At www.astronomy.com/news/2016/10/the-newest-weird-solar-systems-lonely-hot… … when scientists began cataloguing exoplanets they compared them to solar system bodies. Hence we have terms such as hot Jupiters and super Earths. We also have hot Earths. They have now found hot earths can exist further from their home sun/star than previously thought (and are still classified as hot earths) – so what is going on? Out of 144 hot earths identified researchers estimate 24 if them orbit without a close planet. They are now thinking these are the corpses of hot Jupiters (the left behind cores of gas giants).
Hot Jupiters are also a puzzle. See link above.