1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
2. Department of Physics & Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA
3. NASA/Ames Research Center, Moffett Field, California 94035, USA

Correspondence to: Gary J. Melnick¹ Correspondence and requests for materials should be addressed to G.J.M. (e-mail: Email: gmelnick@cfa.harvard.edu).

Abstract

Since 1995, planets with masses comparable to that of Jupiter have been discovered around approximately 60 stars¹. These planets have not been seen directly, but their presence has been inferred from the small reflex motions that they gravitationally induce on the star they orbit; these motions result in small periodic wavelength shifts in the stellar spectrum. The presence of analogues of the smaller bodies in our Solar System cannot, however, be determined using this technique, because the induced reflex motions are too small—so an alternative approach is needed. Here we report the observation of circumstellar water vapour around the ageing carbon star IRC+10216; water is not expected in measurable quantities around such a star. The only plausible explanation for this water is that the recent evolution of IRC+10216, which has been accompanied by a prodigious increase in its luminosity, is causing the vaporization of a collection of orbiting icy bodies—a process considered in an earlier theoretical study².