New Space Archaeology Method Shows How NGC 1365 Galaxy Grew Over 12 Billion Years

Scientists can now study galaxy history using chemical 'fingerprints' in gas. This is like finding ancient clues in space to see how galaxies like NGC 1365 grew over billions of years.
By Newsroom | Astronomy, Science |

Extragalactic Archaeology Emerges as a Tool for Galactic Histories

Astronomers have unveiled what they term 'extragalactic archaeology,' a novel methodology that probes the past of galaxies by analyzing the chemical composition of their gas. This technique, detailed in Nature Astronomy, has provided an unprecedentedly detailed, dynamic history of a giant spiral galaxy, specifically NGC 1365. This approach allows researchers to reconstruct a galaxy's evolution over billions of years by examining chemical fingerprints within its interstellar clouds. The method’s success suggests it could become a standard for future galaxy evolution studies.

'Space archaeology' reveals first dynamic history of a giant spiral galaxy - 1

The researchers focused on chemical signatures, such as hydrogen, nitrogen, and sulfur, within the galaxy's gas. These elements act as 'chemical fingerprints,' revealing where and when they formed. For instance, the presence of significant amounts of oxygen in a galaxy's outer regions suggests those regions once resided closer to the galactic center, implying substantial movement over cosmic time. This analytical process allows scientists to map the distribution and evolution of elements, effectively piecing together a galaxy's life story, including its formation, growth, and interactions with other celestial bodies.

Read More: Brown Dwarfs Orbiting Hourly May Merge or Become Stars

'Space archaeology' reveals first dynamic history of a giant spiral galaxy - 2

The study, led by Lisa Kewley, Director and Scientist at the Center for Astrophysics | Harvard & Smithsonian, utilized data from the TYPHOON survey. This survey employed the 'step-and-stare' observation method, providing exceptionally high-resolution data that enabled the study of individual star-forming clouds within NGC 1365. This level of detail was crucial for dissecting the galaxy’s chemical composition and inferring its historical processes.

'Space archaeology' reveals first dynamic history of a giant spiral galaxy - 3

A Deep History of Mergers and Growth

The 'archaeological' findings reveal that NGC 1365, a galaxy similar in structure to our own Milky Way, began as a smaller entity. Over approximately 12 billion years, it grew into its current massive spiral form through numerous mergers with smaller dwarf galaxies. The central region of the galaxy is indicated to have formed very early in cosmic history, becoming rich in oxygen, while its outer arms developed later through these accretional events. This contrasts with a galaxy that might form uniformly over time.

Read More: Cadell Last's Philosophy Portal Changes How We Think About Reality

'Space archaeology' reveals first dynamic history of a giant spiral galaxy - 4

The scientific endeavor seeks to answer fundamental questions about galactic origins, including the formation of our own Milky Way and the distribution of elements essential for life, such as oxygen. By comparing distant galaxies with our own, researchers aim to ascertain whether the Milky Way is unique or follows a common evolutionary path.

The collaborative effort involved a range of institutions, including the Center for Astrophysics | Harvard & Smithsonian, the Australian National University, the University of Florida, the University of Virginia, and the Carnegie Institution for Science. Key figures beyond Kewley include Kathryn Grasha, Alex Garcia, Paul Torrey, Jeff Rich, and Barry Madore.

Background

'Extragalactic archaeology' draws parallels with earth-based archaeology and the existing field of 'galactic archaeology,' which reconstructs the Milky Way's history using stellar records. However, this new approach extends such detailed analysis to galaxies beyond our immediate cosmic neighborhood. The ability to study galaxies from a single perspective, as is often the case with distant objects, presents challenges that this chemical analysis method aims to overcome.

Read More: Webb Telescope Sees New Stars Forming in Galaxy NGC 628

Frequently Asked Questions

Q: What is 'extragalactic archaeology' and how does it work?
'Extragalactic archaeology' is a new way scientists study galaxy history. They look at the chemicals in the gas inside galaxies, like finding clues. These chemical 'fingerprints' show where and when the gas formed, helping to build a galaxy's life story.
Q: What did scientists learn about the NGC 1365 galaxy using this new method?
Scientists found that the NGC 1365 galaxy grew over 12 billion years. It started small and became a big spiral galaxy by joining with smaller galaxies. The center formed very early, and the outer parts grew later.
Q: Why is studying the chemical makeup of gas in galaxies important?
The chemicals in gas, like oxygen, act like 'fingerprints.' They tell scientists about the galaxy's past, such as how it formed and grew. This helps us understand how galaxies, including our own Milky Way, change over time.
Q: What does the presence of oxygen in outer galaxy regions suggest?
Finding a lot of oxygen in the outer parts of a galaxy suggests that those areas were once closer to the galaxy's center. This means parts of the galaxy have moved around a lot over billions of years.
Q: Which scientists and groups worked on this 'space archaeology' study?
This study involved scientists from the Center for Astrophysics | Harvard & Smithsonian, the Australian National University, the University of Florida, the University of Virginia, and the Carnegie Institution for Science.