Analysis of a long-duration AR throughout five solar rotations: Magnetic properties and ejective events

Abstract

Coronal mass ejections (CMEs), which are among the most magnificent solar eruptions, are a major driver of space weather and can thus affect diverse human technologies. Different processes have been proposed to explain the initiation and release of CMEs from solar active regions (ARs), without reaching consensus on which is the predominant scenario, and thus rendering impossible to accurately predict when a CME is going to erupt from a given AR. To investigate AR magnetic properties that favor CMEs production, we employ multi-spacecraft data to analyze a long duration AR (NOAA 11089, 11100, 11106, 11112 and 11121) throughout its complete lifetime, spanning five Carrington rotations from July to November 2010. We use data from the Solar Dynamics Observatory to study the evolution of the AR magnetic properties during the five near-side passages, and a proxy to follow the magnetic flux changes when no magnetograms are available, i.e. during farside transits. The ejectivity is studied by characterizing the angular widths, speeds and masses of 108 CMEs that we associated to the AR, when examining a 124-day period. Such an ejectivity tracking was possible thanks to the mulit-viewpoint images provided by the Solar-Terrestrial Relations Observatory and Solar and Heliospheric Observatory in a quasi-quadrature configuration. We also inspected the X-ray flares registered by the GOES satellite and found 162 to be associated to the AR under study. Given the substantial number of ejections studied, we use a statistical approach instead of a single-event analysis. We found three well defined periods of very high CMEs activity and two periods with no mass ejections that are preceded or accompanied by characteristic changes in the AR magnetic flux, free magnetic energy and/or presence of electric currents. Our large sample of CMEs and long term study of a single AR, provide further evidence relating AR magnetic activity to CME and Flare production.

Long-term evolution of magnetic fields in flaring Active Region NOAA 12673

“…Therefore, we found that EUV intensity evolution of the AR could be a proxy for the total magnetic flux evolution. This is in agreement with other results that studied the long-term evolution of EUV intensities of several ARs in solar cycle 24 (Ugarte- Urra et al 2015;Iglesias et al 2020). However, we could not find any clear signature of a flare precursor in the EUV intensity evolution of the flaring ARs prior to the flares.…”

“…Ugarte-Urra et al (2015) found the lifetimes of several ARs to be continuously proportional to the maximum 304 Å intensity. Recently, Iglesias et al (2020) studied longterm evolution of a long-duration AR in the early phase of solar cycle 24 and found that its characteristics varied significantly during five solar rotations.…”

Lifetime of Long-Lived Sunspot Groups

“…The present results show that its validity can not be simply extended to recurrent active regions because in the domains of very long lifetimes and very large areas the relationship is more complex as is illustrated by Figure 4. Iglesias et al [13] followed a recurrent sunspot group in 1990. In my data its maximum umbral area was 78, it is a relatively small group.…”

The Advective Flux Transport Model: Improving the Far Side with Active Regions Observed by STEREO 304 Å

“…The proxy is given by an empirical power-law relationship between the total photon flux in 304 Å and the total unsigned magnetic flux. This method was shown to be sufficient to obtain accurate information about active regions emerging on the far side of the Sun, and was employed to study the continuous long-term evolution of active region magnetic flux (Ugarte- Urra et al 2015Urra et al , 2017Iglesias et al 2019).…”