Tessal is about 1.5x bigger than our sun, but not as hot as ours. It is an averagesize and is about 2 billion years old. It has lots of sun spots, thus making up the lack of heat output. Solar flares are common on Tessal.
About 1.5 million Earths can fit into Tessal. One of the planets that orbits it, Nerco, is 1/4 the size of Tessal, surprisingly. Tessal, because it does not transfer much heat to its planets, no life can survive on them, thus making the Vergo star system devoid of life. The 'rockies' orbitting Tessal are undersized and rather close to their star.
Nobody has yet explored or observed Tessal clearly enough to know if it is safe to send a shuttle to explore it. However, star fleets are planning on an expedition directed towards Tessal.