Swirling, shapeless, giant molecular clouds float around like strange spooks haunting the secretive shadows of the space between stars. Wandering silently though our large spiral Milky Way Galaxy, these dark, ghostly clouds, composed of dust and gas, serve as the weird, frigid cradles for sparkling baby stars that light up the surrounding darkness with their wonderful fires. In July 2014, astronomers at the European Southern Observatory (ESO) in Chile released a fabulous image of baby stars huddling together against a background of glowing clouds of gas and dusty lanes. Such images of objects that dance around in space are very important, because they help astronomers in their efforts to learn about the hidden secrets of our mysterious Cosmos!
The nest of huddling newborn stellar sparklers resides in a star cluster dubbed NGC 3293 . The star-blazing cluster itself would have been a murky, billowing cloud of gas and dust itself approximately ten million years ago, but as the baby stars started to form within it, it morphed into a brilliant group of stars! Clusters like NGC 3293 are laboratories in the sky that help astronomers to learn more and more about how baby stars are born, grow, and evolve!
Within the swirling depths of billowing molecular clouds, baby stars are born, setting the relentless, ambient darkness on fire with their light – as they burst into existence within these floating stellar nurseries that inhabit our Milky Way in great abundance. These giant, dark clouds are composed primarily of hydrogen gas, but they also harbor small quantities of cosmic dust.
All stars are born within these eerie, ghostly clouds, when an especially dense and embedded blob of material collapses under the staggering, heavy weight of its own crushing gravity – thus giving birth to searing-hot, glittering neonatal stars, or protostars. Within the billows of these huge clouds of dust and gas, delicate strands of star-making material braid themselves together, and then merge, continuing to grow in size for literally hundreds of thousands of years. The crush of gravity at last becomes so intense that the hydrogen atoms – that are jitter-bugging around within these weak blobs – suddenly fuse. This lights the protostar's new stellar fires, that will boil and churn and flash with glaring brilliance for as long as the star "lives"!
The process of nuclear fusion ignites the new star. Brilliant, hot protostars struggle for their existence by balancing two warring forces in order to reach sparkling stellar maturity. Indeed, all main-sequence (hydrogen-burning) stars, regardless of their age, must spend their "lives" maintaining a delicious balance between the two antagonistic forces of radiation pressure and gravity. While the merciless hug of gravity pulls in the ambient gas, radiation pressure keeps the star blissfully bouncy by pushing everything out and away from the star. This vital balance between these two antagonistic forces keeps the star "alive," and on the main-sequence. Unfortunately, stars grow old, and when an elderly star at long last has burned up its own necessary supply of "life" -sustaining hydrogen fuel, its core experiences collapse – which is the end of the road for the aged star. Small stars, like our Sun, die with great beauty and relative peace, gently casting off their varicolored outer layers of gas into the space between stars. The relic core of a small star like our own Sun evolves into a small stellar corpse called a white dwarf. However, more massive stars meet their fate with a terrible beauty and magnificent rage. Massive stars, when it's their time to go into that "good night", blow themselves up in the fury of a Type II (core-collapse) supernova blast that can – at least for a short time – outshine their own host galaxy .
Enormous, dark, and frigid molecular clouds are precursors to what are termed HII regions , which make dazzling spectacles of themselves as they cast their glowing light into intersellar space. The huge, dusty, gaseous molecular clouds can exist in a stable condition for extremely long time spans, but collisions between clouds, magnetic interactions, and supernova blasts can trigger collapse – and when this happens, because of this collapse and fragmentation, baby stars may be born. An HII region appeared irregular and clumpy, and could potentially give birth to literally thousands of fiery baby stars over the course of several million years – and some of these new and brilliant stars can cause it to glow, as well as sculpt its shape. HII regions come in a variety of different shapes, because the gas and stars within them are distributed irregularly.
Once the newly ignited, active baby stars inhabiting an HII region have become toddlers, their fiercely winds of flying particles flee shrieking away from these massive stars, both shaping and ferociously hurling away the surrounding gases.
Picturing The Way Stellar Siblings Live And Die
The lovely stellar cluster, NGC 3293 , is found about 8,000 light-years from our planet in the constellation Carina (The Keel). This cluster was first discovered by the French astronomer Nicolas-Louis de Lacaille in 1751, while he was living in what is now South Africa. Lacaille spotted NGC 3293 using only a tiny telescope with an aperture of merely 12 millimeters . The cluster is one of the most brilliant of its kind in the southern sky and it can easily be observed with the naked eye on a clear, dark night.
NGC 3293 , like other stellar clusters similar to it, harbors stars that were all born at about the same time, out of the same cloud of dust and gas, and at the same distance from our planet. This basically means that they should all have the same composition, and as a result they are excellent celestial objects for astronomers to use when testing theories of stellar evolution.
Most of the stars inhabiting NGC 3293 are young, and the cluster itself is less than 10 million years old. This makes that sparkling stellar population mere babies in "star-years," when you realize that our Star, the Sun, is about 4.56 billion years old, and considered to be only middle-aged – with another 5 billion years or so to go. Myriads of bright, blue, very hot, young active stars are quite common in open clusters like NGC 3293. The Kappa Crucis cluster (NGC 4755) , more often known as the Jewel Box– for obvious reasons – hosts an abundance ofdazzling, young, blue stars.
Such open clusters came into being from a giant, dark molecular cloud, and their stars are bound together by their mutual gravitational embrace. However, this embrace is not sufficient to keep the cluster in one piece while experiencing disastrous close brushes with wandering gas clouds, as well as with other clusters – while, at the same time, its own rich supply of dust and gas is being depleted . Therefore, open clusters can not exist for long, and only end for about a few hundred million years. Their short life contrasts with that of their larger kin, called globular clusters , which can remain intact for billions of years, while keeping a strong grip on their much more numerous population of stars.
It is thought that most, if not all, of the nearly fifty stars inhabiting NGC 3293 were all born at the same time, in one magnificent starburst event. However, there is some evidence suggesting that there is still some ongoing starbirth occurring in NGC 3293. Even though all of the stars in NGC 3293 are generally thought to have formed in the same event, at about the same time, they do not have the sparkling appearance of a brilliant young star in its babyhood. In fact, some of the stars look quite elite, and this provides astronomers with the opportunity to investigate how and why stars apparently evolve at different rates.
One bright orange star, that can be observed in the new ESO image, is a red giant that would have been born as one of the largest and most brilliant in the entire stellar nursery. Alas, bright stars tend to burn up very fast. As this star consumed its nuclear fuel at its core, its internal dynamics altered – and it became red and swollen, evolving into the red giant seen today. Red giants are approaching the end of that long stellar road, but this particular red giant's sister stars are still on what is termed the pre-main-sequence. This basically means that they are still at a point in their "lives" that precedes the stable– and very long – middle stage of their existence.
The ESO image shows these stars in the prime of their stellar "lives" as brilliant, hot, and white against a dusty and red background.
The beautiful image was taken with the Wide Field Imager (WFI) installed on the MPG / ESO 2.2-meter telescope at ESO's La Silla Observatory in northern Chile.