Brazilian astrophysicist Duilia de Mello is studying collisions of distant galaxies from images made by a team of amateur astronomers in Brazil.

Duilia de Mello. Photo: alumni.usp.br/reprodução

The collision between galaxies is one of the most incredible phenomena in the Universe. These are extremely time-consuming processes for the human time scale, and can last for several million, or even a few billion years.

Interestingly, due to the huge distances between stars in a galaxy, star shocks hardly occur during the collision of two galaxies. However, there is a huge mess generated by the gravitational interactions of the process. In the end, the stars are merged into a single galaxy, greatly deformed by the collision, but that is not all.

Simulation of the collision between the Milky Way and the Andromeda Galaxy. Credits: Universe Sandbox

Part of the matter that makes up these galaxies (gases, dust and even some stars), is launched into intergalactic space, where they can regroup forming star clusters, small peripheral galaxies and also some gas shells.

And these shells are the focus of the research developed by Brazilian astrophysicist Duilia de Mello, a researcher at the Catholic University of Washington and a collaborator at NASA's Goddard Space Center.

ARP 230 galaxy shells. Credits: DIM Team

The study of these gas shells allows us to learn more about the evolution of galaxies and the dynamics of their collisions. But to register them, it is necessary to take photos with several hours of exposure, and time is something that is increasingly difficult to obtain in large observatories.

To solve this problem, Mello used a resource in which Brazil is very well served: amateur astronomy. In an unprecedented initiative, she brought together a team of amateur astronomers, with experience in Astrophotography to contribute to the research.

The project was named Deep Images of Merges, or simply DIM. Today it initially has five amateur astronomers:

  • João Antônio Mattei, engineer and CEO of a civil construction company;
  • Marcelo Domingues, civil servant;
  • Cristóvão Jacques, engineer and entrepreneur;
  • Eduardo Oliveira, professor of Pharmaceutical Sciences at UFVJM;
  • Sérgio José Gonçalves da Silva, telecommunications engineer
Duilia de Mello and a team of amateur astronomers presenting the DIM Project during the National Astronomy Meeting in 2020. Credits: YouTube

These astronomers use their telescopes to make images of the galaxies studied by Mello. Obviously, these telescopes do not have the same quality and definition as the large professional telescopes. And to compensate for this problem, the team is working to integrate the images of several hours of exposure made by various telescopes in different locations in Brazil.

And the first results of this work were presented last week, at the Meeting of the American Astronomical Society. On the occasion, an image of the Centaurus A Galaxy was shown, made from the integration of photos that add up to 41 hours of exposure.

Centaurus A is a peculiar galaxy, located 14 million light years away, in the direction of the Centaur Constellation. It is the result of a collision between two smaller galaxies, and this collision is responsible for its irregular shape and the shells now seen in the DIM project.

Image of the Centaurus A Galaxy integrating 41 hours of exposure. In yellow, the shells identified in 1983 and in red, the new shells identified by the Brazilian team. Photo: DIM Team

In addition to the shells already observed in this galaxy, the Brazilian team identified 9 new shells around Centaurus A, once again proving the excellence of Brazilian amateur astronomy and the scientific potential of partnerships like this, idealized by Mello.

Text by Marcelo Zurita, president of the Paraibana Astronomy Association - APA; member of SAB - Sociedade Astronômica Brasileira; technical director of Bramon - Brazilian Meteor Observation Network - and regional coordinator (Northeast) of Asteroid Day Brasil