Mrk 938 is a luminous infrared galaxy in the local Universe believed to be the remnant of a galaxy merger .
It shows a Seyfert 2 nucleus and intense star formation according to optical spectroscopic observations .
We have studied this galaxy using new Herschel far-IR imaging data in addition to archival X-ray , UV , optical , near-IR and mid-IR data .
Mid- and far-IR data are crucial to characterise the starburst contribution , allowing us to shed new light on its nature and to study the coexistence of AGN and starburst activity in the local Universe .
The decomposition of the mid-IR Spitzer spectrum shows that the AGN bolometric contribution to the mid-IR and total infrared luminosity is small ( L _ { bol } ( AGN ) / L _ { IR } \sim 0.02 ) , which agrees with previous estimations .
We have characterised the physical nature of its strong infrared emission and constrained it to a relatively compact emitting region of \leq 2 kpc .
It is in this obscured region where most of the current star formation activity is taking place as expected for LIRGs .
We have used Herschel imaging data for the first time to constrain the cold dust emission with unprecedented accuracy .
We have fitted the integrated far-IR spectral energy distribution and derived the properties of the dust , obtaining a dust mass of 3 \times 10 ^ { 7 } { M } _ { \odot } .
The far-IR is dominated by emission at 35 K , consistent with dust heated by the on-going star formation activity .