Hydrogen recombination lines near 327 MHz−II: A Galactic plane survey with a 2°×6′ beam

In a previous paper we presented a low-resolution (2°×2°) survey of radio recombination lines (RRLs) at 327 MHz in the longitude rangel=330° to 0° to 89°. In this paper, we present the results of a higher resolution (2°×6′) survey of RRLs from seven 2°-wide fields and two 6°-wide fields in the same longitude range. Observations were made using the Ooty Radio Telescope (ORT). A total of 252 spectra that were obtained are presented. RRLs were detected in almost all the individual positions within the fields withl<35° and at several individual positions within the fields in the longitude rangel=35° to 85°. Detailed analysis of the data towards the field centered at G45.5+0.0, shows that the line emission consists of discrete zones of ionized gas. The angular extent of these zones are likely to be one degree or more corresponding to a linear size of >110 pc at the kinematic distance.     

Strongly-cooled ionizing plasma flows with application to venus

On the solar wind's penetration into an atmosphere of hydrogen or helium, symmetric charge exchange interactions give energy and momentum losses as the dominant source terms in the flow equations. One-dimensional, supersonic to subsonic solutions are available if the cooling is strong enough. In a model with transverse field and adiabatic (non-thermal) ions, a range of weakly-shocked solutions with upstream mach number less than 2.5 are discovered. As in the case of detonation waves, the shock strength is independent of downstream boundary conditions. The solutions may apply in the solar wind flow into the Venusian atmosphere.     

Observations of GRS 1915+105 from the USA Experiment on ARGOS

We present first results from a monitoring campaign of GRS 1915+105 undertaken with the USA X-ray timing experiment on the ARGOS satellite. A variety of behaviour has been observed, ranging from low, steady X-ray emission to rapid quasi-periodic flaring on timescales of approximately 10–120 seconds.     

Barbados

In the words of the noted Antillean geologist C.T. Trechmann (1937 , p.337), 'Barbados, 21 miles long, 14 miles wide, rising to 1101 feet, is probably the most considerable Pleistocene non-volcanic bleb on the face of our planet, at least in the Antillean region.' The island's geology shows a stark contrast between the allochthonous siliciclastic succession of an accretionary prism, deposited in water depths measurable in kilometres, and the autochthonous Pleistocene raised reef cap exposed over 90 per cent of Barbados.     

Observations of High Resolution Spectra of Comet Hale-Bopp (C/1995 O1) at the SAO of the RAS

We present the results of the preliminary study of the comet Hale-Bopp spectrum obtained April 17, 1997 by K. Churyumov and F. Mussayev with the help of the 1-meter Zeiss reflector and the echelle spectrometer (spectral resolutionλ/Δ λ ≈ 50000), CCD and the long slit, oriented along the radius-vector(“Sun-comet direction”). Energy distributions for three selected regions including the C₃, C₂ (0-0) and CN(Δ ν = 0) molecules emissions of the comet Hale-Bopp spectrum were built. The rotational lines of the CN(Δ ν = 0) band were identified. The nature of the high emission peak near λ 4020 Å in the C₃ band is discussed. The presence of the cometary continuum of the nonsolar origin is assumed.     

RADIO MAPS OF THE SOLAR WIND TRANSITION REGION

Occultation studies of near-Sun plasmas using several natural sources simultaneously result in large-scale patterns, radio maps of the solar wind flow. Large radio telescopes of the P.N. Lebedev Physical Institute, Pushino, were used. Previously it had been shown that the plasma acceleration and traverse of the sound barrier proceed in an extended region, the transition region of the solar wind, located at radial distances of about 10–40 solar radii from the Sun. The 1989–1994 experiments showed that the evolution of the transition region geometry is very close to that of the optical corona. On the other hand, the plasma flow structures characteristic of the transition region persist in the course of the 11-year cycle, which demonstrates the existence of some specific mechanism of the solar wind acceleration, independent of wide variations of the general solar activity state. These experimental facts are discussed in connection with the existing theoretical approaches.     

UV Photopolarimetric Imaging of C/1995 O1 (Hale-Bopp) with the Wide Field Imaging Survey Polarimeter (WISP)

We report on the reduction and analysis of UVpolarimetric images of CI (λ1657 Å) and dust continuum (2696 Å emissions from C/1995 O1 (Hale-Bopp) taken using the Wide Field Imaging Survey Polarimeter (WISP) sounding rocket on 8 April, 1997. These observations represent the first imaging polarimetry of comets in the UV, and were performed in consort with ground based measurements of gas and dust polarization and distribution. The continuum results show 9% polarization across the image field with a polarization phase angle close to the 129° prediction. Comparison with ground based data implies minimal color dependence for Hale-Bopp in either the degree of polarization and in the position angle. The carbon polarimetry implies that most production occurs in the dense inner coma, and that it leaves that area in thermodynamic equilibrium. Its radial profile further constrains the carbon outflow speed to be sufficient to travel ≥5 × 10⁶ km without photoionization.     

ISO Observations of Symbiotic Stars

A number of symbiotic stars have been observed with ISO. In addition to a number of emission lines, SWS observations of the symbiotic novae RR Tel and V1016 Cyg reveal prominent, broad 10 & 18 μm silicate dust features. The 10 μm features are similar to the crystalline silicate profiles seen in classical novae. There is some evidence that the silicate brightness in V1016 Cyg varies with Mira-component phase. However, the silicate feature in RR Tel also showed some variation even though observations were made at very similar Mira-component phases. PHT observations of S-type symbiotic stars show the IR emission to be dominated by the red-giant component. However, an excess in the PHT-P filters from 10 to 15 μm is evident in all the stars, and there may be a broad 3.2 μm absorption feature or a broad 3.8 μm emission feature. At this time we have no adequate physical explanations for any of these features. This revised version was published online in August 2006 with corrections to the Cover Date.     

Neutrino reactions in strong magnetic field

We present the energy losses due to several neutrinos processes: (1) synchrotron neutrinos, (2) pair annihilation neutrinos, (3) plasmon neutrinos, and (4) photoneutrinos in the presence of a superstrong magnetic field. Numerical results are tabulated and illustrated for several values of densities and temperatures. In the low density regime (10⁷ g cm^–3) the presence of a magnetic field decreases the luminosity, whereas the opposite is true at higher densities. This last effect is however almost entirely due to the existence of a new process the synchrotron neutrinos that disappear whenH0. Even though the overall effect can only be quantitatively ascertain after a complete cooling computation is performed, one should however expect a much lower temperature for neutron star surface than the one computed in theH=0 case.