http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?docsPerPage%3D100;f20-associated-Lesson%3DUltraviolet%20Science Results for your query: docsPerPage=100;f20-associated-Lesson=Ultraviolet Science Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/1975ApJ___197___85M/1975ApJ___197___85M.dc.xml The spectrum was recorded with the Copernicus satellite (1972) by Don Morton. The abscissa (x-axis) is in units of Ångstroms and the ordinate (y-axis) is in units of counts per 14 seconds. The spectrum was recorded point by point using a photo cell. The spectrum from 1197 Å to 1254 Å, which took 20 hours to record, contains four types of features: a) the strong absorption from the interstellar hydrogen line known as Lyman alpha near 1216 Å; b) a set of very narrow, deep lines due to neutral nitrogen at 1200 Å, twice ionized silicon at 1206 Å, and once ionized sulfur just past 1250 Å, all from interstellar gas; c) a wind containing four times ionized nitrogen blowing off the surface of the star at 1000 km/second (1233 Å and 1238 Å); d) general undulations across the top which are due to absorption lines in the atmosphere of the star itself. The sharp, narrow interstellar lines, item b, actually contain two components which cannot be distinguished in this spectrum because of insufficient resolution. This is the... http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/1975ApJ___197___85M/1975ApJ___197___85M.dc.xml Sat, 01 Jan 1972 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/Tumlinson_fig4/Tumlinson_fig4.dc.xml The LMC star is Sanduleak -67 166. The top two panels cover the spectral region from 920 - 1120 Å. To obtain this spectrum a special telescope, FUSE, had to be built with very few reflections and with a much more sophisticated detector than was used for Copernicus. This spectrum took 60 hours to record, three times longer than it took the Copernicus satellite to observe 50 Å in zeta Ophiuchi, a star that is 10,000 time brighter than this one. For this example, FUSE is effectively 7,500 times more efficient than Copernicus. The spectrum is completely dominated by the lines of molecular hydrogen from interstellar space, some in our Galaxy and some in the Large Magellanic Cloud. The spectrum of molecular hydrogen, which contains two hydrogen nuclei (protons) and two electrons, is obviously much more complex than the spectrum of atomic hydrogen. The vibration of the two protons leads to the bands denoted 1-0, 2-0, 4-0, etc., at the top of the two panels. Within each band are very narrow components more closely sp... http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/Tumlinson_fig4/Tumlinson_fig4.dc.xml Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/apj430279f6_hr/apj430279f6_hr.dc.xml The spectra were shifted to appear as if they were not redshifted before being averaged. All the objects have spectra that look like quasi-stellar objects, but some are of low enough luminosity that the host galaxy is visible and has a name. The main features of the spectrum are as follows: a purple/blue line drawn through the spectrum is the "continuum," mostly due to the AGN, a continuous glow caused by a very hot gas in a strong magnetic field; a red line represents the fitted spectrum of emission lines, thought to arise in a disk that surrounds the central black hole of the AGN. (These are most clear at the right end.) The ions that are seen in emission are labelled: N V, C IV, He II etc. The Roman numeral is the charge of the ion plus one: N V is four-times ionized oxygen, meaning that four electrons have been stripped off the atom. The ion has a net charge of positive four. The black line traces the actual data. Below about 950 Å, neutral hydrogen absorption lines from the intergalactic medium exist in ... http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/apj430279f6_hr/apj430279f6_hr.dc.xml Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/fg7/fg7.dc.xml SN1987A is the brightest supernova seen from Earth in several centuries. The abscissa is in kilometers per second (km/sec), and the ordinate goes from 0 to 1 for each panel and reflects the relative strength of each component set. The absorption features shown are predominantly interstellar lines from gas between us and the supernova. However, the supernova is in a nearby galaxy, the Large Magellanic Cloud (LMC). The LMC is just beyond the Milky Way and is moving away from us. The labels above the second spectral strip show groups of interstellar components moving at different velocities, which cannot be resolved separately. The component groups 2, 3, and 4 are in the Milky Way galaxy, and the component groups 5 through 10 are in the LMC. The black dots are the data points, and the black line is a prediction (a model) including all of the subcomponents for what the interstellar spectrum should look like. The model and the data points agree very well. The ions represented are once-ionized nickel, once-ionized ... http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/fg7/fg7.dc.xml Thu, 01 Jan 1970 12:00:00 GMT