A growing planet has been found by astronomers around a nearby young star named TW Hydrae. The discovery has been made using the Chile-based Atacama Large Millimeter/Sub-millimeter Array (ALMA) which is the most expensive telescope in operation on the ground. Based upon the distance from the central star and the distribution of tiny dust grains, the planet is observed to be an icy giant which is comparable to Neptune and Uranus. The finding is a key step towards understanding the origins of different types of planets.
A research team led by Takashi Tsukagoshi from Japan's Ibaraki University has observed TW Hydrae in the hope of taking a closer look at a planet formation site. According to estimates, the star, which is one of the closest young ones to earth, is around 10 million years old. Since its proximity and axis of rotation points roughly in the earth's direction, TW Hydrae, which is 176 light years from earth, is a favorable reference for investigating planet evolution.
Past observations have shown that the young star is surrounded by a disk of tiny dust particles. Planet formation happens within the disk. Recent ALMA sightings have unveiled multiple gaps in the area. Theoretically, these gaps are evolutionary evidence.
In observing the disk around TW Hydrae, two frequencies have been utilized. Since the ratio of the radio intensities in different frequencies depends on the size of the dust grains, researchers can estimate the size of the dust grains. Indications have revealed that smaller or micrometer dust particles dominated while larger dusts are absent in the most prominent gap with a radius of 22 astronomical units. Theoretically, the gravitational interaction and friction between gas and dust particles pushes the larger ones out from the gap.
Basing on the width and the depth of the 22 AU gap, experts have calculated the mass of the unseen planet. There are indications that the celestial body is bigger than Neptune. According to Tsukagoshi, combined with the orbit size and the brightness of TW Hydrae, the planet will be an icy giant.
The secret to ALMA's incredible resolution comes from its height and distance. The observatory area sits on a plateau that is 16,500 feet above sea level which is far above most of earth's atmosphere and water vapor. Astronomers working in the facility at 9,500 feet or 2,900 meters must use supplemental oxygen for extended stays.
