Bibcode
Beck, C.; Rezaei, R.; Puschmann, K. G.; Fabbian, D.
Referencia bibliográfica
Solar Physics, Volume 291, Issue 8, pp.2281-2328
Fecha de publicación:
10
2016
Revista
Número de citas
10
Número de citas referidas
9
Descripción
Spicules of the so-called type II were suggested to be relevant for
coronal heating because of their ubiquity on the solar surface and their
eventual extension into the corona. We investigate whether solar
spicules are heated to transition-region or coronal temperatures and
reach coronal heights ({≫} 6 Mm) using multiwavelength observations
of limb spicules in different chromospheric spectral lines (Ca ii H,
Hɛ, Hα, Ca ii IR at 854.2 nm, He i at 1083 nm) taken with
slit spectrographs and imaging spectrometers. We determine the line
width of spectrally resolved line profiles in individual spicules and
throughout the field of view, and estimate the maximal height that
different types of off-limb features reach. We derive estimates of the
kinetic temperature and the non-thermal velocity from the line width of
spectral lines from different chemical elements. We find that most
regular, i.e. thin and elongated, spicules reach a height of at most
about 6 Mm above the solar limb. The majority of features found at
larger heights are irregularly shaped with a significantly larger
lateral extension, of up to a few Mm, than spicules. Both individual and
average line profiles in all spectral lines show a decrease in their
line width with height above the limb with very few exceptions. The
kinetic temperature and the non-thermal velocity decrease with height
above the limb. We find no indications that the spicules in our data
reach coronal heights or transition-region or coronal temperatures.