A candidate substellar companion to HR 7329

We present the discovery of a candidate substellar companion from a survey of nearby young stars made with the Near-Infrared Camera and Multiobject Sp ectrometer coronagraph on the Hubble Space Telescope. The H approximate to 12 mag object was discovered approximately 4 " from the young A0 V star HR 7329. Using follow-up spectroscopy from the Space Telescope Imaging Spectro graph, we derive a spectral type between M7 V and M8 V with an effective te mperature of similar to 2600 K. We estimate that the probability of a chanc e alignment with a foreground dwarf star of this nature is similar to 10(-8 ), and therefore we suggest that the object (HR 7329B) is physically associ ated with HR 7329, with a projected separation of 200 AU. Current brown dwa rf cooling models indicate a mass of less than 50 M-Jup for HR 7329B based on age estimates of less than or equal to 30 Myr for HR 7329A.