Discussion of infrared measurements of T Tauri stars and related objects It is pointed out that in comparison with main-sequence stars of thesame spectral type, all irregular variable stars in thepre-main-sequence stage (briefly called T Tauri stars), show an infraredexcess. Infrared observations provide information concerning thephysical characteristics of stars, including the total energy output.The reported investigation considers infrared observations of T Tauristars conducted during the last ten years. The exclusion of some starsnot belonging to the group of the T Tauri stars is considered along withaspects related to a subdivision of the T Tauri stars. The various typesof T Tauri stars with their characteristics are represented in graphs.It is found that in some cases the infrared excess may be caused by thethermal radiation of the circumstellar particles which are heated by thestar. In other stars, thermal bremsstrahlung and dust radiation areresponsible for the infrared excess.
An infrared survey of RW Aurigae stars An infrared photometric survey of 89 RW Aur type variables in bothhemispheres has been made. JHKL magnitudes and colors are listed. The RWAur variables include a small number of highly reddened late-type stars.All T Tauri and hot Orion population stars show infrared excesses andthe infrared properties mark certain field stars as being young. Thegreatest infrared excesses are found for A and F stars while youngvariable B stars usually show no excesses. The location of the RW Aurstars in the two-color H-K, K-L diagram favor dust re-radiation overfree-free emission as the mechanism responsible for the infrared excess.A weak correlation of H-K with emission class links the occurrence ofcircumstellar dust and gas shells.
