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Astron. Astrophys. 345, 605-610 (1999)

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2. Observations

For both supergiants in our sample, we have full-grating ISO/SWS spectra with a complete wavelength coverage from 2-45 µm (AOT01). We obtained a fast scan for [FORMULA] Sco (speed 1, resolution of 250) and a slow scan for [FORMULA] Ori (speed 4, resolution about 1000).

The data were reduced using the SWS Interactive Analysis (SIA) reduction software package using standard ISO pipeline data products (version 6.0) at the data centre in Groningen. Although in principle flux levels may be affected by the uncertainty in the dark current the high flux levels of our stars ensure that this effect can be neglected here. The main uncertainty in the observed flux comes from the pointing uncertainty and the relative spectral response function (RSRF). A bump at 28 µm in Fig. 1 may be spurious, due to instrumental effects in band 3E between 27.5 and 29 µm. Spectra of both supergiants are presented in Fig. 1 and line fluxes are given in Table 1.

[FIGURE] Fig. 1. Grating spectra of [FORMULA] Ori (top ) and [FORMULA] Sco (bottom ) showing the three atomic fine-structure lines. Note that the flux for [FORMULA] Sco has been multiplied by 1.6 in this plot.


Table 1. Observed line fluxes and the critical densities.
a fluxes taken from HGT
b values taken from Tielens & Hollenbach (1985)

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© European Southern Observatory (ESO) 1999

Online publication: April 19, 1999