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Particle Acceleration at 5 au Associated with Turbulence and Small-scale Magnetic Flux Ropes
Chen, Y.; Zank, G. P.; Zhao, L. -L. +4 more
An observational analysis of an atypical energetic particle event near 5 au measured by the Ulysses spacecraft is presented. A previous study has attributed the unusual enhancement of energetic proton flux to the presence of small-scale dynamic magnetic islands or flux ropes. Here, we find that the generation of these magnetic islands may be relat…
GRB 161219B/SN 2016jca: a powerful stellar collapse
D'Avanzo, P.; Melandri, A.; Pian, E. +26 more
We report observations and analysis of the nearby gamma-ray burst GRB 161219B (redshift z = 0.1475) and the associated Type Ic supernova (SN) 2016jca. GRB 161219B had an isotropic gamma-ray energy of ∼1.6 × 1050 erg. Its afterglow is likely refreshed at an epoch preceding the first photometric points (0.6 d), which slows down the decay …
Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2
Handler, G.; Niemczura, E.; Suárez, J. C. +36 more
We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with period…
ASASSN-18tb: a most unusual Type Ia supernova observed by TESS and SALT
Gromadzki, M.; Kochanek, C. S.; Stanek, K. Z. +16 more
We present photometric and spectroscopic observations of the unusual Type Ia supernova ASASSN-18tb, including a series of Southern African Large Telescope spectra obtained over the course of nearly six months and the first observations of a supernova by the Transiting Exoplanet Survey Satellite. We confirm a previous observation by Kollmeier et al…
Discovery of Strongly Inverted Metallicity Gradients in Dwarf Galaxies at z ∼ 2
Schmidt, Kasper B.; Treu, Tommaso; Daddi, Emanuele +12 more
We report the first measurements with sub-kiloparsec spatial resolution of strongly inverted gas-phase metallicity gradients in two dwarf galaxies at z ∼ 2. The galaxies have stellar masses ∼109 {M}⊙ , specific star formation rate ∼20 Gyr-1, and global metallicity 12+{log}({{O}}/{{H}})∼ 8.1 (1/4 solar), assuming t…
GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre. II. First data release of the catalogue and the most detailed CMDs of the GC
Nishiyama, S.; Najarro, F.; Nogueras-Lara, F. +7 more
Context. The high extinction and extreme source crowding of the central regions of the Milky Way are serious obstacles to the study of the structure and stellar population of the Galactic centre (GC). Existing surveys that cover the GC region (2MASS, UKIDSS, VVV, SIRIUS) do not have the necessary high angular resolution. Therefore, a high-angular-…
Tidally Induced Radius Inflation of Sub-Neptunes
Millholland, Sarah
Recent work suggests that many short-period super-Earth and sub-Neptune planets may have significant spin axis tilts (“obliquities”). When planets are locked in high-obliquity states, the tidal dissipation rate may increase by several orders of magnitude. This intensified heat deposition within the planets’ interiors should generate significant st…
The SkyMapper DR1.1 search for extremely metal-poor stars
Schmidt, B. P.; Da Costa, G. S.; Marino, A. F. +10 more
We present and discuss the results of a search for extremely metal-poor stars based on photometry from data release DR1.1 of the SkyMapper imaging survey of the southern sky. In particular, we outline our photometric selection procedures and describe the low-resolution (R ≈ 3000) spectroscopic follow-up observations that are used to provide estima…
Multiple Spiral Arms in the Disk around Intermediate-mass Binary HD 34700A
Monnier, John D.; Kraus, Stefan; Oppenheimer, Rebecca +14 more
We present the first images of the transition disk around the close binary system HD 34700A in polarized scattered light using the Gemini Planet Imager instrument on Gemini South. The J- and H-band images reveal multiple spiral-arm structures outside a large (R = 0.″49 = 175 au) cavity, along with a bluish spiral structure inside the cavity. The c…
The PAU Survey: early demonstration of photometric redshift performance in the COSMOS field
Carretero, J.; Castander, F. J.; Crocce, M. +23 more
The Physics of the Accelerating Universe Survey (PAUS) is an innovative photometric survey with 40 narrow-bands at the William Herschel Telescope (WHT). The narrow-bands are spaced at 100 Å intervals covering the range 4500-8500 Å and, in combination with standard broad-bands, enable excellent redshift precision. This paper describes the technique…