SOLAR FILAMENT
They are regions colder than the neighborhood plasma and are held in place by the force of the intense magnetic field.
Because they are cooler than the neighboring regions, the filaments appear in h-alpha images as darker traces. For ease of observation, the recorded scene displays the inverted colors, highlighting the fainter details.
astrobin
https://www.astrobin.com/full/353050/0/...
Equipments:
Apo 150mm triplet
Asi 174mm
Daystar Cromosphere + ERF
Date: June 24, 2018
Sao Paulo-SP