The Hubble Space Telescope has offered a breathtaking new view of the spiral galaxy NGC 4535, a celestial wonder that has long carried the mysterious nickname, the ‘Lost Galaxy’. This latest observation, rich with glowing stellar nurseries and brilliant young star clusters, is providing astronomers with vital clues about the mechanics of star formation and the evolution of galaxies across the universe.
The Mystery of the ‘Lost Galaxy’ (NGC 4535).
Located approximately 50 million light-years away in the constellation Virgo, NGC 4535 earned its evocative moniker from its appearance through small ground-based telescopes. To amateur observers, the galaxy appears faint and hazy, almost ghostly—as if lost in the black expanse of space.
However, the Hubble Space Telescope, with its nearly eight-foot mirror positioned above Earth’s light-obscuring atmosphere, reveals the true magnificence of this object. Hubble’s images penetrate the haze, showcasing a spectacular barred spiral galaxy complete with:
- Massive spiral arms coiling outwards.
- A bright central bar composed of densely packed stars.
Peering into a Cosmic Nursery: Star Clusters and H II Regions.
The most striking features in Hubble’s new data are the brilliant blue star clusters and the surrounding patches of glowing pink gas. These vibrant areas are critical to understanding the galaxy’s activity.
The Significance of H II Regions.
The pink clouds are known as H II regions. The term refers to clouds of hydrogen that have been ionized (stripped of electrons) by intense radiation from extremely young, hot, and massive stars recently born within them.
These H II regions are essentially massive stellar nurseries and act as a key indicator of a galaxy’s birth rate. Their presence confirms that NGC 4535 is a galaxy currently undergoing powerful and energetic star formation.
As these enormous young stars blaze brightly, they heat and shake up their surrounding birth clouds with powerful stellar winds. Eventually, they will meet a spectacular end, exploding as supernovae and seeding the galaxy with the heavy elements necessary for future generations of stars and planets.
The PHANGS Program: Mapping Galaxy Evolution.
This remarkable portrait of the ‘Lost Galaxy’ is more than just a beautiful image; it is part of a major international collaborative effort known as the PHANGS (Physics at High Angular resolution in Nearby GalaxieS) observing program.
The overall goal of PHANGS is ambitious: to catalog and study roughly 50,000 H II regions across nearby star-forming galaxies. By focusing on galaxies like NGC 4535, the program aims to unravel the fundamental connections between young stars and the cold gas from which they are formed.
The new Hubble data, which captures the brilliant red glow of the nebulae that encircle these massive stars in their first few million years of life, adds a new layer of detail to the earlier 2021 image of NGC 4535, advancing our understanding of how spiral galaxies like our own Milky Way grow and evolve over cosmic time.