ar X iv : a st ro - p h / 04 05 53 6 v 2 7 J un 2 00 4 To appear in ApJ 9 / 04 A Minimum - Mass Extrasolar Nebula

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β < 2, the center of the disk is the likely cradle of planet formation. Subject headings: planetary systems: protoplanetary disks — solar system formation