Bibcode
DOI
Sobotka, M.; Vázquez, M.; Sánchez Cuberes, M.; Bonet, J. A.; Hanslmeier, A.
Referencia bibliográfica
The Astrophysical Journal, Volume 544, Issue 2, pp. 1155-1168.
Fecha de publicación:
12
2000
Revista
Número de citas
16
Número de citas referidas
14
Descripción
Simultaneous time series of broadband images of two active regions close
to the disk center were acquired at the Swedish Vacuum Solar Telescope,
La Palma, in the infrared bands at 1.55 and 0.80 μm, corresponding to
the minimum and maximum continuum opacities, respectively. Dark faculae
are detected in images obtained as weighted intensity differences
between both wavelength bands. Maps of brightness temperatures
Tb (1.55 μm) and Tb (0.80 μm) were computed
for the best pairs of images. In the scatter plots Tb (1.55)
versus Tb (0.80), the elements of quiet regions can be
clearly distinguished from those of faculae and pores, while the
transition between faculae and pores is smooth. The temperature
difference Tb(1.55)-Tb(0.80) in faculae is lower
than that in the quiet photosphere but increases with decreasing
Tb and is higher inside pores. Most of the pores are
surrounded by ringlike regions of low temperature difference. The
minimum intensity of pores at both wavelengths decreases with increasing
diameter. Maps of horizontal motions of dark faculae and pores were
derived from time series of intensity-difference images, using the local
correlation tracking technique. Velocities corresponding to large-scale
separation of polarities, an emergence of magnetic flux, twist and
contraction related to a pore formation, shear motions, and a twist in
dark faculae were measured.