explanation blue bibcodes open ADS page with paths to full text
Author name code: bodnarova
ADS astronomy entries on 2022-09-14
author:"Bodnarova, Marcela"
---------------------------------------------------------
Title: The Effect of Area Averaging on the Approximated Profile of
the H α Spectral Line
Authors: Bodnárová, M.; Utz, D.; Rybák, J.
2016ASPC..504...23B Altcode:
The Hα line is massively used as a diagnostics of the
chromosphere. Often one needs to average the line profile over some
area to increase the signal to noise ratio. Thus it is important to
understand how derived parameters vary with changing approximations. In
this study we investigate the effect of spatial averaging of a selected
area on the temporal variations of the width, the intensity and the
Dopplershift of the Hα spectral line profile. The approximated profile
was deduced from co-temporal observations in five points throughout
the Hα line profile obtained by the tunable Lyot filter installed
on the Dutch Open Telescope. We found variations of the intensity and
the Doppler velocities, which were independent of the size of the area
used for the computation of the area averaged Hα spectral line profile.
---------------------------------------------------------
Title: Long-term trends of magnetic bright points. I. Number of
magnetic bright points at disc centre
Authors: Utz, D.; Muller, R.; Thonhofer, S.; Veronig, A.; Hanslmeier,
A.; Bodnárová, M.; Bárta, M.; del Toro Iniesta, J. C.
2016A&A...585A..39U Altcode: 2015arXiv151107767U
Context. The Sun shows an activity cycle that is caused by its varying
global magnetic field. During a solar cycle, sunspots, I.e. extended
regions of strong magnetic fields, occur in activity belts that are
slowly migrating from middle to lower latitudes, finally arriving
close to the equator during the cycle maximum phase. While this
and other facts about the strong extended magnetic fields have been
well known for centuries, much less is known about the solar cycle
evolution of small-scale magnetic fields. Thus the question arises
if similar principles exist for small-scale magnetic fields. <BR />
Aims: To address this question, we study magnetic bright points (MBPs)
as proxies for such small-scale, kG solar magnetic fields. This study is
based on a homogeneous data set that covers a period of eight years. The
number of detected MBPs versus time is analysed to find out if there
is an activity cycle for these magnetic features too and, if so, how
it is related to the sunspot cycle. <BR /> Methods: An automated MBP
identification algorithm was applied to the synoptic Hinode/SOT G-band
data over the period November 2006 to August 2014, I.e. covering the
decreasing phase of Cycle 23 and the rise, maximum, and early decrease
of Cycle 24. This data set includes, at the moment of investigation, a
total of 4162 images, with about 2.9 million single MBP detections. <BR
/> Results: After a careful preselection and monthly median filtering
of the data, the investigation revealed that the number of MBPs close
to the equator is coupled to the global solar cycle but shifted in time
by about 2.5 yr. Furthermore, the instantaneous number of detected MBPs
depends on the hemisphere, with one hemisphere being more prominent,
I.e. showing a higher number of MBPs. After the end of Cycle 23 and at
the starting point of Cycle 24, the more active hemisphere changed from
south to north. Clear peaks in the detected number of MBPs are found
at latitudes of about ±7°, in congruence with the positions of the
sunspot belts at the end of the solar cycle. <BR /> Conclusions: These
findings suggest that there is indeed a coupling between the activity of
MBPs close to the equator with the global magnetic field. The results
also indicate that a significant fraction of the magnetic flux that
is visible as MBPs close to the equator originates from the sunspot
activity belts. However, even during the minimum of MBP activity,
a percentage as large as 60% of the maximum number of detected MBPs
has been observed, which may be related to solar surface dynamo action.
---------------------------------------------------------
Title: The Košice meteorite fall: Recovery and strewn field
Authors: Tóth, Juraj; Svoreň, Ján; BorovičKa, Jiří Spurný,
Pavel; Igaz, Antal; Kornoš, Leonard; Vereš, Peter; Husárik,
Marek; Koza, Július; Kučera, Aleš Zigo, Pavel; Gajdoš, Štefan;
Világi, Jozef; Čapek, David; Krišandová, Zuzana; Tomko, Šdušan;
Ilha, Jiří Schunová, Eva; Bodnárová, Marcela; Búzová, Diana;
Krejčová, Tereza
2015M&PS...50..853T Altcode: 2015M&PS..tmp..174T
We provide the circumstances and details of the fireball observation,
search expeditions, recovery, strewn field, and physical characteristics
of the Košice meteorite that fell in Slovakia on February 28,
2010. The meteorite was only the 15th case of an observed bolide with
a recovered mass and subsequent orbit determination. Despite multiple
eyewitness reports of the bolide, only three videos from security
cameras in Hungary were used for the strewn field determination and
orbit computation. Multiple expeditions of professionals and individual
searchers found 218 fragments with total weight of 11.3 kg. The strewn
field with the size of 5 × 3 km is characterized with respect to the
space distribution of the fragments, their mass and size-frequency
distribution. This work describes a catalog of 78 fragments, mass,
size, volume, fusion crust, names of discoverers, geographic location,
and time of discovery, which represents the most complex study of a
fresh meteorite fall. From the analytical results, we classified the
Košice meteorite as an ordinary H5 chondrite.
