Top: regions of non-zero HCO+ (blue) and DCO+ (red) abundance, overlaid with contours indicating the hydrogen density (solid gray lines) and temperature (dashed gray lines). The 19 and 21 K contours are shown with a thick dark gray line. The region containing HCO+ is bounded on the upper and lower sides by CO photodissociation and by freezeout at 19 K, respectively. The DCO+ region is bounded by the temperature range 19–21 K. Bottom: the column density of HCO+ and its isotopologues (colored lines), with the 19 K CO snowline indicated by the thick dark gray dashed line. The broad plateau of the DCO+ column density from ~110–150 AU explains the ring morphology seen in line emission. The 3σ line sensitivities (from Sect. 3.2) are shown with the horizontal gray lines.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.