Effect of envelope density on the CO snowline location. Molecular distributions are shown in the top four rows. The fifth row shows the intensity integrated simulated line emission maps for N₂H⁺ 1−0. Images that have been scaled for better comparison have the scaling factor on the top right corner. The sixth row shows the corresponding slice extracted along z = 0 from the N₂H⁺ simulated emission maps. The average distance of the peaks from the center (i.e., peak radius) is indicated in AU in the top left corner. These positions are shown with orange vertical lines. No scaling has been applied to the N₂H⁺ profiles. The second and fifth columns show the fiducial model without and with disk, respectively, having a density of ρ_env = 10⁶ cm⁻³. First and fourth columns show densities of ρ_env = 10⁵ cm⁻³, while the third and sixth columns show ρ_env = 10⁷ cm⁻³. Fractional abundances of all molecular species are relative to total number density of H₂ (top row). The black and gray contours show gas temperature and density, respectively. The simulated line emission maps are shown at i = 45° and convolved to a beam of 2″.