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Stars and brown dwarfs in the σ Orionis cluster. IV. IDS/INT and OSIRIS/GTC spectroscopy and Gaia DR2 astrometry
Alonso-Floriano, F. J.; Caballero, J. A.; Montes, D. +3 more
Context. Only a few open clusters are as important for the study of stellar and substellar objects, and their formation and evolution, as the young σ Orionis cluster. However, a complete spectroscopic characterisation of its whole stellar population is still missing.
Aims: We filled most of that gap with a large spectroscopic and astrometric …
Kinematic Properties of Open Star Clusters with Data from the Gaia DR2 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We consider open star clusters (OSCs) with the proper motions, parallaxes, and line-of-sight velocities calculated by various authors from Gaia DR2 data. The distance scale factor has been found by analyzing the separate solutions of the basic kinematic equations to be p =1.00 ± 0.04. It shows that the distances calculated using the parallaxes fro…
K2-295 b and K2-237 b: Two Transiting Hot Jupiters
Kuzuhara, M.; Alonso, R.; Deeg, H. +32 more
We report the discovery from K2 of two transiting hot Jupiter systems. K2-295 (observed in Campaign 8) is a K5 dwarf which hosts a planet slightly smaller than Jupiter, orbiting with a period of 4.0 d. We have made an independent discovery of K2-237 b (Campaign 11), which orbits an F9 dwarf every 2.2 d and has an inflated radius 60-70% larger than…
High-redshift Massive Quiescent Galaxies Are as Flat as Star-forming Galaxies: The Flattening of Galaxies and the Correlation with Structural Properties in CANDELS/3D-HST
Franx, Marijn; Muzzin, Adam; van Dokkum, Pieter +5 more
We investigate the median flattening of galaxies at 0.2 < z < 4.0 in all five CANDELS/3D-HST fields via the apparent axis ratio, q. We separate the sample into bins of the redshift, stellar mass, Sérsic index, size, and UVJ-determined star-forming state to discover the most important drivers of the median q (q med). Quiescent gala…
Physical Constraints from Near-infrared Fast Photometry of the Black Hole Transient GX 339-4
Petrucci, P.; Gandhi, P.; Tomsick, J. A. +9 more
We present results from the first multi-epoch X-ray/IR fast-photometry campaign on the black hole transient GX 339-4, during its 2015 outburst decay. We studied the evolution of the power spectral densities finding strong differences between the two bands. The X-ray power spectral density follows standard patterns of evolution, plausibly reflectin…
Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind
Raymond, John; Velli, Marco; Downs, Cooper +4 more
Ion fractional charge states, measured in situ in the heliosphere, depend on the properties of the plasma in the inner corona. As the ions travel outward in the solar wind and the electron density drops, the charge states remain essentially unaltered or "frozen in". Thus they can provide a powerful constraint on heating models of the corona and ac…
K2-287 b: An Eccentric Warm Saturn Transiting a G-dwarf
Henning, Thomas; Jordán, Andrés; Espinoza, Néstor +23 more
We report the discovery of K2-287b, a Saturn mass planet orbiting a G-dwarf with a period of P ≈ 15 days. First uncovered as a candidate using K2 campaign 15 data, follow-up photometry and spectroscopy were used to determine a mass {M}{{P}}=0.317+/- 0.026 {M}{{J}}, radius {R}{{P}}=0.833+/- 0.013 {R}{{J}}…
Rediscovering the tidal tails of NGC 288 with Gaia DR2
Carlberg, Raymond; Hunt, Jason A. S.; Webb, Jeremy J. +2 more
NGC 288 is a Galactic globular cluster having observed extra-tidal structure, without confirmed tidal tails. Gaia DR2 provides photometric and astrometric data for many of the stars in NGC 288 and its extra-tidal structure. To compare with the Gaia data, we simulate a N-body model of a star cluster with the same orbit as NGC 288 in a Milky Way pot…
Effect of radiative heat transfer in porous comet nuclei: case study of 67P/Churyumov-Gerasimenko
Shi, Xian; Blum, Jürgen; Gundlach, Bastian +2 more
Context. Radiative heat transfer occurs in a porous medium, such as regolith on planetary bodies. Radiation enhances the efficiency of heat transport through the subsurface, effecting a strong temperature dependence of thermal conductivity. However, this effect has been omitted in many studies of comet 67P/Churyumov-Gerasimenko (67P).
Aims: W…
Deep ALMA search for CO gas in the HD 95086 debris disc
MacGregor, Meredith A.; Hughes, A. Meredith; Wilner, David J. +7 more
One of the defining properties of debris discs compared to protoplanetary discs used to be their lack of gas, yet small amounts of gas have been found around an increasing number of debris discs in recent years. These debris discs found to have gas tend to be both young and bright. In this paper, we conduct a deep search for CO gas in the system H…