Line-driven disc wind models with an improved line force

We describe an efficient method of calculating the radiation pressure resulting from spectral lines, including all the terms in the velocity gradient tensor. We apply this method to calculate the two-dimensional, time-dependent structure of winds from luminous discs. Qualitative features of our new models are very similar to those we calculated including only the dominant terms in the tensor. In particular, we find that models which displayed unsteady behaviour in our earlier paper are also unsteady with the new method, and gross properties of the winds, such as mass-loss rate and characteristic velocity, are not changed by the more accurate approach. The largest change caused by the new method is in the disc-wind opening angle: winds driven only by the disc radiation are more polar with the new method, whilst winds driven by the disc and central object radiation are typically more equatorial. In the closing discussion, we provide further insight into the way the geometry of the radiation field and consequent flow determine the time properties of the flow.     

Solar Spectral Irradiance Variations in 240 – 1600 nm During the Recent Solar Cycles 21 – 23

Regular solar spectral irradiance (SSI) observations from space that simultaneously cover the UV, visible (vis), and the near-IR (NIR) spectral region began with SCIAMACHY aboard ENVISAT in August 2002. Up to now, these direct observations cover less than a decade. In order for these SSI measurements to be useful in assessing the role of the Sun in climate change, records covering more than an eleven-year solar cycle are required. By using our recently developed empirical SCIA proxy model, we reconstruct daily SSI values over several decades by using solar proxies scaled to short-term SCIAMACHY solar irradiance observations to describe decadal irradiance changes. These calculations are compared to existing solar data: the UV data from SUSIM/UARS, from the DeLand & Cebula satellite composite, and the SIP model (S2K+VUV2002); and UV-vis-IR data from the NRLSSI and SATIRE models, and SIM/SORCE measurements. The mean SSI of the latter models show good agreement (less than 5%) in the vis regions over three decades while larger disagreements (10 – 20%) are found in the UV and IR regions. Between minima and maxima of Solar Cycles 21, 22, and 23, the inferred SSI variability from the SCIA proxy is intermediate between SATIRE and NRLSSI in the UV. While the DeLand & Cebula composite provide the highest variability between solar minimum and maximum, the SIP/Solar2000 and NRLSSI models show minimum variability, which may be due to the use of a single proxy in the modeling of the irradiances. In the vis-IR spectral region, the SCIA proxy model reports lower values in the changes from solar maximum to minimum, which may be attributed to overestimations of the sunspot proxy used in modeling the SCIAMACHY irradiances. The fairly short timeseries of SIM/SORCE shows a steeper decreasing (increasing) trend in the UV (vis) than the other data during the descending phase of Solar Cycle 23. Though considered to be only provisional, the opposite trend seen in the visible SIM data challenges the validity of proxy-based linear extrapolation commonly used in reconstructing past irradiances.     

A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. III. Catastrophe of the Eruptive Filament at a Magnetic Null Point and Formation of an Opposite-Handedness CME

Our analysis in Papers I and II (Grechnev et al., Solar Phys. 289, 289, 2014b and Solar Phys. 289, 1279, 2014c) of the 18 November 2003 solar event responsible for the 20 November geomagnetic superstorm has revealed a complex chain of eruptions. In particular, the eruptive filament encountered a topological discontinuity located near the solar disk center at a height of about 100 Mm, bifurcated, and transformed into a large cloud, which did not leave the Sun. Concurrently, an additional CME presumably erupted close to the bifurcation region. The conjectures about the responsibility of this compact CME for the superstorm and its disconnection from the Sun are confirmed in Paper IV (Grechnev et al., Solar Phys. submitted, 2014a), which concludes about its probable spheromak-like structure. The present article confirms the presence of a magnetic null point near the bifurcation region and addresses the origin of the magnetic helicity of the interplanetary magnetic clouds and their connection to the Sun. We find that the orientation of a magnetic dipole constituted by dimmed regions with the opposite magnetic polarities away from the parent active region corresponded to the direction of the axial field in the magnetic cloud, while the pre-eruptive filament mismatched it. To combine all of the listed findings, we propose an intrinsically three-dimensional scheme, in which a spheromak-like eruption originates via the interaction of the initially unconnected magnetic fluxes of the eruptive filament and pre-existing ones in the corona. Through a chain of magnetic reconnections their positive mutual helicity was transformed into the self-helicity of the spheromak-like magnetic cloud.     

Fluctuations of electron precipitation to the dayside auroral zone modulated by compression and expansion of the magnetosphere

Concurrent variations of CNA fluctuations and geomagnetic fluctuations are classified into Type 1 (substorm-type), Type 2 (Pc5-type), and Type 3 which is the object of the present study. Type 3 apparently has peculiar characteristics in that CNA fluctuations at a certain auroral-zone station show a pronounced positive correlation with magnetic fluctuations at distant low-latitude stations. The magnetic fluctuations of this type are identified to generalized Si which tends to take place much more frequently than the so-called Si. The CNA fluctuations of this type are found to take place on the dayside auroral zone only when preceded by a magnetic substorm on the night side. Considering the change of the growth rate of electron cyclotron instability and enhancement of pitch angle diffusion due to the change of magnetic field intensity, the following model is proposed to explain the occurrence mechanism of Type 3 concurrent variations. The CNA fluctuations take place only when two conditions are satisfied; generation of the accelerated electrons in association with substorm onset and modulation of the precipitation of the electrons by compression and expansion of the magnetosphere, in other words, by generalized Si.     

