7.4.4 Magnetic Reconnection
It is widely accepted that the powerful energy in solar flares is released through
magnetic reconnection of antiparallel magnetic fields. It converts magnetic energy
into heat and kinetic energy. It is believed that magnetic reconnection is ubiquitous
in the universe.
In the Sun, magnetic reconnection is best seen in the case of loop solar flares often
observed at the solar limb. Figure 7.18 presents a schematic picture of a loop flare,
modeled by Hori Kuniko, Yokoyama Takaaki, and others (Hori et al. 1997). A
closed magnetic loop is formed by magnetic tubes rising up from the inner convection layer of the Sun. Outside the closed loop, open magnetic lines extend toward the
corona. High above the closed loop, the open magnetic field on both sides of the loop
provokes a magnetic reconnection at point X, which produces a large amount of
energy and forms upward and downward jet streams. The rising jet flows up to the
corona and turns to the coronal streamer, whereas the falling jet collides with the
magnetic loop and causes an X-ray loop flare. Theoretical studies were conducted by
the group of Shibata Kazunari and Yokoyama Takaaki in the 1990s (Yokoyama and
Shibata 1994, 1998).
7.5 Stellar Physics
7.5.1 Physics of Early- and Late-Type Stars
In this section, the extensions of Osawa Kiyoteru’s works on early-type stars and
those of Fujita Yoshio’s works on late-type stars are briefly summarized.
Fig. 7.17 SXT images of a radio flare that occurred on August 12, 1992 (Takano et al. 1994)
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7 Postwar Development of Astrophysics, 1946–2000 (Part II: Astrophysics)
It is widely accepted that the powerful energy in solar flares is released through
magnetic reconnection of antiparallel magnetic fields. It converts magnetic energy
into heat and kinetic energy. It is believed that magnetic reconnection is ubiquitous
in the universe.
In the Sun, magnetic reconnection is best seen in the case of loop solar flares often
observed at the solar limb. Figure 7.18 presents a schematic picture of a loop flare,
modeled by Hori Kuniko, Yokoyama Takaaki, and others (Hori et al. 1997). A
closed magnetic loop is formed by magnetic tubes rising up from the inner convection layer of the Sun. Outside the closed loop, open magnetic lines extend toward the
corona. High above the closed loop, the open magnetic field on both sides of the loop
provokes a magnetic reconnection at point X, which produces a large amount of
energy and forms upward and downward jet streams. The rising jet flows up to the
corona and turns to the coronal streamer, whereas the falling jet collides with the
magnetic loop and causes an X-ray loop flare. Theoretical studies were conducted by
the group of Shibata Kazunari and Yokoyama Takaaki in the 1990s (Yokoyama and
Shibata 1994, 1998).
7.5 Stellar Physics
7.5.1 Physics of Early- and Late-Type Stars
In this section, the extensions of Osawa Kiyoteru’s works on early-type stars and
those of Fujita Yoshio’s works on late-type stars are briefly summarized.
Fig. 7.17 SXT images of a radio flare that occurred on August 12, 1992 (Takano et al. 1994)
196
7 Postwar Development of Astrophysics, 1946–2000 (Part II: Astrophysics)