SpitzerObservations of the New Luminous Red Nova M85 OT2006‐1

M85OT2006-1 is the latest and most brilliant addition to the small group ofknown Luminous Red Novae (LRNe). An identifying characteristic of thepreviously detected events (M31 RV, V4322 Sgr & V838 Mon) was a spectralred-ward evolution connected with an emerging infrared component following theoptical decay. Here we report on the discovery of a similar feature inKeck/NIRC and Spitzer photometry of M85OT2006-1 six months post-eruption. Wefind that its 2.1-22 micrometer spectral energy distribution is best describedby a black body with effective temperature T_eff=950+-150 K and bolometricluminosity L=2.9+-0.5x10^5 L_sun. Assuming spherical geometry, the black bodyeffective radius, R=2.0+-0.5x10^4 R_sun, and corresponding expansion velocity,v=870+-260 km/s, are remarkably similar to the properties of M31 RV 70 daysafter its eruption. Furthermore, we propose a search strategy for LRNe in thelocal Universe making use of the longevity of their infrared excess emissionand discuss the expected number of events in the Spitzer Infrared NearbyGalaxies Survey.Comment: manuscript after minor revisions, accepted for Ap