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Constraints on the Galactic Inner Halo Assembly History from the Age Gradient of Blue Horizontal-branch Stars
Whitten, Devin D.; Beers, Timothy C.; Placco, Vinicius M. +6 more
We present an analysis of the relative age distribution of the Milky Way halo, based on samples of blue horizontal-branch (BHB) stars obtained from the Panoramic Survey Telescope and Rapid Response System and Galaxy Evolution Explorer photometry, as well a Sloan Digital Sky Survey spectroscopic sample. A machine-learning approach to the selection …
Kepler Object of Interest Network. III. Kepler-82f: a new non-transiting 21 M⊕ planet from photodynamical modelling
Mallonn, M.; Becker, A. C.; Ribas, I. +13 more
Context. The Kepler Object of Interest Network (KOINet) is a multi-site network of telescopes around the globe organised for follow-up observations of transiting planet candidate Kepler objects of interest with large transit timing variations (TTVs). The main goal of KOINet is the completion of their TTV curves as the Kepler telescope stopped obse…
TOI-150: A Transiting Hot Jupiter in the TESS Southern CVZ
Butler, R. Paul; Schneider, Donald P.; Kollmeier, Juna A. +24 more
We report the detection of a hot Jupiter ({M}p={1.75}-0.17+0.14 {M}{{J}}, R p = 1.38 ± 0.04 R J) orbiting a middle-aged star ({log}g={4.152}-0.043+0.030) in the Transiting Exoplanet Survey Satellite (TESS) southern continuous viewing zone (β = -79.°59). We co…
Constraining the thermal properties of planetary surfaces using machine learning: Application to airless bodies
Furfaro, Roberto; Cambioni, Saverio; Delbo, Marco +2 more
We present a new method for the determination of the surface properties of airless bodies from measurements of the emitted infrared flux. Our approach uses machine learning techniques to train, validate, and test a neural network representation of the thermophysical behavior of the atmosphereless body given shape model, illumination and observatio…
Ongoing astrometric microlensing events from VVV and Gaia
Evans, N. W.; Belokurov, V.; Lucas, P. W. +2 more
We extend predictive microlensing event searches using the Vista Variables in the Via Lactea survey and the second Gaia data release. We identify two events with maxima in 2019 that require urgent follow-up. First, we predict that the nearby M2 dwarf L 338-152 will align with a background source with a closest approach of 35^{+35}_{-23} mas on 201…
Directly testing gravity with Proxima Centauri
Kroupa, Pavel; Banik, Indranil
The wide binary orbit of Proxima Centauri around α Centauri A and B differs significantly between Newtonian and Milgromian dynamics (MOND). By combining previous calculations of this effect with mock observations generated using a Monte Carlo procedure, we show that this prediction can be tested using high precision astrometry of Proxima Centauri.…
Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere
Gurnett, D. A.; Němec, F.; Morgan, D. D. +5 more
We use more than 10 years of the Martian topside ionospheric data measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar sounder on board the Mars Express spacecraft to derive an empirical model of electron densities from the peak altitude up to 325 km. Altogether, 16,044 electron density profiles obtained at spacecraft a…
A comparative study of size frequency distributions of Jupiter Trojans, Hildas and main belt asteroids: A clue to planet migration history
Terai, Tsuyoshi; Takato, Naruhisa; Ohtsuki, Keiji +4 more
Since 2002, we have obtained size frequency distributions (SFDs) of main belt asteroids (MBAs), Hildas, and Jupiter Trojans (JTs) by using the 8.2-m Subaru Telescope equipped with the wide-field CCD cameras: Suprime-Cam (SC) or Hyper Suprime-Cam (HSC). After combining these SFDs with SFDs obtained from other surveys, we performed a comparative stu…
Electron Intensity Measurements by the Cluster/RAPID/IES Instrument in Earth's Radiation Belts and Ring Current
Daly, P. W.; Kronberg, E. A.; Taylor, M. G. G. T. +7 more
The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earth's magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high-energy electrons (>400 keV) and i…
Luminous and Variable Stars in NGC 2403 and M81
Humphreys, Roberta M.; Davidson, Kris; Gordon, Michael S. +2 more
We present the results of spectroscopy and multi-wavelength photometry of luminous and variable star candidates in the nearby spiral galaxies NGC 2403 and M81. We discuss specific classes of stars, the Luminous Blue Variables (LBVs), B[e] supergiants (sgB[e]), and the high-luminosity yellow hypergiants. We identify two new LBV candidates, and thre…