See Hubble’s most beautiful star-forming image ever

The Large Magellanic Cloud appears larger than all other galaxies.

Behind the dome of a series of European Southern Observatory telescopes, the Milky Way towers in the southern skies, flanked by the Large and Small Magellanic Clouds, at right. Although there are several thousand stars and the plane of the Milky Way all visible to human eyes, there are only four galaxies beyond our own that the typical unaided human eye can detect. We did not know they were located outside of the Milky Way until the 1920s: after Einstein’s general relativity has already superseded Newtonian gravity.

At 7° across, it’s the 4th most massive Local Group galaxy.

The Large Magellanic Cloud is home to the closest supernova of the last century, having occurred in 1987. The pink regions here are not artificial, but are signals of ionized hydrogen and active star formation, likely triggered by gravitational interactions and tidal forces. The pink regions specifically arise when electrons fall back onto ionized hydrogen nuclei, and transition from the n=3 to the n=2 energy level, producing photons of precisely 656.3 nm.

Only 165,000 light-years distant, it’s copiously forming stars.

Our Local Group of galaxies is dominated by Andromeda and the Milky Way, but there’s no denying that Andromeda is the biggest, the Milky Way is #2, Triangulum is #3, and the LMC is #4. At just 165,000 light-years away, it’s by far the closest among the top 10+ galaxies to our own, and as such it takes up the largest angular span on the sky of all galaxies outside the Milky Way. There are over 100 galaxies within the Local Group, but Andromeda and the Milky Way contain most of the stars, as well as most of the mass.

This spectacular Hubble composition captures 520 light-years of its full 32,000 light-year extent.

This image showcases the scale of a composition created with data from the Hubble Space Telescope known as the “Cosmic Reef.” Spanning 520 light-years across, under 2% of the extent of the Large Magellanic Cloud, the large red nebula is catalogued as NGC 2014, with the smaller blue nebula known as NGC 2020.

Thousands of brilliant, massive stars shine throughout it.

Amidst the top, red, wispy portion of the large nebula composing the Cosmic Reef, NGC 2014, a series of young star clusters, highlighted by bright, young blue stars that weigh in at ten times the Sun’s mass or greater, shine brightly. The reddish dust highlights relatively cool matter that’s sufficiently far away from the stars themselves.

The cyan-colored regions highlight superheated oxygen, with temperatures exceeding 50,000 K.

This portion of Hubble’s image of the Cosmic Reef highlights the densest, dustiest region of gas and dust. New stars are being formed inside, and the cyan colored “wisps” highlight doubly-ionized oxygen, which indicates temperatures in excess of 50,000 K. When the last of the gas in this region has been blown away, no new stars will form. However, if the gas isn’t completely expelled from the galaxy, it may yet recollapse and form new stars someday.

The dustiest background regions reflect blue starlight.

The deep blue color that’s highlighted in this portion of the large star-forming region within the Large Magellanic Cloud arises from starlight reflecting off of nearby neutral matter. The starlight here is dominated by bright blue stars, and so this reflection nebula shines blue as well.

Others contain foreground material, blocking the light from stars inside.

This tiny portion of the complete Cosmic Reef panorama showcases a dusty region being bombarded by radiation from the upper left, while a brilliant young, shrouded star ionizes the gas inside and shines even through the light-blocking material in the foreground.

The pink regions highlight where stellar radiation ionizes hydrogen atoms.

The bright pink regions are created when young, bright, massive stars radiate high-energy light out into the surrounding hydrogen gas, ionizing it. From 165,000 light-years away, this portion of the Large Magellanic Cloud is similar in many ways to the Pillars of Creation, with new stars, evaporating gas globules, dust, and radiation all interplaying to carve a series of gorgeous shapes.

The matter-rich regions possess more stars due to recent and ongoing star-formation.

Here, at the very edge of the nebular region of NGC 2014 there’s a sharp difference in the number of stars along the line-of-sight where the nebula is and on the other side, where the nebula ends. The matter, which shines in infrared light, traces out where new stars have recently formed; beyond the nebula, predominantly older, cooler stars are found.

Below, a smaller, isolated star-forming region spans 25 light-years across.

This region on the outskirts of the nebula NGC 2014 is a disconnected, separate star-forming region all of its own, where collapsing matter continues to form new stars while the internal energy works to ionize and evaporate the remaining matter. This small nebula is likely similar to Messier 78 on the outskirts of the Orion Nebula within the Milky Way.

An even smaller, dust-rich clump contains new, clearly identifiable stars.

This might be the smallest identified self-contained star-forming region, spanning only perhaps ~10 light-years across. At the lower portion of the image, a pair of stars shine brightly in a dusty region of space, perhaps hinting at a momentous end-of-life event soon to come.

Meanwhile, the adjacent blue nebula extends for over 100 light-years.

This portion of the Cosmic Reef composition highlights the blue reflection nebula created by winds blown off of a hot, massive, giant blue star that are then illuminated in reflected light by the original star that created it. The Wolf-Rayet star that powers it may be destined, in short order, for a stellar cataclysm such as a core-collapse supernova, but we can only see the presence of the cold, expelled gas from its outer layers as they reflect the starlight from the luminous, blue star powering it.

Light reflects off of ejected gas, powered by a solitary star 200,000 times the Sun’s brightness.

The swirling ring of gas at the center of NGC 2020 arises from material blown off from the hot Wolf-Rayet star that blew it away. The fact that the nebula and the massive, bright star shine with the same color provides an excellent hint that the reflected light from the star is what’s creating the color of the nebula.

Hot, massive blue stars highlight young star clusters within the main nebula.

This fragment of the young star-forming region NGC 2014 showcases many stars that are bluer, more massive, and much shorter lived than our Sun. However, the fainter, redder, less luminous stars are far more numerous, making us wonder just what “typical” truly is for a star. NGC 2014 is also found in the Large Magellanic Cloud: over 160,000 light-years away.

As radiation blows matter away, stars race to form within evaporating gas globules.

This one small region near the heart of NGC 2014 showcases a combination of evaporating gaseous globules and free-floating Bok globules, as the dust goes from hot, tenuous filaments at top to denser, cooler clouds where new stars form inside below. The mix of colors reflects a difference in temperatures and emission lines from various atomic signatures. This neutral matter reflects starlight, where this reflected light is known to be distinct from the cosmic microwave background.

The knots in the ionized gas create a wispy, cliff-like boundary between gas-rich and gas-poor regions.

This rotated view of the boundary between the dust-poor region (right) and the dust-rich region (left) of the Cosmic Reef nebula, NGC 2014, shows off a variety of rich features. The biggest dichotomy is that on the right, star-formation has completed, while on the left, it is still ongoing within those dust-rich structures.

All told, the full-resolution panorama contains ~200 megapixels of Hubble data.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.