Parallel-sequencing of early-type and spiral galaxies

TL;DR

Recent research suggests a closer evolutionary connection between spiral galaxies and early-type galaxies than traditionally believed, challenging the classic Hubble tuning fork classification.

Contribution

The paper reviews recent findings that revise the traditional view, indicating a closer link and potential evolutionary connection between spiral galaxies and early-type galaxies.

Findings

New evidence links spiral and early-type galaxies more closely.

Revised understanding of galaxy formation pathways.

Challenging the traditional Hubble classification.

Abstract

Since Edwin Hubble introduced his famous tuning fork diagram more than 70 years ago, spiral galaxies and early-type galaxies (ETGs) have been regarded as two distinct families. The spirals are characterized by the presence of disks of stars and gas in rapid rotation, while the early-types are gas poor and described as spheroidal systems, with less rotation and often non-axisymmetric shapes. The separation is physically relevant as it implies a distinct path of formation for the two classes of objects. I will give an overview of recent findings, from independent teams, that motivated a radical revision to Hubble's classic view of ETGs. These results imply a much closer link between spiral galaxies and ETGs than generally assumed.