51 Pegasi is a yellow dwarf star that is thought to be around 7.5 billion years old , which is somewhat older than our Sun . 51 Pegasi is also 4-6 % more massive than our Sun with more metal content . 51 Pegasi is a yellow dwarf star estimated to be 6.1 â `` 8.1 billion years old , somewhat older than the Sun , 4 â `` 6 % more massive , with more metal content and running low in hydrogen .