We have obtained the first high resolution spectra of individual stars in the dwarf irregular galaxy , NGC 6822 .
The spectra of the two A-type supergiants were obtained at the VLT and Keck Observatories , using UVES and HIRES , respectively .
A detailed model atmospheres analysis has been used to determine their atmospheric parameters and elemental abundances .
The mean iron abundance from these two stars is < [ Fe/H ] > = - 0.49 \pm 0.22 ( \pm 0.21 ) In this paper , abundances shall be reported with two uncertainties ; the first is the line-to-line scatter , and the second ( in parentheses and italics ) is an estimate of the systematic error due to uncertainties in the atmospheric parameters . , with Cr yielding a similar underabundance , < [ Cr/H ] > = - 0.50 \pm 0.20 ( \pm 0.16 ) .
This confirms that NGC 6822 has a metallicity that is slightly higher than that of the SMC , and is the first determination of the present-day iron-group abundances in NGC 6822 .
The mean stellar oxygen abundance , 12+log ( O/H ) =8.36 \pm 0.19 ( \pm 0.21 ) , is in good agreement with the nebular oxygen results .
Oxygen has the same underabundance as iron , < [ O/Fe ] > =+0.02 \pm 0.20 ( \pm 0.21 ) .
This O/Fe ratio is very similar to that seen in the Magellanic Clouds , which supports the picture that chemical evolution occurs more slowly in these lower mass galaxies , although the O/Fe ratio is also consistent with that observed in comparatively metal-poor stars in the Galactic disk .
Combining all of the available abundance observations for NGC 6822 shows that there is no trend in abundance with galactocentric distance .
However , a subset of the highest quality data are consistent with a radial abundance gradient .
More high quality stellar and nebular observations are needed to confirm this intriguing possibility .