A method for uncertainty constraint of catchment discharge and phosphorus load estimates

River discharge and nutrient measurements are subject to aleatory and epistemic uncertainties. In this study, we present a novel method for estimating these uncertainties in colocated discharge and phosphorus (P) measurements. The “voting point”‐based method constrains the derived stage‐discharge rating curve both on the fit to available gaugings and to the catchment water balance. This helps reduce the uncertainty beyond the range of available gaugings and during out of bank situations. In the example presented here, for the top 5% of flows, uncertainties are shown to be 139% using a traditional power law fit, compared with 40% when using our updated “voting point” method. Furthermore, the method is extended to in situ and lab analysed nutrient concentration data pairings, with lower uncertainties (81%) shown for high concentrations (top 5%) than when a traditional regression is applied (102%). Overall, for both discharge and nutrient data, the method presented goes some way to accounting for epistemic uncertainties associated with nonstationary physical characteristics of the monitoring site.     

Zum Umweltverhalten von Fluortensiden Teil 1: Prüfung auf Aquatoxizität

Poecilia reticulata PETERS (guppy) and the green alga Monoraphidium griffithii were used for testing of different fluorotensides. After the representation of the methods of investigation and the definition of criteria of toxicity the obtained results of investigation are discussed. In general, the toxicity of the four investigated fluorotensides to algae was lower than to fish. The anionic fluorotenside CF₃—(CF₂)n—CFH—COONa was an exception. In tables and diagrams the results are summarized. Finally, for the condition of the receiving-water biocenosis class “2” the respective still permissible matter concentrations are proposed. They vary between 0.05 and 0.2 mg/1.     

Observations of the infrared FeXIII lines in the solar corona of 12 November, 1966

The purpose of this paper is to report on some intensity measurements of the Fe xiii lines at 10 747 Å and 10 798 Å made during the total eclipse of 12 November, 1966. Infrared spectra were taken of the solar corona at a dispersion of 90 Å per mm, using an RCA image converter and spectrograph aboard the NASA CV 990 aircraft off the coast of southern Brazil. The spectra have been reduced to equivalent width in terms of the coronal continuum and values derived for different points in the corona.The observed equivalent widths of the lines lie in the range 10 to 30 Å for the 10 747 line and 5 to 12 Å for the 10 798 line. The ratio of these equivalent widths is found to vary from 2.3 in the inner corona to 6 at a point 1.36 solar radii from the center of the Sun.The above results are discussed in terms of the excitation mechanisms involved in producing the lines. In particular, the results are compared with the recent theoretical calculations of Chevalier and Lambert, who are the first to include the effects of proton collisions in the excitation of the 3p ^{2 3} P levels of Fexiii. Our observations are consistent with an electron density of 4 × 10⁸ in the inner corona; a value which compares favorably with those derived by other observers from the strength of the K continuum. These are, to our knowledge, the first eclipse observations of the infrared Fe xiii lines which indicate that proton collisions are important in the excitation of the coronal lines. The coronal abundance of iron is estimated from the equivalent width of the 10 747 line, and in common with other observers we find an overabundance as compared to the photospheric abundance by a factor of 10.     

Kinematics in the z = 2.81 Galaxy and the Evidence for Rotation

The existence of rotation signatures in damped Lyαabsorption systems represents a crucial test of the hypothesis that these features arise in disks of normal spiral galaxies. We apply the method for evaluating such signatures to the metal absorption lines in QSO 0528-250. In particular, the systemic redshift of the absorber is inferred from the recent detection of emission in the absorber by Möller and Warren. The kinematics of this absorber are particularly interesting because molecular hydrogen, the densest ISM component of the assumed foreground absorbing galaxy, is detected. Contrary to a recent claim, the method yields a satisfactory value for the assumed rotation velocity of the absorber.     

Two strong radio bursts at high and medium Galactic latitude

The Nasu Observatory, which is composed of eight 20 m elements, was constructed for observing radio transients over a wide field at 1400 MHz. We report on two radio transients detected in consecutive drift scanning observations at declination 32° over a period of about two months. One of the two transients, WJN J1039+3200, appeared at =10^h39^m40^s±10^s, δ=32°±0.4° on March 4, 2005, and the other one, WJN J0645+3200, appeared at =06^h45^m25^s±10^s, δ=32°±0.4° on March 24, 2005. Both exhibited flux densities in excess of 1 Jy, and the burst durations were up to two days. Since there are few examples of radio transients outside the Galactic plane, these are very important observations. We have previously reported on four radio transients with features that look like the two transients detected this time. Of these six WJN transients in total, five had a duration of up to two days, and one up to three days. Four of the transients were detected at high Galactic latitude of b > 30°. Counterparts of the six WJN transients included X-ray sources in four events and had a consistency of 66%. The consistency of γ-ray, PGC Galaxy, NVSS, and FIRST sources was concentrated at about 50%. We were not able to find any special features in the counterparts. The distribution was verified by making a log N–log S plot using data for the four previously detected transients and the new ones. As a result, the distribution of the radio transients that we observed might have an isotropic distribution not dependent on Galactic longitude and Galactic latitude. The detection probability was calculated based on the assumption of an isotropic distribution. The 2σ upper probability limit for detection of transients of 1000 mJy or more is 0.0049 [deg⁻² yr⁻¹]. We cannot yet identify these two radio transients, because their features are different from any radio bursts observed in the past.