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Proxima Centauri - the nearest planet host observed simultaneously with AstroSat, Chandra, and HST
Schmitt, J. H. M. M.; Burwitz, V.; Loyd, R. O. Parke +6 more
Our nearest stellar neighbour, Proxima Centauri, is a low-mass star with spectral type dM5.5 and hosting an Earth-like planet orbiting within its habitable zone. However, the habitability of the planet depends on the high-energy radiation of the chromospheric and coronal activity of the host star. We report the AstroSat, Chandra, and HST observati…
Connecting the Wilson depression to the magnetic field of sunspots
Solanki, S. K.; Lagg, A.; Löptien, B. +1 more
Context. In sunspots, the geometric height of continuum optical depth unity is depressed compared to the quiet Sun. This so-called Wilson depression is caused by the Lorentz force of the strong magnetic field inside the spots. However, it is not understood in detail yet how the Wilson depression is related to the strength and geometry of the magne…
An elliptic expansion of the potential field source surface model
Wimmer-Schweingruber, R. F.; Kruse, M.; Heidrich-Meisner, V. +1 more
Context. The potential field source surface model is frequently used as a basis for further scientific investigations where a comprehensive coronal magnetic field is of importance. Its parameters, especially the position and shape of the source surface, are crucial for the interpretation of the state of the interplanetary medium. Improvements have…
Identification of Single Spectral Lines through Supervised Machine Learning in a Large HST Survey (WISP): A Pilot Study for Euclid and WFIRST
Rodighiero, G.; Malkan, M.; Henry, A. +13 more
Future surveys focusing on understanding the nature of dark energy (e.g., Euclid and WFIRST) will cover large fractions of the extragalactic sky in near-IR slitless spectroscopy. These surveys will detect a large number of galaxies that will have only one emission line in the covered spectral range. In order to maximize the scientific return of th…
Velocity Response of the Observed Explosive Events in the Lower Solar Atmosphere. I. Formation of the Flowing Cool-loop System
Tiwari, Sanjiv K.; Srivastava, A. K.; Konkol, P. +6 more
We observe plasma flows in cool loops using the Slit-Jaw Imager on board the Interface Region Imaging Spectrometer (IRIS). Huang et al. observed unusually broadened Si IV 1403 Šline profiles at the footpoints of such loops that were attributed to signatures of explosive events (EEs). We have chosen one such unidirectional flowing cool-loop system …
Extended X-ray emission from the classic nova DQ Her - on the possible presence of a magnetized jet
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +2 more
We present an analysis of archival Chandra and XMM-Newton observations of the magnetically active cataclysmic variable DQ Her and the shell around it ejected in a nova event in 1934. A careful revision of the Chandra observations confirms previous claims on the presence of extended X-ray emission around DQ Her and reveals that it actually correspo…
Is NGC 300 a pure exponential disk galaxy?
Bell, Eric F.; Holwerda, Benne W.; Monachesi, Antonela +6 more
NGC 300 is a low-mass disk galaxy in the Sculptor group. In the literature, it has been identified as a pure exponential disk galaxy, as its luminosity profile can be well fit with a single exponential law over many disk scale lengths (Type I). We investigate the stellar luminosity distribution of NGC 300 using Hubble Space Telescope archive data,…
Is Nightside Outflow Required to Induce Magnetospheric Sawtooth Oscillations
Zhang, Binzheng; Brambles, Oliver J.; Lotko, William +1 more
Ionospheric outflow plays an important role in the mass coupling between the ionosphere and the coupled solar wind-magnetosphere system. Previous modeling studies have shown that outflowing ionospheric ions may induce magnetospheric sawtooth oscillations through mass loading of the magnetotail, stretching the magnetic field lines, and reducing nig…
Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the Double-peaked Broad Emission Line of a Red Active Galactic Nucleus
Ho, Luis C.; Im, Myungshin; Kim, Minjin +1 more
Galaxy mergers are expected to produce multiple supermassive black holes (SMBHs) in close-separation, but the detection of such SMBHs has been difficult. 2MASS J165939.7 + 183436 is a red active galactic nucleus (AGN) that is a prospective merging SMBH candidate owing to its merging features in Hubble Space Telescope imaging and double-peaked broa…
Wide binaries in planetary nebulae with Gaia DR2
Dafonte, C.; González-Santamaría, I.; Manteiga, M. +3 more
Context. The Gaia Data Release 2 (DR2) was used to select a sample of 211 central stars of planetary nebulae (CSPNe) with good-quality astrometric measurements, which we refer to as Golden Astrometry Planetary Nebulae (GAPN). Gaia astrometric and photometric measurements allowed us to derive accurate distances and radii and to calculate luminositi…