New Hubble Portrait of NGC 6723
The Hubble Space Telescope has delivered a breathtaking ultraviolet image of the globular cluster NGC 6723, affectionately dubbed the “Chandelier Cluster” for its sparkling appearance. Situated roughly 27,000 light‑years away in the constellation Sagittarius, this dense sphere of stars spans about 100 light‑years across. While the picture dazzles the eye, it also serves as a time‑machine, allowing astronomers to peer into the tumultuous infancy of our Milky Way.
Why This Cluster Matters
Globular clusters like NGC 6723 are among the Milky Way’s oldest constituents, with ages exceeding 10 billion years. They predate the formation of the Galactic disk that hosts our Sun. For decades, scientists assumed that all stars within a given cluster formed simultaneously from a single cloud of gas and dust. The new Hubble data, however, challenges that simplistic view.
Ultraviolet Vision Reveals Chemical Nuances
Hubble’s unique sensitivity to ultraviolet light enables the detection of subtle differences in stellar chemistry. By examining these variations, researchers uncovered evidence for two distinct star‑formation episodes. The second burst occurred a mere 634 million years after the first—a blink of an eye on cosmic timescales, especially for a system older than ten billion years.
Implications for Galactic Evolution
This discovery reshapes our understanding of how early Galactic structures assembled. Rather than a single, monolithic event, the birth of NGC 6723 appears to have been a staggered process, possibly triggered by external perturbations such as gas inflows or minor mergers. The finding aligns with recent JWST observations of other ancient clusters, suggesting that multi‑phase star formation may be more common than previously thought.
Building on a Legacy of Observations
NGC 6723 is not new to Hubble’s gaze. Earlier campaigns (program #10775) surveyed 65 globular clusters in visible and near‑infrared wavelengths, spawning hundreds of scientific papers. The latest ultraviolet campaign (#13297, led by G. Piotto) adds a crucial piece to the puzzle, allowing astronomers to refine models of chemical enrichment and dynamical evolution within these dense stellar environments.
What This Means for the Future
Each new observation of the “Chandelier Cluster” illuminates a different facet of the Milky Way’s formative years. As telescopes grow more powerful, we can expect further surprises that will continue to challenge long‑standing assumptions about star‑cluster formation, chemical mixing, and the early life of our galaxy.
Source: https://scientias.nl/hubbles-nieuwe-foto-onthult-een-verrassend-geheim-van-een-oude-sterrenhoop/
