Search Publications
Characterizing non-thermal equilibrium contact binaries
Wang, Z. H.; Zhu, L. Y.; Yuan, K.
Formation and evolution of marginal contact binaries with larger temperature difference between their two components remain inexplicable to date. To get a better understanding of the nature of such population we investigate on an individual, NSVS 7358116, by analysing observational data obtained from ground-based and space-based telescopes. It is …
Detection of spicules termed rapid blueshifted excursions as seen in the chromosphere via H α and the transition region via Si IV 1394 Å line emission
Shetye, Juie; Doyle, J. Gerry; Vilangot Nhalil, Nived
We show signatures of spicules termed rapid blueshifted excursions (RBEs) in the Si IV 1394 Å emission line using a semi-automated detection approach. We use the H α filtergrams obtained by the CRISP imaging spectropolarimeter on the Swedish 1-m Solar Telescope and co-aligned Interface Region Imaging Spectrograph data using the SJI 1400 Å channel …
External or internal companion exciting the spiral arms in CQ Tau?
Testi, Leonardo; Benisty, Myriam; Pinte, Christophe +9 more
We present new high-contrast images in near-infrared wavelengths (λc = 1.04, 1.24, 1.62, 2.18, and 3.78 µm) of the young variable star CQ Tau, aiming to constrain the presence of companions in the protoplanetary disc. We reached a Ks-band contrast of 14 mag with SPHERE/IRDIS at separations greater than 0${_{.}^{\prime\prime}}$4 fr…
Massive young stellar objects in the Local Group spiral galaxy M 33 identified using machine learning
van Loon, Jacco Th; Oliveira, Joana M.; Kinson, David A.
We present a supervised machine learning classification of stellar populations in the Local Group spiral galaxy M 33. The Probabilistic Random Forest (PRF) methodology, previously applied to populations in NGC 6822, utilizes both near and far-IR classification features. It classifies sources into nine target classes: young stellar objects (YSOs), …
On the origin of core radio emissions from black hole sources in the realm of relativistic shocked accretion flow
Stalin, C. S.; Rakshit, Suvendu; Nandi, Anuj +5 more
We study the relativistic, inviscid, advective accretion flow around the black holes and investigate a key feature of the accretion flow, namely the shock waves. We observe that the shock-induced accretion solutions are prevalent and such solutions are commonly obtained for a wide range of the flow parameters, such as energy (${\cal E}$) and angul…
NGTS-21b: an inflated Super-Jupiter orbiting a metal-poor K dwarf
Wheatley, Peter J.; Bayliss, Daniel; Worters, Hannah L. +29 more
We report the discovery of NGTS-21b , a massive hot Jupiter orbiting a low-mass star as part of the Next Generation Transit Survey (NGTS). The planet has a mass and radius of 2.36 ± 0.21 MJ and 1.33 ± 0.03 RJ, and an orbital period of 1.543 d. The host is a K3V (Teff = 4660 ± 41 K) metal-poor ([Fe/H] = -0.26 ± 0.07…
Redshift and stellar mass dependence of intrinsic shapes of disc-dominated galaxies from COSMOS observations below z = 1.0
Tallada-Crespí, P.; Teyssier, R.; Laigle, C. +4 more
The high abundance of disc galaxies without a large central bulge challenges predictions of current hydrodynamic simulations of galaxy formation. We aim to shed light on the formation of these objects by studying the redshift and mass dependence of their intrinsic 3D shape distributions in the COSMOS galaxy survey below redshift z = 1.0. This dist…
Discovery of a pulse-phase-transient cyclotron line in the X-ray pulsar Swift J1808.4-1754 and identification of an optical companion
Tsygankov, Sergey S.; Lutovinov, Alexander A.; Molkov, Sergey V. +3 more
In this work, the temporal and spectral properties of the poorly studied X-ray pulsar Swift J1808.4-1754 were investigated in the 0.8-79 keV energy range based on the data from the NuSTAR and Swift observatories collected during the 2014 outburst. Strong pulsations with a period of 909.73 ± 0.03 s were detected in the source light curve, with the …
Probabilistic orbits and dynamical masses of emission-line binaries
Grant, David; Blundell, Katherine
The observed orbits of emission-line stars may be affected by systematics owing to their broad emission lines being formed in complex and extended environments. This is problematic when orbital parameter probability distributions are estimated assuming radial-velocity data are solely comprised of Keplerian motion plus Gaussian white noise, leading…
Tracing a decade of activity towards a yellow hypergiant. The spectral and spatial morphology of IRC+10420 at au scales
de Wit, W. -J.; Black, J. H.; Mérand, A. +3 more
The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss history and geometry, with the yellow hypergiants (YHGs) being key objects. We present near-IR interferometric observations of the famous YHG IRC+10420 and blue spectra taken between 1994 and 2019. Our 2.2-µm GRAVITY/VLTI observations at…