Search Publications
Are magnetic fields universal in O-type multiple systems?
Ilyin, I.; Hubrig, S.; Schöller, M. +2 more
Although significant progress has been achieved in recent surveys of the magnetism in massive stars, the origin of the detected magnetic fields remains to be the least understood topic in their studies. We present an analysis of 61 high-resolution spectropolarimetric observations of 36 systems with O-type primaries, among them 10 known particle-ac…
The EBLM project X. Benchmark masses, radii, and temperatures for two fully convective M-dwarfs using K2
Hellier, Coel; Triaud, Amaury H. M. J.; Sairam, Lalitha +23 more
M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, their intrinsic faintness and complex spectra inhibit precise characterization. We only know of dozens of M-dwarfs with fundamental parameters of mass, radius, and effective temperature characterized to better than a few per cent. Eclipsing bina…
Optical and X-ray studies of Be/X-ray binary 1A 0535+262 during its 2020 giant outburst
Naik, Sachindra; Jana, Arghajit; Jaisawal, Gaurava K. +3 more
We report results obtained from the optical and X-ray studies of the Be/X-ray binary 1A 0535+262/HD 245770 during the 2020 October giant X-ray outburst, using the 1.2-m telescope at Mount Abu Infrared observatory and AstroSat, respectively. The peak flux of the outburst was recorded to be ~11 Crab in the 15-50 keV range, the highest ever observed …
An excursion into the core of the cluster lens Abell 1689
Scarlata, Claudia; Liesenborgs, Jori; Alavi, Anahita +3 more
Abell 1689 is a well-studied cluster of galaxies and one of the largest gravitational lens systems ever observed. We have obtained a reconstruction of the cluster Abell 1689 using GRALE, a free-form lens inversion method that relies exclusively on the multiple image data. Non-inclusion of any data related to cluster member galaxies ensures an unbi…
Discovery of delta Scuti variables in eclipsing binary systems II. Southern TESS field search
Kahraman Aliçavuş, F.; Aliçavuş, F.; Çoban, Ç. G. +3 more
The presence of pulsating stars in eclipsing binary systems (EBs) makes these objects significant since they allow us to investigate the stellar interior structure and evolution. Different types of pulsating stars could be found in EBs, such as δ Scuti variables. δ Scuti stars in EBs have been known for decades, and the increasing number of such s…
Spectroscopic follow-up of statistically selected extremely metal-poor star candidates from GALAH DR3
Spitler, Lee R.; Da Costa, G. S.; Buder, Sven +5 more
The advent of large-scale stellar spectroscopic surveys naturally leads to the implementation of machine learning techniques to isolate, for example, small sub-samples of potentially interesting stars from the full data set. A recent example is the application of the t-SNE statistical method to ~600 000 stellar spectra from the GALAH survey in ord…
Accelerated phase-mixing in the stellar halo due to a rotating bar
Vasiliev, Eugene; Belokurov, Vasily; Davies, Elliot Y. +1 more
In a galaxy merger, the stars tidally stripped from the satellite and accreted onto the host galaxy undergo phase-mixing and form finely grained structures in the phase space. However, these fragile structures may be destroyed in the subsequent galaxy evolution, in particular, by a rotating bar that appears well after the merger is completed. In t…
Multiwavelength study of NGC 1365: The obscured active nucleus and off-nuclear compact X-ray sources
Shalima, P.; Swain, Subhashree; Dewangan, Gulab Chand +2 more
We present a multiwavelength study of the active nucleus and the off-nuclear X-ray sources in the nearby spiral galaxy, NGC 1365 using three simultaneous UV/X-ray observations by AstroSat over a two months period and archival IR observations performed with Spitzer and Herschel. Utilizing the data from the Soft X-ray Telescope (SXT) onboard AstroSa…
New stellar velocity substructures from Gaia DR3 proper motions
McMillan, Paul J.; Hobbs, David; Mikkola, Daniel
Local stellar motions are expected, and have been shown, to include signatures of the Galaxy's past dynamical evolution. These are typically divided into the disc, which shows the dynamical effects of spiral arms and the bar, and the stellar halo, with structures thought to be debris from past mergers. We use Gaia Data Release 3 to select large sa…
Reconstructing the genesis of a globular cluster system at a look-back time of 9.1 Gyr with the JWST
Forbes, Duncan A.; Romanowsky, Aaron J.
Using early-release data from the JWST, Mowla et al. and Claeyssens et al. recently measured various properties for gravitationally lensed compact sources ('sparkles') around the 'Sparkler' galaxy at a redshift of 1.378 (a look-back time of 9.1 Gyr). Here, we focus on the Mowla et al. as they were able to break the age-metallicity degeneracy and d…