Sun Area Research Articles

Periploca sepium leaf dry weight, area, and thickness scale differently under different light environments in Taohe riparian forests

Understanding the variation in plant morphological characteristics under heterogeneous light environments is important to comprehend the adaptation strategies of riparian forest plants. Among the plant parts, leaves are the most sensitive to changes in the environment, and their functional traits and correlations among them can reflect the pathways and mechanisms of a plant's response to environmental changes. The allometric relationship between leaf dry weight (LDW), leaf area (LA) and leaf thickness (LT) in Periploca sepium under three natural habitat conditions, namely, under canopy, gap, and full sun areas in the Taohe riparian forest, was examined by using the standardized major axis (SMA) estimation method and correlation analysis. In the under canopy area, LDW and LA showed an allometric growth relationship (SMA slope < 1), whereas LDW and LT displayed an isometric relationship (SMA slope = 1). In the gap area, LDW was isometrically related to the LA and LT (SMA slope = 1). In the full sun area, LDW and LT showed an allometric relationship (SMA slope > 1), whereas LDW and LA showed an isometric relationship (SMA slope = 1). LA, LT, and LDW decreased by 34.3%, 45.0%, and 40.4%, respectively, in plants from the under canopy area to the full light area. Moreover, the transpiration rate (Tr), net photosynthetic rate (Pn), stomatal conductance (Gs), and vapour pressure deficit (VPD) of Periploca sepium increased 1.29-fold, 13.5%, 63.2%, and 29.7%, respectively, from the under canopy area to the full sun area. Periploca sepium developed large, thick leaves in the under canopy area, and small, thin leaves in the full sun area, demonstrating the investment trade-off mechanism of plant leaf functional traits to adapt to the heterogeneous light environment.

Magnetic field evolution around a fast-moving pore emerging from the quiet Sun

Context. Solar pores are intense concentrations of magnetic fields on the solar surface and plasma flows have always played a key role in spurring the evolution of the pores. Aims. In this study, we present the evolution of the magnetic field and plasma velocity around a fast-moving pore. The target pore expands into the quiet Sun area with a sufficiently fast speed after its emergence, while the background magnetic fields around the pore are simple. These characteristics provide us with an excellent opportunity to study the interaction between plasma motions and ambient magnetic fields. Methods. We analyzed the Helioseismic and Magnetic Imager (HMI) vector magnetograms with a pixel size of 0.5″ and a temporal cadence of 12 min across a duration of 11 h. We also adopted he HMI dopplergrams present the line-of-sight velocities. The horizontal flow fields were obtained using the Differential Affine Velocity Estimator for Vector Magnetograms method. Results. Pure horizontal magnetic fields are generated in the moving frontwards when the pore is subject to fast movement. The generated magnetic fields occur outside the emerging site and thus can be ruled out as the emerging flux from the interior. Instead, they are highly correlated with the broader downflows and expanding horizontal plasma motions in front of the pore. A magnetic gap can be observed between the magnetic fields inside and outside the pore. The temporal evolution of the generated magnetic fields is related to the speed of the pore, which is also distinguished from the original fields within the pore. Conclusions. The observations suggest that the plasma flows driven by the fast proper motion of the pore compress and stretch the local magnetic field to a horizontal non-radial direction, ultimately leading to the magnetic field amplification in the front part of the moving pore.

Natural shade from integrated crop–livestock–forestry mitigates environmental heat and increases the quantity and quality of oocytes and embryos produced in vitro by Gyr dairy cows