---------------------------------------------------------
Title: Long time variations of Magnetic Bright Points observed
by Hinode/SOT
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot-Rubio, L.;
Bodnárová, M.; Muller, R.; Bárta, M.; Thonhofer, S.; Hanslmeier, A.
2015CEAB...39...91U Altcode:
Magnetic bright points (MBPs) are manifestations of small-scale solar
magnetic flux concentrations, best observable due to their high contrast
in molecular bands like the G-band. Moreover, they are among the most
interesting magnetic features to be studied in high spatial and temporal
resolution in the solar photosphere. Their relevance for solar physics
is not only given by their contribution to fundamental solar plasma
physics on small scales but in addition due to their involvement in
processes like the solar atmospheric heating problem (chromosphere
and corona), their influence on granulation and hence the convective
energy transport, as well as their contribution to the variations in
total solar irradiance caused by their higher relative intensity. In
this ongoing study we focus on the long-time evolution of statistical
parameters of MBPs over the solar cycle. Are parameters like the mean
intensity, average size/diameter, and number of MBPs per unit surface
element variable with time? If so, how do these parameters vary and is
there a relationship to the solar cycle? In the actual contribution
we will discuss preliminary results regarding the variation of the
number of MBPs with time. We saw a decrease in the number of MBPs for
the first years of observation (2006 until 2011) with two distinct
local minima in the years 2009 and 2011. After 2011 the number of MBPs
is increasing again along with an increase in general solar activity
(as seen by the number of sunspots, flares, and CMEs).
---------------------------------------------------------
Title: On Dynamics of G-Band Bright Points
Authors: Bodnárová, M.; Utz, D.; Rybák, J.
2014SoPh..289.1543B Altcode: 2013arXiv1312.5464B
Various parameters describing the dynamics of G-band bright points
(GBPs) were derived from G-band images, acquired by the Dutch Open
Telescope (DOT), of a quiet region close to the disk center. Our
study is based on four commonly used diagnostics (effective velocity,
change in the effective velocity, change in the direction angle, and
centrifugal acceleration) and two new ones (rate of motion and time lag
between recurrence of GBPs). The results concerning the commonly used
parameters are in agreement with previous studies for a comparable
spatial and temporal resolution of the used data. The most probable
value of the effective velocity is ∼ 0.9 km s<SUP>−1</SUP>,
whereas we found a deviation of the effective velocity distribution
from the expected Rayleigh function for velocities in the range from
2 to 4 km s<SUP>−1</SUP>. The change in the effective velocity
distribution is consistent with a Gaussian one with FWHM=0.079 km
s<SUP>−2</SUP>. The distribution of the centrifugal acceleration
exhibits a highly exponential nature (a symmetric Gaussian centered
at the zero value). To broaden our understanding of the dynamics of
GBPs, two new parameters were defined: the real displacement between
their appearance and disappearance (rate of motion) and the frequency
of their recurrence at the same locations (time lag). For ∼ 45 % of
the tracked GBPs, their displacement was found to be small compared to
their size (the rate of motion smaller than one). The locations of the
tracked GBPs mainly cover the boundaries of supergranules representing
the network, and there is no significant difference in the locations
of GBPs with small (m<1) and large (m>2) values of the rate of
motion. We observed a difference in the overall trend of the obtained
distribution for the values of the time lag smaller (slope of the trend
line being −0.14) and greater (−0.03) than ∼ 7 min. The time
lags mostly lie within the interval of ∼ 2 - 3 min, with those up to
∼ 4 min being more abundant than longer ones. Results for both new
parameters indicate that the locations of different dynamical types
of GBPs (stable/farther traveling or with short/long lifetimes) are
bound to the locations of more stable and long-living magnetic field
concentrations. Thus, the disappearance/reappearance of the tracked
GBPs cannot be perceived as the disappearance/reappearance of their
corresponding magnetic field concentrations.
