Potential exoplanet in a debris disk around a star

(ORDO NEWS) — Fragment disks around main sequence stars are thin belts of dust that are thought to form when asteroids or other planetesimals collide and break apart. Such structures are widespread in the Universe – more than a quarter of all main sequence stars have fragment disks, and since such disks are difficult to detect, it is likely that their proportion is actually even higher.

Modern instruments are only capable of detecting debris disks in systems that have about an order of magnitude greater luminosity when compared to the disk generated by the Kuiper belt in our solar system.

The dust in these debris disks is noteworthy on its own, but it also allows us to determine the properties of planetary systems. The largest dust grains (more than one millimeter in size), the co-scattering of which can be measured with the Atacama Large Millimeter / submillimeter Array (ALMA) observatory, are subject to only relatively little influence from stellar winds or star radiation pressure.

Their distribution is largely influenced by factors such as gravity and collisions. This “chaotic zone” is a vast area within which dust particles do not have stable gravitational orbits, resulting in a gap, the width of which depends, among other things, on the mass of the planet. A planet in a fragment disk can form such a gap,

In the new work, astronomers at the Harvard-Smithsonian Astrophysical Center Sean Andrews and David Wilner were part of a team that used the ALMA observatory to study the famous debris disk around HD 206893, about 135 light-years from US. The star’s system also has a companion – a brown dwarf with a mass of about 15-30 Jupiter masses.

High spatial resolution images of the fragmentation disk made with the ALMA observatory made it possible to establish that the radius of the disk is from 50 to 185 astronomical units (1 AU is equal to the average distance from the Earth to the Sun), while a gap was found in the disk. starting at a distance of 63 AU from the center and extending along the radius to about 94 AU. from the center.

The work was published in the Astrophysical Journal; lead author Ava Nederlander.

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