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Discussion of infrared measurements of T Tauri stars and related objects
Author(s) -
Rössiger S.
Publication year - 1977
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.19772980405
Subject(s) - t tauri star , stars , physics , astrophysics , infrared , circumstellar envelope , astronomy , infrared excess , circumstellar dust , stellar classification , k type main sequence star , envelope (radar) , telecommunications , radar , computer science
It is at first reported that certain kinds of stars which have been classified as T Tauri stars or related objects are in reality not of this type. After the exclusion of those objects, the infrared measurements accessible in the literature permit to draw some astrophysical inferences. It is then possible to distinguish three classes of light variations. All T Tauri stars have an infrared excess. From the colour indices H – K and K – L it can be deduced that the infrared excess for more than one half of the objects is due to the thermal radiation of the circumstellar dust envelope; for the remaining stars also free‐free radiation from the gas envelope can play an essential part. The largest infrared excesses E H–K were found with the hotter stars (spectral type A) and the strongest emission lines with the cooler stars (spectral types G, K, M). This can finally be explained by the fact that the convection zone in cooler stars reaches far down into their interior than in hotter stars.