789 research outputs found
First ALMA Observation of a Solar Plasmoid Ejection from an X-ray Bright Point
Eruptive phenomena such as plasmoid ejections or jets are an important
feature of solar activity with the potential for improving our understanding of
the dynamics of the solar atmosphere. Such ejections are often thought to be
signatures of the outflows expected in regions of fast magnetic reconnection.
The 304 A EUV line of Helium, formed at around 10^5 K, is found to be a
reliable tracer of such phenomena, but the determination of physical parameters
from such observations is not straightforward. We have observed a plasmoid
ejection from an X-ray bright point simultaneously at millimeter wavelengths
with ALMA, at EUV wavelengths with AIA, in soft X-rays with Hinode/XRT. This
paper reports the physical parameters of the plasmoid obtained by combining the
radio, EUV and X-ray data. As a result, we conclude that the plasmoid can
consist either of (approximately) isothermal 10^5 K plasma that is optically
thin at 100 GHz, or else a 10^4 K core with a hot envelope. The analysis
demonstrates the value of the additional temperature and density constraints
that ALMA provides, and future science observations with ALMA will be able to
match the spatial resolution of space-borne and other high-resolution
telescopes.Comment: 10 page, 5 figures, accepted for publication in Astrophysical Journal
Letter. The movie can be seen at the following link:
http://hinode.nao.ac.jp/user/shimojo/data_area/plasmoid/movie5.mp
Dynamics and plasma properties of an X-ray jet from SUMER, EIS, XRT and EUVI A & B simultaneous observations
Small-scale transient phenomena in the quiet Sun are believed to play an
important role in coronal heating and solar wind generation. One of them named
as "X-ray jet" is the subject of our study. We indent to investigate the
dynamics, evolution and physical properties of this phenomenon. We combine
spatially and temporally multi-instrument observations obtained simultaneously
with the SUMER spectrometer onboard SoHO, EIS and XRT onboard Hinode, and
EUVI/SECCHI onboard the Ahead and Behind STEREO spacecrafts. We derive plasma
parameters such as temperatures and densities as well as dynamics by using
spectral lines formed in the temperature range from 10 000 K to 12 MK. We also
use image difference technique to investigate the evolution of the complex
structure of the studied phenomenon. With the available unique combination of
data we were able to establish that the formation of a jet-like event is
triggered by not one but several energy depositions which are most probably
originating from magnetic reconnection. Each energy deposition is followed by
the expulsion of pre-existing or new reconnected loops and/or collimated flow
along open magnetic field lines. We derived in great detail the dynamic process
of X-ray jet formation and evolution. We also found for the first time
spectroscopically in the quiet Sun a temperature of 12~MK and density of 4
10^10~cm^-3 in a reconnection site. We raise an issue concerning an uncertainty
in using the SUMER Mg X 624.9 A line for coronal diagnostics. We clearly
identified two types of up-flow: one collimated up-flow along open magnetic
field lines and a plasma cloud formed from the expelled BP loops. We also
report a cooler down-flow along closed magnetic field lines. A comparison is
made with a model developed by Moreno-Insertis \etal\ (2008).Comment: 15 pages, 15 figure
Hard X-ray emission from a flare-related jet
<p><b>Aims:</b> We aim to understand the physical conditions in a jet event which occurred on the 22nd of August 2002, paying particular attention to evidence for non-thermal electrons in the jet material.</p>
<p><b>Methods:</b> We investigate the flare impulsive phase using multiwavelength observations from the Transition Region and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Spectroscopic Imager (RHESSI) satellite missions, and the ground-based Nobeyama Radioheliograph (NoRH) and Radio Polarimeters (NoRP).</p>
<p><b>Results:</b> We report what we believe to be the first observation of hard X-ray emission formed in a coronal jet. We present radio observations which confirm the presence of non-thermal electrons present in the jet at this time. The evolution of the event is best compared with the magnetic reconnection jet model in which emerging magnetic field interacts with the pre-existing coronal field. We calculate an apparent jet velocity of ~500 km s-1 which is consistent with model predictions for jet material accelerated by the <b>J</b> X <b>B</b> force resulting in a jet velocity of the order of the Alfvén speed (~100–1000 km s-1).</p>
Effect of Frequency and Time of Cutting on the Production of Three Strains of Tropical Forage Legume \u3cem\u3eAeschynomene americana\u3c/em\u3e L. in Drained Paddy Field and Upland Field
First analysis of solar structures in 1.21 mm full-disc ALMA image of the Sun
Various solar features can be seen on maps of the Sun in the mm and sub-mm
wavelength range. The recently installed Atacama Large Millimeter/submillimeter
Array (ALMA) is capable of observing the Sun in that wavelength range with an
unprecedented spatial, temporal and spectral resolution. To interpret solar
observations with ALMA the first important step is to compare ALMA maps with
simultaneous images of the Sun recorded in other spectral ranges. First we
identify different structures in the solar atmosphere seen in the optical, IR
and EUV parts of the spectrum (quiet Sun (QS), active regions (AR), prominences
on the disc, magnetic inversion lines (IL), coronal holes (CH) and coronal
bright points (CBPs)) in a full disc solar ALMA image. The second aim is to
measure the intensities (brightness temperatures) of those structures and
compare them with the corresponding QS level. A full disc solar image at 1.21
mm obtained on December 18, 2015 during a CSV-EOC campaign with ALMA is
calibrated and compared with full disc solar images from the same day in
H\alpha, in He I 1083 nm core, and with SDO images (AIA at 170 nm, 30.4 nm,
21.1 nm, 19.3 nm, and 17.1 nm and HMI magnetogram). The brightness temperatures
of various structures are determined by averaging over corresponding regions of
interest in the ALMA image. Positions of the QS, ARs, prominences on the disc,
ILs, CHs and CBPs are identified in the ALMA image. At 1.21 mm ARs appear as
bright areas (but sunspots are dark), while prominences on the disc and CHs are
not discernible from the QS background, although having slightly less intensity
than surrounding QS regions. ILs appear as large, elongated dark structures and
CBPs correspond to ALMA bright points. These results are in general agreement
with sparse earlier measurements at similar wavelengths. The identification of
CBPs represents the most important new result.Comment: 9 pages, 3 figure
Internal structure of nanoparticles of Al generated by laser ablation in liquid ethanol
Al NPs are synthesized by laser ablation of a bulk Al target immersed into
liquid ethanol saturated with hydrogen at atmospheric pressure. The
nanoparticles possess a well-distinguished core-shell structure. High
Resolution Transmission Electron Microscopy shows several layers inside the Al
nanoparticle: oxide layer, amorphous Al, single crystal Al, and a cavity in the
center. Formation of the cavity is attributed to the sharp increase of hydrogen
dissolution in Al upon its melting and its eventual release after the
solidification
Thermo-mechanic-electrical coupling in phospholipid monolayers near the critical point
Lipid monolayers have been shown to represent a powerful tool in studying
mechanical and thermodynamic properties of lipid membranes as well as their
interaction with proteins. Using Einstein's theory of fluctuations we here
demonstrate, that an experimentally derived linear relationship both between
transition entropy S and area A as well as between transition entropy and
charge q implies a linear relationships between compressibility \kappa_T, heat
capacity c_\pi, thermal expansion coefficient \alpha_T and electric capacity
CT. We demonstrate that these couplings have strong predictive power as they
allow calculating electrical and thermal properties from mechanical
measurements. The precision of the prediction increases as the critical point
TC is approached
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