Rocky Planetis overheated planet, about 1.4 times as big around as Earth, has a sky that one-ups Star Wars’ Tatooine – three stars instead of two. It is one of 12 recent discoveries just added to NASA’s Exoplanet Archive, and was found by a Harvard Center for Astrophysics team using data from the TESS space telescope.
Likely a rocky planet, LTT 1445 A b takes only five days to go once around its star – a “year” on this world, which is about 22 light-years away from Earth. Its scorchingly close orbit helps explain why its surface basks in temperatures on the order of 320 degrees Fahrenheit (160 Celsius) – comparable to a preheated oven.
While the planet itself remains in what is probably a stable orbit around its star, that star also orbits, at greater distance, two sibling stars that are locked in close orbit around each other. This isn’t the first three-star system to be found with at least one planet. Our nearest stellar neighbor, in fact, is Proxima Centauri, orbiting the more distant pair, Alpha Centauri A and B. Proxima is only 4.25 light-years away from Earth. In orbit around it is Proxima b, a small, probably rocky world that takes an estimated 11 days to circle its star.
All three stars in the LTT 1445 system are red dwarfs, cooler and far longer-burning than larger yellow stars like our Sun. The planet also is the second-closest discovered so far that “transits” its star – that is, the orbit of LTT 1445 A b is tilted at the correct angle to, from our vantage point, pass across the face of its star. The “transit” observing method allows space telescopes like TESS to detect planets orbiting other stars by the shadows they cast – the tiny dip in starlight as the planet makes its crossing.
The very nearest transiting planetary system so far discovered is HD 219134 bc, about 21 light-years away.