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Age Dependence of the Vega Phenomenon: Observations
We study the time dependency of Vega-like excesses using infraredstudies obtained with the imaging photopolarimeter ISOPHOT on board theInfrared Space Observatory. We review the different studies published onthis issue and critically check and revise ages and fractionalluminosities in the different samples. The conclusions of our studydiffer significantly from those obtained by other authors (e.g., Hollandand coworkers; Spangler and coworkers), who suggested that there is aglobal power law governing the amount of dust seen in debris disks as afunction of time. Our investigations lead us to conclude that (1) forstars at most ages, a large spread in fractional luminosity occurs, but(2) there are few very young stars with intermediate or small excesses;(3) the maximum excess seen in stars of a given age is aboutfd~10-3, independent of time; and (4) Vega-likeexcess is more common in young stars than in old stars.
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| Сазвежђа: | Кит |
| Ректацензија: | 02h51m35.59s |
| Deклинација: | +07°33'00.0" |
| Apparent магнитуда: | 8.416 |
| Даљина: | 200 parsecs |
| Proper motion RA: | 2.7 |
| Proper motion Dec: | 6.1 |
| B-T magnitude: | 9.861 |
| V-T magnitude: | 8.536 |
Каталог и designations:
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