Search Publications
Transiting Exoplanet Survey Satellite (TESS) Observations of Flares and Quasi-Periodic Pulsations from Low-Mass Stars and Potential Impact on Exoplanets
Ramsay, Gavin; Doyle, Lauren; Doyle, J. Gerry +1 more
We have performed a search for flares and quasi-periodic pulsations (QPPs) from low-mass M-dwarf stars using Transient Exoplanet Survey Satellite (TESS) two-minute cadence data. We find seven stars that show evidence of QPPs. Using Fourier and empirical mode decomposition techniques, we confirm the presence of 11 QPPs in these seven stars with a p…
Heliosheath Proton Distribution in the Plasma Reference Frame
McComas, D. J.; Dayeh, M. A.; Swaczyna, P. +2 more
Properties of the inner heliosheath (IHS) plasma are inferred from energetic neutral atom (ENA) observations by ∼1 au spacecraft. However, the Compton-Getting effect due to the plasma velocity relative to the spacecraft is rarely taken into account, even though the plasma speed is a significant fraction of the ENA speed. In this study, we transfor…
Long-term and multiwavelength evolution of a changing-look AGN Mrk 1018
Wu, Qingwen; Lyu, Bing; Yan, Zhen +1 more
The physical mechanism for triggering the changing-look phenomenon in active galactic nuclei (AGNs) is still unclear. We explore this issue based on the multiwavelength spectral and flux variations for a changing-look AGN Mrk 1018 with long-term observations in the X-ray, optical/ultraviolet (UV), and radio bands. Both the optical and the X-ray em…
Kinematics and star formation toward W33: a central hub as a hub-filament system
Zhang, Chuan-Peng; Wang, Jun-Jie; Xu, Jin-Long +4 more
Aims: We investigate the gas kinematics and physical properties toward the W33 complex and its surrounding filaments. We study clump formation and star formation in a hub-filament system.
Methods: We performed a large-scale mapping observation toward the W33 complex and its surroundings, covering an area of 1.3° × 1.0°, in 12C…
A Homogeneous Comparison between the Chemical Composition of the Large Magellanic Cloud and the Sagittarius Dwarf Galaxy
Bellazzini, M.; Mucciarelli, A.; Origlia, L. +3 more
Similarities in the chemical composition of two of the closest Milky Way satellites, namely, the Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf galaxy, have been proposed in the literature, suggesting similar chemical enrichment histories between the two galaxies. This proposition, however, rests on different abundance analyses, whic…
Observations of the Quiet Sun during the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM: Sub-A-class Microflares outside Active Regions
Joshi, Bhuwan; Janardhan, P.; Bhardwaj, Anil +12 more
Solar flares, with energies ranging over several orders of magnitude, result from impulsive release of energy due to magnetic reconnection in the corona. Barring a handful, almost all microflares observed in X-rays are associated with the solar active regions. Here we present, for the first time, a comprehensive analysis of a large sample of quiet…
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, …