This study aimed to evaluate the effect of natural shade from integrated crop–livestock–forestry (CLF) on the comfort of lactating Gyr cows, as well as their oocyte and embryo quantity and quality. Twenty animals were separated into two experimental groups: grazing under full sun (control) and under natural shade provided by the CLF system. Meteorological variables and bioclimatic indicators, rectal and animal surface temperatures, milk quantity and quality, follicle number, oocyte quantity and quality, and in vitro embryo quantity and quality were measured. Data were collected in the rainy season (from November until April) and compared with data obtained in the dry season (from May until October). During the dry season, the natural shade from CLF maintained the dry-bulb temperature at 6.9°C, 5.9°C, and 4.3°C lower than that in the full sun in August, September, and October, respectively. The environment with tree shade presented a black globe-humidity index (BGHI) 3%–7% lower than that in the full sun environment. In the dry season, the most challenging period for animals, the microenvironment produced by the shade of trees reduced the surface temperatures of the udder, rump, and area around the eye of cows by 1.0°C–1.8°C compared to those of animals in the full sun area. Rectal temperature and milk production were not influenced by treatment. However, the higher thermal comfort influenced the reproduction of cows; they presented a higher number of ovarian follicles (37.05 ± 3.40 vs. 31.73 ± 3.86), higher number of total oocytes (11.41 ± 4.69 vs. 6.5 ± 2.60), and more viable oocytes (6.27 ± 3.36 vs. 3.45 ± 1.38) per animal than cows directly exposed to the sun during the dry season. Gyr cows maintained under shade presented more transferable embryos per cow than did those in the CLF environment. CLF systems are a technological alternative to provide improved microclimate within grasslands and thermal comfort to dairy cows, including zebu cows.

PENGARUH JARAK TANAM TERHADAP PRODUKTIVITAS INDIGOFERA (Indigofera zolingeriana) DI AREAL TERBUKA

The Effect of Planting Space On Productivity of Indigofera (Indigofera zollingeriana) in Full Sun Area. The purpose of this research was determines the productivity of Indigofera zollingeriana with three different planting space. This experiment was conducted using Completely Randomized Design (CRD). The treatment consisted of three planting space, (1) 1.0 m x 0.5 m, (2) 1.0 m x 1.0 m, and (3) 1.0 m x 1.5 m, each treatment had six replications. Data were analyzed using analysis of variance and HSD test. The variables measured were fresh and dried stem weight, fresh and dried leaf weight. The results showed that planting space were significant different (P&lt;0.01) on fresh and dried stem weight, fresh and dried leaf weight. HSD test showed that planting space 1.0 m x 1.5 m were significant (P&lt;0.01) have higher stem fresh weight, stem dry matter weight, fresh leaf weight and leaf dry matter weight than planting space 1.0 m x 1.0 m and 1.0 m x 0.5 m. It can be concluded that planting space 1.0 m x 1.5 m have the highest productivity that were highest stem freshweight, stem dry matter weight, leaf freshweight and leaf dry matter weight.Key words: Indigofera zollingeriana, planting space, productivity

Physical processes in the ionosphere during the solar eclipse on March 20, 2015 over Kharkiv, Ukraine (49.6° N, 36.3° E)

We present the results of observations of variations in the mid-latitude ionospheric parameters and physical processes in the geospace during March 20, 2015 partial solar eclipse over Kharkiv (49.60° N, 36.30° E) where the eclipse magnitude was about 0.54. The Kharkiv incoherent scatter (IS) radar and digital ionosonde were used for ionospheric observations and estimations of the parameters of the thermal and dynamical processes. At the time of the maximum obscuration of the Sun's area, an increase in the ionospheric F2 peak height by about 40 km was observed. At the same time, the electron density at altitudes of 190 and 210 km decreased by approximately 18.5 and 16.5%, respectively. During the eclipse, a decrease in the electron temperature and apparent changes in the vertical plasma drift velocity were observed. The observations and analysis have shown that the solar eclipse led to significant restructuring of the thermal and dynamic state of the ionospheric plasma over Kharkiv.

A COMPARATIVE STUDY OF MORPHO-ANATOMY, THE CONTENT OF CHLOROPHYLL AND ASCORBIC ACID ON ARDISIA HUMILIS THUNBERG IN THE AREA WITH DIFFERENT LIGHT INTENSITY AT THE NATURE PRESERVE OF PANANJUNG PANGANDARAN, WEST JAVA, INDONESIA

