The following document lists the file abstract/ALAGRANG_TYCRA.abs
from catalogue VI/111.
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Herbig stars are young stars surrounded by dust and gas, probably in the form of a protoplanetary disk.They are on going phases of activity through winds and accretion. Their study is expected to bring clues to early stages of planetary systems formation. Young objects are also widely thought to be formed in binary or multiple environments, and many studies have been devoted to star and disk formation around binary and/or multiple systems during the past years. We started the study of a relatively evolved, Herbig binary star TY CrA. From high resolution (HR) spectroscopy, we found this star to be a double-lined eclipsing spectroscopic binary with a period of 2.9 days and determined the orbital parameters and masses of both components of the system. This is the first double-lined eclipsing binary known among HAEBE stars. It thus offers a unique opportunity for a detailed study of its circumstellar matter (both gas and dust) in the framework of star/disk formation and evolution around binary systems. HR spectroscopy suggests the presence of a third component, much cooler and probably of T Tauri type. Part of the strong IR excess of TY CrA might come from this third companion; if its presence is confirmed through proposed HST and ground based observations, circumstellar environment models developed so far for this system should be revised. Furthermore recent 10 micron imaging revealed on top of the complex 10 micron emission region associated to TY CrA, an intense close-by emitting region, which may as well have been erroneously included in the photometry of TY CrA. We propose here to perform IR imaging with ISOCAM, as well photometry with ISOPHOT, to get an accurate IR photometric budget of the star and its close environment, so as to perform new and more adequate models. In addition, photometric observations during primary and secondary eclipses will allow us to investigate the immediate circumstellar environment. Spectroscopic observations are planned to study the structure of the surrounding gas.