Tether-cutting Energetics of a Solar Quiet-Region Prominence Eruption

Abstract

We study the morphology and energetics of a slowly evolving quiet-region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fe XV EUV 284 Å data from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO). After rising at ~1 km s^-1 for about six hours, the prominence accelerates to a velocity of ~10 km s^-1, leaving behind EUV and soft X-ray loop arcades of a weak flare in its source region. Intensity dimmings occur in the eruption region cospatially in EUV and soft X-rays, indicating that the dimmings result from a depletion of material. Over the first two hours of the prominence's rapid rise, flarelike brightenings occur beneath the rising prominence that might correspond to ``tether-cutting'' magnetic reconnection. These brightenings have heating requirements of up to ~10²⁸-10²⁹ ergs, and this is comparable to the mechanical energy required for the rising prominence over the same time period. If the ratio of mechanical energy to heating energy remains constant through the early phase of the eruption, then we infer that coronal signatures for the tether cutting may not be apparent at or shortly after the start of the fast phase in this or similar low-energy eruptions, since the plasma-heating energy levels would not exceed that of the background corona.