On the relationships between sfe (crochet) and solar X-ray and microwave bursts

Geomagnetic crochets (sfe) observed at Kodaikanal over the period 1966–71 have been studied in relation to solar X-ray bursts observed by NRL satellite (SOLRAD-9) in the 0.5–3 Å, 1–8 Å and 8–20 Å bands and radio bursts observed in the frequency range 1000–17000 MHz. The amplitude of sfe is linearly correlated with the peak intensities of X-ray bursts in the 1–8 Å and 8–20 Å bands. The single frequency correlation of sfe with radio bursts is a flat maximum in the frequency range 2000–3750 MHz. Following the spectral classification of AFCRL for microwave bursts, it is noticed that sfe are mostly associated with the A type burst spectra and are very poorly correlated with bursts with the G, C and M type spectra. These features differ from those of other SID's reported earlier.     

On the relation between filaments (prominences) and Hα loops

The relation between occurrence of H loops and filaments is discussed on the occasion of the observation of a new type of transient loops during a flare associated filament activation. Considering all known types of loop systems crossing neutral lines it is concluded that concurrent existence of stable filaments and H loops is incompatible.Mitt. aus dem Fraunhofer Institut No. 112.     

Profiles of the H and K lines of CaII in disk flares

The profiles of the resonance lines of Caii have been studied in two large disk flares and in the surrounding plage. In the brightest portions of the flares no self-reversal in the central emission core was detected; self-reversed cores were present in the less bright portions of the flares. We find that as the intensity of the emission core increases the separation of the H₂ and K₂ peaks decreases monotonically, becoming unobservable at intensities near to 0.90 the local continuum. Possible reasons for the behavior of the H and K lines in flares are considered. It is suggested that the largest density enhancements in flares are found near the strongest magnetic field.     

On the relationships between impact crater diameters and projectile kinetic energy

By reforming a series of expressions derived by Öpik (1969), we have shown explicitly the dependence of impact crater diameter on projectile kinetic energy. Comparisons between this reformed version of Öpik's theory and the models of Gault (1973) and Oberbeck and Aoyagi (1972) have demonstrated good agreement between experiment and theory over seventeen orders of magnitude of projectile kinetic energy.     

On the line intensity ratios E(Hα)/E(D3) and E(Hβ)/E(D3) in prominences

The intensity ratios E(H)/E(D3) and E(H)/E(D3) in prominences depend on the total optical thickness in H of the layer. The emission of the He D3 line appears relatively enhanced in thin layers and in outer parts of the prominences.     

On the nature of the unique eclipsing system H 187 (HMW 15)

We present our photometric observations of the T Tauri star H 187. They confirm our conclusion that a new extended eclipse has begun in this young object. By the end of 2005, H 187 reached its minimum light following which its brightness began to slowly increase. Comparison with the previous ～3.5-yr-long eclipse observed by Cohen et al. shows that the new eclipse follows the previous eclipse fairly closely and, hence, it was caused by a second passage of the same extended dust or gas-dust cloud around the object. We have estimated the period between these events to be 4.7 yr. The object reddened during the eclipse, suggesting that the extinction was produced by small grains ～0.1μm in size. Possible mechanisms of such unusual eclipses are discussed. We draw an analogy between these eclipses and the cycles of photometric activity observed in UX Ori stars. Light curves similar to those observed for H 187 are shown to be obtained in the model of a young binary system with a low-mass companion accreting matter from the remnants of a protostellar cloud at a rate of ～10^?9 M _⊙ yr^?1.     

