Near- and Mid-Infrared Imaging Study of Young Stellar Objects around LkHα 234

Abstract

Abstract We present high-resolution (0$''\!\!\!.$2) near-infrared images of the area surrounding the Herbig Be star LkH$\alpha $ 234 taken with the Coronagraphic Imager with Adaptive Optics (CIAO) and the adaptive optics on the Subaru Telescope. The near-infrared ($J$, $H$, $K$, $L'$, and $M'$ bands) images reveal circumstellar structures around LkH$\alpha $ 234 in detail. Eight young stellar object (YSO) candidates (Object B, C, D, E, F, G, NW1, and NW2) were detected at 2$\arcsec$–11$\arcsec$ from LkH$\alpha $ 234. Objects B and C are likely variable stars, which is consistent with a young evolutionary status. Three objects (LkH$\alpha $ 234, NW1, and NW2) were identified in the 11.8$\ \mu$m (SiC) and 17.65$\ \mu$m images obtained with the Long Wavelength Spectrometer (LWS) on the Keck Telescope. NW1 and NW2 are thought to be embedded young stars. We suggest that NW1, and not LkH$\alpha $ 234, is the source illuminating the reflection nebula west of LkH$\alpha $ 234, although Object G may be another candidate. In our images, these objects are located at the center of the 2$\ \mu$m polarization, and NW1 resides at the center of a monopolar cavity. The SED of NW1 suggests that it is a YSO with a spectral type of B6–B7. Object F and G were discovered by our observations at 1$''\!\!\!.$9 and 2$''\!\!\!.$3, respectively, from LkH$\alpha $ 234, and their proximity to LkH$\alpha $ 234 suggests that they may be its lower-mass companions.