We present time‐resolved photometry of the cataclysmic variable PTF1J2224+17 obtained during four nights in October 2018 and January 2019 from Inastars observatory. The object is variable on a period of 103.82 min. Archival Catalina Real‐Time Transient Survey (CRTS), Palomar Transient Factory, and Zwicky Transient Facility‐data show frequent changes between high and low states. Based on its photometric

Solar twins are stars with a mass and chemical composition similar to the Sun; therefore, they follow about the same evolution and can be used to study the past and future of the Sun. I review the evolution of lithium and beryllium in solar‐mass solar‐metallicity main sequence stars, using a differential spectroscopic analysis of solar twins relative to the Sun, allowing precise determination of stellar

SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) is a space mission which aims to measure Earth's global system responses to solar wind and geomagnetic variations with innovative instrumentation, for example, wide–field X‐ray telescope of Lobster–Eye type, on board. It is a collaborative project of the European Space Agency and the Chinese Academy of Sciences. The SMILE international consortium

The recent status of the European Space Agency's (ESA) THESEUS (Transient High‐Energy Sources and Early Universe Surveyor) project and the recent and expected Czech participation in this project are briefly presented and discussed. THESEUS is a mission concept proposed in response to the ESA's call for medium‐size mission (M5) within the Cosmic Vision Programme and selected by ESA on May 7, 2018, to

A summary of the long‐term, 1974–2018, measurements of the line‐of‐sight velocity of the solar photosphere, performed at the Crimean Astrophysical Observatory, is presented. The work shows that the Sun is pulsating with two periods: P 0 = 9,600.606(12) s and P 1 = 9,597.924(13) s. The new measurements, 1996–2018, confirm the remarkable phase stability of the second period. The true origin of both pulsations

In our previous work in Xiao et al. (SCPMA, 2019, 62, 129811), we suggested that six superluminal sources could be γ‐ray candidates, and in fact, five of them have been confirmed in the fourth Fermi‐LAT source catalog (4FGL). In this work, based on the 4FGL, we report a sample of 229 Fermi detected superluminal sources (FDSs), including 40 new FDSs and 62 non‐FDSs. Thus, we believe that all superluminal

The aim of this paper is to unveil, by means of self‐organizing maps (SOMs), the connections between intrinsic properties of radio quasars, namely redshift (z), luminosity (P), continuum slope (α), and parameters characterizing radio morphology of the host galaxy: observed linear size and bending. The strong luminosity–redshift correlation established by a prior traditional principal component analysis

Supernova remnants (SNRs) are the outcome of supernovae (SNe, either core collapse or thermonuclear). The remnant results from the interaction between the stellar ejecta and the ambient medium around the progenitor star. Young SNRs are characterized by strong shocks that heat and ionize the gas, generate magneto‐hydrodynamic turbulence, and accelerate particles to relativistic energies. They radiate

Presence of recombining (overionized) plasma in several supernova remnants (SNRs), first suggested by ASCA observations, was anchored by the detection of enhanced radiative recombination continua in Suzaku spectra of the SNRs IC 443 and W49B. This discovery was surprising, because X‐ray‐emitting SNRs were thought to have ionizing plasmas in general. Since then, similar spectral features have been detected

Supernova remnants (SNRs) are the aftermath of stellar explosions, which inject large amounts of energy into the interstellar medium (ISM), carving out new structures and transferring kinetic energy to the ISM. They also act as recycling centers, which return elements processed in stars to the ISM, and cosmic particle accelerators. The evolution of SNRs can be best studied in soft X‐ray line and continuum

We analyze the X‐ray emission from the supernova remnant DEM L71 using the smoothed particle inference (SPI) technique. The high Fe abundance found appears to confirm the Type Ia origin. Our method allows the separation of the material ejected in the supernova explosion from the material swept up by the supernova shock wave. We are able to calculate the total mass of this swept‐up material to be about

