Revisiting the formation History of the minor-axis dust lane galaxy NGC1947

TL;DR

This study investigates the formation history of galaxy NGC1947, focusing on its dust lane and kinematic properties, to determine whether it resulted from merging or accretion, with evidence favoring external accretion.

Contribution

It provides a detailed analysis of NGC1947's structure and kinematics, offering new insights into its formation through accretion or merging scenarios.

Findings

Decoupled gas and dust rotate along the minor axis.

Stellar rotation occurs along the major axis.

Evidence suggests external accretion of gas and dust.

Abstract

In this paper we present a detailed study of the peculiar early-type galaxy NGC1947. The main goal of this work is to constrain the dynamical status and the formation history of NGC1947 by comparing the observed properties with the predictions derived from different galaxy formation scenarios. To this aim, we derived the photometric and kinematical properties of NGC1947. Due to the presence of an extended dust-lane, which crosses the galaxy center along the photometric minor axis, we used near-infrared images (J and K bands) to derive an accurate analysis of the stellar light distribution. Optical images (in the V and R bands) are used to derive the color profiles and color maps to study the structure of the dust-lane. The observed kinematics confirm the presence of two components with decoupled angular momentum: gas and dust rotate along the minor axis, while the rotation velocities of the stars are observed along the major axis. The complex structure observed in NGC1947 support the hypothesis that some kind of interactions happened in the evolution of this object. We analyzed two alternatives: a merging process and an accretion event. We discussed how the observed properties strongly suggest that the decoupled ring of gas and dust have been accreted from outside.