Search Publications
A search for the missing baryons with X-ray absorption lines towards the blazar 1ES 1553+113
de Plaa, Jelle; Bonamente, Massimiliano; Nevalainen, Jukka +5 more
This paper presents an analysis of XMM-Newton and Chandra X-ray spectra of the quasar 1ES 1553+113, in search for absorption lines from the intervening warm-hot intergalactic medium (WHIM). A search for O VII, O VIII, and Ne IX resonance absorption lines was performed at eight fixed redshifts that feature O VI or H I broad Lyman α absorption lines…
Quantifying the influence of bars on action-based dynamical modelling of disc galaxies
Green, Gregory M.; Trick, Wilma H.; Ghosh, Soumavo
Action-based dynamical modelling, using stars as dynamical tracers, is an excellent diagnostic to estimate the underlying axisymmetric matter distribution of the Milky Way. However, the Milky Way's bar causes non-axisymmetric resonance features in the stellar disc. Using RoadMapping (an action-based dynamical modelling framework to estimate the gr…
Constraining dark matter substructure with Gaia wide binaries
Buckley, Matthew R.; Ramirez, Edward D.
We use a catalogue of stellar binaries with wide separations (up to 1 pc) identified by the Gaia satellite to constrain the presence of extended substructure within the Milky Way galaxy. Heating of the binaries through repeated encounters with substructure results in a characteristic distribution of binary separations, allowing constraints to be p…
New insight into the massive eccentric binary HD 165052: self-consistent orbital solution, apsidal motion, and fundamental parameters
Rauw, G.; Rosu, S.; Eenens, P. +1 more
HD 165052 is a short-period massive eccentric binary system that undergoes apsidal motion. As the rate of apsidal motion is directly related to the internal structure constants of the binary components, its study allows getting insight into the internal structure of the stars. We use medium- and high-resolution spectroscopic observations of HD 165…
Far beyond the Sun - II. Probing the stellar magnetism of the young Sun ι Horologii from the photosphere to its corona
Sanz-Forcada, J.; Redfield, S.; Drake, J. J. +14 more
A comprehensive multiwavelength campaign has been carried out to probe stellar activity and variability in the young Sun-like star ι-Horologii. We present the results from long-term spectropolarimetric monitoring of the system by using the ultra-stable spectropolarimeter/velocimeter HARPS at the ESO 3.6-m telescope. Additionally, we included high-…
Deep search for glycine conformers in Barnard 5
Bergman, P.; Charnley, S. B.; Carl, Tadeus +3 more
One of the most fundamental hypotheses in astrochemistry and astrobiology states that crucial biotic molecules like glycine (NH2CH2COOH) found in meteorites and comets are inherited from early phases of star formation. Most observational searches for glycine in the interstellar medium have focused on warm high-mass molecular …
X-ray emission from Ae/Be Herbig stars due to disc-stellar magnetosphere interaction
Lyutikov, Maxim; Ryspaeva, Elizaveta; Kholtygin, Alexander
We reanalyse archival X-ray data of 16 Ae/Be Herbig stars obtained by the XMM-Newton and Chandra satellites. Stellar X-ray spectra in the energy range 0.2-8 keV were fitted with the use of APEC and MEKAL hot plasma emission models, and with models with an additional power-law component. We find that for Herbig stars, the dependence of the unabsorb…
Field blue straggler stars: discovery of white dwarf companions to blue metal-poor stars using UVIT/AstroSat
Subramaniam, Annapurni; Panthi, Anju; Vaidya, Kaushar +4 more
Blue metal-poor (BMP) stars are the main-sequence stars that appear bluer and more luminous than normal turn-off stars of metal-poor globular clusters. They are believed to be either field blue straggler stars (FBSS) formed via post-mass transfer mechanism or accreted from dwarf satellite galaxies of the Milky Way. A significant fraction of BMP st…
Everything that glitters is not gold: V1315 Cas is not a dormant black hole
Guenther, E. W.; Shenar, T.; Boffin, H. M. J. +11 more
The quest for quiet or dormant black holes has been ongoing since several decades. Ellipsoidal variables possibly indicate the existence of a very high-mass invisible companion and are thought to be one of the best ways to find such dormant black holes. This, however, is not a panacea as we show here with one example. We indeed report the discover…
Automated classification of Chandra X-ray point sources using machine learning methods
Bhattacharyya, Sudip; Kumaran, Shivam; Mandal, Samir +1 more
A large number of unidentified sources found by astronomical surveys and other observations necessitate the use of an automated classification technique based on machine learning (ML) methods. The aim of this paper is to find a suitable automated classifier to identify the point X-ray sources in the Chandra Source Catalogue (CSC) 2.0 in the catego…