IS ESO H-ALPHA-279 A PRE-MAIN-SEQUENCE BINARY

We present 1-3.4 mum near-IR array images of ESO Halpha 279, the optic al emission line star proposed to be the exciting source of the bipola r Herbig-Haro complex HH106/107 in Serpens. These images show the pres ence of a close, bright infrared stellar companion to ESO Halpha 279 l ocated 8.2'' due south. At 2 mum, no other sources are seen within app roximately 1' of these stars suggesting that ESO Halpha 279 and its co mpanion may form a pre-main sequence (PMS) binary. Our NIR photometry has shown that the optical emission line star, ESO Halpha 279a, is a y oung, PMS object possessing a strong thermal excess beyond 2 mum. Addi tionally, 2 mum spectroscopy has revealed that ESO Halpha 279a possess es very strong CO bandhead emission from 2.29-2.45 mum indicative of t he presence of an active accretion disk and/or molecular outflow. The companion source, ESO Halpha 279b, was found to be extremely red with a J-K approximately 7. Spectroscopy showed that it possesses strong CO bandhead absorption. From both the relative strengths of the deredden ed spectral features and evidence provided by the near-IR photometry, we suggest that ESO Halpha 279b is likely not a PMS companion to ESO H alpha 279a, but rather it is a highly reddened (A(V)=30-40) background M5 III giant. This result emphasizes the extreme care that needs to b e taken when using infrared imaging data to study the frequency of bin aries amongst PMS stars.