Context :

Aims : We analyze the distribution of the molecular gas and the dust in the molecular clump linked to IRAS 10361-5830 , located in the environs of the bubble-shaped H ii region Gum 31 in the Carina region , with the aim of determining the main parameters of the associated material and investigating the evolutionary state of the young stellar objects identified there .

Methods : Using the APEX telescope , we mapped the molecular emission in the J = 3-2 transition of three CO isotopologues , ^ { 12 } CO , ^ { 13 } CO and C ^ { 18 } O , over a 1 \aas@@fstack { \prime } 5 \times 1 \aas@@fstack { \prime } 5 region around the IRAS position .
We also observed the high density tracers CS and HCO ^ { + } toward the source .
The cold dust distribution was analyzed using submillimeter continuum data at 870 \mu m obtained with the APEX telescope .
Complementary IR and radio data at different wavelengths were used to complete the study of the ISM .

Results : The molecular gas distribution reveals a cavity and a shell-like structure of \sim 0.32 pc in radius centered at the position of the IRAS source , with some young stellar objects ( YSOs ) projected onto the cavity .
The total molecular mass in the shell and the mean H _ { 2 } volume density are \sim 40 M _ { \odot } and \sim ( 1-2 ) \times 10 ^ { 3 } cm ^ { -3 } , respectively .
The cold dust counterpart of the molecular shell has been detected in the far-IR at 870 \mu m and in Herschel data at 350 \mu m. Weak extended emission at 24 \mu m from warm dust is projected onto the cavity , as well as weak radio continuum emission .

Conclusions : A comparison of the distribution of cold and warm dust , and molecular and ionized gas allows us to conclude that a compact H ii region has developed in the molecular clump , indicating that this is an area of recent massive star formation .
Probable exciting sources capable of creating the compact H ii region are investigated .
The 2MASS source 10380461-5846233 ( MSX G286.3773-00.2563 ) seems to be responsible for the formation of the H ii region .