Profiles of Hi (La), Mgii (h and k), Caii (H and K) Lines of an active filament at the limb,with the LPSP instrument aboard the OSO-8 Satellite

We scanned the H i L, Mg ii h and k, Ca ii K and H lines simultaneously with the LPSP instrument on OSO-8, to investigate the low and moderate temperature regions of an active region filament. The L line is not reversed except for the innermost position in the prominence. Intensity (k/h), (K/H) ratios are respectively 2 and 1.1, indicating that the Mg ii lines are optically thin, and that Ca ii K is saturated, although not clearly reversed. The results obtained during the second sequence of observations (K saturated before L for example) indicate that within the size of the slit (1 × 10) we are not observing the same emitting features in the different lines.We also observe an important line-of-sight velocity at the outer edge of the feature, increasing outwards from a few km s^–1 to 20 km s^–1 within 2. Less than half an hour later, this velocity is reduced to 15 km s^–1 while the intensities increase. Full width at half maximum intensities for this component indicate turbulence variations from 22 to 30 km s^–1. The observed high velocities at the top of the prominence can be compared with radial velocities that Mein (1977) observed in H at the edges of an active filament and interpreted as velocity loops slightly inclined on the axis of the filament.     

On nova Scorpii 2007 N.1 (V1280 Sco)

We present the results of our photometric and spectroscopic observations of Nova Sco 2007 N.1 (V1280 Sco). The photometric data was represented by a single data point in the light curve since the observation was carried out only for one night. The spectra cover two different phases of the object’s evolution during the outburst, i.e. pre-maximum and post-maximum. Measurements of the P-Cygni profile on Na I ‘D’ line (5889 Å) was derived as the velocity of shell expansion, yielding 1567.43±174.14 km s^?1. We conclude that V1280 Sco is a fast Fe II-type nova.     

On the relation between the Sun's (geocentric) angular diameter and the observed (topocentric) ‘drift time’

It is pointed out that the relation between the Sun's geocentric diameter and the so-called drift time observed on the Earth's surface does not depend on topocentric data (distance, declination, parallax, refraction), but only on the geocentric values of distance, declination, and variation of right ascension.     

Partition Functions of the Light Elements (H to Na), A Revision

As the extensive calculations of atomic partition functions (APFs) made by Traving, Baschek and Holweger, Irwin, and Sauval and Tatum, have been widely used in the literature, the aim of this paper is to analyze whether the numerical values derived from their approximations are homogeneous and accurate, and which are their limitations. Irwin, and Sauval and Tatum, made their calculations for a lowering of the ionization energy Δχ =0.1 eV, and within a limited range of temperature; we found here, that in the solar atmosphere 0.005 ≤ Δχ ≤ 0.154 eV for a neutral atom (0.008 ≤ Δχ ≤ 0.245 eV for a singly ionized atom), whereas in a B-star atmosphere Δχ may become as large as 0.416 eV. Therefore, it is quite clear that the selection of a unique value for Δχ, may result in a poor determination of the APF-value. The representation of APFs made by Traving et al. has no limitation on temperature range, it gives the correct result for Δχ ≤ Δχlimit (Δχlimit being a function of the element and its ionization stage) and has the advantage of being computed in single numerical precision. One limitation it has is practical: if used in the analysis of the excitation and ionization equilibrium of a medium with many elements present, the full calculations require excessive computer time; other shortcomings were also found for the Traving et al. formulae, e.g., owing to overestimation of the ionization energy for Li I, Be II, B III, etc., too many terms are added up in the APF computation, and the value so obtained is larger than the right one if Δχ ≤ 0.01 eV. In a broad sense, it is shown that the representations of APFs made by Traving et al., Irwin, and Sauval and Tatum, are quite homogeneous and accurate; some exceptions are analyzed. This revised version was published online in July 2006 with corrections to the Cover Date.     

THE CHEMICAL COMPOSITIONS OF THE STONE METEORITES YAMATO (a), (b), (c) and (d), AND NUMAKAÍ

The stone meteorites Yamato (a), (b), (c) and (d) were found in Antarctica in 1969, and the chondrite Numakai was seen to fall in Hokkaido, Japan, in 1925. The chemical compositions of these meteorites have been determined by classical and instrumental methods. With the help of the stepwise fractional dissolution method the chemical composition confirmed the author's previous classification of Yamato (a), (b), (c) and (d) as enstatite chondrite, Ca-poor achondrite, type III carbonaceous chondrite and H-group chondrite, respectively. Numakai is classified as an H-group olivine-bronzite chondrite. The distribution of the major elements in each phase of these chondrites is discussed.     

