Mass of IF1 (top panel), radial distance of IF1 (middle panel), and central temperature of IF1 (bottom panel), all vs. time. The horizontal dashed line shows a threshold temperature of 2000 K, above which molecular hydrogen dissociates and the second collapse is supposed to ensure. The vertical dashed line shows the time instance when the central temperature of IF1 reaches the threshold value. The red circles indicate time instances at which the mass growth rate of IF1 is calculated: (1) 6.6 × 10⁻³ M_Jup yr⁻¹, (2) 1.45× 10⁻² M_Jup yr⁻¹, (3) − 1.8 × 10⁻² M_Jup yr⁻¹, and (4) − 3.3 × 10⁻² M_Jup yr⁻¹.