This study was conducted in order to seek out different morpho-anatomy responses, the content of chlorophyll and ascorbic acid in Ardisia humilis Thunberg in the area of different light intensity in the nature preserve of Pangandaran. The determination of the location was based on the existence of Ardisia humilis Thunberg in the area both with direct exposure of sun light and not. The location to obtain the open area-sample was located behind the office of Conservation of Natural Resources (BKSDA) with the light intensity of 922.000 Lux. The light intensity of the area without direct sun light exposure was 7906.6 Lux and the location was in Ciborok. Three leaves of three different plants were obtained as the samples. The observed parameter was the width and thickness of the leaves, the density of stomatal, the thickness of palisade, the content of chlorophyll and ascorbic acid. Ascorbic acid test used the method of iodometric titration. The result of the study showed that the average of the leaf thickness, leaf area, stomatal density, palisade thickness, chlorophyll content, and ascorbic acid on sun leaves were 0.25 mm, 46.032 cm 2 , 132.48 cells/mm 2 , 54.89 µm, 10.88 CCI, and 0.0077 mg/g, respectively; while, for shade leaves were 0.23 mm, 57.159 cm 2 , 116.63 cells/mm 2 , 47.66 µm, 32.41 CCI, and 0.0107 mg/g, respectively. In the sun area, it has higher average of leaf thickness, lower level of surface, higher level of stomata density and palisade thickness, and lower average of chlorophyll and ascorbic acid content compared to the one in the shade area. Article DOI: https://dx.doi.org/10.20319/mijst.2018.33.227239 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Zingiber zerumbet flower stem postharvest characterization

About the Zingiber zerumbet little is known about its cut flower postharvest and market, despite its high ornamental potential. The inflorescences, which resemble a compact cone, emerge from the base of the plants and start with green color changing to red with the age. This study objective was to characterize floral stem of ornamental ginger in two cultivate conditions and to evaluate the longevity of those submitted to post-harvest treatments. Flower stems were harvest from clumps cultivated under full sun and partial shade area, and were submitted to the postharvest treatments: complete flower immersion in tap water (CFI) or only the base stem immersion (BSI). The flower stems harvested from clumps at partial shade presented higher fresh weight, length and diameter of the inflorescences compared to flower stems harvested from clumps at full sun area. The flower stem bracts cultivated in full sun area changed the color from green to red 10.69 and 11.94 days after BSI and CFI postharvest treatments, and the vase life were 22.94 and 28.19 days, respectively. Flower stem harvest in partial shade area change the color only after 18.94 and 18.43 days and the vase life durability was 27.56 and 31.81, respectively. The complete immersion of the flower stem increase the vase life durability in 5.25 and 4.25 days compared to flowers kept with the stem base immersed only, in flower stems harvested from clumps cultivated in full sun area and partial shade area, respectively. Flower stems harvested from clumps cultivated in partial shade area and completely immerse in tap water during 3 hours increase the vase life durability in 8.87 days compared to flowers harvested from clumps cultivated in full sun area and base immersed only.

Clinical relevance of pre-ovulatory follicular temperature in heat-stressed lactating dairy cows.

Temperature gradients in female reproductive tissues seem to influence the success of key processes such as ovulation and fertilization. The objective of this study was to investigate whether pre-ovulatory follicles are cooler than neighbouring uterine tissue and deep rectal temperatures in lactating dairy cows under heat stress conditions. Temperatures within the pre-ovulatory follicle, on the uterine adjacent surface and 20cm deep within rectum, were measured using fine thermistor probes within 45min after sunrise (dawn). Cows were selected from synchronized groups for fixed-time insemination during the warm period of the year. Five cows under direct sun radiation and 11 cows in the shade were included in the study. None of the cows in the sun area ovulated within 24hr, whereas 10 of the 11 cows in the sun area ovulated. Four of the 10 ovulating cows became pregnant. In the ovulating cows, follicular temperatures were 0.74 and 1.54°C significantly cooler than uterine surface and rectal temperatures, respectively, whereas temperatures in the uterine area were 0.80°C significantly cooler than rectal temperatures. No significant differences among temperatures were found in non-ovulating cows. Follicular size was similar for ovulating and non-ovulating cows. Environmental temperatures in the shade area were 6.4°C significantly lower than those in the sun area. Results of this study indicate that pre-ovulatory follicles are cooler than neighbouring uterine tissue and deep rectal temperatures and those temperature gradients were not found in cows suffering ovulation failure.

ARE INTERNETWORK MAGNETIC FIELDS IN THE SOLAR PHOTOSPHERE HORIZONTAL OR VERTICAL?

