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The G 305 Star-forming Region. II. Irregular Variable Stars
Bayo, A.; Kounkel, Marina; Minniti, Dante +11 more
We present a catalog of 167 newly discovered, irregular variables spanning a ~7 deg2 area that encompasses the G 305 star-forming complex, one of the most luminous giant H II regions in the Galaxy. We aim to unveil and characterize the young stellar object (YSO) population of the region by analyzing the Ks-band variability an…
Trends and characteristics of high-frequency type II bursts detected by CALLISTO spectrometers
Kumari, A.; Monstein, C.; Sasikumar Raja, K. +2 more
Solar radio type II bursts serve as early indicators of incoming geo-effective space weather events such as coronal mass ejections (CMEs). In order to investigate the origin of high-frequency type II bursts (HF type II bursts), we have identified 51 of them (among 180 type II bursts from SWPC reports) that are observed by ground-based Compound Ast…
Photometric and kinematical analysis of Koposov 12 and Koposov 43 open clusters
Elsanhoury, W. H.
We present a photometric and kinematical analysis of two poorly studied open clusters, Koposov 12 (FSR 802) and Koposov 43 (FSR 848), by using cross-matched data from PPMXL and Gaia DR2 catalogs. We used astrometric parameters to identify 285 and 310 cluster members for Koposov 12 and Koposov 43, respectively. Using the extracted member candidates…
Stellar X-rays and magnetic activity in 3D MHD coronal models
Peter, H.; Zhuleku, J.; Warnecke, J.
Context. Observations suggest a power-law relation between the coronal emission in X-rays, LX, and the total (unsigned) magnetic flux at the stellar surface, Φ. The physics basis for this relation is poorly understood.
Aims: We use three-dimensional (3D) magnetohydrodynamics (MHD) numerical models of the coronae above active region…
On the Origin of High–Frequency Magnetic Fluctuations in the Interplanetary Medium: A Brownian–like Approach
Vecchio, Antonio; Chiappetta, Federica; Lepreti, Fabio +2 more
Low–frequency fluctuations in the interplanetary medium have been extensively investigated and described in the framework of turbulence, and the observed universal scaling behavior represents a clear signature of the underlying energy cascade. On the contrary, the interpretation of observations of plasma fluctuations at high frequencies, where wav…
Planck Galactic Cold Clumps at High Galactic Latitude-a Study with CO Lines
Kim, Gwanjeong; Lee, Chin-Fei; Lee, Jeong-Eun +28 more
Gas at high Galactic latitude is a relatively little noticed component of the interstellar medium. In an effort to address this, 41 Planck Galactic Cold Clumps at high Galactic latitude (HGal; ∣b∣ > 25°) were observed in 12CO, 13CO, and C18O J = 1-0 lines, using the Purple Mountain Observatory 13.7 m telescope. …
Study of Close Stellar Encounters with the Solar System Based on Data from the Gaia EDR3 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We have studied stellar candidates for close (within 1 pc) encounters with the Solar system. For all of the stars under consideration the kinematic characteristics have been taken from the Gaia EDR3 catalogue. The parameters of the encounters of these stars with the Solar system have been calculated using three methods: (1) the linear one, (2) by …
In the Trenches of the Solar-stellar Connection. V. High-resolution Ultraviolet and X-Ray Observations of Sun-like Stars: The Curious Case of Procyon
Ayres, Thomas R.
A joint X-ray (0.2-2 keV) and ultraviolet (1150-3000 Å) time-domain study has been carried out on three nearby bright late-type stars, bracketing the Sun in properties. Alpha Cen A (HD 128620: G2 V) is a near twin to the Sun, although slightly more massive and luminous, slightly metal-rich, but older. Alpha Cen B (HD 128621: K1 V) is cooler than t…
Saddle-shaped Solar Flare Arcades
Aulanier, Guillaume; Dudík, Jaroslav; Lörinčík, Juraj
Arcades of flare loops form as a consequence of magnetic reconnection powering solar flares and eruptions. We analyze the morphology and evolution of flare arcades that formed during five well-known eruptive flares. We show that the arcades have a common saddle-like shape. The saddles occur despite the fact that the flares were of different classe…
The Polar Cusps of the Earths Magnetosphere
Lavraud, Benoit; Trattner, Karlheinz J.