We report the detection of \ion N5 1239Å transition region emission in HST /GHRS spectra of the A7 V stars , \alpha Aql and \alpha Cep .
Our observations provide the first direct evidence of 1 - 3 \times 10 ^ { 5 } K material in the atmospheres of normal A-type stars .
For both stars , and for the mid-A–type star \tau ^ { 3 } Eri , we also report the detection of chromospheric emission in the \ion Si3 1206Å line .
At a \bv color of 0.16 and an effective temperature of \sim 8200 K , \tau ^ { 3 } Eri becomes the hottest main sequence star known to have a chromosphere and thus an outer convection zone .
We see no firm evidence that the \ion Si3 line surface fluxes of the A stars are any lower than those of moderately active , solar-type , G and K stars .
This contrasts sharply with their coronal X-ray emission , which is > 100 times weaker than that of the later-type stars .
Given the strength of the \ion N5 emission observed here , it now appears unlikely that the X-ray faintness of the A stars is due to their forming very cool , \leq 1 MK coronae .
An alternative explanation in terms of mass loss in coronal winds remains a possibility , though we conclude from moderate resolution spectra of the \ion Si3 lines that such winds , if they exist , do not penetrate into the chromospheric \ion Si3–forming layers of the star , since the profiles of these lines are not blueshifted , and may well be redshifted with respect to the star .