Massive early-type emission-line stars: an attempt to distinguish a new group of stellar objects

A new sample of possibly massive early-type emission-line stars (METELS) based on the previous lists of peculiar Be stars is presented. It consists of 36 objects divided amongst supergiants, possible binaries, and candidates to the list. The central stars are probably more massive than 10M . Two new relations allowing idientification of possible binaries among the objects are proposed.     

The intermetallic compound Ni<Subscript>3</Subscript>Au and gold-nickel solid solutions in metalliferous sediments of the triassic chert formation in Sikhote-Alin in the Far East

The intermetallic compound Ni₃Au and Au-Ni solid solutions (native nickel Au and Au-bearing native Ni) were found in the contact metamorphosed metalliferous sediments of the Triassic chert formation in Sikhote-Alin. The metalliferous rocks are characterized by high contents of Au, Ag, and PGE, as well as the presence of diverse minerals of precious metals. Nickel gold (Au0._91-0.88 Ni_0.09-0.12) is found as grains and crystals (3 to 4 im in size) in Au-bearing cherts with hematite, which are conventionally defined as “itabir-ites” and in the altered siliceous rocks of the Dal’nerechensky district (the upper reaches of the Gornya River). The nickel gold is associated with copper Au, pure native Au (Au_1.00), and Au-Ag and Au-Ag-Pb solid solutions (Au_0.86/_0.84Ag_0.14__0.16 and Au_0.78Ag_0.19Pb_0.03, respectively). The Au-bearing Ni is found in the metamorphosed carbonaceous mudstones and Au-bearing “itabirites” of the Shirokopadninsky area (Olgin-sky district). The Au content varies from 6.09 wt % (Ni_0.98Au_0.02) to 11.30 wt % (Ni_0.96Au_0.04) in some Au-bearing Ni grains (about 10—15 im in diameter) taken from the metamorphosed mudstones. The grains of Au-bearing Ni (Co_0.001__0.00Au_00.2 - _0.17 Ni _0.98__0.83) in the “itabirites” are also characterized by their heterogeneous composition and the fine impregnation of the Ni₃ Au intermetallic compound (Ni_2.99Au_1.01 based on the microprobe analysis).     

Size Distrtibutions of the >10 MeV Solar Proton Events

As has been recognized recently, data on size (frequency) distributions for different sets of solar flare parameters are very helpful in modeling flare and acceleration processes. Relying upon a new arising paradigm of particle acceleration at different sources at/near the Sun (flares, shock waves, etc.), in this paper, we analyze long-term data (1955–1996) from several Catalogues of Solar Proton Events (SPEs). Above 1 p.f.u. (proton cm^–2 s^–1 sr^–1) of the >10 MeV protons, we have separated in all 320 events associated with identified sources (flares). Then, within this database of flare-related events, a second group (a subgroup) has been formed of the 159 events, additionally having a certain or probable sudden storm commencement (SSC) association (SSC-related events). The basic result is that the power-law slope of size distribution for the 320 flare-related events at integral energy intensities is about 1.37 ± 0.05 over the entire range of the proton intensities, from 1.0 to 10⁵ p.f.u. This slope is in general agreement with earlier analyses of integral energy distributions, but steeper than that for differential energy distributions. A second result is that the SSC-associated events have a double power-law distribution with two different exponents, near 1.00 ± 0.04 and 1.53 ± 0.03 below and above 10³ p.f.u., respectively. The longitude distributions of the proper sources for these two groups display different behaviour suggesting different origins of the two particle populations. A certain difference was also found to exist in the slopes of integral size distributions at >10 MeV and >500 MeV. This may point to a dependence of slope on the proton energy under consideration.     

Manifestation of the 399-day variations in solar wind parameters

Astronomy Letters - Based on a large series (N = 14 038) of daily solar wind densities, we obtained the fluctuation power spectrum. The spectrum shows that the 399-day variation (the synodic period...     

Skin-layer of the eruptive magnetic flux rope in large solar flares

The analysis of observations of large solar flares made it possible to propose a hypothesis on existence of a skin-layer in magnetic flux ropes of coronal mass ejections. On the assumption that the Bohm coefficient determines the diffusion of magnetic field, an estimate of the skin-layer thickness of ~10⁶ cm is obtained. According to the hypothesis, the electric field of ~0.01–0.1 V/cm, having the nonzero component along the magnetic field of flux rope, arises for ~5 min in the surface layer of the eruptive flux rope during its ejection into the upper corona. The particle acceleration by the electric field to the energies of ~100 MeV/nucleon in the skin-layer of the flux rope leads to their precipitation along field lines to footpoints of the flux rope. The skin-layer presence induces helical or oval chromospheric emission at the ends of flare ribbons. The emission may be accompanied by hard X-ray radiation and by the production of gamma-ray line at the energy of 2.223 MeV (neutron capture line in the photosphere). The magnetic reconnection in the corona leads to a shift of the skin-layer of flux rope across the magnetic field. The area of precipitation of accelerated particles at the flux-rope footpoints expands in this case from the inside outward. This effect is traced in the chromosphere and in the transient region as the expanding helical emission structures. If the emission extends to the spot, a certain fraction of accelerated particles may be reflected from the magnetic barrier (in the magnetic field of the spot). In the case of exit into the interplanetary space, these particles may be recorded in the Earth’s orbit as solar proton events.