Study of the HII regions in the spiral galaxy NGC6384

TL;DR

This study analyzes 98 HII regions in galaxy NGC6384, examining their physical parameters, luminosity and diameter functions, and chemical composition gradients, providing insights into star formation and galaxy properties.

Contribution

It presents detailed measurements and analysis of HII regions in NGC6384, including their size, luminosity functions, and chemical abundance gradients, which are comparable to those in normal galaxies.

Findings

HII region diameters follow an exponential distribution with a characteristic size of 217 pc.

Luminosity function exhibits double power-law profile with a turnover at log L(H alpha)=38.75.

Negative radial gradient of [NII]/H alpha ratio indicates higher nitrogen abundance in the galaxy's center.

Abstract

The galaxy NGC6384 has been observed with an IPCS through H alpha and [NII] narrow-band interference filters for direct imagery with the 2.6 m Byurakan telescope. We studied main physical parameters of identified 98 HII regions, their diameter and luminosity functions, as well [NII]/H alpha ratio distribution. The integrated distribution function of the HII region diameters can be well fitted by the exponential function. The characteristic diameter has the value (Do = 217 pc) predicted for a galaxy of its measured absolute luminosity. The luminosity function of HII regions has double power laws profile with relatively shallow slope at low luminosities (a = - 0.4), an abrupt turnover at log L(H alpha) = 38.75, and sharper slope at higher luminosities (a = - 2.3). Correlation between luminosity and diameter of HII regions confirms that in general they are constant density, radiation-bound systems. [NII]/H alpha ratio data for HII regions show that there is a negative radial gradient of [NII]/H alpha. In the central region of the galaxy, nitrogen abundance is higher than in the periphery. The properties of the HII regions population of this AGN galaxy does not differs significantly from the properties of the HII regions population of the "normal" galaxies. Reexamining the location of the type Ia SN 1971L in the galaxy, we confirm that it lies on the spiral arm at about 8.6" far from the closest HII region #53 (F81). Such a location can be taken as prove that the progenitor of this SN do not belong to an old, evolved stellar population.