PETROLOGY OF THE YAMATO METEORITES (j), (k), (l), AND (m) FROM ANTARCTICA*

The Yamato (j), (k), (l), and (m) meteorites collected from near the Yamato Mountains in December, 1973, are respectively an H-4 and L-5 chondrite, a howardite, and an L-5 chondrite. Yamato (l), the howardite, is a polymict breccia of diogenite and eucrite clasts. Olivine in the chondrites ranges in composition from Fo₇₅ to Fo₈₀, whereas in the howardite, where it is rare, the composition is about Fo₆₀. Pyroxenes in the chondrites are mostly orthopyroxenes and (En₈₃), while the pyroxenes in the howardite are more complex, comprising orthopyroxene, pigeonite, augite, and rare clinohypersthene (in the order of decreasing abundance), with the range from En₈₀ to En₃₇. They form a definite trend, probably formed by the fractional crystallization of the parental magma of the achondrite, and later subjected to exsolution phenomena during the slow cooling. Plagioclase is high-temperature oligoclase in the chondrites, and anorthite in the howardite. Maskelynitization is sometimes observed. Other shock effects are also observed. Opaque phases consist mostly of nickel-iron, troilite, chromite, and rarely ilmenite. Intergrowth of these minerals are common. The accessory minerals comprise quartz, cristobalite, apatite, spinel, and rare uranium-bearing minerals. The bulk composition and genetic significance are discussed.     

Morphological relationships in the chromospheric Hα fine structure

A continuous relationship is proposed between the basic elements of the dark fine structure of the quiet and active chromosphere. A progression from chromospheric bushes to fibrils, then to chromospheric threads and active region filaments, and finally to diffuse quiescent filaments, is described. It is shown that the horizontal component of the field on opposite sides of an active region quiescent filament can be in the same direction and closely parallel to the filament axis. Consequently, it is unnecessary to postulate twisted or otherwise complex field configurations to reconcile the support mechanism of filaments with the observed motion along their axis.     

Nierite (Si3N4), a new mineral from ordinary and enstatite chondrites

Abstract— Nierite (Si₃N₄) is a new mineral that has been found in perchloric acid-resistant residues of three ordinary chondrites (Adrar 003 [LL3.2], Inman [L3.4] and Tieschitz [H3.6]) and one enstatite chondrite (Indarch [EH4]). This mineral occurs as very small (～2 × 0.4 μm) lath-shaped grains, which have been characterised by transmission electron microscopy. The d-spacings of nierite are, within errors, comparable to those of synthetic α-Si₃N₄, which has trigonal symmetry (P31c, a = 0.7758 nm, c = 0.5623 nm, V = 0.2931 nm³ Z = 4). Energy-dispersive x-ray analyses confirm that nierite is a Si- and N-rich mineral. A few nierite crystals in the Indarch, Inman and Tieschitz residues are intergrown with whiskers of another nitride. Only two crystals of this additional nitride were found that were of sufficient size to give electron diffraction patterns uncontaminated by nierite reflections. The d-spacings of this second nitride are comparable to those of β-Si₃N₄, the hexagonal polymorph of synthetic Si₃N₄. The majority of nierite crystals in Indarch are interpreted to have formed by exsolution of Si and N from kamacite, perryite and schreibersite during parent-body metamorphism. Some grains have evidence for two discrete episodes of nierite crystallization. The origin of nierite in Adrar 003, Inman and Tieschitz is not known, but formation during exsolution is again possible. The petrographic relationships between nierite and β-Si₃N₄ in Indarch, Inman and Tieschitz suggests that the β-Si₃N₄ whiskers predated nierite and acted as a seed on which nierite crystals later nucleated. The nierite/β-Si₃N₄ ratio in ordinary chondrites is controlled by their metamorphic grade and possibly also their oxidation state.