... The first task assumes the searching for chemical composition and sizes of particles which give the wavelength dependence of the extinction efficiencies close to the observed dependence of . Figure 7: Wavelength dependence of the extinction efficiency factors for homogeneous spherical particles of different sizes consisting of astronomical silicate and amorphous carbon. The dashed segment shows the approximate wavelength dependence of the mean galactic extinction curve at optical wavelengths. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Australia Telescope User Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . Australia Telescope Compact Array . Mopra radio telescope . ... Australia Telescope Online Archive (ATOA) . ... ATCA | ... Australia Telescope 20GHz Survey . ... Visiting Parkes radio telescope . Visiting Australia Telescope Compact Array . ... Parkes radio telescope webcam . ...

There is often dust associated with ionized regions. Compact HII regions usually have associated dust from a molecular cloud in which the massive star is being "born". ... For such stars the dust is not produced by the star, and a variety of dust features are observed. The planetary nebulae also usually have associated dust from the previous stage of evolution where they were either carbon stars or M-type giants. ... The feature near 11.5 microns in the IC 418 spectrum may be due to SiC dust. ...

... Does the time it takes different methods to create all the elements coincide with the universeт??s accepted age? ... Illinois Urbana-Champaign) Different kinds of stars create elements at different rates, all of which are consistent with the age of the universe. Get instant access to subscriber content on Astronomy.com! ... Registration is FREE and takes only a few seconds to complete. If you are already registered on Astronomy.com, please log in below. ...

Next: Radial velocity of the Up: Optical spectrum of IRAS04296 Previous: Observations and spectra reduction . ... However, molecular emission features are only very rarely observed in the optical spectra of PPNe. ... On the other hand, it is well known that cometary nuclei spectra show prominent Swan band emission. In both spectra of IRAS04296 we have discovered strong emission in the (0;0) and (0;1) bands of the Swan system of the molecule. ... Now consider the case of IRAS04296. ...

... An ionospheric trough is a region of decreased F layer plasma density. ... It is quite typical to make a distinction between the sub-auroral troughs at mid-latitudes, and high-latitude troughs within the auroral region or polar cap . ... working for mid-latitude trough and some types of high-latitude troughs, like the polar hole . ... Collis, P. N., and I. HДggstrЖm, Plasma convection and auroral precipitation processes associated with the main ionospheric trough at high latitudes, J. atmos. terr. ...

We model the spectral chanages of late oxygen-rich Miras observed in different pulsation phases. From a combination of variable near-IR spectra and UKIRT spectrophotometry of the 9.7 \mu m silicate dust emission feature in different phases we study the influence of the changing atmospherical circumstances on the conditions in the circumstellar dust shell. ... A comparision with the modelling results for another long period Mira U Ori is also provided. ...

... April 15, 1997 . Hale-Bopp and Plateau de Bure Interferometer . ... Explanation : Comet Hale-Bopp is being observed by many different telescopes. Here the comet is pictured behind the array of radio telescopes which compose the Plateau de Bure Interferometer . These telescopes are being used to detect the presence of different molecules in the coma and tail of Comet Hale-Bopp. Molecules detected in the comet include carbon monoxide and sulfur dioxide. ... About APOD > . ...

... Under certain conditions, like those in the nucleus of a QSO, all atoms can be made to emit light at particular wavelengths. ... If that source is approaching the observer, the wave is squashed up onto itself making the wavelength shorter. ... This is redshift. ... You can see how the section of the QSO spectrum which we observe changes with redshift. ... We then see how far we had to slide the observed spectrum along the scale to make it match and that is the objects redshift. ... The 2QZ team . ...

... ESO, the European Southern Observatory . ... Travel and Contacts . ... Green ESO . ... Survey Telescopes . ... 2002 . ... Images of Titan taken on November 26, 2002 through nine different filters to probe different altitudes, ranging from the stratosphere to the surface. ... Due to these good observing conditions, Titan's trailing hemisphere was observed with contrasts of about 40%, allowing the detection of several bright features on this surface region, once thought to be quite dark and...

... October 16, 1995 . Starburst Galaxy M94 . Credit: NASA , Ultraviolet Imaging Telescope . Explanation: The spiral galaxy M94 is somewhat unusual in that it shows a great ring of bright young stars particularly apparent when observed in ultraviolet light , as shown above. Such a high abundance of these young blue stars may cause a galaxy to be designated a starburst galaxy. ... Tomorrow's picture: Galaxy Dwingeloo 1 Emerges . ... About APOD | ... NASA Technical Rep.: ...