NGC 4102: High Resolution Infrared Observations of a Nuclear Starburst Ring

TL;DR

This study uses high-resolution infrared observations to analyze the nuclear starburst ring in galaxy NGC 4102, revealing its structure, star formation activity, and properties of the nuclear region.

Contribution

It provides detailed spatial and spectral mapping of the starburst ring in NGC 4102, highlighting its size, mass, and star formation characteristics with high-resolution infrared data.

Findings

Star formation is confined to a 300 pc ring inside the Inner Lindblad Resonance.

The nuclear region has a dynamical mass of approximately 3 billion solar masses.

Young stars in the ring account for the majority of the galaxy's [NeII] emission.

Abstract

The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5" spatial and 25 km/s spectral, resolution. Combining near-infrared, radio, and the [NeII] data shows that the extinction to the starburst is substantial, more than 2 magnitudes at K band, and that the neon abundance is less than half solar. We find that the star formation in the nuclear region is confined to a rotating ring or disk of 4.3" (~300 pc) diameter, inside the Inner Lindblad Resonance. This region is an intense concentration of mass, with a dynamical mass of ~3 x 10^9 solar masses, and of star formation. The young stars in the ring produce the [NeII] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [NeII]; it is not a normal AGN outflow.