These and the previously mentioned fact, namely, that the spatial fluctuations of the longitudinal field values decrease with height, confirm that the plage magnetic field is highly structured in the photosphere, with strong and weak field variations, and that it expands rapidly, merging and spreading horizontally in the overlying chromosphere where the field is weaker and has smoother spatial variations. However, at the spatial positions where the longitudinal component of the magnetic field in the lower chromosphere (blue symbols) reaches its smallest values, we find similar ones in the middle chromosphere and at the top of the upper chromosphere (black and red symbols, respectively). Last, note that at almost all of the spatial positions where the fluctuating green curve reaches its local minima, the photospheric longitudinal field values are smaller than at the same locations in the overlying layers (e.g., see position b and the corresponding fig. The longitudinal magnetic field values found near the TR (red symbols, inferred from the inner lobes of the Stokes V/ I profiles of Mg ii h & k) are not much weaker than those found in the middle chromosphere (black symbols, determined from the outer V/ I lobes of the h line), although it must be noted that the latter values are a lower limit (Supplementary Material 2C). 3 indicate that the longitudinal component of the magnetic field varies from almost 0 G (slit positions around +12 and −65 arc sec) to more than 300 G (locations a, c and −44 arc sec), showing a smoother spatial variation than in the lower chromosphere (blue symbols) and photosphere (green curve). In the middle chromosphere of the plage and at the top of its upper chromosphere, the black and red symbols of Fig. In the low chromosphere, the maximum longitudinal magnetic field values are about 700 G (blue symbols). In the lower chromosphere (blue symbols), the magnetic field also shows a substantial fluctuation on similar spatial scales, but the amplitude of the spatial variation is considerably smaller, and this variation is not exactly in phase with the one in the underlying photosphere (e.g., note that the spatial locations of the blue-symbol peaks do not coincide exactly with those of the green curve). As expected, the strongest magnetic fields are found in the photosphere of the observed plage, where the magnetic field appears to be organized into small regions with strong magnetic concentrations (with longitudinal field components as large as 1250 G) separated by small regions with longitudinal field values of the order of 10 G (see the green curve and its spatial fluctuation, which has typical scales of less than 10 arc sec). 3 that the magnetic field always shows a single magnetic polarity, except perhaps at the −65 and +12 arc sec positions, where the retrieved opposite polarity fields may not be statistically significant because they are comparable to or smaller than the 1σ uncertainty.
In the bright plage region, we see clearly in Fig. This, together with the fact that the non-thermal energy needed to heat the corona must propagate through the chromosphere, explains why it is indeed a crucial interface region to solve many of the key problems in solar and stellar physics. Above the β = 1 surface, the magnetic field essentially dominates the structuring and dynamics of the plasma. As a result, the β = 1 corrugated surface, where the ratio of gas to magnetic pressure is unity, lies inside the chromosphere. Moreover, from the visible photospheric surface to the chromosphere-corona transition region (TR), the plasma density decreases exponentially by several orders of magnitude, more rapidly than the magnetic field strength. Although the temperature of the chromospheric plasma does not exceed 10 4 K, the fact that its density is much larger than that of the extended and rarified corona implies that much more mechanical energy is required to sustain the chromosphere than the million-degree corona. The chromosphere is a very important region of the solar atmosphere, with an extension of several thousand kilometers, located between the relatively cool surface layers of the photosphere and the overlying hot corona ( 1– 3). Vigil, Amy Winebarger, Ernest Alsina Ballester, Luca Belluzzi, Jiří Štěpán, Andrés Asensio Ramos, Mats Carlsson, and Jorrit Leenaarts Show Fewer Rachmeler, Ken Kobayashi, Hirohisa Hara, Masahito Kubo, Noriyuki Narukage, Taro Sakao, Toshifumi Shimizu, Yoshinori Suematsu, Christian Bethge, Bart De Pontieu, Alberto Sainz Dalda, Genevieve D.
McKenzie, Frédéric Auchère, Ryouhei Kano, … Show All …, Donguk Song, Masaki Yoshida, Laurel A. Ryohko Ishikawa, Javier Trujillo Bueno, Tanausú del Pino Alemán, Takenori J.
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