Champaign-Urbana Astronomical Society
The Story of NGC 7635 – The Bubble Nebula
Quote from David Berns on May 29, 2025, 12:29 pmIn the autumn of 1787, the ever-vigilant eye of Sir William Herschel swept the star-laden fields of the constellation Cassiopeia. With his powerful telescope, Herschel recorded a faint, nebulous patch that would later bear the designation NGC 7635. To him, it was merely a diffuse glow—an unremarkable smudge of light catalogued amidst thousands of others during his prolific sky surveys. There was no grand revelation. The tools of his age lacked the resolution to reveal the ethereal structure hidden within the mist.
For decades, NGC 7635 remained largely ignored. Early astronomers could discern little more than its presence. Even in the era of photographic plates in the late 19th and early 20th centuries, its form was obscure, buried in the grain of underexposed emulsions. To most observers, it was simply another dim gas cloud nestled in the galactic plane—a curiosity, perhaps, but not a headline.
That all changed with the advent of modern astrophotography and space-based telescopes.
In the latter half of the 20th century, astronomers began to turn their increasingly sophisticated instruments toward the nebula. What they saw astonished them. NGC 7635 was not just a hazy cloud—it was a bubble, a near-perfect sphere of glowing gas carved out of the interstellar medium like a cosmic sculpture.
Today, NGC 7635 is celebrated as the Bubble Nebula—a name both poetic and scientifically apt. The nebula lies approximately 7,100 to 11,000 light-years from Earth, embedded in a complex region of star formation in Cassiopeia. Its defining feature is the immense, translucent sphere of ionized gas being blown outward by the fierce stellar wind of a massive central star.
At the heart of the bubble is BD+60°2522, an O-type star roughly 10 to 20 times the mass of our Sun and thousands of times as luminous. This stellar giant is young and volatile, ejecting material at over 1,600 kilometers per second. The force of this wind is what sculpts the bubble, pushing against the surrounding molecular cloud and creating a shock front that compresses the gas into a luminous shell. The bubble spans roughly 7 light-years in diameter—large enough to engulf our entire solar system many times over.
But this elegant structure is not static. The nebula is a dynamic interplay of forces—stellar wind, radiation pressure, and turbulence—all caught in a celestial dance. The bubble’s symmetry is distorted on one side, evidence of resistance from denser pockets of interstellar material that inhibit its expansion. It’s not a perfect sphere, but rather a living record of a star’s ongoing battle with its environment.
Spectroscopic studies reveal a rich composition of ionized hydrogen (H II), oxygen, and other elements—glowing in characteristic colors when excited by the central star’s ultraviolet radiation. The region is not only beautiful but also informative. It serves as a natural laboratory for studying the interaction between high-mass stars and their natal clouds—processes critical to understanding star formation and galactic evolution.
The Hubble Space Telescope’s 1990s-era image of NGC 7635 transformed the Bubble Nebula into an icon of celestial beauty. That high-resolution photograph—depicting the shimmering arc of the bubble rimmed in glowing gas—has adorned textbooks, posters, and screensavers across the globe. Yet behind its aesthetic appeal lies a deeper truth: this nebula embodies the destructive and creative forces that shape our universe
NGC 7635, once a dim curiosity in Herschel’s eyepiece, is now a symbol of the dynamic and violent nature of stellar birth and evolution. What early observers dismissed as a faint blur is, in truth, a monument to the raw energy of young stars—proof that even the most subtle patches of sky can conceal wonders beyond imagination.
And so the Bubble Nebula continues to expand, centuries after its light first brushed the eye of its discoverer—an ever-growing testament to the power of light, wind, and time.
Data collected using a robotic telescope situated at a remote observatory in the "Telescope Live" network.
Observatory: IC Astronomy Observatory, Spain
Location: Oria, Spain
Telescope: Officina Stellare 700 RC
Imager: FLI PL16803
Mount: Officina Stellare equatorial fork mount
Filters: Astrodon Halpha, SII, OIII
Exposures: Halpha = 12 X 600 seconds, OIII = 12 X 600 seconds, SII = 12 X 600 secondsMy Astrobin Gallery:
https://app.astrobin.com/u/dfberns#gallery
Ancient Photons Observatory FB Group:
https://www.facebook.com/groups/448595136986311
Ancient Photons Observatory FB Page:
https://www.facebook.com/profile.php?id=61576226439299
Ancient Photons Observatory Website:
https://ancientphotonsobservatory.com/Data processed by me using the following software:
Siril 1.4, GraXpert, Seti Astro Cosmic Clarity, Astronomy Tools PS action set, Photoshop 2025, and Lightroom Classic.
