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The circumnuclear environment of the peculiar galaxy NGC 3310

Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC3310 using high resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet in the near-IR, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the Hb 4861A and [OIII]5007A emission lines. The CNSFRs stellar velocity dispersions range from 31 to 73 km/s. These values, together with the sizes measured on archival HST images, yield upper limits to the dynamical masses for the individual star clusters between 1.8 and 7.1 x 10$^6$ M$_\odot$, for the whole CNSFR between 2 x 10$^7$ and 1.4 x 10$^8$ M$_\odot$, and 5.3 x 10$^7$ M$_\odot$ for the nucleus inside the inner 14.2 pc. The masses of the ionizing stellar population responsible for the HII region gaseous emission have been derived from their published Ha luminosities and are found to be between 8.7 x 10$^5$ and 2.1 x 10$^6$ M$_\odot$ for the star-forming regions, and 2.1 x 10$^5$ M$_\odot$ for the galaxy nucleus; they therefore constitute between 1 and 7 per cent of the total dynamical mass. The ionized gas kinematics is complex; two different kinematical components seem to be present as evidenced by different line widths and Doppler shifts.