We investigate the broadband emission properties of the pulsar wind nebula (PWN) 3C 58 using a spectral energy distribution (SED) model. We attempt to match simultaneously the broadband SED and spatial variations of X‐ray emission in the PWN. We further use the model to explain a possible far‐IR feature of which a hint was recently suggested in 3C 58: a small bump at ∼1011 GHz in the PLANCK and Herschel

The hot circum‐galactic medium (CGM) represents the hot gas distributed beyond the stellar content of the galaxies while typically within their dark matter halos. It serves as a depository of energy and metal‐enriched materials from galactic feedback and a reservoir from which the galaxy acquires fuels to form stars. It thus plays a critical role in the coevolution of galaxies and their environments

Hot plasma is the dominant phase of the interstellar medium of early‐type galaxies. It can originate from stellar mass losses, residual gas from the formation epoch, and accretion from outside the galaxies. Its evolution is linked to the dynamical structure of the host galaxy, to the supernova and active galactic nuclei (AGN) feedback, and to (late‐epoch) star formation in a way that has yet to be

The Atomic Database project (AtomDB) atomic database provides access to a curated collection of atomic data, along with tools that convert this data into emissivities used in many analysis tools. We present the outline of some of the tools now available for accessing AtomDB using the new Python interface, developed to handle the larger datasets that exist since the release of version 3 in 2016. We

Charge exchange (CX) is a semi‐resonant recombination process that can lead to spectral line emission in the X‐ray band. It occurs in nearly any environment where hot plasma and cold gas interact: in the solar system, in comets and planetary atmospheres, and likely astrophysically, in, for example, supernova remnants and galaxy clusters. It also contributes to the soft X‐ray background. Accurate spectral

Accurate chemical abundance measurements of X‐ray‐emitting atmospheres pervading massive galaxies, galaxy groups, and clusters provide essential information on the star formation and chemical enrichment histories of these large‐scale structures. Although the collisionally ionized nature of the intracluster medium (ICM) makes these abundance measurements relatively easy, the underlying spectral models

We present the constraints on the helium abundance in 12 X‐ray‐luminous galaxy clusters that have been mapped in their X‐ray and Sunyaev–Zeldovich (SZ) signals out to R200 for the XMM‐Newton Cluster Outskirts Project (X‐COP). The unprecedented precision available for the estimate of H0 allows us to investigate how much the reconstructed X‐ray and SZ signals are consistent with the expected ratio x

The intracluster medium (ICM) contains the vast majority of the baryonic matter in galaxy clusters and is heated to X‐ray radiating temperatures. X‐ray spectroscopy is therefore a key to understanding both the morphology and the dynamics of galaxy clusters. Here we recall crucial evolutionary problems of galaxy clusters unveiled by 19 years of high‐resolution X‐ray spectroscopy with the reflection

The properties (temperature, density, chemical composition, velocity) of hot astrophysical plasma and the physical processes affecting them (heating/cooling, turbulence, shocks, acceleration) can be probed by high‐resolution X‐ray spectroscopy, to be complemented by high‐spatial‐resolution imaging. The paper presents the status of the European Space Agency's Advanced Telescope for High Energy Astrophysics

We analyzed the optical photometric data of short‐term variability (flickering) of the accreting white dwarf in the jet‐ejecting symbiotic star MWC 560. The observations were obtained on 17 nights during the period November 2011 to October 2019. The color‐magnitude diagram shows that the hot component of the system becomes redder as it gets brighter. For the flickering source, we find that it has color

The present problem is devoted to the special case of restricted problem of three bodies, always referred as the Copenhagen problem when we consider the primaries of equal masses. In this manuscript, we have considered the third body of infinitesimal mass as variable and moreover, instead of taking only Newtonian potential and forces, a quasi‐homogeneous potential produced by the main primaries has

Machine learning techniques have been widely used in attempts to forecast several solar datasets such as the sunspot count, the sunspot area, flare activity, solar wind magnitude, and solar storms/coronal mass ejections (CMEs) activity. Most of these approaches employ supervised machine learning algorithms which are, in general, very data hungry. This hampers the attempts to forecast some of these

