Two plasma filament eruptions were detected on the Sun on July 5, 2018, and it seems at least one weak Earth-directed Coronal Mass Ejection (CME) was produced; ETA July 9 or 10. In addition, a relatively strong farside eruption took place on July 5 and its CME (not Earth-directed) is visible in SOHO/LASCO imagery.
While solar activity remains at very low levels and there are no sunspots on the visible disk, our sun produced two plasma filament eruptions on its Earth-side and one farside eruption over the past 48 hours.
At around 23:25 UTC on July 4, a somewhat impulsive area of coronal dimming was seen in SDO/AIA 193 imagery in the southwest quadrant of the Sun, SWPC said 00:30 UTC on July 6. This activity was likely to have been the source region for a CME which was seen in STEREO-A coronagraph imagery around 13:09 UTC on July 5. SWPC added that they are still awaiting additional imagery from SOHO/LASCO in order to determine if there is an Earth-directed component.
Another filament eruption occurred near N12E11 at approximately 01:00 UTC on July 5. However, after reviewing available coronagraph imagery from SOHO/LASCO, SWPC determined that most of the eruptive material appears to have been re-absorbed into the Sun and a CME was not produced.
While we await further official analysis, take a look at AIA videos above and analysis by Dr. Tamitha Skov and CME prediction model below.
“Our Sun wakes up launching 2 Earth-directed solar storms today,” Dr. Tamitha Skov said in a tweet at 01:31 UTC, July 6.
“Its a 1,2-punch! NASA model predicts impact late July 9 or early July 10. Storms are weak so effects may be moderate, but aurora could reach mid-latitudes over several days. Expect ham radio and GPS issues as well,” she said.
Image courtesy Dr. Tamitha Skov. Open image in a new tab to see the full version.
Another CME is visible in SOHO/LASCO C3 imagery starting at 12:24 UTC on July 5, this time off the northwest limb. However, this was farside eruption and its CME is not expected to affect Earth.
Image courtesy ESA/NASA SOHO/LASCO C3
Meanwhile, the solar wind environment became enhanced early July 5 after several days of near-background conditions. Solar wind speeds increased from 325 to 450 km/s and total field from less than 5 nT to 12 nT before settling near 5 nT. The phi angle varied between positive and negative solar sectors, suggesting a close proximity to the Heliospheric Current Sheet (HCS).
As a result, the geomagnetic field became active with one period of G1 – Minor geomagnetic storming observed between 18:00 and 21:00 UTC. K-index of 5 (G1 – Minor geomagnetic storm) threshold was reached at 19:36 UTC.
Solar wind parameters are expected to decrease to background levels today and are likely to remain at those levels on July 7 and 8 with a chance for active levels as a result of periodic influences from the HCS and northern crown Coronal Hole High Speed Stream (CH HSS).
Unsettled to active geomagnetic field conditions are expected on July 6, followed by quiet levels on July 7 and 8 with occasional unsettled and active periods as a result of minor enhancements in the solar wind.
Here is a summary of what happened on the Sun since last night. Three eruptions. The first one was a nice EUV wave, but was not quite a CME. Event 2 may have an impact on Earth on July 9-10. pic.twitter.com/JIV1g0FUWh
— Halo CME (@halocme) July 5, 2018
Featured image: Plasma filament eruption on July 5, 2018. Credit: NASA/SDO AIA 304