The Geminga supernova as a possible cause of the local interstellar bubble

Deciphering the Dipole Anisotropy of Galactic Cosmic Rays

Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120°≲l≲300° dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong ordered magnetic field in our local environment, (iii) the relative motion of the solar system, and (iv) the limited reconstruction capabilities of ground-based observatories. We show that an excellent candidate of the local CR source responsible for the dipole anisotropy at 1-100 TeV is the Vela supernova remnant.

Note: Void effects on eddy current distortion in two-phase liquid metal

A model based on the first order perturbation expansion of magnetic flux in a two-phase liquid metal flow has been developed for low magnetic Reynolds number Rem. This model takes into account the distortion of the induced eddy currents due to the presence of void in the conducting medium. Specific experiments with an eddy current flow meter have been realized for two periodic void distributions. The results have shown, in agreement with the model, that the effects of velocity and void on the emf modulation are decoupled. The magnitude of the void fraction and the void spatial frequency can be determined from the spectral density of the demodulated emf.

Geminga's tails: a pulsar bow shock probing the interstellar medium

We report the X-ray Multimirror Mission-Newton European Photon Imaging Camera observation of two elongated parallel x-ray tails trailing the pulsar Geminga. They are aligned with the object's supersonic motion, extend for approximately 2', and have a nonthermal spectrum produced by electron-synchrotron emission in the bow shock between the pulsar wind and the surrounding medium. Electron lifetime against synchrotron cooling matches the source transit time over the x-ray features' length. Such an x-ray detection of a pulsar bow shock (with no Halpha emission) allows us to gauge the pulsar electron injection energy and the shock magnetic field while constraining the angle of Geminga's motion and the local matter density.

Uranium decay products found on Mir space blanket mitt

The space blanket mitt which covered the Trek detector on Mir during four years of orbital flight has been measured for gamma radiation with HPGe and multidimensional spectrometers. Difference spectra from very-long-period spectrometer runs on the mitt and on a similar non-deployed mitt from the same manufacturer show that the mitt has acquired small but significant amounts of gamma radioactivity during orbital flight. Twelve gamma-ray peaks have been measured in the difference spectra, including peaks identified as due to 214Bi and 214Pb from the uranium-radium alpha decay series, and others possibly due to the uranium-actinium series. This implies the presence of a sparse population of uranium decay products in lower orbital space which can only have come from nuclear explosions, burned-up satellite nuclear batteries, the solar wind, or supernova fragments in the local interstellar medium.