A Radio Pinwheel Emanating from WR 147

Pinwheel Nebula around WR 98a.

We present the first near-infrared images of the dusty Wolf-Rayet star WR 98a. Aperture-masking interferometry has been utilized to recover images at the diffraction limit of the Keck I telescope, less, similar50 mas at 2.2 µm. Multiepoch observations spanning about 1 yr have resolved the dust shell into a "pinwheel" nebula, the second example of a new class of dust shell first discovered aroun...

Radio Properties of Pinwheel Nebulae

A small number of dusty Wolf-Rayet stars have been resolved into pinwheel nebulae, defined by their “rotating” spiral dust shells observed in the infrared. This morphology is naturally explained by dust formation associated with colliding winds in a binary system. In order to confirm and further explore this hypothesis, we have observed the known pinwheel nebulae (WR 104 and WR 98a) as well as ...

Colliding Stellar Wind Models with Nonequilibrium Ionization: X-rays from WR 147

The effects of nonequilibrium ionization are explicitly taken into account in a numerical model which describes colliding stellar winds (CSW) in massive binary sytems. This new model is used to analyze the most recent X-ray spectra of the WR+OB binary system WR 147 . The basic result is that it can adequately reproduce the observed X-ray emission (spectral shape, observed flux) but some adjustm...

DIGITAL RADIO -- The Eureka 147 DAB System

Flexibility and choice -The DAB signal is essentially a highly flexible over-air 'data-pipe' that can broadcast a wide range of service types, from purely audio-based to multimedia. Typically, each multiplex can broadcast five or more high-quality audio services plus a number of extra services. The multiplex can be dynamically reconfigured to introduce additional services, temporary or permanen...

DAB Eureka-147: a European vision for digital radio