---------------------------------------------------------
Title: Density, porosity and magnetic susceptibility of the Košice
meteorite shower and homogeneity of its parent meteoroid
Authors: Kohout, Tomáš; Havrila, Karol; Tóth, Juraj; Husárik,
Marek; Gritsevich, Maria; Britt, Daniel; Borovička, Jiří; Spurný,
Pavel; Igaz, Antal; Svoreň, Ján; Kornoš, Leonard; Vereš, Peter;
Koza, Július; Zigo, Pavol; Gajdoš, Štefan; Világi, Jozef; Čapek,
David; Krišandová, Zuzana; Tomko, Dušan; Šilha, Jiří; Schunová,
Eva; Bodnárová, Marcela; Búzová, Diana; Krejčová, Tereza
2014P&SS...93...96K Altcode: 2014arXiv1404.1245K
Bulk and grain densities, porosities, and magnetic susceptibilities
of 67 individuals of Košice H chondrite fall were measured. The mean
bulk and grain densities were determined to be 3.43 g/cm<SUP>3</SUP>
with standard deviation (s.d.) of 0.11 g/cm<SUP>3</SUP> and 3.79
g/cm<SUP>3</SUP> with s.d. 0.07 g/cm<SUP>3</SUP>, respectively. Porosity
is in the range from 4.2% to 16.1%. The logarithm of the apparent
magnetic susceptibility (in 10<SUP>-9</SUP> m<SUP>3</SUP>/kg) shows
narrow distribution from 5.17 to 5.49 with mean value at 5.35 with
s.d. 0.08. These results indicate that all studied Košice meteorites
are of the same composition down to ~g scale without the presence of
foreign (non-H) clasts and are similar to other H chondrites. Košice is
thus a homogeneous meteorite fall derived from a homogeneous meteoroid.
---------------------------------------------------------
Title: New insights into the temporal evolution of MBPs
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.;
Jurčak, J.; Thonhofer, S.; Bodnárová, M.; Hanslmeier, A.; Lemmerer,
B.; Piantschitsch, I.; Guttenbrunner, S.
2014CEAB...38...73U Altcode:
Magnetic bright points (MBPs) are among the most fascinating and
interesting manifestations of small-scale solar magnetic fields. In the
present work the temporal evolution of MBPs is followed in data sets
taken by the Hinode satellite. The analysed data and obtained results
confirm a recently presented study done with Sunrise/IMaX data, namely
that MBPs are features undergoing fast evolution with magnetic fields
starting around the equipartition field strength, then showing strong
downflows (between 2 to 4 km/s) causing the magnetic field to amplify
into the kG range (700 to 1500 G) before dissolving again. Furthermore
the initial field inclinations depend on the initial magnetic field
strengths and show an evolution with more vertical angles at some
point during the evolution.
---------------------------------------------------------
Title: Košice meteorite - recovery and the strew field
Authors: Toth, J.; Porubčan, V.; Borovička, J.; Igaz, A.; Spurný,
P.; Svoreň, J.; Husárik, M.; Kornoš, L.; Vereš, P.; Zigo, P.;
Koza, J.; Kučera, A.; Gajdoš, S.; Világi, J.; Čapek, D.; Šilha,
J.; Schunová, E.; Krišandová, Z.; Tomko, D.; Bodnárová, M.;
Búzová, D.; Krejčová, T.
2012epsc.conf..708T Altcode: 2012espc.conf..708T
The glare of the bolide on the night of February 28, 2010,
illuminated streets and interior of apartments, at some places in
Eastern Slovakia and Northern Hungary and cannon-like burst or series
of low frequency blasts were heard. Due to bad weather, cloudy skies
and scatter showers the Central European Fireball Network (operated
by Pavel Spurný of the Czech Academy of Sciences) did not take direct
optical records of the bolide and also the Slovak Video Meteor Network
(operated by Juraj Tóth of Comenius University in Bratislava) did
not operate that night so that at first moment it seemed that there
were no scientific records available of this event. Fortunately, fast
photoelectric sensors on 7 automated fireball stations in the Czech
Republic (6) and Austria (1) worked also under cloudy sky and recorded
the light curve of the bolide. It enabled to determine the exact time
and duration of the event and to estimate its brightness as well. The
bolide reached the maximum brightness of at least -18 magnitudes in one
huge flare. This light curve was used also for modeling of meteoroid
atmospheric fragmentation. Later, several surveillance cameras data
were published showing the moment when the night became a day. Three
videos from Hungary (Örkény village, Fazzi Daniella and Vass Gábor;
Telki village, contact persons Sárneczky Krisztián, Kiss László and
Budapest) actually captured the fireball itself. Thanks to calibration
of videos by several members of the Hungarian Astronomical Association
(MCSE - www.mcse.hu, namely by Igaz Antal) and the trajectory analysis
done by Jiří Borovička gave the hope that significant number
of meteorite fragments reached the surface. He also calculated the
impact area western of the city of Košice in Eastern Slovakia. The
data from the Local Seismic Network of Eastern Slovakia (Peter Moczo
of the Comenius University) analyzed by Pavel Kalenda confirmed the
atmospheric trajectory as well [1].
