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The loud and the quiet: searching for radio counterparts of two radio-weak BL Lac candidates with VLBI
Frey, Sándor; Yang, Jun; An, Tao +4 more
BL Lac objects are known to have compact jets inclined to our line of sight at a small angle, showing prominent radio emission. Two radio-weak BL Lac candidates with no counterparts in current radio surveys were recently reported by Massaro et al. Both sources were selected as candidate low-energy counterparts of unassociated Fermi γ-ray sources. …
HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT
Holdsworth, Daniel L.; Saio, Hideyuki; Kurtz, Donald W.
We present a multi-instrument analysis of the rapidly oscillating Ap (roAp) star HD 42659. We have obtained B photometric data for this star and use these data, in conjunction with the Transiting Exoplanet Survey Satellite (TESS) observations, to analyse the high-frequency pulsation in detail. We find a triplet that is split by the rotation freque…
Post-rendezvous radar properties of comet 67P/CG from the Rosetta Mission: understanding future Earth-based radar observations and the dynamical evolution of comets
Kofman, Wlodek; Heggy, Essam; Palmer, Elizabeth M. +2 more
Radar observations provide crucial insights into the formation and dynamical evolution of comets. This ability is constrained by our knowledge of the dielectric and textural properties of these small-bodies. Using several observations by Rosetta as well as results from the Earth-based Arecibo radio telescope, we provide an updated and comprehensiv…
2MASS J10274572+0629104: the very short period young M6 dwarf binary system identified in K2 data
Burgasser, A. J.; Gizis, J. E.; Paudel, R. R. +1 more
We report the identification of a very low mass new binary system 2MASS J10274572+0629104, based on Kepler K2 photometry and Gaia DR2 astrometry. It is located at a distance of 90.0 ± 2.9 pc. The K2 light curve is consistent with a beat pattern of two periodic signals, and using Lomb-Scargle periodogram, we find two rotation periods of 0.2114 ± 0.…
Data-driven stellar parameters for southern TESS FGK targets
Henning, Th; Deacon, N. R.; Kossakowski, D. E.
We present stellar parameter estimates for 939 457 southern FGK stars that are candidate targets for the Transiting Exoplanet Survey Satellite (TESS) mission. Using a data-driven method similar to the CANNON, we build a model of stellar colours as a function of stellar parameters. We then use these in combination with stellar evolution models to e…
A study of full space motions of outer Galactic disc A and F stars in two deep pencil beams
Monguió, M.; Harris, A.; Drew, J. E.
A and F stars can be used as probes of outer Galactic disc kinematics: here we extend the work of Harris et al. by cross-matching their A/F sample with Gaia DR2 to bring in proper motions. These are combined with the already measured radial velocities and spectrophotometric distances to obtain full space motions. We use this sample of 1173 stars, …
A revisit to the enigmatic variable star 21 Comae
Kallinger, Thomas; Pribulla, Theodor; Walczak, Przemysław +12 more
The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, albeit with widely differing and sometimes contradictory results, in particular concerning the occurrence of short-term variability between about 5 to 90 min. We have performed a new investigation of 21 Com using Microvariability and Oscillations of Sta…
Envelopes and vertical amplitudes of disc-crossing orbits
Vieira, Ronaldo S. S.; Ramos-Caro, Javier
We recently found that regular orbits in axially symmetric galactic discs have their envelopes Z(R) accurately described by the relation Z(R)∝[ΣI(R)]-1/3, if their amplitudes are comparable to the disc thickness, where ΣI is the surface density of the disc (integrated over its whole vertical range). Moreover, the u…
Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116 + 111
Böhringer, H.; Simionescu, A.; Mernier, F. +4 more
MRC 0116 + 111 is a nearby (z = 0.132) poor galaxy group, which was previously known for exhibiting a bright diffuse radio emission with no central point-like source, presumably related to a past activity of the active galactic nucleus (AGN) in its central cD galaxy. Here, we present an X-ray observation (∼30 ks of cleaned XMM-Newton/EPIC exposure…
Two merging galaxy clusters with very hot shock fronts observed shortly before pericentric passage
Lopes, P. A. A.; Laganá, T. F.; Machado, R. E. G. +2 more
We present a detailed analysis of two merging clusters, from XMM-Newton X-ray archival data: PLCKESZ G036.7+14.9 (z = 0.15; hereafter G036) and PLCK G292.5+22.0 (z = 0.30; hereafter G292). We notice that the intracluster medium (ICM) is heated as a result of the merger, and we find evidence for a merger shock in the region between both subcluster …