24/7 Space News
STELLAR CHEMISTRY
Large and small galaxies may grow in ways more similar than expected
illustration only
Large and small galaxies may grow in ways more similar than expected
by Daniel Stolte
Tucson AZ (SPX) Jan 17, 2025

A team of astronomers led by University of Arizona researcher Catherine Fielder has obtained the most detailed images of a small galaxy and its surroundings, revealing features typically associated with much larger galaxies. The observations provide a rare, elusive glimpse into how small galaxies form and evolve, suggesting that the mechanisms fueling galaxy growth may be more universal than previously thought.

Fielder presented the findings at the 245th meeting of the American Astronomical Society in National Harbor, Maryland, during a press briefing on Jan. 16.

Galaxies, including the Milky Way, grow and evolve by merging with smaller galaxies over billions of years in a process called hierarchical assembly. This cosmic "building block" approach has been well observed in large galaxies, where streams of ancient stars - remnants of swallowed-up galaxies - trace their turbulent history. These streams, along with other faint features such as old, scattered stars, form a so-called stellar halo: a sprawling, low-density cloud of stars that surrounds the bright central disk of a galaxy and traces its evolutionary history.

According to traditional wisdom, smaller galaxies such as the nearby Large Magellanic Cloud may have fewer opportunities to attract mass and merge with smaller systems, including other dwarf galaxies, because of their weaker gravitational pull. Understanding how such galaxies acquire mass and grow in the context of hierarchical assembly remains an open question.

The researchers used the Dark Energy Camera, or DECam, on the 4-meter Blanco Telescope in Chile's Cerro Tololo Inter-American Observatory to conduct a deep imaging survey of 11 dwarf galaxies, including the spiral galaxy NGC 300, which is similar in mass to the Large Magellanic Cloud. The observations were made as part of the DECam Local Volume Survey, or DELVE, and revealed unprecedented details of NGC 300's features. Spanning about 94,000 light-years, NGC 300's galactic disk is a little smaller than the Milky Way and packs only about 2% of its stellar mass.

"NGC 300 is an ideal candidate for such a study because of its isolated location," said Fielder, a research associate at the U of A Steward Observatory. "This keeps it free from the influential effects of a massive companion like the Milky Way, which affects nearby small galaxies like the Large Magellanic Cloud. It's almost a bit like looking at a cosmic 'fossil record.'"

Fielder and her collaborators created stellar maps around the small galaxy and discovered a vast stellar stream extending more than 100,000 light-years from the galaxy's center.

"We consider a stellar stream a telltale sign that a galaxy has accreted mass from its surroundings, because these structures don't form as easily by internal processes," said Fielder, whose findings will be published in The Astrophysical Journal.

In addition, the researchers found traces of stars arranged in shell-like patterns reminiscent of concentric waves emanating from the center of the galaxy, as well as hints of a stream wrap - evidence that whatever caused the stream may have changed direction in its orbit around NGC 300.

"We weren't sure we were going to find anything in any of these small galaxies," she said. "These features around NGC 300 provide us with 'smoking gun' evidence that it did accrete something."

The team also identified a previously unknown, metal-poor globular star cluster in the galaxy's halo, another "smoking gun" of past accretion events.

When gauging the age of stellar populations, astronomers frequently turn to a feature known as "metallicity" - a term referring to the chemical elements present inside stars. Because heavier elements are forged mostly in more massive stars at or near the end of their lifespans, it takes several generations of star formation to enrich those elements. Therefore, stellar populations lacking heavier elements - or having low metallicity - are presumed to be older, Fielder explained.

"The stars in the features we observed around NGC 300 are ancient and metal-poor, telling a clear story," Fielder said. "These structures likely originated from a tiny galaxy that was pulled apart and absorbed into NGC 300."

Together, these findings clearly reveal that even dwarf galaxies can build stellar halos through the accretion of smaller galaxies, echoing the growth patterns seen in larger galaxies, Fielder said.

"NGC 300 now stands as one of the most striking examples of accretion-driven stellar halo assembly in a dwarf galaxy of its kind, shedding light on how galaxies grow and evolve across the universe."

Research Report:Streams, Shells, and Substructures in the Accretion-Built Stellar Halo of NGC 300

Related Links
Steward Observatory
Stellar Chemistry, The Universe And All Within It

Subscribe Free To Our Daily Newsletters
Tweet

RELATED CONTENT
The following news reports may link to other Space Media Network websites.
STELLAR CHEMISTRY
Ultra-faint, rare dwarf galaxies offer clues to the early cosmos
Tucson AZ (SPX) Jan 17, 2025
A team of astronomers led by David Sand, a professor of astronomy at the University of Arizona Steward Observatory, has uncovered three faint and ultra-faint dwarf galaxies in the vicinity of NGC 300, a galaxy approximately 6.5 million light-years from Earth. These rare discoveries - named Sculptor A, B and C - offer an unprecedented opportunity to study the smallest galaxies in the universe and the cosmic forces that halted their star formation billions of years ago. Sand presented the findings, ... read more

STELLAR CHEMISTRY
NASA Opens New Challenge to Inspire Climate Solutions

India becomes 4th nation to complete unmanned docking in space

India achieves 'historic' space docking mission

Stranded astronaut Suni Williams performs spacewalk at ISS

STELLAR CHEMISTRY
ISRO demonstrates restart of Vikas engine

Galactic Energy launches five satellites into orbit

Top Beijing official urges Musk to deepen ties with China: state media

China deploys three spacecraft with Long March 2D rocket

STELLAR CHEMISTRY
The Mars Pivot

ORBIMARS: A proposed terminology for Mars orbital operations

Now That's Ingenuity: First Aircraft Measurement of Winds on Another Planet

NASA Sets Sights on Mars Terrain with Revolutionary Tire Tech

STELLAR CHEMISTRY
Shenzhou XIX crew completes second spacewalk

Shenzhou XIX crew completes second spacewalk mission

China unveils logos for three space missions in 2025

China's space station to drive over 1000 research projects

STELLAR CHEMISTRY
The Tyranny of the VC Equation Why Your Company Might Not Be "VC-able"

South American Space Programs: No Cooperation, No Gains

Stoke Space secures $260M in Series C Funding

The Space Economy to Reach $944 Billion by 2033

STELLAR CHEMISTRY
Flexential Links Up with Lonestar to Support First Commercial Space Data Center

Bright Ascension software powers Czech Republic's largest satellite mission

Technological to-do list for zero space debris by 2030

Surrey Satellite Opens Advanced Imaging R&D Cleanroom

STELLAR CHEMISTRY
Not all Hot Jupiters orbit solo

Discovery of two planets challenges planetary formation theories

Super Venus discovery reveals new type of exoplanet

Double the disks double the discovery new insights into planet formation in DF Tau

STELLAR CHEMISTRY
SwRI models suggest Pluto and Charon formed similarly to Earth and Moon

Citizen scientists help decipher Jupiter's cloud composition

Capture theory unveils how Pluto and Charon formed as a binary system

Texas A and M researchers illuminate the mysteries of icy ocean worlds

Subscribe Free To Our Daily Newsletters




The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.