Does the Sun always rotate correctly? On the basis of the measurements of its mean magnetic field (more than 27 thousand daily values, obtained by seven observatories during 1968–2018) and resonance relations of the solar system, the sidereal spin period of the Sun as a star is determined as 25.165(6) days and that of the solar equator as 25.081(7) days. After 1993, however, a remarkable violation

The ability of digital sky surveys to collect and store very large amounts of data provides completely new ways to study the local universe. Perhaps one of the most provocative observations reported with such tools is the asymmetry between galaxies with clockwise and counterclockwise spin patterns. Here, I use ∼1.7 × 105 spiral galaxies from Sloan Digital Sky Survey (SDSS) and sort them by their spin

We perform near‐infrared photometry of a large sample of 49 superthin edge‐on galaxies. These galaxies are selected based on optical photometry because of high radial‐to‐vertical scale ratio in their stellar disks. The near infrared (NIR) H and K observations were conducted with the cryogenic‐cooled camera ASTRONIRCAM on the 2.5 m telescope at the Caucasus Mountain Observatory of Lomonosov Moscow State

Optical surveys, such as the MACHO project, often uncover variable stars whose classification requires follow‐up observations by other instruments. We performed X‐ray spectroscopy and photometry of the unusual variable star MACHO 311.37557.169 with XMM‐Newton in April 2018, supplemented by archival X‐ray and optical spectrographic data. The star has a bolometric X‐ray luminosity of about 1 × 1032 erg s−1 cm−2

The Next Generation Transit Survey (NGTS) is a photometric survey for transiting exoplanets, consisting of 12 identical 0.2‐m telescopes. We report a measurement of the transit of HD 106315 c using a novel observing mode in which multiple NGTS telescopes observed the same target, with the aim of increasing the signal‐to‐noise ratio. Combining the data allows the robust detection of the transit, which

Follow‐up imaging observations of the first detected interstellar comet 2I/Borisov are presented, which were carried out with the Schmidt‐Teleskop‐Kamera at the University Observatory Jena in 11 observing epochs in October and November 2019. The orbital solution of the comet, derived from the obtained astrometric measurements, confirms its highly eccentric (e  = 3.3570 ± 0.0006) and inclined (i  = 44

Based on the shell and pair effects and the decay energy, we investigate the comparative half‐lives of β −‐decay for some iron group nuclei and mainly discuss the electron energy, beta decay threshold energy, and the antineutrino energy losses by β −‐decay of several typical iron isotopes in the presence of strong electron screening (SES) and in the framework of linear response theory. Our main findings

Space debris larger than 1 cm can damage space instruments and impact Earth. The low‐Earth orbits (at heights smaller than 2,000 km) and orbits near the geostationary‐Earth orbit (at 35,786 km height) are especially endangered because most satellites orbit at these latitudes. With current technology, space debris smaller than 10 cm cannot be tracked. Smaller space debris fragments burn up and evaporate

It is shown how the large‐scale inhomogeneous distribution of chemical elements in the primordial medium contributes to temperature fluctuations of the cosmic microwave background radiation (CMB). The magnitude of the chemical anisotropy of the CMB, which is sensitive to the absolute and relative abundance of chemical elements at the time of decoupling, is compared with the primary Sachs‐Wolfe anisotropy

We analyze emission line properties and their correlations for 18,043 type 1 active galactic nucleus (AGN) in the range of 0.02 ≤ z  ≤ 0.8, based on Sloan Digital Sky Survey Data Release 14 data. We complement the data with photometric measurements from ROSAT, GALEX, 2MASS, and FIRST. We find the following: (a) The average correlation between luminosity of [O III] and AGN luminosity is stronger than

The results of the analysis of the single‐color (B) observations undertaken at the Stefanion Observatory for the red dwarf star AD Leo at any stage of the stellar activity (quiescence, weak flares, strong flares) indicate that (a) transient high‐frequency oscillations occur during the flare event and during the quiet‐star phase as well, and (b) the observed frequencies range between 0.0005 Hz (period