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A Hot Mars-sized Exoplanet Transiting an M Dwarf
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath +21 more
We validate the planetary nature of an ultra-short-period planet orbiting the M dwarf KOI-4777. We use a combination of space-based photometry from Kepler, high-precision, near-infrared Doppler spectroscopy from the Habitable-zone Planet Finder, and adaptive optics imaging to characterize this system. KOI-4777.01 is a Mars-sized exoplanet (R …
UVIT view of Centaurus A: a detailed study on positive AGN feedback
Mathew, Blesson; Paul, K. T.; Stalin, C. S. +4 more
Supermassive black holes at the centre of active galactic nuclei (AGNs) produce relativistic jets that can affect the star formation characteristics of the AGN hosts. Observations in the ultraviolet (UV) band can provide an excellent view of the effect of AGN jets on star formation. Here, we present a census of star formation properties in the Nor…
Statistical Analysis of Circular-ribbon Flares
Xu, Zhe; Li, Shuting; Zhang, Qingmin +4 more
Circular-ribbon flares (CFs) are a special type of solar flares owing to their particular magnetic topology. In this paper, we conducted a comprehensive statistical analysis of 134 CFs from 2011 September to 2017 June, including 4 B-class, 82 C-class, 40 M-class, and 8 X-class flares. The flares were observed by the Atmospheric Imaging Assembly on…
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…