ABSTRACT Using many observations obtained during 2007 with the Spectro-Polarimeter of the Hinode Solar Optical Telescope, we explore the angular distribution of magnetic fields in the quiet internetwork regions of the solar photosphere. Our work follows from the insight of Stenflo, who examined only linear polarization signals in photospheric lines, thereby avoiding complications of the analysis arising from the differing responses to linear and circular polarization. We identify and isolate regions of a strong polarization signal that occupy only a few percent of the observed quiet Sun area yet contribute most to the net linear polarization signal. The center-to-limb variation of the orientation of linear polarization in these strong signal regions indicates that the associated magnetic fields have a dominant vertical orientation. In contrast, the great majority of the solar disk is occupied by much weaker linear polarization signals. The orientation of the linear polarization in these regions demonstrates that the field orientation is dominantly horizontal throughout the photosphere. We also apply our analysis to Stokes profiles synthesized from the numerical MHD simulations of Rempel as viewed at various oblique angles. The analysis of the synthetic data closely follows that of the observations, lending confidence to using the simulations as a guide for understanding the physical origins of the center-to-limb variation of linear polarization in the quiet Sun area.

English

This study evaluated the forage yield and feed chemical composition of a Brachiaria decumbens natural pasture as undergrowth to a Myracrodruon urundeuva (aroeira) tree stand in a silvopasture system at&nbsp; UNESP/Ilha Solteira, Selv&iacute;ria, Mato Grosso do Sul, Brazil. Sampling was conducted in a completely randomized block design with a factorial scheme of two plots and two sub-plots, with plots as the light regimen (full sunlight or shade from aroeira trees, spaced 3 &times; 3 m) and sub-plots as the grazing rotation scheme (pre-grazing and post-grazing). Sampling was performed along the four seasons of a year in four replicates. Canopy height, forage mass, morphological composition, nutritive value, and forage digestibility (whole-plant sample) were evaluated. Forage mass was significantly higher in the full sun area (1,306 kg DM/ha) than in the shaded site (727 kg DM/ha). Forage yield was low during the experimental period (1,529 and 58 kg/ha in the full sun and shaded sites, respectively). The nutritive value of B. decumbens was not significantly different between light regimens. Growing B. decumbens as undergrowth in aroeira stands may be an option in areas where the trees still occur, but other planting densities should be examined. Key words: Forage yield, Myracrodruon urundeuva, rising plate meter, shading, sward height.

PROMOÇÃO DO CRESCIMENTO E ENRAIZAMENTO DE MINIESTACAS DE Eucalyptus dunnii POR RIZOBACTÉRIAS E BACTÉRIAS DO FILOPLANO

O uso de microrganismos com efeito de promotores de crescimento e enraizamento de plantas tem apresentando resultados promissores no desenvolvimento de mudas clonais. Assim, o objetivo do estudo foi avaliar o potencial de isolados de rizobactérias e residentes do filoplano na promoção de crescimento e enraizamento de miniestacas de Eucalyptus dunnii. O experimento foi conduzido no delineamento de blocos casualizados, em arranjo fatorial 4 x 4 x 3, sendo os fatores constituídos por quatro coletas, quatro isolados bacterianos e três métodos de aplicação. Foram avaliados o percentual de sobrevivência das miniestacas na saída da casa de vegetação, casa de sombra e área de pleno sol e, o enraizamento das miniestacas aos 90 dias de idade. A resposta na sobrevivência de mudas na casa de vegetação, sombra e área de pleno sol variaram de acordo com o isolado, forma de aplicação e período de realização da coleta. Não foi observado efeito significativo dos isolados bacterianos sobre o enraizamento das miniestacas. Os isolados bacterianos apresentaram ora efeito benéfico, ora ausência de efeito para a sobrevivência e enraizamento das miniestacas. Por ser o primeiro relato do uso de rizobactérias e residentes de filoplano na promoção de crescimento de E. dunnii há demanda de novos estudos para a confirmação da efetividade destes microrganismos.

Miniestaquia de Eucalyptus benthamii: efeito do genótipo, AIB, zinco, boro e coletas de brotações

