Evidence of Separator Reconnection in a Survey of X‐Ray Bright Points

Abstract

X-ray bright points are among the simplest coronal structures hypothesized to be powered by magnetic reconnection. Their magnetic Ðeld appears to consist of a simple loop of Ðeld lines connecting positive to negative photospheric sources. Quantitative three-dimensional models of reconnection in this geometry are therefore expected to apply directly to X-ray bright points. We assemble a survey from archival Solar and Heliospheric Observatory data of 764 X-ray bright points (EUV Imaging Telescope) along with their associated photospheric magnetic Ðelds (Solar Oscillation Imager/Michelson Doppler Imager). Measurements are made of each quantity relevant to the simple three-dimensional reconnection model. These data support several predictions of a magnetic reconnection model providing further evidence in favor of the hypothesis that magnetic reconnection supplies heating power to the quiet solar corona.

Temperature variability in X-ray bright points observed with Hinode/XRT

“…XBPs have been studied in great detail using Skylab and Yohkoh X-ray images (Golub et al 1974;Harvey 1996;Nakakubo & Hara 1999;Longcope et al 2001;Hara & Nakakubo 2003). Their correspondence with small bipolar magnetic regions was discovered by combining ground-based magnetic field measurements with simultaneous space-borne X-ray imaging observations (Krieger et al 1971;Golub et al 1977).…”

Height correction in the measurement of solar differential rotation determined by coronal bright points

“…Observational characteristics and physical properties of coronal bright points in various wavelength ranges were recently summarized by Brown et al (2001), Longcope et al (2001) and Madjarska et al (2003). Note that coronal bright points are magnetic tracers associated with bipolar magnetic features (Webb et al 1993); 1/3 of them lie over ephemeral regions (new emerging regions of magnetic flux) and the remaining 2/3 lie above cancelling magnetic features (consisting of opposite polarity fragments that approach and disappear).…”

“…Coronal bright points were also considered to be indirect signatures of the solar dynamo located at the bottom of the convective zone (Golub et al 1981;Gilman & DeLuca 1986). Furthermore, their significance for the coronal heating was also discussed (Gokhale 1975;Priest et al 1994;Longcope et al 2001). …”

Astrophysics in 2001

“…Promising studies attempt to pin down the relation between magnetic quasi-separatrix layers and soft X-ray brightenings (Longcope et al 2001;Wang et al 2000aWang et al , 2001. Popular as ever are many nanoflare heating scenarios, regarding theoretical models (Aletti et al 2000;Galsgaard, Parnell, & Blaizot 2000;Katsukawa & Tsuneta 2001;Klimchuk & Cargill 2001;Vekstein & Katsukawa 2000;Roussev 2001aRoussev , 2001bWalsh & Galtier 2000;Mitra-Kraev & Benz 2001), as well as concerning observational studies (Brkovic, Solanki, & Ruedi 2001;Shimojo & Shibata 2000;Cauzzi, Falchi, & Falciani 2001;Harra, Gallagher, & Phillips 2000;Berghmans, McKenzie, & Clette 2001;Pauluhn et al 2000;Lin, Feffer, & Schwartz 2001).…”