We observed a group of galaxies , HCG 57 , with ASCA .
Regardless that their member galaxies are dominated by spiral galaxies , we detected extended thermal X-ray emission that is attributed to hot gas with a temperature of 1.04 \pm 0.10 keV .
This is the second clear detection of thermal X-ray emission from a spiral-dominant group of galaxies after HCG 92 .
The luminosity of the thermal emission is about 5 \times 10 ^ { 41 } erg s ^ { -1 } in the 0.5–10 keV band , which is higher than that of HCG 92 , but relatively less luminous among groups of galaxies .
The X-ray emission is extended over several member galaxies , and is thus associated with the group rather than an individual galaxy .
The metal abundance can not be well constrained with a lower limit of 0.08 solar .
The gas-to-stellar mass ratio is \sim 0.3 .
Although this is relatively low among groups , the hot gas is also a significant component even in the spiral-dominant group .
We suggest that the X-ray faintness of spiral-dominant groups is due to the low surface brightness and somewhat low gas mass , at least in the case of HCG 57 .