Objetivou-se avaliar o enraizamento adventício em miniestacas de Eucalyptus benthamii em relação ao genótipo, concentrações de Zn e B, coleta de brotações e aplicação de AIB. As brotações foram oriundas de minicepas fertirrigadas com soluções nutritivas variando nas concentrações de Zn e B (S1 - isento de Zn e B, S2 - 0,5 mg L-1 de Zn, S3 - 0,5 mg L-1 de B, S4 - 0,5 mg L-1 de Zn e B, S5 - 1,0 mg L-1 de Zn e B, S6 - 2,0 mg L-1 de Zn e B). A região basal da miniestaca foi imersa durante 10 s em solução contendo 2.000 mg L-1 de AIB, sendo uma solução isenta de AIB utilizada como controle. Avaliaram-se a sobrevivência das miniestacas na saída da casa de vegetação, na saída da casa de sombra e em área de pleno sol. Em área de pleno sol foram avaliadas apenas as miniestacas enraizadas, e destas, o comprimento total do sistema radicial. O enraizamento adventício em miniestacas de Eucalyptus benthamii dependeu do material genético, da coleta de brotações, da aplicação de AIB e das concentrações de Zn e B. A porcentagem de enraizamento foi baixa, sendo que os materiais genéticos foram considerados de difícil propagação pela miniestaquia. Em termos gerais, as miniestacas obtidas de minicepas fertirrigadas com as soluções nutritivas S5 (1,0 mg L-1 de Zn e B) e S6 (2,0 mg L-1 de Zn e B) associadas a presença de AIB na concentração de 2.000 mg L-1 apresentaram os maiores índices de enraizamento.

DETECTION OF SMALL-SCALE GRANULAR STRUCTURES IN THE QUIET SUN WITH THE NEW SOLAR TELESCOPE

Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO) and with a broad-band filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0.$"$0375) augmented by the very high image contrast (15.5$\pm$0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties and role of the newly discovered population of mini-granular structures in the solar magneto-convection are yet to be explored.

Investigation of Quasi-periodic Solar Oscillations in Sunspots Based on SOHO/MDI Magnetograms

In this work we study quasi-periodic solar oscillations in sunspots, based on the variation of the amplitude of the magnetic field strength and the variation of the sunspot area. We investigate long-period oscillations between three minutes and ten hours. The magnetic field synoptic maps were obtained from the SOHO/MDI. Wavelet (Morlet), global wavelet spectrum (GWS) and fast Fourier transform (FFT) methods are used in the periodicity analysis at the 95 % significance level. Additionally, the quiet Sun area (QSA) signal and an instrumental effect are discussed. We find several oscillation periods in the sunspots above the 95 % significance level: 3 – 5, 10 – 23, 220 – 240, 340 and 470 minutes, and we also find common oscillation periods (10 – 23 minutes) between the sunspot area variation and that of the magnetic field strength. We discuss possible mechanisms for the obtained results, based on the existing models for sunspot oscillations.

The solar hydrogen Lymanαto Lymanβline ratio

Aims. We investigate the variation in the solar hydrogen Lyman α (Lyα )t o Lymanβ (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE. Methods. We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then re-examine data obtained on the solar disk with SUMER and compare them with previous data. In a second step, we use the full Sun H i Lyβ profiles to determine the Lyβ contribution to the SEE profiles obtained with a 0.4 nm full width at half-maximum. The variation in the Lyα to Lyβ line ratio is then measured for part of the solar cycle 23 (2002–2008). Results. We determine the radiance line ratio of the solar H i Lyα to Lyβ line for a quiet Sun area and the relation between the ratio of the Lyα to Lyβ irradiance and the Lyα solar irradiance.

The statistical study of quasi‐periodic oscillations of the radio emission in solar quiet regions

AbstractIn this study we discuss variations of the radio emission from the Quiet Sun Areas (QSA) at centimeter wavelength (1.76 cm). Data were obtained from Nobeyama Radioheliograph (NoRH). Oscillations of selected areas were studied carefully from data taken over one week. We try to find quasi‐periodic solar oscillations from the QSA. We used the traditional Fast Fourier Transform (FFT), Global Wavelet Spectrum (GWS) and Wavelet (Morlet) for studying signals in the frequency/time‐frequency domain. We used the Fisher randomization test to verify the significance of the observed signal. Instrumental and sky noises were studied using a cross‐correlation analysis. Additionally, a single pixel analysis were done. Wide ranges of solar oscillation periods were found from the Quiet Sun Area (QSA): 3–15, 35–70, and 90 minutes. Some physical explanations are suggested for these oscillations. However, it is not possible to give a conclusive statement about the origin of the long quasi‐periodic (&gt;60 min) oscillations from the QSA (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Strategy for the Inversion of Hinode Spectropolarimetric Measurements in the Quiet +n

Abstract In this paper we propose an inversion strategy for the analysis of spectropolarimetric measurements taken by Hinode in the quiet Sun. The Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records the Stokes spectra of the Fe I line pair at 630.2 nm with unprecendented angular resolution, high spectral resolution, and high sensitivity. We discuss the need to consider a local stray-light contamination to account for the effects of telescope diffraction. The strategy is applied to observations of a wide quiet Sun area at disk center. Using these data we examine the influence of noise and initial guess models in the inversion results. Our analysis yields the distributions of magnetic field strengths and stray-light factors. They show that quiet Sun internetwork regions consist mainly of hG fields with stray-light contamination of about 0.8.

