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Ultraviolet and X-ray properties of Coma's ultra-diffuse galaxies
Gallo, Elena; Hodges-Kluck, Edmund; Lee, Chris H.
Many ultra-diffuse galaxies (UDGs) have been discovered in the Coma cluster, and there is evidence that some, notably Dragonfly 44, have Milky Way-like dynamical masses despite dwarf-like stellar masses. We used X-ray, ultraviolet (UV), and optical data to investigate the star formation and nuclear activity in the Coma UDGs, and we obtained deep U…
The historical record of massive star formation in Cygnus
Comerón, F.; Schneider, N.; Pasquali, A. +1 more
Context. The Cygnus region, which dominates the local spiral arm of the Galaxy, is one of the nearest complexes of massive star formation, extending over several hundred parsecs. Its massive stellar content, regions of ongoing star formation, and molecular gas have been studied in detail at virtually all wavelengths. However, little is known of th…
A Non-Linear Magnetic Field Calibration Method for Filter-Based Magnetographs by Multilayer Perceptron
Ji, Kaifan; Su, Jiangtao; Deng, Yuanyong +5 more
For filter-based magnetographs, the linear calibration method under the weak-field assumption is usually adopted; this leads to magnetic saturation effect in the regions with strong magnetic field. This article explores a new method to overcome the above disadvantage using a multilayer perceptron network, which we call MagMLP, based on a back-prop…
Mapping and spatial statistical analysis of Mars Yardangs
Di, Kaichang; Liu, Bin; Liu, Jia +4 more
Mars yardang fields were mapped using the newly available high-resolution Context Camera (CTX) mosaics (30°N to 30°S) through visual interpretation and manual digitization. We classified the Martian yardangs into three types according to their shapes: long ridge, inverted hull and curvilinear shapes, and found that the number of long ridge yardang…
Space debris observations with the Slovak AGO70 telescope: Astrometry and light curves
Šilha, Jiří; Krajčovič, Stanislav; Zigo, Matej +12 more
The Faculty of Mathematics, Physics and Informatics of Comenius University in Bratislava, Slovakia (FMPI) operates its own 0.7-m Newtonian telescope (AGO70) dedicated to the space surveillance tracking and research, with an emphasis on space debris. The observation planning focuses on objects on geosynchronous (GEO), eccentric (GTO and Molniya) an…
Do bulges stop stars forming?
Eales, Stephen; Eales, Oliver; de Vis, Pieter
In this paper, we use the Herschel Reference Survey to make a direct test of the hypothesis that the growth of a stellar bulge leads to a reduction in the star formation efficiency of a galaxy (or conversely a growth in the gas-depletion time-scale) as a result of the stabilization of the gaseous disc by the gravitational field of the bulge. We fi…
Sporadic and intense accretion in a 1 Myr-old brown dwarf candidate
Bessell, M. S.; Murphy, S. J.; Nguyen-Thanh, D. +1 more
Context. Studying the accretion process in very low-mass objects has important implications for understanding their formation mechanism. Many nearby late-M dwarfs that have previously been identified in the field are in fact young brown dwarf members of nearby young associations. Some of them are still accreting. They are therefore excellent targe…
Dynamical Mass Estimates of the β Pictoris Planetary System through Gaussian Process Stellar Activity Modeling
Vandal, Thomas; Doyon, René; Rameau, Julien
Nearly 15 yr of radial velocity (RV) monitoring and direct imaging enabled the detection of two giant planets orbiting the young, nearby star β Pictoris. The δ Scuti pulsations of the star, which overwhelm planetary signals, need to be carefully suppressed. In this work, we independently revisit the analysis of the RV data following a different ap…
The nature of the symbiotic candidate 2MASS J07363415+6538548 in the field of NGC 2403
Merc, J.; Gális, R.; Wolf, M. +2 more
New Online Database of Symbiotic Variables includes several poorly characterized objects and candidate symbiotic stars, not only in the Milky Way but also in other galaxies. The goal of the research presented in this paper was to reveal the nature of 2MASS J07363415+6538548, the object discovered as an X-ray source in the field of NGC 2403, and te…
Determining the origin of the building blocks of the Ice Giants based on analogue measurements from comets
Mousis, O.; Mandt, K. E.; Treat, S.
The abundances of the heavy elements and isotopic ratios in the present atmospheres of the giant planets can be used to trace the composition of volatiles that were present in the icy solid material that contributed to their formation. The first definitive measurements of noble gas abundances and isotope ratios at comet 67P/Churyumov-Gerasimenko (…