In the autumn of 1787, the ever-vigilant eye of Sir William Herschel swept the star-laden fields of the constellation Cassiopeia. With his powerful telescope, Herschel recorded a faint, nebulous patch that would later bear the designation NGC 7635. To him, it was merely a diffuse glow—an unremarkable smudge of light catalogued amidst thousands of others during his prolific sky surveys. There was no grand revelation. The tools of his age lacked the resolution to reveal the ethereal structure hidden within the mist.
For decades, NGC 7635 remained largely ignored. Early astronomers could discern little more than its presence. Even in the era of photographic plates in the late 19th and early 20th centuries, its form was obscure, buried in the grain of underexposed emulsions. To most observers, it was simply another dim gas cloud nestled in the galactic plane—a curiosity, perhaps, but not a headline.
That all changed with the advent of modern astrophotography and space-based telescopes.
In the latter half of the 20th century, astronomers began to turn their increasingly sophisticated instruments toward the nebula. What they saw astonished them. NGC 7635 was not just a hazy cloud—it was a bubble, a near-perfect sphere of glowing gas carved out of the interstellar medium like a cosmic sculpture.
Today, NGC 7635 is celebrated as the Bubble Nebula—a name both poetic and scientifically apt. The nebula lies approximately 7,100 to 11,000 light-years from Earth, embedded in a complex region of star formation in Cassiopeia. Its defining feature is the immense, translucent sphere of ionized gas being blown outward by the fierce stellar wind of a massive central star.
At the heart of the bubble is BD+60°2522, an O-type star roughly 10 to 20 times the mass of our Sun and thousands of times as luminous. This stellar giant is young and volatile, ejecting material at over 1,600 kilometers per second. The force of this wind is what sculpts the bubble, pushing against the surrounding molecular cloud and creating a shock front that compresses the gas into a luminous shell. The bubble spans roughly 7 light-years in diameter—large enough to engulf our entire solar system many times over.
But this elegant structure is not static. The nebula is a dynamic interplay of forces—stellar wind, radiation pressure, and turbulence—all caught in a celestial dance. The bubble’s symmetry is distorted on one side, evidence of resistance from denser pockets of interstellar material that inhibit its expansion. It’s not a perfect sphere, but rather a living record of a star’s ongoing battle with its environment.
Spectroscopic studies reveal a rich composition of ionized hydrogen (H II), oxygen, and other elements—glowing in characteristic colors when excited by the central star’s ultraviolet radiation. The region is not only beautiful but also informative. It serves as a natural laboratory for studying the interaction between high-mass stars and their natal clouds—processes critical to understanding star formation and galactic evolution.
The Hubble Space Telescope’s 1990s-era image of NGC 7635 transformed the Bubble Nebula into an icon of celestial beauty. That high-resolution photograph—depicting the shimmering arc of the bubble rimmed in glowing gas—has adorned textbooks, posters, and screensavers across the globe. Yet behind its aesthetic appeal lies a deeper truth: this nebula embodies the destructive and creative forces that shape our universe
NGC 7635, once a dim curiosity in Herschel’s eyepiece, is now a symbol of the dynamic and violent nature of stellar birth and evolution. What early observers dismissed as a faint blur is, in truth, a monument to the raw energy of young stars—proof that even the most subtle patches of sky can conceal wonders beyond imagination.
And so the Bubble Nebula continues to expand, centuries after its light first brushed the eye of its discoverer—an ever-growing testament to the power of light, wind, and time.
Data collected using a robotic telescope situated at a remote observatory in the "Telescope Live" network.
Observatory: IC Astronomy Observatory, Spain
Location: Oria, Spain
Telescope: Officina Stellare 700 RC
Imager: FLI PL16803
Mount: Officina Stellare equatorial fork mount
Filters: Astrodon Halpha, SII, OIII
Exposures: Halpha = 12 X 600 seconds, OIII = 12 X 600 seconds, SII = 12 X 600 seconds
My Astrobin Gallery:
https://app.astrobin.com/u/dfberns#gallery
Ancient Photons Observatory FB Group:
https://www.facebook.com/groups/448595136986311
Ancient Photons Observatory FB Page:
https://www.facebook.com/profile.php?id=61576226439299
Ancient Photons Observatory Website:
https://ancientphotonsobservatory.com/
Data processed by me using the following software:
Siril 1.4, GraXpert, Seti Astro Cosmic Clarity, Astronomy Tools PS action set, Photoshop 2025, and Lightroom Classic.
Uploaded files: