CEN1A: Chandra grating spectrum
The data shown here are from James MacArthur's first extraction (9 July 2009), using Pat Broos's software, and carefully separating the dispersed spectra of the two components (A + B), using narrower than usual extraction apertures. The exposure time in 149.0 ks.
The Chandra observing proposal has some background information.
Component A - whose data are shown here - is the somewhat dimmer source to the SW. This is a quick and dirty presentation and analysis of the data, showing the entire MEG and HEG (first order, coadded -1 and +1) spectra, and Gaussian fits to one line and one line complex. There are 1703 MEG counts and 866 HEG counts in the first order spectra.
Component B is shown here.
The HETGS spectra
MEG
HEG
Note that the light, vertical lines are the wavelengths of emission lines seen in the Chandra spectrum of DoAr 21.
I fit a one temperature bapec*wabs model to these data. The fit was not good. The best-fit parameters of interest were kT = 11.9 keV; sigma = 667 km/s; N_H = 0.12 X 1022 (seems lower than it should be).
6.182 Angstroms: Si XIV Ly-alpha
These data were fit with a wgauss + powerlaw model. The MEG and HEG data were fit simultaneously. The dashed vertical line is the rest wavelength of the line, and the two dotted vertical lines represent Doppler shifts of +/- 3000 km/s (arbitrarily; we don't know the wind properties of this star or stars).
MEG
HEG
This fit is not statistically good. It has a best-fit σ = 1750 km/s. Very broad. I fit the nearby continuum first; that fit wasn't very good either.
6.7 Angstroms: Si XIII helium-like res., int., for.
These data were fit with a hegauss + powerlaw model. The MEG and HEG data were fit simultaneously.
MEG
HEG
This fit is statistically good. It has a best-fit R = f/i = 0.79 (interesting, intermediate value, but 68% confidence range is 0 to 1.47). G = (f+i)/r = 1.41, and the line width σ = 1380 km/s.
last modified: 10 July 2009