Downton Abbey star Joanne Froggatt sparked a fan reaction on Monday when she shared a radiant, sun-drenched selfie. In the throwback snapshot, which was posted on Instagram, the 43-year-old TV star resembled a glowing goddess with her golden tresses flowing in loose waves down her back.   View this post on Instagram   A post shared by Joanne Froggatt (@jofroggatt) …