A Study of a Tiny Two‐Ribbon Flare Driven by Emerging Flux

Abstract

We present observations of the eruption of a miniature filament that occurred near NOAA Active Region 9537 on 2001 July 14. The eruption was observed by the Hida Observatory Domeless Solar Telescope, in the H line center and AE0.4 8 wings, the Solar and Heliospheric Observatory EUV Imaging Telescope (EIT) and Michelson Doppler Imager, and the Yohkoh Soft X-Ray Telescope (SXT). The miniature filament began to form and was clearly visible in H images by around 06:50 UT. It erupted about 25 minutes later, accompanied by a small tworibbon subflare (with an area of 61 arcsec 2 ). The two ribbons were also found to approach each other at a speed of 3.33 km s À1 . We found that this event was caused by the emergence of new magnetic flux in a quiet region. The emerging flux appeared as a bright region in the EIT and SXT images taken on the previous day. It moved southward into an area of preexisting opposite-polarity flux, where a cancelling magnetic flux region was formed. The miniature filament then appeared, and we suggest that it played some role in inhibiting the release of energy by delaying reconnection between the emerging and preexisting flux, as evidenced by the disappearance of the bright region between opposite polarities in the EUV and soft X-ray images. Consequently, magnetic energy was stored as a result of the slow converging motion of the two opposite-polarity flux regions (0.17 km s À1 ). Reconnection below the filament provoked the filament eruption, and the two-ribbon flare occurred. Miniature filaments are thought to be small-scale analogs of large-scale filaments. Our observations also suggest some common properties between small-scale and large-scale flares. These results support the view that a unified magnetic reconnection model may be able to explain all scales of flares.

Astrophysics in 2005

“…The CME sped off with a velocity of 1500-2000 km s Ϫ1 , and lateral reconnection inflow speeds of 10-100 km s Ϫ1 and outflow speeds of 500-1000 km s Ϫ1 were measured, leading to a reconnection rate with Mach numbers of (Lin M p 0.01-0.23 et al 2005b). In the early stages of 13 well-observed tworibbon flares, a strong correlation was found between the magnetic reconnection rate and the acceleration of the associated erupting filaments, yielding support for the flare model developed by Forbes and Lin, which is driven by the converging footpoints (Jing et al 2005;Sakajiri et al 2004). An indirect calculation of the reconnection rate (of ≈0.001-0.03) was determined from the footpoint motion seen in the EUV (Noglik et al 2005) and UV (Fletcher et al 2004).…”

Flux Emergence (Theory)

“…Finally, some recent observations suggest there are other types of coronal jets called blowout jets (Moore et al, 2010). This type of jet is thought to be a miniature version of large-scale eruptive events such as filament eruptions and CMEs (see Sakajiri et al, 2004, for similar observations in H ). The difference from "standard" jets (e.g., Figure 53) seem to be following: while the standard jets can be more or less regarded as a consequence of direct reconnection between emerging flux and ambient field, the blowout jets are more likely to be a store-and-release process.…”

Magnetic Flux Cancellation as the Origin of Solar Quiet-region Pre-jet Minifilaments

“…Eruptive small-scale features, such as minifilaments, are frequently observed on the solar surface (Moore et al 1977;Hermans & Martin 1986;Chae et al 1999;Wang et al 2000;Sakajiri et al 2004;Zuccarello et al 2007;Ren et al 2008). They are located above a magnetic neutral line (also known as polarity inversion line, PIL) between adjacent oppositepolarity magnetic flux clumps in the photosphere (Martin 1986(Martin , 1998.…”