Yes, this is possible, though probably not ideal. You could use the Background object (a sphere), but you would need to make it much smaller so that the luminosity and GI sampling work best. So, slightly larger than the default planet would be ideal I think.
Rather than explain at length how to do this, I've just attached a TGD project file that shows it. I made a copy of the Background object and made it much smaller, then added an image map shader fed into a default shader to provide luminosity. You can use your own EXR image in place of the one I used (which I did not include). I would suggest using higher GI settings than are in my file, but for speed and ease of illustration I left it at default.
- Oshyan