Search Publications
Shape of the outer stellar warp in the Large Magellanic Cloud disk
Subramanian, S.; Saroon, S.
Warps are vertical distortions of the stellar or gaseous disks of galaxies. One of the proposed scenarios for the formation of warps involves tidal interactions among galaxies. A recent study identified a stellar warp in the outer regions of the south-western (SW) disk of the Large Magellanic Cloud (LMC) and suggested that it might have originated…
Scandium Abundance in F-G-K Stars in a Wide Metallicity Range
Mashonkina, L. I.; Romanovskaya, A. M.
A new Sc II model atom has been constructed using up-to-date atomic data. To test it, we have carried out nonlocal thermodynamic equilibrium (non-LTE) calculations for three stars with reliably determined atmospheric parameters: the Sun, HD 61421 (Procyon), and HD 84937. Allowance for the departures from LTE leads to a decrease in the root-mean-sq…
Automated Crater detection from Co-registered optical images, elevation maps and slope maps using deep learning
Tewari, Atal; Verma, Vinay; Srivastava, Pradeep +2 more
Craters are topographic structures resulting from impactors striking the surface of planetary bodies. This paper proposes a novel way of simultaneously utilizing optical images, digital elevation maps (DEMs), and slope maps for automatic crater detection on the lunar surface. The proposed system utilizes Mask R-CNN by tuning it for the crater dete…
Searching for stellar flares from low-mass stars using ASKAP and TESS
Ramsay, Gavin; Gallagher, Peter T.; Kaplan, David L. +7 more
Solar radio emission at low frequencies (<1 GHz) can provide valuable information on processes driving flares and coronal mass ejections (CMEs). Radio emission has been detected from active M dwarf stars, suggestive of much higher levels of activity than previously thought. Observations of active M dwarfs at low frequencies can provide informat…
Cycle dependence of a quasi-biennial variability in the solar interior
Broomhall, A. -M.; Jain, K.; Tripathy, S. C. +3 more
We investigated the solar cycle dependence on the presence and periodicity of the Quasi-Biennial Oscillation (QBO). Using helioseismic techniques, we used solar oscillation frequencies from the Global Oscillations Network Group (GONG), Michelson Doppler Imager (MDI), and Helioseismic and Magnetic Imager (HMI) in the intermediate-degree range to in…
Photodynamical analysis of the nearly resonant planetary system WASP-148. Accurate transit-timing variations and mutual orbital inclination
Bonfils, X.; Jenkins, J. M.; Laskar, J. +23 more
WASP-148 is a recently announced extra-solar system harbouring at least two giant planets. The inner planet transits its host star. The planets travel on eccentric orbits and are near the 4:1 mean-motion resonance, which implies significant mutual gravitational interactions. In particular, this causes transit-timing variations of a few minutes, wh…
Reappraising the Production and Transfer of Hydrogen Atoms From the Middle to the Upper Atmosphere of Mars at Times of Elevated Water Vapor
Montmessin, F.; Fedorova, A. A.; Lefèvre, F. +7 more
Water escape on Mars has recently undergone a paradigm shift with the discovery of unexpected seasonal variations in the population of hydrogen atoms in the exosphere where thermal escape occurs and results in water lost to space. This discovery led to the hypothesis that, contradicting the accepted pathway, atomic hydrogen in the exosphere was no…
Determination of stellar parameters for Ariel targets: a comparison analysis between different spectroscopic methods
Danielski, Camilla; Adibekyan, Vardan; Delgado-Mena, Elisa +9 more
Ariel has been selected as the next ESA M4 science mission and it is expected to be launched in 2028. During its 4-year mission, Ariel will observe the atmospheres of a large and diversified population of transiting exoplanets. A key factor for the achievement of the scientific goal of Ariel is the selection strategy for the definition of the inpu…
Carina High-contrast Imaging Project for massive Stars (CHIPS). II. O stars in Trumpler 14
Absil, O.; Sana, H.; Bodensteiner, J. +2 more
Context. Most massive stars belong to multiple systems, yet the formation process leading to such high multiplicity remains insufficiently understood. To help constrain the different formation scenarios that exist, insights into the low-mass end of the companion mass function of such stars is crucial. However, this is a challenging endeavour as (s…
Orbits of the Irregular Satellites of Uranus and Neptune
Jacobson, Robert A.; Brozović, Marina
We report on an ephemerides update for the irregular satellites of Uranus and Neptune, including Nereid. Our data set contains ground-based and Voyager 2 position measurements of the satellites. Some of the new observations were reduced with respect to the GAIA star catalog and represent high-quality, modern astrometry. The orbital fits are based …