WISDOM Project - XXVII. Giant molecular clouds of the lenticular galaxy NGC 1387: similarities with spiral galaxy clouds

TL;DR

This study analyzes the properties of giant molecular clouds in the lenticular galaxy NGC 1387, revealing similarities with spiral galaxy clouds and highlighting diversity in molecular cloud characteristics within early-type galaxies.

Contribution

First detailed high-resolution analysis of GMCs in an early-type galaxy showing their properties are similar to those in spiral galaxies, challenging previous assumptions.

Findings

GMCs in NGC 1387 follow Milky Way-like scaling relations.

Most GMCs are virialised.

GMC properties show diversity and are influenced by galactic rotation and viewing angle.

Abstract

Molecular gas is crucial to understanding star formation and galaxy evolution, but the giant molecular clouds (GMCs) of early-type galaxies (ETGs) have rarely been studied. Here, we present analyses of the spatially resolved GMCs of the lenticular galaxy NGC 1387, exploiting high spatial resolution (0.15" or 14 pc) 12CO(2-1) line observations from the Atacama Large Millimeter/submillimeter Array. We identify 1285 individual GMCs and measure the fundamental properties (radius, velocity dispersion, and molecular gas mass) of each with a modified version of the CPROPStoo package. Unusually for an ETG, the GMCs of NGC 1387 follow scaling relations very similar to those of the Milky Way disc and Local Group galaxy clouds, and most are virialised. GMCs with large masses and radii and/or small galactocentric distances have their angular momenta aligned with the large-scale galactic rotation, while other GMCs do not. These results show that ETGs have more diversified GMC properties than previously thought. We discuss potential reasons for such diversity, and viewing-angle dependency is a plausible candidate.