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Evolution of exploding granules from coordinated observations by THEMIS, IRIS, SDO/HMI, and HINODE, and a simulation
Malherbe, J. M.; Dalmasse, K.; Roudier, T. +3 more
Exploding granules constitute the strongest horizontal flows on the quiet Sun and contribute to the structure of the surface horizontal velocity fields which build the large-scale organization of the discrete magnetic field. In this work we explore exploding granule expansion through the observations of the ground-based THEMIS telescope, IRIS, SDO…
How to disentangle geometry and mass-loss rate from AGB-star spectral energy distributions. The case of EP Aquarii
Jorissen, A.; Decin, L.; Groenewegen, M. A. T. +2 more
Context. High-angular-resolution observations of asymptotic giant branch (AGB) stars often reveal non-spherical morphologies for the gas and dust envelopes.
Aims: We aim to make a pilot study to quantify the impact of different geometries (spherically symmetric, spiral-shaped, and disc-shaped) of the dust component of AGB envelopes on spectra…
K2-HERMES II. Planet-candidate properties from K2 Campaigns 1-13
Kane, Stephen R.; Casey, Andrew R.; Wittenmyer, Robert A. +22 more
Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present complete results for planet-candidate hosts from the K2-HERMES survey, which uses the HERMES multi-object spectrograph on…
The Kasei Valles, Mars: a unified record of episodic channel flows and ancient ocean levels
Duran, Sergio; Coulthard, Tom J.
There is widespread evidence across Mars of past flows in major channel systems as well as more than one palaeo ocean level. However, evidence for the timing of channel flows and ocean levels is based on geographically diverse sources with a limited number of dates, making reconstructions of palaeo flows and ocean levels patchy. Here, based on hig…
Machine-learning Regression of Extinction in the Second Gaia Data Release
Bai, Yu; Wang, Song; Liu, JiFeng +1 more
Machine learning has become a popular tool to help us make better decisions and predictions, based on experiences, observations, and analyzing patterns, within a given data set without explicit functions. In this paper, we describe an application of the supervised machine-learning algorithm to the extinction regression for the second Gaia data rel…
Physical Conditions of Gas Components in Debris Disks of 49 Ceti and HD 21997
Moór, Attila; Kóspál, Ágnes; Nomura, Hideko +2 more
Characterization of the gas component in debris disks is of fundamental importance for understanding their origin. To address this goal, we have conducted non-LTE (local thermodynamic equilibrium) analyses of the rotational spectral lines of CO including those of rare isotopologues (13CO and C18O) that have been observed towa…
Geometry of the Draco C1 Symbiotic Binary
Sarazin, Craig L.; Cunha, Katia; Smith, Verne V. +14 more
Draco C1 is a known symbiotic binary star system composed of a carbon red giant and a hot, compact companion—likely a white dwarf—belonging to the Draco dwarf spheroidal galaxy. From near-infrared spectroscopic observations taken by the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2), part of Sloan Digital Sky Survey IV, we provi…
Subaru Near-infrared Imaging Polarimetry of Misaligned Disks around the SR 24 Hierarchical Triple System
Henning, Thomas; Nakagawa, Takao; Terada, Hiroshi +66 more
The SR 24 multistar system hosts both circumprimary and circumsecondary disks, which are strongly misaligned with each other. The circumsecondary disk is circumbinary in nature. Interestingly, both disks are interacting, and they possibly rotate in opposite directions. To investigate the nature of this unique twin disk system, we present 0.″1 reso…
Distorted surfaces of magnetic helium-peculiar stars: an application to a Cen
Niemczura, E.; Leone, F.; Krtička, J. +3 more
Helium-peculiar magnetic chemically peculiar stars show variations of helium abundance across their surfaces. As a result of associated atmospheric scale height variations, the stellar surface becomes distorted, with helium-rich regions dented inwards. Effectively, on top of flux variations due to opacity effects, the depressed helium-rich surface…
EVR-CB-004: An Inflated Hot Subdwarf O Star + Unseen WD Companion in a Compact Binary Discovered with the Evryscope
Law, Nicholas M.; Kupfer, Thomas; Glazier, Amy +10 more
We present the discovery of EVR-CB-004, a close binary with a remnant stellar core and an unseen white dwarf (WD) companion. The analysis in this work reveals that the primary is potentially an inflated hot subdwarf (sdO) and more likely is a rarer post-blue horizontal branch (post-BHB) star. Post-BHBs are the short-lived shell-burning final stage…