Formation of primordial gas envelopes atop rocky interiors embedded at 1 au in the MMSN of C. Hayashi (1981), with the gas density depleted by a factor of f_dep = 10⁻². Top: radial profiles (solid) of the temperature and pressure (T, P) of the envelope with mass M_env for a rocky interior of mass M_rock = 0.2 M_⊕, extending from the radius of the rocky interior R_rock to the Bondi radius R_B. Each color represents a hydrostatic snapshot of the envelope for specific values of M_env/M_rock. The dotted line indicates the melting temperature T_melt ≈ 1800 K of the basaltic mantle. Center: the same as the top, but for M_rock = 0.3 M_⊕. Bottom: the envelope-to-rock mass ratio M_env/M_rock over the accretion timescale t_acc for M_rock = 0.2 M_⊕ (solid) and M_rock = 0.3 M_⊕ (dashed). A dotted vertical line shows the maximal disk lifetime (E. E. Mamajek 2009), and a horizontal dotted line denotes the isothermal end state of the M_rock = 0.2 M_⊕ case. Values of t_acc for which the rocky interior is molten are indicated in red.