Preliminary Capella analysis |
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Data will soon be re-processed w/ better calibrations. Data are from the HETG/ACIS-S Focus Test. Top: obsid 1098 and 1099, merged MEG +1, -1 (about 30ks worth) These spectra had empirically determined shifts applied to adjust for chip-gap errors. Shifts were determined by determining chip boundaries in the MEG spectrum from the zero order dither centroid in detector coordinates, then examining the left-right orders, and adjusting. (gap positions will be fixed in automatic processing) In addition, an ad hoc shift was applied to long-wavelengths to put the O VII, VIII lines in the right place. (This is a bug to be resolved!) Bottom: a simulation of a 70ks HETG/ACIS-S observation, based on the EUVE-determined emission measure distribution (Brickhouse 1995) and the SPEX line-list, and a continuum hacked from NEI code. (The long-wavelength error has not been removed; you can see the tic-marks are slightly off-center.) Line IDs are PRELIMINARY! There were done via automatic search of the emissivity table for the strongest emitter within the profile region. They need careful review. (Some are just plain wrong. Like Fe XX instead of Fe XVII 15.01A.) No blends have been marked, where contributers are of comparable strength. The images are in a table 9 panels wide - scroll to see them all! |
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The whole thing:
| Given the emissivity database, a nominal effective area, exposure time, and counts in each feature, we can sum all the emissivities which contribute to the feature and compute an diagram of the EMT (Emission Mess vs Temperature). Each quasi-parabolic line represents the emission measure vs. temperature of all lines which contribute to the wavelengths of the feature (as present in the SPEX line-list, for zero-density, Solar abundances). The solid, thick histogram is the model distribution, taken from the EUVE fit (Brickhouse and Dupree 1993). (The histogram model DEM is scaled by delta log T, which has the value 0.1; the derived curves have been scaled by 0.1 to match this distribution.) Untangling this Emission Mess will take some time, since each curve's lines need to be understood, and correlations between curves (line-ratios) need to be examined. In addition, lines not present (upper limits) also can constrain the emissivity. |
Postscript plots (for
best viewing, use swap landscape, and turn anti-aliasing off):
Capella detail, in 9 pages: Capella_1098-1099_Mpm1_detail.ps
A wide version:
Capella_1098-1099_Mpm1_detail_long.ps
The simulation
in 9 pages:
AS_014_detail.ps
A wide version: AS_014_detail_long.ps
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Top:
The model spectrum. Features above a lower threshold have been
identified from the SPEX line-list. The model was a continuous
emission measure distribution as determined by Brickhouse (1995) from
the EUVE data.
Bottom:
The observation (obsid 1098+1099) has been scaled by the nominal MEG
+-1 orders' effective area into a flux. The model is overplotted,
after dividing by 10 (to roughly be comparable to instrumentally
broadened spectra).
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The whole thing:
Postscript plots:
A table of the "detected" peaks in the model can be found in
Capella_mdl_peaks.tbl
A table of the peaks' line-identifications for the model can be found in
Capella_mdl_ids.tbl
A graphical guide to the peaks:
Capella_mdl_peaks.ps
Brickhouse,
N.S., 1995, Harvard-Smithsonian Preprint No.4119, and IAU Colloq.152.
Model detail, in 9 pages:
Capella_mdl_detail.ps
The model overlayed on the observation, in 9 pages:
Capella_mdl_obs_detail.ps
Reference: