Near-Infrared Water Lines in V838 Monocerotis

V838 Monocerotis had an intriguing, nova-like outburst in January 2002 whichhas subsequently led to several studies of the object. It is now recognizedthat the outburst of V838 Mon and its evolution are different from that of aclassical nova or other classes of well-known eruptive variables. V838 Mon,along with two other objects that have analogous properties, appears tocomprise a new class of eruptive variables. There are limited infrared studiesof V838 Mon. Here, we present near-infrared H band (1.5 - 1.75micron) spectraof V838 Mon from late 2002 to the end of 2004. The principal, new result fromour work is the detection of several, rotation-vibration lines of water in theH band spectra. The observed water lines have been modeled to first establishthat they are indeed due to water. Subsequently the temperature and columndensities of the absorbing material, from where the water absorption featuresoriginate, are derived. From our analysis, we find that the water featuresarise from a cool ~750-900 K region around V838 Mon which appears to begradually cooling with time.Comment: 11 pages, 2 figures. Accepted in Ap.J Letter