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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…
Constraining the surface properties of Helene
Royer, E.; Howett, C. J. A.
We analyze two sets of observations of Dione's co-orbital satellite Helene taken by Cassini's Composite Infrared Spectrometer (CIRS). The first observation was a CIRS FP3 (600 to 1100 cm-1, 9.1 to 16.7 µm) stare of Helene's trailing hemisphere, where two of the ten FP3 pixels were filled. The daytime surface temperatures derived f…
Multispacecraft Measurements In The Magnetosphere
De Keyser, Johan; Shen, Chao; Pu, ZuYin +9 more
Kinematic Properties of the GAIA EDR3 Catalogue
Tsvetkov, A. S.
We have obtained a solution of the Ogorodnikov-Milne stellar-kinematics equations based on the material of the entire Gaia EDR3 star catalogue containing 1.8 billion objects. In view of the insufficient accuracy of individual trigonometric parallaxes, we have also obtained an analogous solution based on a sub-catalogue of selected 98 million stars…
Numerical Study of Two Injection Methods for the 2007 November 15 Coronal Mass Ejection in the Inner Heliosphere
Shen, Fang; Feng, Xueshang; Zhang, Man +1 more
In this paper, we use two injection methods, i.e., coronal mass ejection (CME) with and without radial compression, to investigate the propagation of the 2007 November 15 CME in the inner heliosphere with a three-dimensional, time-dependent, numerical magnetohydrodynamic model. In order to reproduce the large-scale interplanetary magnetic field as…
Measurement of Hubble constant: were differences in secondary distance indicators apparent as early as the HST Key Project?
Gupta, Shashikant; Thakur, Rahul Kumar; Nigam, Rahul +1 more
Different measurements of the Hubble constant (H0) are not consistent, and a tension between the CMB based methods and cosmic distance ladder based methods has been observed. Measurements from various distance based methods are also inconsistent. To aggravate the problem, the same cosmological probe (Type Ia SNe for instance) calibrated…
Controls on the Global Distribution of Martian Landslides
Ehlmann, Bethany L.; Roback, Kevin P.
Recent acquisition of high resolution satellite imagery of the Martian surface has permitted landslides to be studied on a global scale on Mars for the first time. We apply the Scoops3D software package to compute slope stability for select regions of the Martian surface, combining calculations of slope stability with number of observed landslides…