SIMBAD references

We report limits in the planetary-mass regime for companions around the nearest single white dwarf to the Sun, van Maanen's star (vMa2), from deep J-band imaging with Gemini North and Spitzer Infrared Array Camera (IRAC) mid-IR photometry. We find no resolved common proper motion companions to vMa2 at separations from 3 to 45 arcsec, at a limiting magnitude of J ∼ 23. Assuming a total age for the system of 4.1±1Gyr, and utilizing the latest evolutionary models for substellar objects, this limit is equivalent to companion masses >7±1M_Jup(T_eff∼ 300K). Taking into account the likely orbital evolution of very low mass companions in the post-main-sequence phase, these J-band observations effectively survey orbits around the white dwarf progenitor from 3 to 50au. There is no flux excess detected in any of the complimentary Spitzer IRAC mid-IR filters. We fit a white dwarf model atmosphere to the optical BVRI, JHK and IRAC photometry. The best solution gives T_eff = 6030±240K, logg = 8.10±0.04 and, hence, M = 0.633±0.022M_solar. We then place a 3σ upper limit of 10±2M_Jup on the mass of any unresolved companion in the 4.5µm band.