Vega Phenomenon in general

Circumstellar disks are believed to be ubiquitous around young stars. These disks are eroded in time due to stellar wind, Poynting-Robertson drag, radiation pressure, sublimation and coagulation into planets. Although the timescale of this erosion is less than 10 million years many older main-sequence stars have thermal emission from cold dust. These disks usually have a disklike or ring morphology at optical, infrared and submillimeter wavelengths with typical radii of 50 AU. Thus the sizes of these disks resemble the size of the Kuiper belt in our solar system. In our current knowledge, collisions between comets and asteroids in an extra-solar Kuiper belt can replenish the dust in "debris disks" around main-sequence stars.

The thermal emission of the cold circumstellar dust can be detected as an excess above the normal photospheric flux density of the star at far-infrared wavelengths. Since our atmosphere is not transparent at far-infrared wavelengths satellites play crucial role in the study of this spectral regime. Following the discovery of Vega's disk by the IRAS, the Infrared Space Observatory (ISO) continued the study of the so-called "Vega phenomenon". New important results are expected from the Spitzer Space Telescope. The most important aspects of our research at Konkoly Observatory are to determine the conditions under which stars posses debris disks and to study the temporal evolution of these disks via examining their infrared emission.