NEAR-IR PHOTOMETRIC STUDY OF THE FU ORIONIS OBJECT HBC 722

Abstract

We present near-infrared light curves of HBC 722 after its the September 2010 outburst. We have been monitoring its near-infrared light curves since November 2010 with Korean Astronomy and Space Science Institute Infrared Camera System (KASINICS). HBC 722 exhibits large changes in optical and near-infrared brightness since its outburst. The J, H, and <TEX>$K_s$</TEX> light curves over about 2.5 years show that in all observed bands HBC 722 progressively became fainter until around April 2011, down to J ~10.7, H ~9.9, <TEX>$K_s$</TEX> ~9.3, but it is getting brighter again. Large scatter in the obtained light curve prevents us from finding whether there is any short timescale variation as reported in other optical observations. The near-infrared color of HBC 722 is becoming bluer since its outburst. The pre-outburst Spectral Energy Distribution (SED) of HBC 722 is consistent with that of a slightly reddened Class II YSO with the exception of the extraordinary IR-excess in the far-infrared region.