The nature of the KW object^*

¹ Astronomisches Institut der Ruhr-Universität Bochum, Universitätsstrasse 150/NA 7, 44780 Bochum, Germany e-mail: chini@astro.ruhr-uni-bochum.de
² Institut für Astrophysik, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
³ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany

Received: 15 January 2004
Accepted: 2 August 2004

Abstract

The KW object, which has been one of the most puzzling infrared sources for three decades, has been resolved into a system of two early B-type stars with a projected separation of 2600 AU. While the more luminous component shows a huge IR excess due to circumstellar dust, the fainter one displays X-ray emission. The system is deeply embedded ( mag) in the molecular cloud M 17 SW and associated with an IR reflection nebula. A radiative transfer model of the spectral energy distribution of the IR excess object requires a stellar source of 5.1   – equivalent to a B0 star – surrounded by 10  of circumstellar material. The KW object is associated with a small cluster of about 150 red stars. The stellar density within 0.1 pc is >2.4  10³ pc^-3. From all new evidence we suggest that the KW object is one of the youngest, most deeply embedded Herbig Be stars known to date.