eddington rates on to a neutron star (NS). Monitorin…
The TELPERION survey for distant [O III] clouds around luminous and hibernating AGN
Keel, William C.; Eselevich, M. V.; Smirnova, A. A. +5 more
We present a narrow-band [O III] imaging survey of 111 active galactic nucleus (AGN) hosts and 17 merging-galaxy systems, in search of distant extended emission-line regions (EELRs) around AGNs (either extant or faded). Our data reach deeper than detection from the broad-band SDSS data and cover a wider field than some early emission-line surveys …
New photometry of 12 ultrashort-period late-type binary stars
Koen, C.
Candidate late-type binary stars were selected on the basis of their red g - i and r - z colours, and short (0.1159-0.2059 d) published periods. At least one cycle of variation of each star was observed in the RC and IC bands. For the five brightest stars, observations were also obtained in V. Typically ~17 standardized photo…
Mid-infrared imaging of Supernova 1987A
Matsuura, Mikako; Barlow, M. J.; Meixner, Margaret +9 more
At a distance of 50 kpc, Supernova 1987A is an ideal target to study how a young supernova (SN) evolves in time. Its equatorial ring, filled with material expelled from the progenitor star about 20 000 yr ago, has been engulfed with SN blast waves. Shocks heat dust grains in the ring, emitting their energy at mid-infrared (IR) wavelengths We prese…
The VMC survey - XLIX. Discovery of a population of quasars dominated by nuclear dust emission behind the Magellanic Clouds
Maitra, Chandreyee; Hopkins, Andrew M.; Haberl, Frank +14 more
Following the discovery of SAGE0536AGN (z ~ 0.14), with the strongest 10-µm silicate emission ever observed for an active galactic nucleus (AGN), we discovered SAGE0534AGN (z ~ 1.01), a similar AGN but with less extreme silicate emission. Both were originally mistaken as evolved stars in the Magellanic Clouds. Lack of far-infrared emission, …
SRG/eROSITA view of X-ray reflection in the Central Molecular Zone: a snapshot in September-October 2019
Khabibullin, Ildar; Churazov, Eugene; Sunyaev, Rashid
X-ray reflection off dense molecular clouds in the Galactic Centre region has established itself as a powerful probe for the past activity record of the supermassive black hole Sgr A* on a time-scale of a few hundred years. Detailed studies of the reflection signal from individual clouds allow us to estimate parameters of the brightest flare(s) an…