95 research outputs found
The height dependence of temperature - velocity correlation in the solar photosphere
We derive correlation coefficients between temperature and line-of-sight
velocity as a function of optical depth throughout the solar photosphere for
the non-magnetic photosphere and a small area of enhanced magnetic activity.
The maximum anticorrelation of about -0.6 between temperature and line-of-sight
velocity in the non-magnetic photosphere occurs at log tau5 = -0.4. The
magnetic field is another decorrelating factor along with 5-min oscillations
and seeing.Comment: In press,"Modern Solar Facilities - Advanced Solar Science",
(Gottingen), Universitatsverlag Gottingen, 139-142, 200
Magnetic loop emergence within a granule
We investigate the temporal evolution of magnetic flux emerging within a
granule in the quiet-Sun internetwork at disk center. We combined IR
spectropolarimetry performed in two Fe I lines at 1565 nm with
speckle-reconstructed G-band imaging. We determined the magnetic field
parameters by a LTE inversion of the full Stokes vector using the SIR code, and
followed their evolution in time. To interpret the observations, we created a
geometrical model of a rising loop in 3D. The relevant parameters of the loop
were matched to the observations where possible. We then synthesized spectra
from the 3D model for a comparison to the observations. We found signatures of
magnetic flux emergence within a growing granule. In the early phases, a
horizontal magnetic field with a distinct linear polarization signal dominated
the emerging flux. Later on, two patches of opposite circular polarization
signal appeared symmetrically on either side of the linear polarization patch,
indicating a small loop-like structure. The mean magnetic flux density of this
loop was roughly 450 G, with a total magnetic flux of around 3x10^17 Mx. During
the ~12 min episode of loop occurrence, the spatial extent of the loop
increased from about 1 to 2 arcsec. The middle part of the appearing feature
was blueshifted during its occurrence, supporting the scenario of an emerging
loop. The temporal evolution of the observed spectra is reproduced to first
order by the spectra derived from the geometrical model. The observed event can
be explained as a case of flux emergence in the shape of a small-scale loop.Comment: 10 pages, 13 figures; accepted for Astronomy and Astrophysics; ps and
eps figures in full resolution are available at
http://www.astro.sk/~koza/figures/aa2009_loop
High-resolution spectroscopy of a chromospheric subflare: Ca II K line measurement
Anin vestigationof the quiet and active (subflare) solar atmosphere is made using high spatial and spectral resolution observations of the Ca II K line performed at the VTT, Observatorio del Teide, Tenerife. Spectral characteristics IK1, IK2, IK3, integrated intensity Iint, separations of K1 minima SepK1, separations of K2 maxima SepK2 and their ratios are compared for both quiet and active regions. Preliminary results are discussed
Dynamics of the solar photosphere and chromosphere derived from high resolution Fe I and Ca II spectra
The analysis of high-resolution spectra of the Fe I (522.5 nm, 557.6 nm) and Ca II K (393.3 nm) lines in the solar photosphere and chromosphere is presented. A dynamic coupling of the photosphere and chromosphere was
determined from the ratios of both the photospheric and chromospheric line characteristics. All results are discussed for quiet and plage regions. It is found that
inthe plage regionthe meanv alues of K1, K2, K3 intensities inCa II K are increased 2, 5 and 6 times, respectively, as compared to the quiet region. The mean values of Fe I line core intensities increased in plage only 1.32 and 1.64 times for the magnetic non-sensitive and magnetic sensitive line, respectively. The ranges of Fe I core intensity values are larger for the magnetic sensitive line than for the magnetic non-sensitive line
High resolution CCD spectra reduction: Temporal changes of the flat-field compensation
A new method suitable for long-time series of
