Mid-infrared size survey of Young Stellar Objects: Description of Keck segment-tilting experiment and basic results

TL;DR

This study used a novel segmented Keck telescope configuration to perform a mid-infrared size survey of young stellar objects, revealing that their sizes do not follow the expected near-infrared size-luminosity relation and providing detailed imaging of complex structures.

Contribution

It introduces a new sparse-aperture interferometry technique with segment tilting for high-precision mid-infrared imaging of young stellar objects.

Findings

Most objects are partially resolved in mid-infrared.

Mid-infrared sizes deviate from near-infrared size-luminosity relation.

Detailed images of complex emission and binary systems.

Abstract

The mid-infrared properties of pre-planetary disks are sensitive to the temperature and flaring profiles of disks for the regions where planet formation is expected to occur. In order to constrain theories of planet formation, we have carried out a mid-infrared (wavelength 10.7 microns) size survey of young stellar objects using the segmented Keck telescope in a novel configuration. We introduced a customized pattern of tilts to individual mirror segments to allow efficient sparse-aperture interferometry, allowing full aperture synthesis imaging with higher calibration precision than traditional imaging. In contrast to previous surveys on smaller telescopes and with poorer calibration precision, we find most objects in our sample are partially resolved. Here we present the main observational results of our survey of 5 embedded massive protostars, 25 Herbig Ae/Be stars, 3 T Tauri stars, 1 FU Ori system, and 5 emission-line objects of uncertain classification. The observed mid-infrared sizes do not obey the size-luminosity relation found at near-infrared wavelengths and a companion paper will provide further modelling analysis of this sample. In addition, we report imaging results for a few of the most resolved objects, including complex emission around embedded massive protostars, the photoevaporating circumbinary disk around MWC 361A, and the subarcsecond binaries T Tau, FU Ori and MWC 1080.