A dynamic sunspot
posted: March 30, 2016

Continuing the ongoing trend of low solar activity, last week was once again very quiet with flaring levels barely reaching the C-class level. Only NOAA 2524 was able to produce a C1 flare on 23 March (long duration event), and a C2 flare early on Monday 28 March. By then, this active region had decayed into a small single sunspot and was rounding the west limb. Despite its simple outlook, this region showed quite some activity in extreme ultraviolet wavelengths.

On 27 and 28 March, numerous jets (see the STCE news item of 5 February 2015) can be seen emanating from an area to the north and northwest of the sunspot. Some but not all of these jets were related to B-class flares (e.g. the one around 19:50UT), with only one related to a C-class flare (around 02:30UT on 28 March). The latter event was also the only one associated with a coronal mass ejection.

Using SDO-imagery, this movie first shows a four-frame clip covering the period from 27 March (12:00UT) till 29 March (00:00UT) at a cadence of 1 image per 5 minutes. It shows a view at several million degrees (top left) and at about 700.000 degrees (top right), at about 80.000 degrees (bottom left) and in white light (bottom right). The next clips compare the EUV-imagery side by side, but for a more restricted time period (from 18:00UT till 06:00UT) and at a higher cadence (1 image every 2 minutes). Clearly, some of the activity looks entirely different depending the filter used.