arXiv subjects

Cristiana Dumitrache

Publications and source records attributed to Cristiana Dumitrache.

3 recordsLinked to original sources

arXiv2017

Numerical Simulations of the Evolution of Solar Active Regions: the Complex AR12565 and AR12567

We have performed numerical magnetohydrodynamic (MHD) simulations of two closed active regions (AR). The input magnetic field values were the coronal magnetic field computed as extrapolation coronal from observations of the photospheric magnetic field. The studied active regions, NOAA AR12565 and AR12567, were registered as different bipolar region. Our investigation, the 3D coronal extrapolations, as well as the numerical MHD experiments, revealed that actually they evolved together as a quadrupolar active region. The second region emerged later under the loops system of AR12565 and separated from this one. A natural current sheet formed between then and it plays an important role in the explosive events (flares and coronal mass ejections) occurrence.

astro-ph.SR↗

arXiv2016

A new approach to detect the boundaries of interplanetary events

We propose a new method to scan the data and then to infer the boundaries of the interplanetary coronal mass ejections, especially the interplanetary events observed by \emph{Ulysses}. The local minima of the temperatures ratio measured by the spacecraft are used to scan and compute the potential boundaries of the interplanetary events. The low plasma beta values are then invoked to detect at least four boundaries, two for the beginning and two for the end of an interplanetary coronal mass ejection (ICME). Intermediate boundaries can be identified, as indicated by other plasma and magnetic field signatures, and these ones mark substructures of a complex event. Using the algorithm described in this article, we have compiled a list of the ICME events registered by \emph{Ulysses} spacecraft during 2000-2002, with their boundaries. After a statistical analysis, four relationships of the plasma beta with the speed are then inferred for the computed ICMEs, for each of the four detected boundaries in our compiled list. In order to exemplify the method we analyse in detail four events. This method provides premises for an alternative way of semi-automatic detection of the interplanetary events' boundaries observed by \emph{Ulysses} spacecraft. We introduce here also a method for visualisation of the magnetic field components that allows detection of plasma insulations and boundaries detection for other satellites too.

astro-ph.SR↗

arXiv2014

The interplanetary mass ejections behaviour in the heliosphere

We present here an overview of an important solar phenomenon with major implication for space weather and planetary life. The coronal mass ejections (CMEs) come from the Sun and expand in the heliosphere, becoming interplanetary coronal mass ejections (ICMEs). They represent huge clouds of plasma and magnetic fields that travel with velocities reaching even 2000 km/s and perturbing the planetary and interplanetary field. The magnetic clouds (MC) are a special class of ICMEs. We summarize some aspects as the ICMEs identification, propagation and track back to the Sun, where the solar source could be found. We notice here few known catalogs of the ICMEs and magnetic clouds.

astro-ph.SR↗