Hinode observations reveal boundary layers of magnetic elements in the solar photosphere

We study the structure of the magnetic elements in network-cell interiors. A quiet Sun area close to the disc centre was observed with the spectro-polarimeter of the Solar Optical Telescope on board the Hinode space mission, which yielded the best spatial resolution ever achieved in polarimetric data of the Fe I 630 nm line pair. For comparison and interpretation, we synthesize a similar data set from a three-dimensional magneto-hydrodynamic simulation. We find several examples of magnetic elements, either roundish (tube) or elongated (sheet), which show a central area of negative Stokes-V area asymmetry framed or surrounded by a peripheral area with larger positive asymmetry. This pattern was predicted some eight years ago on the basis of numerical simulations. Here, we observationally confirm its existence for the first time. We gather convincing evidence that this pattern of Stokes-V area asymmetry is caused by the funnel-shaped boundary of magnetic elements that separates the flux concentration from the weak-field environment. We also conclude that this kind of magnetic element of the internetwork is accompanied by electric current sheets.

Can the solar wind originate from a quiet Sun region?

Context. It is well known that the fast solar wind originates from coronal holes (CHs). However, the question whether it can also originate from quiet Sun regions has not yet been answered. Aims. To study this problem we analyze SOHO data obtained from observations made in a quiet Sun area. The data set includes far-ultraviolet data from SUMER, magnetic field data from MDI, and extreme-ultraviolet data from EIT. Methods. We make a potential-field extrapolation of the coronal magnetic field and calculate the field lines from the photosphere up to 80 Mm height. Those field lines which can be traced from the bottom to the top of the extrapolation box are called (locally) open field lines. By a combined analysis of the coronal magnetic field structures inferred from MDI data, the flows indicated by the Ne viii Doppler shifts in the SUMER data, and the Fe xii radiance images from EIT, it is possible to study this problem in depth. Results. We find that most of the sites with plasma outflow, which can be recognized by the Ne viii blue shift, are not located in regions with an open magnetic field. Most likely, these outflows just correspond to plasma being delivered to magnetic loops. It is further found that, in a cross-section plane located at a height of 25 Mm, the pattern of open field lines intersecting that plane is consistent with the dark pattern of low radiance in the image of the Fe xii 19.5 nm line. Usually, small dark regions are considered to represent small CHs, and thus are assumed to be sources of the solar wind. However, since here the source of the low emission appears to be located at a height of only 25 Mm, it seems more likely that this radiation originates near the foot points of large coronal loops. Conclusions. Previous results obtained at middle latitudes on the quiet Sun indicated that sizable outflow velocities occur at the intersections of the network boundaries. This finding is also confirmed here. However, we could not identify most of these intersections as sources of the solar wind. Only a few small outflow regions might be sources. Yet, one dark area that we found on the EIT map seems to be connected with open field lines, and therefore it could be a source of the solar wind.

Quiet sun magnetic field diagnostics with a Mn line

Context. The Mn line at 553 nm shows strong spectral features in both intensity and polarization profiles due to the hyperfine structure of the atom. These features, their presence or absence, are known to be dependent on the magnetic regime to which the Mn atom is subject. Aims. Our objective is to disentangle strong kilo-Gauss (kG) fields from relatively weak hecto-Gauss (hG) fields in the quiet sun, and compute relative filling factors on the resolution element. Methods. We observed the 553 nm Mn line in a quiet sun area with the Advanced Stokes Polarimeter, and we introduce an in-line ratio between different spectral features. Filling factors can be retrieved from the measurement of this ratio and the total longitudinal flux. Results. In the photospheric network the kG dominate the magnetic flux, although out of the higher concentration areas the hG fields dominate in surface coverage. For the internetwork (granules and lanes confounded) the hG are dominant both in surface and total flux.