A NASA scientist has discovered a world where a sun sets on the horizon, followed by another sun and then a third sun. This world - known as HD 188753 Ab - is the first known to be near a classic triple-star system.
Michal Levinstein
A NASA scientist has discovered a world where a sun sets on the horizon, followed by another sun and then a third sun. This world - known as HD 188753 Ab - is the first known to be near a classic triple-star system.
"The sky on this planet will be amazing, with 3 suns setting every now and then" says Dr. Maciej Konacki (Dr. Maciej Konacki) from the California Institute of Technology, who discovered the planet by the Keck 1 telescope on Mauna Kea mountain in Hawaii. "Before that we had no clue whether planets could form under such complex gravitational conditions." The discovery suggests a theory that planets are more robust than previously thought.
Triple solar systems are common in the universe and account for more than half of the stars. The closest star to our sun - Alpha Centauri is a member of such a triple system.
"Multi-star systems have not been popular hunting grounds for planets," Konaki says, "they are difficult to observe and believed to be unfriendly to planets."
The discovered planet belongs to a type of planets called "Hot Jupiters", which are giant gaseous planets orbiting nearby suns. In such a system, the planet passes every 3.3 days around the sun, which is circled every 25.7 years by a pair of suns trapped in a 156-day orbit.
The circus of the 3 suns is a kind of contracted cluster, which enters the same space as that between Saturn and our sun. Such tight living conditions raise questions about the theory of the formation of Hot Jupiters. Astronomers thought that planets of this type form away from their suns and then migrate inward toward them. "In a dense lattice of such a system, there would be no room at the edge of the star system for a planet to grow," Konaki says.
Before that, astronomers discovered planets around 20 double star systems and one triple star system - but the suns in these systems were very far apart. Most multi-star systems are crowded together and difficult to learn.
Konaki overcame this challenge by using a modified version of the rotational velocity or "wobble" of the star-hunting technique. In the traditional wobble method, the presence of a planet is inferred from its gravitational pull or wobble on its sun. The theory works well for single suns or systems of double or triple stars where the suns are very far apart. But in systems where the suns are close to each other, the light rays coming from them mix with each other.
In developing models of systems with closely spaced glasses, Konaki could separate the entangled light rays. This allowed him to accurately detect for the first time the pull of a planet on a Sun curled together with other Suns. Of the 20 systems examined so far, the new system HD 188753 149 light years away is the only one that is home to a planet.
According to the theory, Hot Jupiters form from disks or "doughnuts" or from material swirling around the edges of young suns. The disc material gathers into a solid core and then attracts gas to it. Finally, the gas giants drift inward. Discovering a world located in a tri-solar system contradicts this scenario. The discovered system could not have had such a disk in its youth, due to the interfering presence of the companion suns. This situation leaves no chance for the formation of a planet and raises new questions.
The mass of each of the 3 suns in the HD 188753 system is in the range of 2/3 to the mass of our Sun. The planet itself is slightly more massive than Jupiter.
