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Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158
Chen, P. F.; Li, Bo; Yan, Yihua +2 more
The structural property of the magnetic field in flare-bearing solar active regions (ARs) is one of the key aspects for understanding and forecasting solar flares. In this paper, we make a comparative analysis on the chirality and magnetic configurations associated with two X-class two-ribbon flares happening in AR 10930 and AR 11158. The photosph…
CHESS: An innovative concept for high-resolution, far-UV spectroscopy
France, Kevin; Youngblood, Allison; Fleming, Brian +4 more
The space ultraviolet (UV) is a critical astronomical observing window, where a multitude of atomic, ionic, and molecular signatures provide crucial insight into planetary, interstellar, stellar, intergalactic, and extragalactic objects. The next generation of large space telescopes require highly sensitive, moderate-to-high resolution UV spectrog…
Local dark energy in the Sculptor Filament of galaxies
Pruzhinskaya, M. V.; Karachentsev, I. D.; Chernin, A. D.
Two dozens of different mass galaxies observed at distances less than 10 Mpc from the Local Group are organized in the elongated structure known as the Sculptor Filament. We use recent Hubble Space Telescope data on local galaxies to study the dynamical structure and evolutionary trends of the filament. An N-body computer model, which reproduces i…
Fast-rotating giant stars behind the Coma Berenices star cluster
Fernández, Matilde; Alfaro, Emilio J.; Casanova, Víctor +2 more
In the frame of a study of the empirical isochrones of young stellar clusters, we have carried out BVIc Johnson-Cousins photometry of a sample of K and M stars of the Coma Berenices star cluster. All these stars have known rotational periods. Our main goal is to get a valuable reference on the colour-magnitude diagram, Mv ver…
Spectral Behavior of the Symbiotic Nova HM Sge in the Ultraviolet
Sanad, M. R.; Abdel-Sabour, M. A.
Ultraviolet observations of the symbiotic nova HM Sge were obtained from the International Ultraviolet Explorer (IUE) through the interval from 1980 - 1992. Three line profiles demonstrating the variations of some emission lines at different dates are presented. We determined the reddening of HM Sge from the 2200 Å absorption feature; the estimate…
Searching for exoplanets by HEPS II. detecting earth-like planets in habitable zone around planet hosts within 30 pc
Yang, Ming; Zhang, Hui; Zhou, Ji-Lin +4 more
HEPS (Habitable ExoPlanet Survey) is a planning astrometry satellite that aims to find Earth-like planets in the solar neighbourhood. In this paper, we selected 140 planet harboring stars within 30 pc of the solar system to be potential targets for HEPS. We calculate the detection probability of the planet in habitable zone (HZ) for each system us…
The long-term optical activity of the propellers AE Aquarii and AR Scorpii
Šimon, Vojtěch
This analysis of the long-term optical activity of the propellers AE Aqr and AR Sco uses data from the Catalina Real-time Transient Survey, DASCH, and AAVSO. The site and character of the emissions from the phenomena caused by the magnetic field of the white dwarf (WD) vary from system to system. The histogram of intensities of the ensemble of fla…
Radio Signature of a Distant behind-the-limb CME on 2017 September 6
Rucker, H. O.; Panchenko, M.; Konovalenko, A. A. +5 more
We discuss properties of a Type IV burst, which was observed on 2017 September 6, as a result of the powerful flare X 9.3. At decameter wavelengths this burst was observed by the radio telescopes STEREO A, URAN-2, and the Nancay Decameter Array at frequencies 5-35 MHz. This moving Type IV burst was associated with a coronal mass ejection (CME) pro…
Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi
Enoto, Teruaki; Yamaoka, Kazutaka; Fukazawa, Yasushi +43 more
Understanding and reducing in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard x-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic number…
Prolonged Lifetime of the Transient Ionized Layer in the Martian Atmosphere Caused by Comet Siding Spring
Gurnett, D. A.; Halekas, J. S.; Morgan, D. D. +4 more
In October 2014, the close encounter between Mars and comet Siding Spring produced a transient ionized layer in the upper atmosphere composed primarily of Mg+ and Fe+ ions. The layer was detected by instruments on three spacecraft, including the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on Mars Expre…