Search Publications
A new framework for understanding systematic errors in cluster lens modelling - I. Selection and treatment of cluster member galaxies
Keeton, Charles R.; Raney, Catie A.; Zimmerman, Dhruv T.
With high-quality data from programs like the Hubble Frontier Fields, cluster lensing has reached the point that models are dominated by systematic rather than statistical uncertainties. We introduce a Bayesian framework to quantify systematic effects by determining how different lens modelling choices affect the results. Our framework includes a …
Substructure analysis of the RXCJ0232.2-4420 galaxy cluster
Kale, Ruta; Parekh, Viral; Laganá, Tatiana F.
RXCJ0232.2-4420, at z = 0.28, is a peculiar system hosting a radio halo source around the cool-core of the cluster. To investigate its formation and nature, we used archival Chandra and XMM-Newton X-ray data to study the dynamical state of the cluster and detect possible substructures in the hot gas. Its X-ray surface brightness distribution shows…
The episodic dust-making Wolf-Rayet star HD 38030 in the Large Magellanic Cloud
Massey, Philip; Boutsia, Konstantina; Williams, Peredur M. +1 more
Mid-infrared photometry of the Wolf-Rayet star HD 38030 in the Large Magellanic Cloud from the NEOWISE-R mission show it to have undergone a dust-formation episode in 2018 and the dust to have cooled in 2019-20. New spectroscopy with the MagE spectrograph on the Magellan I Baade Telescope in 2019 and 2020 show absorption lines attributable to a co…
Modeling of two CoRoT solar analogues constrained by seismic and spectroscopic analysis
Baudin, F.; Samadi, R.; Morel, T. +8 more
Solar analogues are important stars to study for understanding the properties of the Sun. Combined with seismic and spectroscopic analysis, evolutionary modelling becomes a powerful method to characterize stellar intrinsic parameters, such as mass, radius, metallicity and age. However, these characteristics, relevant for other aspects of astrophys…
On ancient solar-type stars - II
Fuhrmann, Klaus; Chini, Rolf
We report on the progress of our survey on ancient solar-type stars down to main-sequence effective temperatures Teff ≥ 5300 K and within 42 pc of the Sun. High signal-to-noise, high-resolution spectroscopy is presented for a second major subset of the Population II (τ ≥ 12 Gyr) and the intermediate-disc stars (τ ≃ 10 Gyr) within that v…
Influence of the Galactic bar on the kinematics of the disc stars with Gaia EDR3 data
Melnik, A. M.; Dambis, A. K.; Berdnikov, L. N. +1 more
A model of the Galaxy with the outer ring R1R2 can explain the observed distribution of the radial, VR, and azimuthal, VT, velocity components along the Galactocentric distance, R, derived from the Gaia EDR3 data. We selected stars from the Gaia EDR3 catalogue with reliable parallaxes, proper motions, an…
Prospects of direct detection of 48V gamma-rays from thermonuclear supernovae
Ruiter, Ashley J.; Siegert, Thomas; Panther, Fiona H. +3 more
Detection of gamma-rays emitted by radioactive isotopes synthesized in stellar explosions can give important insights into the processes that power transients such as supernovae, as well as providing a detailed census of the abundance of different isotope species relevant to the chemical evolution of the Universe. Observations of nearby supernovae…
The dynamics of the broad-line region in NGC 3227
Devereux, Nick
Archival Hubble Space Telescope (HST) observations of the Seyfert 1 nucleus of NGC 3227 obtained with the Space Telescope Imaging Spectrograph (STIS) are re-examined in order to constrain a viable photoionization model for the broad-line region (BLR). The results imply that the BLR is a partially ionized, dust-free, spherical shell that is collaps…
The nuclear environment of NGC 2442: a Compton-thick low-luminosity AGN
Steiner, J. E.; Menezes, R. B.; da Silva, Patrícia +2 more
The detailed study of nuclear regions of galaxies is important because it can help understanding the active galactic nucleus (AGN) feedback mechanisms, the connections between the nuclei and their host galaxies, and ultimately the galaxy formation processes. We present the analysis of an optical data cube of the central region of the galaxy NGC 24…
Detection of an energetic flare from the M5V secondary star in the Polar MQ Dra
Ramsay, Gavin; Hakala, Pasi; Wood, Matt A.
MQ Dra is a strongly magnetic Cataclysmic Variable whose white dwarf accretes material from its secondary star through a stellar wind at a low rate. TESS observations were made of MQ Dra in four sectors in Cycle 2 and show a short duration, high energy flare (~1035 erg) which has a profile characteristic of a flare from the M5V secondar…