About 2300 planet-forming discs have been found around young stars in a vast complex of gas and dust clouds.
NASA鈥檚 Spitzer Space Telescope has been using its infrared vision to peer inside the Orion cloud complex, a set of gas and dust clouds where stars are forming. The complex includes the Orion Nebula, a well-studied stellar nursery, and is 240 light years wide and lies 1450 light years from Earth.
Using the Spitzer data, Thomas Megeath of the University of Toledo in Ohio, US, and his colleagues have found almost 2300 dusty discs around stars in the complex.
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The discs are not seen directly, but the warm dust that makes them up betrays their presence by adding infrared light at relatively long wavelengths to the light of their host stars.
鈥淭hey really stand out as a separate group of objects than the normal stars, which get progressively fainter as you go to longer wavelengths,鈥� team member Joseph Hora of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, told 快猫短视频.
Complete census
A detailed Spitzer image of the Orion cloud complex was released on Monday, showing objects less massive than the Sun for the first time.
鈥淭his is the most complete census of young stars with discs in the Orion cloud complex,鈥� Megeath says. 鈥淏asically, we have a census of potential solar systems, and we want to know how many are born in the cities, how many in small towns, and how many out in the countryside.鈥�
About 60% of the stars with discs are found in large clusters of stars with hundreds of members. Another 15% belong to smaller clusters. About 25% are solitary stars that do not belong to a cluster, a larger proportion than scientists expected.
Prior to these observations, astronomers had thought that up to 90% of stars in general were born in clusters, a proportion they expected to hold for stars with discs, too.
The researchers estimate that overall, between 60% and 70% of the stars in the Orion complex have discs. 鈥淚t is an interesting question why this number isn鈥檛 100%,鈥� Megeath says. 鈥淓ventually, we may be able to understand why some stars don鈥檛 have discs.鈥�
