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BVR photometric study and absolute parameters of the eclipsing binary AG LMi
Ebadi, H.; Mousavi-Sadr, M.
We present the CCD observations and light and radial velocity curves analysis for the eclipsing binary system AG LMi. Three minimum times of light curves were determined and used to calculate the orbital period's value as 1.3590 ±0.0001 days and a new epoch of the system as 2458141.2040 ±0.0002 days. The observed B, V, and R light curves and radia…
Lower Surface Temperature at Bright Ephemeral Feature Site on Titan's North Pole
Barnes, Jason W.; Dhingra, Rajani D.; Cottini, Valeria +1 more
We report a temperature difference in one of the regions on Titan that is, documented as a bright ephemeral feature (BEF). Spectra were recorded by Cassini's Composite Infrared Spectrometer. BEFs are 5 µm bright areas that appear, disappear, and shift from flyby to flyby at Titan's North Pole observed in Visual and Infrared Mapping Spectrometer (V…
A small radio galaxy at z = 4.026
Paragi, Zsolt; Krezinger, Máté; Frey, Sándor +8 more
Less than $200$ radio-loud active galactic nuclei (AGN) are known above redshift $4$. Around $40$ of them have been observed at milliarcsecond (mas) scale resolution with very long baseline interferometry (VLBI) technique. Some of them are unresolved, compact, relativistically beamed objects, blazars with jets pointing at small angles to the obser…
Imprints of the secondary interstellar hydrogen atoms at 1 AU
Katushkina, O. A.; Izmodenov, V. V.; Alexashov, D. B. +1 more
In this paper, we search for the possible imprints of the secondary interstellar hydrogen atoms created at the heliospheric boundary in the full-sky maps of the hydrogen fluxes at the Earth orbit. By using our three-dimensional time-dependent kinetic model, the maps of the hydrogen fluxes are calculated for different phases of the solar cycle and …
Orbital and sub-orbital period determination of the candidate high-mass X-ray binary HD 3191
Luque-Escamilla, Pedro L.; Martí, Josep; Paredes, Josep M. +1 more
Aims: The final aim of this paper is to expand the sparse group of X-ray binaries with gamma-ray counterparts as laboratories to study high-energy processes under physical conditions that periodically repeat.
Methods: A follow-up of a candidate system has been carried out. We applied both photometric and spectroscopic techniques in the o…
A New Concept to Measure the Ambipolar Electric Field Driving Ionospheric Outflow
Li, Kun; Wei, Yong; Haaland, Stein
Over the last few decades, the role of ionospheric outflow for the loss of atmospheric constituents, as a plasma supplier to the magnetosphere and hence for the evolution of the Earth's atmosphere has been recognized. A substantial amount of the outflow is thought to be caused by the presence of an ambipolar electric field aligned with the open ma…
Improved Approach in the Coupling Function Between Primary and Ground Level Cosmic Ray Particles Based on Neutron Monitor Data
Georgoulis, M. K.; Xaplanteris, L.; Livada, M. +3 more
In this work an improved approach of existing approximations on the coupling function between primary and ground-level cosmic-ray particles is presented. The proposed coupling function is analytically derived based on a formalism used in Quantum Field Theory calculations. It is upgraded compared to previous versions with the inclusion of a wider e…
UOCS. V. UV study of the old open cluster NGC 188 using AstroSat
Sahu, Snehalata; Subramaniam, Annapurni; Pandey, Sindhu +3 more
We present the UV photometry of the old open cluster NGC188 obtained using images acquired with Ultraviolet Imaging Telescope (UVIT) on board the AstroSat satellite, in two far-UV (FUV) and one near-UV (NUV) filters. UVIT data is utilised in combination with optical photometric data to construct the optical and UV colour-magnitude diagrams (CMDs).…
Chemical abundances of three new Ba stars from the Keck/HIRES spectra
Wang, Liang; Gao, Qi; Yan, Hong-Liang +4 more
Based on high resolution, high signal-to-noise (S/N) ratio spectra from Keck/HIRES, we have determined abundances of 20 elements for 18 Ba candidates. The parameter space of these stars is in the range of 4880 ≤ T eff ≤ 6050 K, $2.56\le \mathrm{log}\,g\le 4.53\,\mathrm{dex}$ and - 0.27 ≤ [Fe/H] ≤ 0.09 dex. It is found that four of them …
Automatic Detection of the Thermal Electron Density From the WHISPER Experiment Onboard CLUSTER II Mission With Neural Networks
Henri, P.; Rauch, J. -L.; Décréau, P. +7 more
The Waves of HIgh frequency and Sounder for Probing Electron density by Relaxation (WHISPER) instrument has been monitoring the bulk properties of the plasma environment around Earth for more than 20 years. Onboard the 3 D Earth magnetospheric CLUSTER II mission, this experiment delivers active and natural electric field spectra, in a frequency in…