26-08-2009   13:30 hs.


Dr. Guillermo Haguele – Universidad Autónoma de Madrid

Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 3310 using high resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the Ca{\sc ii} triplet in the near-IR, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H\beta \lambda 4861 and [OIII] \lambda 5007 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 7.1×10^6 solar masses, and upper limits to the masses for the whole CNSFR between 2×10^7 and 1.4×10^8 solar masses, and is 5.3×10^7 solar masses 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 H\alpha luminosities and are found to be between 8.7×10^5 and 2.1×10^6 solar masses for the star-forming regions, and 2.1×10^5 solar masses for the galaxy nucleus therefore constituting between 1 and 4 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 widths and Doppler shifts.

Publicado en Charlas de divulgación, 2009.

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