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Solar wind charge exchange in cometary atmospheres. II. Analytical model
Alho, Markku; Simon Wedlund, Cyril; Nilsson, Hans +7 more
Context. Solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet because they mass-load the solar wind through an effective conversion of fast, light solar wind ions into slow, heavy cometary ions. The ESA/Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P) provided a unique oppor…
The 2L1S/1L2S Degeneracy for Two Microlensing Planet Candidates Discovered by the KMTNet Survey in 2017
Kim, S. -L.; Lee, C. -U.; Bennett, D. P. +49 more
We report two microlensing planet candidates discovered by the Korea Microlensing Telescope Network (KMTNet) survey in 2017. However, both events have the 2L1S/1L2S degeneracy, which is an obstacle to claiming the discovery of the planets with certainty unless the degeneracy can be resolved. For KMT-2017-BLG-0962, the degeneracy cannot be resolved…
A Massive Magnetic Helium Atmosphere White Dwarf Binary in a Young Star Cluster
Dufour, Patrick; Bergeron, Pierre; Caiazzo, Ilaria +4 more
We have searched the Gaia DR2 catalog for previously unknown hot white dwarfs in the direction of young open star clusters. The aim of this experiment was to try and extend the initial-final mass relation (IFMR) to somewhat higher masses, potentially challenging the Chandrasekhar limit currently thought to be around 1.38 M ⊙. We discove…
A DECam view of the diffuse dwarf galaxy Crater II: the colour-magnitude diagram
Walker, A. R.; Stetson, P. B.; Bono, G. +12 more
We present a deep Blanco/DECam colour-magnitude diagram (CMD) for the large but very diffuse Milky Way satellite dwarf galaxy Crater II. The CMD shows only old stars with a clearly bifurcated subgiant branch (SGB) that feeds a narrow red giant branch. The horizontal branch (HB) shows many RR Lyrae and red HB stars. Comparing the CMD with [Fe/H] = …
Influence of Wolf-Rayet Stars on Surrounding Star-forming Molecular Clouds
Herczeg, Gregory J.; Bhatt, B. C.; Deng, Licai +5 more
We investigate the influence of Wolf-Rayet (W-R) stars on their surrounding star-forming molecular clouds. We study five regions containing W-R stars in the inner Galactic plane (l ∼ [14°-52°]), using multiwavelength data from near-infrared to radio wavelengths. Analysis of 13CO line data reveals that these W-R stars have developed gas-…
Electron trapping in the coma of a weakly outgassing comet
Divin, Andrey; Deca, Jan; Olshevsky, Vyacheslav +2 more
Measurements from the Rosetta mission have shown a multitude of nonthermal electron distributions in the cometary environment, challenging the previously assumed plasma interaction mechanisms near a cometary nucleus. In this paper, we discuss electron trapping near a weakly outgassing comet from a fully kinetic (particle-in-cell) perspective. Usin…
Galaxy structural analysis with the curvature of the brightness profile
Ferrari, Fabricio; Lucatelli, Geferson
In this work, we introduce the curvature of a galaxy brightness profile to identify its structural subcomponents in a non-parametrically fashion. Bulges, bars, discs, lens, rings, and spiral arms are key to understand the formation and evolution path the galaxy undertook. Identifying them is also crucial for morphological classification of galaxie…
The kinematics of Galactic disc white dwarfs in Gaia DR2
Kilic, Mukremin; Rowell, Nicholas
We present an analysis of the kinematics of Galactic disc white dwarf (WD) stars in the solar neighbourhood using data from Gaia Data Release 2. Selection of WDs based on parallax provides the first large, kinematically unbiased sample of solar neighbourhood WDs to date. Various classical properties of the solar neighbourhood kinematics have been …
Sub-millimetre non-contaminated detection of the disc around TWA 7 by ALMA
de Gregorio-Monsalvo, I.; Bayo, A.; Schreiber, M. R. +9 more
Debris discs can be seen as the leftovers of giant planet formation and the possible nurseries of rocky planets. While M-type stars outnumber more massive stars we know very little about the time evolution of their circumstellar discs at ages older than ∼10 Myr. Sub-millimetre observations are best to provide first order estimates of the available…
Orbital and physical parameters of the close binary system GJ 9830 (HIP 116259)
Al-Wardat, Mashhoor A.; Pathan, J. M.; Masda, Suhail G.
We present the complete set of physical and geometrical parameters of the visual close binary system GJ 9830 for the first time by applying Al-Wardat’s complex method. This method combines magnitude difference from speckle interferometry, synthetic spectral energy distributions of the binary components which are constructed based on grids of Kuruc…