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Chromospheric Activity of M Stars Based on LAMOST Low- and Medium-resolution Spectral Surveys
Shi, Jianrong; Han, Xianming L.; Misra, Prabhakar +5 more
We have used the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) low-resolution and medium-resolution spectroscopic surveys to explore the chromospheric statistical properties and variations of M stars. There are 738,477 LAMOST low-resolution spectra of 622,523 M stars. We have calculated equivalent widths of the Ca II H&K, …
Magnetic field orientation in self-gravitating turbulent molecular clouds
de Gouveia Dal Pino, E. M.; Santos-Lima, R.; Barreto-Mota, L. +3 more
Stars form inside molecular cloud filaments from the competition of gravitational forces with turbulence and magnetic fields. The exact orientation of these filaments with the magnetic fields depends on the strength of these fields, the gravitational potential, and the line of sight (LOS) relative to the mean field. To disentangle these effects we…
Matching Globular Cluster Models to Observations
Rui, Nicholas Z.; Rodriguez, Carl L.; Chatterjee, Sourav +4 more
As ancient, gravitationally bound stellar populations, globular clusters represent abundant, vibrant laboratories, characterized by high frequencies of dynamical interactions, coupled to complex stellar evolution. Using surface brightness and velocity dispersion profiles from the literature, we fit 59 Milky Way globular clusters to dynamical model…
Measurements of Photospheric and Chromospheric Magnetic Field Structures Associated with Chromospheric Heating over a Solar Plage Region
Kitai, Reizaburo; Kleint, Lucia; Schad, Thomas A. +6 more
In order to investigate the relation between magnetic structures and the signatures of heating in plage regions, we observed a plage region with the He I 1083.0 nm and Si I 1082.7 nm lines on 2018 October 3 using the integral field unit mode of the GREGOR Infrared Spectrograph (GRIS) installed at the GREGOR telescope. During the GRIS observation, …
New Hydrodynamic Solutions for Line-driven Winds of Hot Massive Stars Using the Lambert W-function
Hillier, D. J.; Najarro, F.; Gormaz-Matamala, A. C. +3 more
Hot massive stars present strong stellar winds that are driven by absorption, scattering, and reemission of photons by the ions of the atmosphere (line-driven winds). A better comprehension of this phenomenon, and a more accurate calculation of hydrodynamics and radiative acceleration, is Required to reduce the number of free parameters in spectra…
Airfall on Comet 67P/Churyumov-Gerasimenko
Zacny, Kris; Bodewits, Dennis; Vincent, Jean-Baptiste +11 more
We here study the transfer process of material from one hemisphere to the other (deposition of airfall material) on an active comet nucleus, specifically 67P/Churyumov-Gerasimenko. Our goals are to: 1) quantify the thickness of the airfall debris layers and how it depends on the location of the target area, 2) determine the amount of H2…
Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1
Fabian, A. C.; Pinto, C.; Walton, D. +15 more
Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broad-band spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details …
Spectroscopic observations of a flare-related coronal jet
Li, D.; Zhang, Q. M.; Huang, Z. H. +3 more
Context. Coronal jets are ubiquitous in active regions and coronal holes.
Aims: In this paper, we study a coronal jet related to a C3.4 circular-ribbon flare in the active region 12434 on 2015 October 16.
Methods: The flare and jet were observed in ultraviolet and extreme ultraviolet wavelengths by the Atmospheric Imaging Assembly on boa…
XMM-Newton observations of the extremely X-ray luminous quasar CFHQS J142952+544717=SRGE J142952.1 + 544716 at redshift z = 6.18
Sunyaev, R.; Sazonov, S.; Schartel, N. +2 more
We present results from a 20 ks XMM-Newton director's discretionary time observation of the radio-loud quasar CFHQS J142952 + 544717 at z = 6.18, whose extreme X-ray luminosity was recently revealed by the SRG/eROSITA telescope in the course of its first all-sky survey. The quasar has been confidently detected with a total of ~1400 net counts in t…
LoCuSS: The Splashback Radius of Massive Galaxy Clusters and Its Dependence on Cluster Merger History
Smith, Graham P.; Babul, Arif; Finoguenov, Alexis +4 more
We present the direct detection of the splashback feature using the sample of massive galaxy clusters from the Local Cluster Substructure Survey (LoCuSS). This feature is clearly detected (above 5σ) in the stacked luminosity density profile obtained using the K-band magnitudes of spectroscopically confirmed cluster members. We obtained the best-fi…