Search Publications
Missions
Journals
Publication Years
Follow-up observations of X-ray emitting hot subdwarf stars: the compact He-poor sdO star Feige 34
Tiengo, A.; Mereghetti, S.; Esposito, P. +1 more
We report on results obtained with the XMM-Newton observation of Feige 34 carried out in April 2018. This is the first spectroscopic X-ray observation of a compact and helium-poor hot subdwarf star. The source was detected at a flux level fX = 3.4 × 10-14 erg cm-2 s-1 in the energy range 0.2-3 keV, which…
Observations of photospheric magnetic structure below a dark filament using the Hinode Spectro-Polarimeter
Shimojo, Masumi; Yokoyama, Takaaki; Katsukawa, Yukio
The structure of the photospheric vector magnetic field below a dark filament on the Sun is studied using the observations of the Spectro-Polarimeter attached to the Solar Optical Telescope onboard Hinode. Special attention is paid to discriminating between two suggested models, a flux rope or a bent arcade. "Inverse polarity" orientation is possi…
Distribution of visual binary stars over masses and separation between components
Tutukov, A. V.; Kovaleva, D. A.
We investigate initial ditributions of visual binary stars over semimajor axes of orbits, initial masses of main components, and mass ratios of components using complete data on wide stellar pairs from WDS catalogue and results of astrometric space missions Gaia and Hipparcos.
Automatic detection of tidal disruption events and other long‑duration transients in XMM‑Newton data
Webb, N. A.
XMM‑Newton's large field of view and excellent sensitivity have resulted in hundreds of thousands of serendipitous X‑ray detections. While their spectra have been widely exploited, their variable nature has been little studied. Part of this is due to the way XMM‑Newton currently operates, where observations generally have a 12‑month proprietary pe…
Influence of Digital Noise on Interpretation of a Transit Light Curve
Abubekerov, M. K.; Gostev, N. Yu.
The algorithms often used for the interpretation of light curves, such as the frequently applied JKTEBOP algorithm, have limited accuracy, which causes rounding errors, and hence a non-physical contribution to the residuals (digital noise). The transit light curve of the binary HD 209458 is used as an example to demonstrate the need to take into a…
Conditions for the formation of anomalous tail of comet
Safarov, Abduljalol G.; Ibadinov, Khursand I.
The time and velocity of ejection of dust particles of anomalous tails from cometary nuclei are determined. It is revealed that some comets cause the formation of an anomalous tail is the collision of their comet nucleus with other bodies of the Solar System. An investigation of the formation conditions of the anomalous tail shows that the dust ej…
Photometric and spectroscopic investigation of nine Cepheids in the Cassiopeia constellation
Handler, G.; Zejda, M.; Paunzen, E. +3 more
We present new multicolor BVRI photometry and low-resolution spectroscopy of 9 fundamental mode Cepheids in the Cassiopeia constellation. Observations were carried out during the 2017/2018 observing season. We investigated each particular light curve in detail using Fourier decomposition techniques which we compare with the Cepheids from the OGLE …
Theoretical Prediction of Asymmetric Instability of Drift Kinetic Alfven Waves in Anisotropic Plasmas
Ilie, Raluca; Chen, Lunjin; Bashir, M. F.
The asymmetric instability of drift kinetic Alfvén waves (DKAWs) is analyzed to study the interplay between the density inhomogeneity and the temperature anisotropy, including the wave-particle interaction and finite ion Larmor radius effects. The asymmetric behavior arises due to the opposite diamagnetic drifts of electrons and ions and quantifie…
SAPREMO: a simplified algorithm for predicting detections of electromagnetic transients in surveys
Stratta, G.; Branchesi, M.; Ciolfi, R. +3 more
The multiwavelength detection of GW170817 has inaugurated multimessenger astronomy. The next step consists in interpreting observations coming from population of gravitational wave sources. We introduce SAPREMO, a tool aimed at predicting the number of electromagnetic signals characterized by a specific light curve and spectrum, expected in a part…
Two temperate sub-Neptunes transiting the star EPIC 212737443
Livingston, John H.; Dominik, Martin; Hernández, Jesús +11 more
We report the validation of a new planetary system around the K3 star EPIC 212737443 using a combination of K2 photometry, follow-up high-resolution imaging and spectroscopy. The system consists of two sub-Neptune sized transiting planets with radii of 2.6R⊕ and 2.7R⊕, with orbital periods of 13.6 and 65.5 d, equilibrium temp…