The interstellar medium in the Seyfert galaxy NGC 7172

We present aperture and surface photometry of the Seyfert galaxy NGC 7172, which is a member of the compact group HCG90, and has a prominent equatorial dust lane. We use the observed colour excess in the dust lane, obtained from broad-band B and V images, to estimate the neutral hydrogen content as $M_{H 1}^{tot}=2.6\times 10^8\enspace \text M_\odot$ and $\text {log}(M_{H1}/L_B)=-1.8.$ We analyse the flux from NGC 7172 at various wavelengths and discuss the properties of the interstellar medium in the galaxy. Based on the results from surface photometry, and the properties of the interstellar medium, we conclude that the morphology of NGC 7172 is of type S0–Sa.