What will the first year of SNO show?

The ratio of the measured to the predicted standard model CC event rates in SNO will be 0.47 if no oscillations occur. The best-fit active oscillation predictions for the CC ratio are: 0.35-39 (MSW) and 0.38-42 (vacuum) (all for a 5 MeV energy threshold), typically about 20% less than the no-oscillation expectation. We calculate the predicted ratios for six active and sterile neutrino oscillation solutions allowed at 99% CL and determine the dependence of the ratios on energy threshold. If the high-energy anomaly observed by SuperKamiokande is due to an enhanced hep flux, MSW active solutions predict that out of a total of 5000 CC events above 5 MeV in SNO between 49 and 54 events will be observed above 13 MeV whereas only 19 events are expected for no-oscillations and a nominal standard hep flux.Comment: Phys Lett accepted. Editorial corrections. Related material and viewgraphs at http://www.sns.ias.edu/~jn

Why Do Solar Neutrino Experiments Below 1 Mev

I discuss why we need solar neutrino experiments below 1 MeV. I also express my prejudices about the desired number and types of such experiments, emphasizing the importance of p-p solar neutrino experimentsComment: To be published in the proceedings of the Second International Workshop on Low Energy Solar Neutrinos, University of Tokyo, Tokyo, Japan, December 4 and 5, 2000 (World Scientific

Neutrino Opacity I. Neutrino-Lepton Scattering

The contribution of neutrino-lepton scattering to the total neutrino opacity of matter is investigated; it is found that, contrary to previous beliefs, neutrino scattering dominates the neutrino opacity for many astrophysically important conditions. The rates for neutrino-electron scattering and antineutrino-electron scattering are given for a variety of conditions, including both degenerate and nondegenerate gases; the rates for some related reactions are also presented. Formulas are given for the mean scattering angle and the mean energy loss in neutrino and antineutrino scattering. Applications are made to the following problems: (a) the detection of solar neutrinos; (b) the escape of neutrinos from stars; (c) neutrino scattering in cosmology; and (d) energy deposition in supernova explosions

Recent Work on Standard Solar Models

Recent results on standard solar models are reviewed. I shall summarize briefly three of the themes that I stressed at the Neutrino '92 Conference: 1) Different solar model codes give the same answers when the same input data are used; 2) Improved calculations of standard solar models include helium diffusion, the Livermore radiative opacity, the meteoritic iron abundance, and a variety of other corrections; and 3) There are a few basic rules that should be followed in using standard solar models. At the Neutrino '92 Conference, I reviewed in more detail the recent work on standard solar models by Marc Pinsonneault and myself. This work has by now appeared in print (Rev. Mod. Phys. 64, 885, 1992, hereafter Paper I, and ApJ Letters, 69, 717, 1992, Paper II). Therefore, there is no need for me to repeat the details here.Comment: 4 pages, Institute for Advanced Study number AST 92/5

Research in extragalactic astrophysics

The spatial distribution of clusters of galaxies and the large scale structure of the universe is investigated. Correlations in the spatial cluster distribution are much stronger than those seen for galaxies, and over scales much larger than previously anticipated. The following main studies are completed and published; (1) The determination of the correlation functions of rich clusters of galaxies, and its dependence on richness and other parameters. Very large scale structure exists in the universe, and rich clusters participate in this structure more efficiently than galaxies. (2) A complete catalog of superclusters, is determined. The selection criteria is that of a volume density enhancement, and is done in 3 dimensions. (3) The giant galaxy void in Bootes is found to be surrouned by rich, large superclusters from the catalog described above. (4) A very large scale void of rich clusters of galaxies is found in the study of the spatial distribution of rich clusters

V-V compact group of galaxies

A search for X-ray emission from five compact groups of galaxies with the Einstein Observatory revealed detections from three groups. Soft, extended X-ray emission was observed in Stephan's Quintet which is most likely caused by hot intracluster gas. This provides evidence for dynamical interaction among the group galaxies. X-ray emission from the group Arp 330 may also originate in hot intracluster gas. Stephan's Quintet and Arp 330 have the largest velocity dispersions among the groups studied suggesting a correlation between high velocity and the release (or properties) of hot gas. X-ray emission from Arp 318 may originate in its member galaxies

Present Status of the Theoretical Predictions for the ^(37)Cl Solar-Neutrino Experiment

The theoretical predictions for the ^(37)Cl solar-neutrino experiment are summarized and compared with the experimental results of Davis, Harmer, and Hoffman. Three important conclusions about the sun are shown to follow

Non-resonant nuclear reactions at stellar temperatures

Procedure for calculating rates of non-resonant nuclear reactions at stellar temperature