---------------------------------------------------------
Title: Dynamika fotosférických jasných bodov v G-páse odvodená
použitím dvoch plne automatických algoritmov
---------------------------------------------------------
Title: Dynamika
fotosférických jasných bodov v G-páse odvodená použitím dvoch
plne automatických algoritmov
---------------------------------------------------------
Title: Dynamics of photospheric bright
points in G-band derived from two fully automated algorithms.
Authors: Bodnárová, M.; Rybák, J.; Hanslmeier, A.; Utz, D.
2010nspm.conf...25B Altcode:
Concentrations of small-scale magnetic field in the solar photosphere
can be identified in the G-band of the solar spectrum as bright
points. Studying the dynamics of the bright points in the G-band
(BPGBs) can also help in addressing many issues related to the
problem of the solar corona heating. In this work, we have used
a set of 142 specled images in the G-band taken by the Dutch Open
Telescope (DOT) on 19 October 2005 to make a comparison of two fully
automated algorithms identifying BPGBs: an algorithm developed by Utz
et al. (2009, 2010), and an algorithm developed following the work
of Berger et al. (1995, 1998). We then followed in time and space
motion of the BPGBs identified by both algorithms and constructed the
distributions of their lifetimes, sizes and speeds. The results show
that both algorithms give very similar results for the BPGB lifetimes
and speeds, but their results vary significantly for the sizes of the
identified BPGBs. This difference is due to the fact that in the case of
the Berger et al. identification algorithm no additional criteria were
applied to constrain the allowed BPGB sizes. As a result in further
studies of the BPGB dynamics we will prefer to use the Utz algorithm
to identify and track BPGBs.
---------------------------------------------------------
Title: Slnečná aktivita a kozmické 'iarenie: magnetické pole
Slnka a úroveň kozmického žiarenia
---------------------------------------------------------
Title: Slnečná aktivita a
kozmické 'iarenie: magnetické pole Slnka a úroveň kozmického
žiarenia
---------------------------------------------------------
Title: Solar activity and cosmic radiation: Sun's magnetic
field and cosmic radiation levels.
Authors: Bodnárová, M.; Rybák, J.; Gömöry, P.; Kudela, K.
2010nspm.conf..175B Altcode:
In this work we have analyzed the correlation of the Sun's magnetic
activity and cosmic radiation levels during the period 1951-2004. As a
solar magnetic activity indicator, affecting the cosmic radiation, we
have chosen open magnetic field configurations which we characterized
by an open magnetic flux factor (OMFF). The OMFF was calculated from
the intensity measurements of the green coronal line. In calculations
leading to the relation between the OMFF and galactic cosmic radiation
(GCR) levels the cross-correlation of these datasets was used. The goal
of this contribution was to find mainly time-dependent changes in the
evolution of the OMFF and GCR correlation. In order to do so,besides
the correlation calculations based on the long time series of the
OMFF and GCR data covering the entire period 1951-2004 we have also
calculated the correlation of the OMFF and GCR data from shorter periods
(180 days). We have found that the cross-correlation evolution varies
depending on the phase of the solar cycle. During the minimum the
evolution is characterized by conspicuous periodicity with a period
~ 14 days and the cross-correlation function takes statistically
significant values. During the maximum the period of the variations
is not clear and the cross-correlation function takes low values that
are not statistically significant.
---------------------------------------------------------
Title: Dynamics of G-band bright points derived using two fully
automated algorithms
Authors: Bodnárová, M.; Utz, D.; Rybák, J.; Hanslmeier, A.
2010CEAB...34...25B Altcode:
Small-scale magnetic field concentrations (∼ 1 kG) in the solar
photosphere can be identified in the G-band of the solar spectrum
as bright points. Study of the G-band bright points (GBPs) dynamics
can help us in solving several questions related also to the coronal
heating problem. Here a set of 142 G-band speckled images obtained
using the Dutch Open Telescope (DOT) on October 19, 2005 are used to
compare identification of the GBPs by two different fully automated
identification algorithms: an algorithm developed by Utz et al. (2009a,
2009b) and an algorithm developed according to papers of Berger et
al. (1995, 1998). Temporal and spatial tracking of the GBPs identified
by both algorithms was performed resulting in distributions of
lifetimes, sizes and velocities of the GBPs. The obtained results show
that both algorithms give very similar values in the case of lifetime
and velocity estimation of the GBPs, but they differ significantly
in case of estimation of the GBPs sizes. This difference is caused
by the fact that we have applied no additional exclusive criteria on
the GBPs identified by the algorithm based on the work of Berger et
al. (1995, 1998). Therefore we conclude that in a future study of the
GBPs dynamics we will prefer to use the Utz's algorithm to perform
identification and tracking of the GBPs in G-band images.
