255 research outputs found
On the Potential of Large Ring Lasers
We describe a new ring laser with area A = 833 m^2 and update performance
statistics for several such machines. Anandan & Chaio 1982 judged ring lasers
inferior to matter interferometers as possible detectors of gravitational
waves. However, we note that geophysically interesting results have been
obtained from large ring lasers and that there is still a lot of room for
improvements.Comment: accepted optics communication
Improved SOT (Hinode mission) high resolution solar imaging observations
We consider the best today available observations of the Sun free of
turbulent Earth atmospheric effects, taken with the Solar Optical Telescope
(SOT) onboard the Hinode spacecraft. Both the instrumental smearing and the
observed stray light are analyzed in order to improve the resolution. The Point
Spread Function (PSF) corresponding to the blue continuum Broadband Filter
Imager (BFI) near 450 nm is deduced by analyzing i/ the limb of the Sun and ii/
images taken during the transit of the planet Venus in 2012. A combination of
Gaussian and Lorentzian functions is selected to construct a PSF in order to
remove both smearing due to the instrumental diffraction effects (PSF core) and
the large-angle stray light due to the spiders and central obscuration (wings
of the PSF) that are responsible for the parasitic stray light. A
Max-likelihood deconvolution procedure based on an optimum number of iterations
is discussed. It is applied to several solar field images, including the
granulation near the limb. The normal non-magnetic granulation is compared to
the abnormal granulation which we call magnetic. A new feature appearing for
the first time at the extreme- limb of the disk (the last 100 km) is discussed
in the context of the definition of the solar edge and of the solar diameter. A
single sunspot is considered in order to illustrate how effectively the
restoration works on the sunspot core. A set of 125 consecutive deconvolved
images is assembled in a 45 min long movie illustrating the complexity of the
dynamical behavior inside and around the sunspot.Comment: 15 pages, 22 figures, 1 movi
Solar Intranetwork Magnetic Elements: bipolar flux appearance
The current study aims to quantify characteristic features of bipolar flux
appearance of solar intranetwork (IN) magnetic elements. To attack such a
problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar
Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and
an enhanced network areas. Cluster emergence of mixed polarities and IN
ephemeral regions (ERs) are the most conspicuous forms of bipolar flux
appearance within the network. Each of the clusters is characterized by a few
well-developed ERs that are partially or fully co-aligned in magnetic axis
orientation. On average, the sampled IN ERs have total maximum unsigned flux of
several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes.
The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx,
separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN
ERs exhibit a rotation of their magnetic axis of more than 10 degrees during
flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by
growth or the reverse, is not unusual. A few examples show repeated
shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic
photosphere. The observed bipolar behavior seems to carry rich information on
magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
Small-scale solar magnetic fields
As we resolve ever smaller structures in the solar atmosphere, it has become
clear that magnetism is an important component of those small structures.
Small-scale magnetism holds the key to many poorly understood facets of solar
magnetism on all scales, such as the existence of a local dynamo, chromospheric
heating, and flux emergence, to name a few. Here, we review our knowledge of
small-scale photospheric fields, with particular emphasis on quiet-sun field,
and discuss the implications of several results obtained recently using new
instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure
Spectroscopic Coronal Observations during the Total Solar Eclipse of 11 July 2010
The flash spectrum of the solar chromosphere and corona was measured with a
slitless spectrograph before, after, and during the totality of the solar
eclipse, of 11 July 2010, at Easter Island, Chile. This eclipse took place at
the beginning of the Solar Cycle 24, after an extended minimum of solar
activity. The spectra taken during the eclipse show a different intensity ratio
of the red and green coronal lines compared with those taken during the total
solar eclipse of 1 August 2008, which took place towards the end of the Solar
Cycle 23. The characteristic coronal forbidden emission line of forbidden Fe
XIV (5303 {\AA}) was observed on the east and west solar limbs in four areas
relatively symmetrically located with respect to the solar rotation axis.
Subtraction of the continuum flash-spectrum background led to the
identification of several extremely weak emission lines, including forbidden Ca
XV (5694 {\AA}), which is normally detected only in regions of very high
excitation, e.g., during flares or above large sunspots. The height of the
chromosphere was measured spectrophotometrically, using spectral lines from
light elements and compared with the equivalent height of the lower
chromosphere measured using spectral lines from heavy elements.Comment: 14 pages, 8 figures, 1 table; Solar Physics, 2012, Februar
Body condition is negatively associated with infection with Syngamus trachea in the ring-necked pheasant (Phasianus colchicus)
Comparative analysis of two-dimensional electrophoresis maps (2-DE) of Helicobacter pylori from Brazilian patients with chronic gastritis and duodenal ulcer: a preliminary report
Expressão e atividade enzimática de glutationa s-transferase em tecidos de fêmeas de Boophilus microplus
Tree and shrub species of the Atlantic Forest on the slopes of Marambaia Island, Rio de Janeiro, Brazil
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