whittet d. dust in the galactic environment

[...]... and references therein.) the intense central ridge because it is dominated by material somewhat closer to the Sun than the other tracers) However, the overall general similarity is striking 10 Dust in the Galaxy: Our view from within 1.3.2 The galactic disc Although it is often convenient to visualize the macroscopic distribution of interstellar matter in the disc of the Galaxy as a continuous layer... uniformity then allow visual extinctions to be calculated The extinction toward the infrared cluster at the galactic centre is estimated to be A V ∼ 30 mag over the ∼8 kpc path (Roche 1988), a result that implies an increase in the rate of extinction per unit distance, compared with the solar neighbourhood, as we approach the nucleus The concentration of dust in the galactic disc seriously hinders investigation... only one photon in every 1012 reaches our telescopes The energy absorbed by the grains is re-emitted in the infrared, accounting for some 20% of the total bolometric luminosity of the Galaxy The in uence of interstellar dust may be discerned with the unaided eye on a dark, moonless night at a time of year when the Milky Way is well placed for observation In the Northern hemisphere, the background light... emission from the interaction of atomic nuclei with cosmic rays) and another tracer of the dust (far infrared continuum emission; see section 1.3.4) Some differences occur (e.g the γ -ray map includes bright point sources identified with supernova remnants; and the extinction map lacks The distribution of dust and gas 9 Figure 1.3 Maps comparing the distributions of dust and gas in the Milky Way The galactic. .. determining the intrinsic properties of external galaxies Corrections for the dimming of primary distance indicators (such as Cepheids, novae and supernovae) in external systems by dust in our Galaxy in uence the extragalactic distance scale The reddening of high-latitude stars (|b| > 20◦ ) is almost independent of distance beyond a few hundred parsecs, because of the general sparsity of dust in the. .. particular reference to the interaction of the solid particles with their environment The discussion is focused on interstellar dust in the solar neighbourhood of our own Galaxy, the Milky Way: our Galaxy is both the environment of planetary systems and the most accessible example of the building blocks of the Universe If we can better understand the nature and evolution of dust in our local Galaxy, this... undergraduate and beginning postgraduate students studying the interstellar medium My aim throughout is to create a compact, coherent text that will stimulate the reader to investigate the subject further Our concept of interstellar space has changed over the years, from a passive, static ‘medium’ to an active environment For this reason, the underlying theme of the book is the significance of dust in interstellar... interstellar extinction hypothesis is correct came some years later as the result of two distinct lines of investigation by the Lick Observatory astronomer R J Trumpler (1930a, b, c) If dust is present in the interstellar medium, its obscuring effect will clearly in uence stellar distance determinations, introducing another degree of freedom in addition to apparent brightness and intrinsic luminosity Trumpler... analogous process is occurring in the interstellar medium (section 4.5) 8 Dust in the Galaxy: Our view from within 1.3 The distribution of dust and gas 1.3.1 Overview Studies of other galaxies give us a qualitative picture of the large-scale distribution of dust in typical spirals like the Milky Way: dust is most evident in galactic discs, producing conspicuous equatorial dark lanes in edge-on spirals such... another and all other solids, maintain them in ultra-high vacuum at low temperature and study photon interactions with the particles at remote wavelengths ranging from the far infrared to the extreme ultraviolet This is the opportunity we have in the case of interstellar dust. ” Acknowledgments are due, first and foremost, to my family: my parents for nurturing my educational development and encouraging . all their hard work and dedication to the task of understanding dust in the galactic environment; and to the National Aeronautics and Space Administration (NASA) for financial support of our endeavours galaxies. Many important new discoveries have been made in the field of cosmic dust since the first edition of Dust in the Galactic Environment was completed in mid- 1991. The Astrophysical Journal. the interstellar medium, its obscuring effect will clearly in uence stellar distance determinations, introducing another degree of freedom in addition to apparent brightness and intrinsic luminosity.