Spatially resolved spectroscopy of infrared companions to T Tauri stars
We describe the technique of spatially resolved spectroscopy of close binary stars and present K band spectra of the Haro 6-10 and UY Aur infrared companion (IRC) systems. The IRC’s are characterized by very low infrared colour temperature and high luminosity. Our observations address the debate between those who suggest that the IRC’s are at an earlier evolutionary stage than their primary stars, and those who believe that these objects are relatively normal pre-main-sequence stars with substantial local extinction and accreting matter.
In both Haro 6-10 and UY Aur, we detect 2 μm molecular hydrogen emission confined to the infrared companions. The line ratios are consistent with shock heating, strengthening the view that the IRC’s are experiencing ongoing accretion. In the case of UY Aur, non-spherical geometry, such as accretion onto a circumstellar disk, can explain the presence of molecular hydrogen emission, low effective temperature, and high luminosity while allowing moderate extinction to the photosphere at near infrared wavelengths.
KeywordsMolecular Hydrogen Spectral Type Line Flux Interstellar Extinction Tauri Star
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