Star transparent

Transparent toughened polystyrene polymers are produced by blending polystyrene with SBS block copolymers (see Section 11.8). During the 1970s and 1980s most development was with block copolymers with a radial (or star) shape. Two types were developed block copolymers with a central butadiene block, and block copolymers with a central polystyrene block. 

The darkness associated with dense interstellar clouds is caused by dust particles of size =0.1 microns, which are a common ingredient in interstellar and circum-stellar space, taking up perhaps 1% of the mass of interstellar clouds with a fractional number density of 10-12. These particles both scatter and absorb external visible and ultraviolet radiation from stars, protecting molecules in dense clouds from direct photodissociation via external starlight. They are rather less protective in the infrared, and are quite transparent in the microwave.6 The chemical nature of the dust particles is not easy to ascertain compared with the chemical nature of the interstellar gas broad spectral features in the infrared have been interpreted in terms of core-mantle particles, with the cores consisting of two populations, one of silicates and one of carbonaceous, possibly graphitic material. The mantles, which appear to be restricted to dense clouds, are probably a mixture of ices such as water, carbon monoxide, and methanol.7... 

Fig. 12.11 Transparent star gel monoliths prepared with calcium alkoxide (right) and without calcium (left).

Given that we in principle can never select a sample of local thick disk stars that is guaranteed to not contain any intervening thin disk stars, I would argue that we should keep the selection schemes as simple and as transparent as possible. In this sense the simplest and most robust selection is based on the kinematics of the stars. This is also the least model dependent method. Of course, should positions be available, i.e. height over the galactic plane, these could, and should, be used. 

Seeing is not just a question of adjusting our eyes to the solar spectrum. We live close to a star called the Sun and at night, when it is hidden, we see only stars similar to our daytime star. This does not mean that darkness is absence. The chilled, the scorching and the non-thermal shine invisibly. The eye is in fact doubly solar, for it is made from the same atoms as our star, and it is the persistence and predominance of the Sun s light that have fashioned our sense of sight. The atmosphere is transparent to solar radiation. The maximal sensitivity... 

And although om natural and personal detector, the retina, shows us a tranquil sky, with a light scatter of stars across it, striking only by its steadfast inaction, the new sky revealed by telescopes and satellites sensitive to invisible emissions is one of tempest. It is animated by the birth of clouds, the creative explosion of stars and the transition of the Universe from opacity to transparence. Human perception now contemplates regions once forbidden to it. 

The star in the numerical model has an inside and an outside. The outside is defined as the limit beyond which it becomes transparent. This boundary is called the photosphere, or sphere of light, for it is here that the light that comes to us is finally emitted. It is thus the visible surface of the star, located at a certain distance R from the centre, which defines the radius and hence the size of the star. The photosphere has a certain temperature with which it is a simple matter to associate a colour, since to the first approximation it radiates as a blackbody, or perfect radiator. Indeed, the emissions from such a body depend only on its temperature. The correspondence between temperature and colour is simple. In fact, the relation between temperature and predominant wavelength (which itself codifies colour) is given by Wien s law, viz. 

Each time a proton changes into a neutron in the Sun s core, a neutrino flies out and crosses the whole enormous body of the star as though there were nothing there. The Earth is a transparent ball for solar neutrinos and we are continually visited by these invisible beings. 

The supernova 1987A in the Large Magellanic Cloud has provided a new opportunity to study the evolution of a young neutron star right after its birth. A proto-neutron star first cools down by emitting neutrinos that diffuse out of the interior within a minutes. After the neutron star becomes transparent to neutrinos, the neutron star core with > 1014 g cm-3 cools predominantly by Urea neutrino emission. However, the surface layers remain hot because it takes at least 100 years before the cooling waves from the central core reach the surface layers (Nomoto and Tsuruta 1981, 1986, 1987). 

Consequently, it is unlikely that Ginga would detect the thermal X-ray emission directly from the surface of a neutron star in SN 1987A even if the ejecta should become transparent right now. 

In Glass Architecture Scheerbart wrote of a transparency that would let in the light of the sun, the moon and the stars. It would allow empathy with... 

In interstellar space, matter is distributed very unevenly. As already mentioned in section 14.4, some stars are ejecting their matter in form of nebulas of dust and gas. These nebulas contain various elements (mainly H, C, O, Si and others) at temperatures between about 10 and 10 K. Far away from the stars, the density of interstellar matter is of the order of 0.1 atom per cm, mainly H and C. In some regions, however, matter is condensed in the form of big interstellar clouds, the mass of which may exceed the mass of the sun by a factor of 10 or more. Two types of interstellar clouds are distinguished optically transparent, diffuse clouds containing <10 atoms per cm (mainly H, but also some compoimds such as CO or HCFIO) at temperatures of the order of 100 K, and opaque, dense clouds containing lO to 10 molecules per cm (mainly H2, but also a variety of compounds) at temperatures varying between about 10 and 10 K. Densities and temperatures increase from the outer parts to the core of the clouds. 

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