info:eu-repo/semantics/article
Kinematics of gas and stars in the circumnuclear starforming ring of NGC3351
Autor
ELENA KIRILOVSKY TERLEVICH
ROBERTO GIOVANNI TERLEVICH AFONSO
Institución
Resumen
We have measured gas and stellar velocity dispersions in 5 circumnuclear starforming regions (CNSFRs) and the nucleus of the barred spiral galaxy NGC3351. The stellar dispersions have been obtained from high resolution spectra of the CaT lines at λλ8494, 8542, 8662Å, while the gas velocity dispersions have been measured by Gaussian fits to the Hβλ 4861 Å line on high dispersion spectra. The CNSFRs, with sizes of about 100 to 150 pc in diameter, are seen to be composed of several individual star clusters with sizes between 1.7 and 4.9 pc on an HST image. Using the stellar velocity dispersions, we have derived dynamical masses for the entire starforming complexes and for the individual star clusters. Values of the stellar velocity dispersions are between 39 and 67kms⁻¹. Dynamical masses for the whole CNSFRs are between 4.9x10⁶ and 4.3x10⁷Mꙩ and between 1.8 and 8.7x10⁶Mꙩ for the individual star clusters. Stellar and gas velocity dispersions are found to differ by about 20kms⁻¹ with the Hβ lines being narrower than both the stellar lines and the [OIII]λ5007Å lines. We have found indications for the presence of two different kinematical components in the ionised gas of the regions. The radial velocity curve shows deviation from circular motions for the ionised hydrogen consistent with its infall towards the central regions of the galaxy at a velocity of about 25kms⁻¹. To disentangle the origin of these two components it will be necessary to map these regions with high spectral and spatial resolution and much better S/N in particular for the O²⁺ lines.