The NGC 454 system: anatomy of a mixed ongoing merger

Journal
Date Issued
2017
Author(s)
Plana, H.
•
•
•
•
Amram, Ph.
•
Ribeiro, A. L. B.
DOI
Abstract
This paper focuses on NGC 454, a nearby interacting pair of galaxies (AM 0112-554, RR23), composed of an early-type (NGC 454 E) and a star-forming late-type companion (NGC 454 W). We aim at characterizing this wet merger candidate via a multi-λ analysis, from near-UV (NUV) to optical using Swift UV/Optical Telescope (UVOT), and mapping the H α intensity (I) distribution, velocity (Vr) and velocity dispersion (σ) fields with SAM+Fabry-Perot@SOAR observations. Luminosity profiles suggest that NGC 454 E is an S0. Distortions in its outskirts caused by the ongoing interaction are visible in both optical and NUV frames. In NGC 454 W, the NUV-UVOT images and the H α show a set of star-forming complexes connected by a faint tail. H α emission is detected along the line connecting NGC 454 E to the NGC 454 main H II complex. We investigate the (I-σ), (I-Vr) and (Vr-σ) diagnostic diagrams of the H II complexes, most of which can be interpreted in a framework of expanding bubbles. In the main H II complex, enclosed in the UV brightest region, the gas velocity dispersion is highly supersonic reaching 60 km s-1. However, H α emission profiles are mostly asymmetric indicating the presence of multiple components with an irregular kinematics. Observations point towards an advanced stage of the encounter. Our smoothed particle hydrodynamic simulations with chemo-photometric implementation suggest that this mixed pair can be understood in terms of a 1:1 gas/halo encounter giving rise to a merger in about 0.2 Gyr from the present stage.
Volume
472
Issue
3
Start page
3074
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2017MNRAS.472.3074P
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

NGC454_arxiv.pdf

Size

7.78 MB

Format

Adobe PDF

Checksum (MD5)

bb75f175e74395e2e682f48d69978121

Loading...
Thumbnail Image
Name

NGC454_editoriale.pdf

Description
PDF editoriale
Size

7.03 MB

Format

Adobe PDF

Checksum (MD5)

4c18623a4a1bdb848afb7b33f6efc9ef