high-resolution CCD spectra reduction is presented. The method allows to compensate the temporal changes of the instrument conditions which leads to temporal changes of the flat-field matrix. Sometimes it is impossible to make the flat-field measurements during long simultaneous observations with satellites (SOHO, TRACE). The method splits the flat-field matrix into two components. The first one, connected with CCD camera is stable in time and is correct for all spectra. The second one varies and reflects temporal changes of the conditions in the spectrograph. Description of the method and its application to real
high-resolution CCD spectra is presented and discussed
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Trans-Di-μ-acetato-[μ-N,N-bis-(diphenyl-phosphino)aniline] bis-[chlorido-molybdenum(II)](Mo - Mo)-dichloro-methane-tetra-hydro-furan (1/0.3/1.7)
The mol-ecular structure of the title compound, [Mo2(CH 3COO)2Cl2(C30H25NP 2)]·0.3CH2Cl2·1.7C 4H8O, features an Mo - Mo dumbbell bridged by two acetate groups which are trans to each other. Perpendicular to the plane spanned by the acetate groups, the Ph2PN(Ph)PPh2 ligand bridges both Mo atoms, having a P - N - P angle of 114.09 (19)°. In a trans position to the PNP ligand are two Cl atoms, one on each molybdenum centre. The Mo - Mo bond distance is 2.1161 (9) Å, within the range known for Mo - Mo quadruple bonds. The Mo complex is located on a crystallographic twofold rotation axis which runs through the N - C bond of the ligand. The site occupation factors of the disordered solvent molecules were fixed to 0.15 for dichloromethane and 0.85 for tetrahydrofuran. © 2009
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[N,N-Bis(diphenylphosphino)isopropylamine]dibromidonickel(II)
The title compound, [NiBr2(C27H27NP2)], was synthesized by the reaction of NiBr2(dme) (dme is 1,2-dimethoxy-ethane) with N,N-bis-(diphenyl-phosphino)isopropyl-amine in methanol/tetra-hydro-furan. The nickel(II) center is coordinated by two P atoms of the chelating PNP ligand, PH2PN(iPr)PPH2, and two bromide ions in a distorted square-planar geometry
Solar differential rotation in the period 1964 - 2016 determined by the Kanzelh\"ohe data set
The main aim of this work is to determine the solar differential rotation by
tracing sunspot groups during the period 1964-2016, using the Kanzelh\"ohe
Observatory for Solar and Environmental Research (KSO) sunspot drawings and
white light images. Two procedures for the determination of the heliographic
positions were applied: an interactive procedure on the KSO sunspot drawings
(1964 - 2008, solar cycles nos. 20 - 23) and an automatic procedure on the KSO
white light images (2009 - 2016, solar cycle no. 24). For the determination of
the synodic angular rotation velocities two different methods have been used: a
daily shift (DS) method and a robust linear least-squares fit (rLSQ) method.
Afterwards, the rotation velocities had to be converted from synodic to
sidereal, which were then used in the least-squares fitting for the solar
differential rotation law. For the test data from 2014, we found the rLSQ
method for calculating rotational velocities to be more reliable than the DS
method. The best fit solar differential rotation profile for the whole time
period is = (14.47 0.01) - (2.66 0.10)
(deg/day) for the DS method and = (14.50 0.01) - (2.87
0.12) (deg/day) for the rLSQ method. A barely noticeable north -
south asymmetry is observed for the whole time period 1964 - 2016 in the
present paper. Rotation profiles, using different data sets (e.g. Debrecen
Photoheliographic Data, Greenwich Photoheliographic Results), presented by
other authors for the same time periods and the same tracer types, are in good
agreement with our results. Therefore, the KSO data set is suitable for the
investigation of the long-term variabilities in the solar rotation profile
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1,1,2,2-Tetra-phenyl-15-diphosphane 1-sulfide
In the title mol-ecule, C24H20P2S, the P - P bond length is 2.2263 (5) Å. The two phenyl rings attached to the three- and five-coordinated P atoms, respectively, form dihedral angles of 56.22 (5) and 71.74 (5)°
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