Search Publications
On extreme space weather events: Solar eruptions, energetic protons and geomagnetic storms
Miteva, Rositsa
The purpose of this study is to identify the extreme space weather events in the available satellite and ground-based databases and to relate them to other associated or accompanied solar activity events. Solar flares, coronal mass ejections, energetic protons and geomagnetic storms are selected among all manifestations/consequences of solar activ…
Statistical analysis of solar wind parameter variation with heliospheric distance: Ulysses observations in the ecliptic plane
Bolzan, M. J. A.; Echer, E.; Franco, A. M. S.
The interplanetary magnetic field magnitude Bo, proton density Np and solar wind speed Vsw data from Ulysses spacecraft during its interplanetary cruise interval from Earth to Jupiter, from 18 November 1990 to 31 January 1992, are analyzed in this study. Statistical and wavelet techniques are employed to characteri…
Gaia: The Galaxy in six (and more) dimensions
Pancino, Elena
The ESA cornerstone mission Gaia was successfully launched in 2013, and is now scanning the sky to accurately measure the positions and motions of about two billion point-like sources of 3 ≲ V ≲ 20.5 mag, with the main goal of reconstructing the 6D phase space structure of the Milky Way. The typical uncertainties in the astrometry will be in the r…
Using cross correlation to estimate Doppler frequency
Li, Fei; Yan, Jianguo; He, Qingbao +2 more
Doppler frequency estimation with high accuracy is very important for precise orbit determination and scientific studies in deep space exploration. In this paper, we propose a new method which implements cross correlation of only received signals from one single station to estimate Doppler frequency. The algorithm is relatively simple and it can a…
X-ray properties of dwarf nova EY Cyg and the companion star using an XMM-Newton observation
Balman, Şölen; Nabizadeh, Armin
We present the X-ray analysis of dwarf nova EY Cyg using the 45 ks XMM-Newton observatory archival data obtained in quiescence. We find orbital modulations in X-rays. We simultaneously fitted EPIC pn, MOS1 and MOS2 data using a model for interstellar medium absorption (tbabs) and a multi-temperature plasma emission model with a power-law distribut…
Latitudinal distribution of solar coronal active regions
Chargeishvili, B. B.; Maghradze, D. A.; Japaridze, D. R. +3 more
We studied the cyclic evolution of the latitudinal distribution of solar coronal active regions based on daily images from SOHO EIT for the period 1995-2017. Fully automated software was used, which included the following steps: initial preparation of images in the data series, normalization of histograms and correction of limb brightening, segmen…
Insights from multi-wavelength observations during high and low states of non-magnetic CVs
Szkody, Paula
Close binaries containing a white dwarf accreting from a disk that receives material from a late stellar companion show an interesting variety of behaviors that depend on their accretion rates and the changes in this rate. The highest accretion rates are evident during the bright states of novalikes, as well as the superoutbursts of the shortest p…
Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158
Chen, P. F.; Li, Bo; Yan, Yihua +2 more
The structural property of the magnetic field in flare-bearing solar active regions (ARs) is one of the key aspects for understanding and forecasting solar flares. In this paper, we make a comparative analysis on the chirality and magnetic configurations associated with two X-class two-ribbon flares happening in AR 10930 and AR 11158. The photosph…