Bibcode
DOI
Socas-Navarro, H.; Elmore, D.
Referencia bibliográfica
The Astrophysical Journal, Volume 619, Issue 2, pp. L195-L198.
Fecha de publicación:
2
2005
Revista
Número de citas
33
Número de citas referidas
24
Descripción
We present full Stokes observations from SPINOR (Spectro-Polarimeter for
INfrared and Optical Regions, at the Dunn Solar Telescope) in the Ca II
infrared triplet and the He I multiplet at 1083 nm from which some
properties of spicules have been derived. There are important advantages
in multiline observations, particularly from different elements. We find
that the orientation of the plane of polarization is very different for
the Ca and He lines, which provides new model-independent direct
evidence of magnetic fields in spicules. Our data show that the Ca and
He lines have almost identical widths. Since the Ca atom is 10 times
heavier than He, we are able to conclude that most of the broadening is
nonthermal (~=16 km s-1) and to set an upper limit of 13 kK
to the spicular temperatures. The bisectors of the lines span a velocity
range of over 15 km s-1 for the He line and 30 km
s-1 for the Ca ones. The vertical gradient of line-of-sight
velocities is also very different for both elements. We obtain 2.8 km
s-1 Mm-1 from He versus 6.4 km s-1
Mm-1 from Ca. These properties, and others from similar
observations, should be taken into account in future physical models of
spicules.