Understanding Galaxies

Many people are aware from basic science classes that our solar system resides in the Milky Way galaxy. In essence, a galaxy is a vast assembly of stars, planets, and all existing matter, bound together by gravitational forces along with an enigmatic substance known as dark matter. Galaxies can be categorized into three primary types, a system initially proposed by Edwin P. Hubble and later refined by astronomer Gerard de Vaucouleurs.

1. Spiral Galaxies: The most prevalent type, characterized by large rotating disks of stars encircled by a halo of dark matter. These galaxies typically host supermassive black holes at their centers.
2. Elliptical Galaxies: These are generally oval-shaped and are predominantly located in clusters or smaller groups. They mostly comprise older, low-mass stars and lack the raw materials necessary for star formation.
3. Irregular Galaxies: As the name implies, these galaxies do not have a defined shape. They can be observed from Earth, such as the Small Magellanic Cloud, and may still have some capacity for active star formation.

The Milky Way, a spiral galaxy, spans approximately 100,000 light-years and is estimated to harbor between 200 and 400 billion stars. However, our focus is on the fate of certain galaxies situated in the far reaches of the Universe. These galaxies are experiencing a cessation of star formation, which astronomers describe as "dying." The crucial question is: why is this happening?

The Virgo Environment Traced in Carbon Monoxide survey (VERTICO), led by astrophysicist Toby Brown from McMaster University, aims to uncover these answers. This initiative is a collaborative effort involving researchers from Europe, the United States, Canada, Japan, South Korea, Taiwan, and Chile.

Since its inception in 2013, with a budget of $1.4 billion, the team is investigating 51 galaxies within our closest Virgo Cluster, hoping to identify similar phenomena. A team of 30 experts is employing the ALMA Observatory in Northern Chile for their research.

The Virgo Cluster has been selected due to its proximity as the nearest massive galaxy cluster and its ongoing formation process, making it an ideal site to examine the life cycle of galaxies and gain insights into why star formation may be diminishing in others.

So far, astronomers have proposed two potential explanations for this phenomenon. The first involves Ram Pressure Stripping, where star-forming gas is expelled by neighboring intergalactic plasma.

The second hypothesis suggests that the environment within a galactic cluster becomes excessively heated, preventing cosmic gases from cooling and condensing into stars. As these gases are utilized in such a hot setting, the entire star formation process gradually comes to a halt.

The VERTICO program ultimately aims to unravel the mystery of why galaxies cease star formation and to enhance our understanding of galaxy formation in the most distant and densely populated areas of the Universe.

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