NGC 4102: High-resolution Infrared Observations of a Nuclear Starburst Ring

• Published in: The Astrophysical journal Vol. 722; no. 2; pp. 1175 - 1179
• Main Authors: Beck, Sara C, Lacy, John H, Turner, Jean L
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 20-10-2010; IOP
• Subjects: ABUNDANCE; Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Earth, ocean, space; ELEMENTS; EMISSION; Exact sciences and technology; FLUIDS; GALAXIES; GASES; MEASURING INSTRUMENTS; NEON; NONMETALS; RARE GASES; SPECTROMETERS; STARS; Rotating ring; galaxies: starburst; Starburst galaxies; Infrared observation; galaxies: individual (NGC 4102); Abundance; Emission line galaxies; M stars; Lindblad resonance; Young stars; Active galaxies; Star formation; Dynamics; Rotating disk; Active galaxy nuclei; Kinematics; Galaxy nuclei; Emission line; galaxies: kinematics and dynamics; Diameter
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/722/2/1175

The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 Delta *mm line of [Ne II], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 15 spatial, and 25 km s--1 spectral, resolution. Combining near-infrared, radio, and the [Ne II] data shows that the extinction to the starburst is substantial, more than 2 mag at the 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 43 (~300 pc) diameter, inside the inner Lindblad resonance. This region is an intense concentration of mass, with a dynamical mass ~3 X 109 M , and of star formation. The young stars in the ring produce the [Ne II] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [Ne II]; it is not a normal active galactic nucleus outflow.