Follow Us| CH UMa | ||||||||||||||||||
| The FUSE Spectrum of the U Gem Dwarf Nova CH Ursa Majoris was taken in quiescence. The spectrum is very noisy especially in the shorter wavelengths. Due to the hydrogen cut-off one expects the flux to drop significantly for wavelengths < 915A, instead the flux keeps on increasing, a sure sign of a noisy detector edge as well as a possible background subtraction problem. We identify ISM H molecular absorption features as well as ISM metal lines, mainly of Fe ii. The spectrum is also affected by terrestrial airglow (sharp emission lines) and the S vi (944) feature, if real, is also probably due to day light reflected in the telescope. There are some broad emission features that are associated with the source: we identify the O vi doublet and C iii (977 \& 1175~\AA ). All the other lines marked in the figure are not detected. In the modeling we add an ISM model to mimic the absorption due to the Hydrogen molecular absorption features. Details on the processing and spectral modeling of the FUSE spectrum are given in Sion et al. 2007. | |||||||||||||||||
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FUSE Data
Synthetic Spectrum
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These data and models were published in the paper: Sion, E.M., Godon, P., Cheng, F., Skzody, P. 2007, ApJ, 134, 886 | ||||||||||||||||||||||||||||||||||||
Notes on figures:The flux (vertical axis) is given in ergs/sec/cm2/A and the wavelength (horizontal axis) is given in Angstroem. For clarity the spectrum is shown on 3 panels: the upper panel from about 900 to 1000A, the middle panel from about 1000A to 1100A, and the lower panel from about 1100A to 1200A. Air glow emission is anoted above each panel with a "+" sign inside a circle. Strong emission lines reaching the upper part of the frame in each pael is marked just above the panel. The Hydrogen series is marked below the x-axis in the upper and middle panel and the hydrogen cut-off limit is clearly marked around 915A with an increasing density of tick marks. The He I (1168A) is marked below the lower panel. Oxygen I lines are shown with an arrow "OI -->" if many (ISM) OI lines are present, they are just annotated with verical tick marks in the lower portion of each panel. ISM molecular hydrogen lines are either individually annotated vertically (e.g. L10R1) or just marked with an arrow "MH -->" and vertical tick marks (usually in the upper part of each panel). Features resulting from fixed pattern noise introduced by FUSE detect ors are indicated with "FPN;.When a model is shown, the portions of the observed spectrum that have been masked before the spectral fit are in blue, while the rest of the observed spectrum is in red. The model fit is shown the solide line in black (or possibly white). If the model is a composite made of a disk model and a white dwarf model, then these are shown with the dashed- and dotted lines (respectively). Some models include the effect of quasi-molecular HI absorption features, these are labelled "Q-mol" in the spectrum. |
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