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The Cushion Region and Dayside Magnetodisc Structure at Saturn
Dougherty, M. K.; Masters, A.; Achilleos, N. +1 more
A sustained quasi dipolar magnetic field between the current sheet outer edge and the magnetopause, known as a cushion region, has previously been observed at Jupiter, but not yet at Saturn. Using the complete Cassini magnetometer data, the first evidence of a cushion region forming at Saturn is shown. Only five examples of a sustained cushion are…
Overall Properties of the ICRF and Gaia-CRF
Liu, N.
The International Celestial Reference System (ICRS) now has realizations at several frequencies, all with an accuracy of several tens of mircoarcsecond (µas) level, including the International Celestial Reference Frame (ICRF) based on observations of the very long baseline interferometry (VLBI) at S/X, K, and X/Ka band, and the Gaia celestia…
Twin stars as tracers of binary evolution in the Kepler era
Çakırlı, Ömür; Hoyman, Barış; Özdarcan, Orkun +2 more
We present results of the combined photometric and spectroscopic analysis of four systems that are eclipsing binaries with a twin component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high-res…
Ice lines as the origin for the gap/ring structure in protoplanetary disks: the issue of the assumed temperature profile
Liu, Yao
Gaps and rings are commonly seen in recent high-resolution ALMA observations of protoplanetary disks. Ice lines of volatiles are one of the mechanisms proposed to explain the origin for these substructures. To examine the ice line hypothesis, literature studies usually parameterize the mid-plane temperature with the analytic formula of a passively…
Reinvestigation of the Multiepoch Direct Detections of HD 88133 b and Upsilon Andromedae b
Barman, Travis S.; Benneke, Björn; Bender, Chad F. +5 more
We reanalyze the multiepoch direct detections of HD 88133 b and ups And b that were published in Piskorz et al. (2016) and Piskorz et al. (2017), respectively. Using simulations to attempt to reproduce the detections, we find that with the six and seven L-band Keck/NIRSPEC epochs analyzed in the original works, the planets would not have been dete…
Using Gaia DR2 to make a systematic comparison between two geometric distortion solutions
Lin, F. R.; Peng, Q. Y.; Zheng, Z. J.
Gaia Data Release 2 (Gaia DR2) provides high accuracy and precision astrometric parameters (position, parallax, and proper motion) for more than 1 billion sources and is revolutionizing astrometry. For a fast-moving target such as an asteroid, with many stars in the field of view that are brighter than the faint limit magnitude of Gaia (21 Gmag), …
Motion of Classic and Spontaneous Hot Flow Anomalies Observed by Cluster
Zhang, Hui; Guo, Ruilong; Zhang, Shuai +12 more
The propagation characteristics of hot flow anomalies (HFAs) near the Earth's bow shock are investigated, using observations from the Cluster spacecraft. A data set comprised of 19 classic HFAs (associated with tangential discontinuities, TDs) and 23 spontaneous HFAs (SHFAs, formed in the absence of solar wind discontinuities) was analyzed. For ea…
Exploring Ceres's Unusual Regolith Porosity and Its Implications for Volatile Retention
Heggy, Essam; Palmer, Elizabeth M.; Letertre, Thibaut +1 more
Asteroid Ceres, the only dwarf planet located in the inner solar system, shows unique surface mineralogy and geomorphology as observed by the Dawn mission. Of particular interest is understanding the role that upper regolith porosity plays in retaining volatiles and shaping Ceres' surface. Unfortunately, Ceres' near-surface porosity remains largel…
The distances of 61 PGCCs in the second galactic quadrant
Huang, Y.; Chen, B. -Q.; Sun, W. -X. +5 more
Determining the distances to the Planck Galactic cold clumps (PGCCs) is crucial for the measurement of their physical parameters and the study of their Galactic distribution. Based on two large catalogues of stars with robust distances and reddening estimates from the literature, we have estimated accurate distances to 61 PGCCs in the second Galac…
Investigating the true nature of three hard X-ray sources
Palazzi, E.; Masetti, N.; Bird, A. J. +6 more
Many of the new high energy sources discovered both by INTEGRAL/IBIS and Swift/BAT have been characterized thanks to extensive, multiband follow-up campaigns, but there are still objects whose nature remains to be asserted. In this paper, we investigate the true nature of three high energy sources, IGR J12134-6015, IGR J16058-7253, and Swift J2037…