The magnificent structure seen in the famous 1995 image of the Eagle Nebula suffers from escape of materials from the ionizing radiation of nearby massive stars
Although the Hubble Space Telescope has captured breathtaking images of the universe during its 25 years of operation in space, one image stands above all others - the iconic sight of the so-called "Pillars of Creation".
The image, taken in 1995, reveals never-before-seen details of three Ank columns of cold gas being heated by ultraviolet light from a cluster of massive young stars in a small region of the Eagle Nebula, or M16.
For Hubble's 25th birthday in April, the telescope was asked to return to the famous columns and provided astronomers with a sharper and wider image. Although the original image was called "The Pillars of Creation" the new image can be called "The Pillars of Destruction".
I am amazed at how quickly these structures are changing," explains Paul Scoven from the University of Arizona in Tampa. "They are disintegrating before our eyes. The blue mist around the dense edge of the columns is material that heats up and evaporates into space. We captured these columns at a unique and short-lived moment in their development." Scoven and astronomer J. Hester of the University of Arizona led Hubble's original observations of the Eagle Nebula.
The original 1995 photo was taken in visible light. The new image also includes details from near-infrared light. This light shows that the columns become mysterious silhouettes against the background of the countless stars. This is because the infrared light penetrates through most of the gas and dust, except for the densest areas of the columns. Newly born stars are seen hiding within the columns.
The infrared image shows that at the edge of the pillars there are tight bonds of gas and dust. They trap the gas below them and keep it cold, creating the long structures that look like columns. The material between the pillars has long since evaporated due to the ionizing radiation from the central star cluster above the pillars.
At the top end of the left column, fragments of gas have heated up and are flying out of the structure, which illustrates the violent nature of the regions where stars are formed. "The columns represent an active dynamic process" says Scoven. "The gas does not heat up passively and moves slowly through space. The columns of gas become ionized, a process in which electrons are torn from the atoms, and are heated by the radiation of the massive stars. They are then eroded by the stars' strong solar winds full of ionized particles, which literally blow them out of the top of the pillars."
When Scoven and Hester used Hubble to make the initial observations of the Eagle Nebula in 1995, the astronomers saw pillar-like structures imaged from ground-based telescopes, but not in detail. They knew that the physical processes were not unique to the Eagle Nebula because star forming regions are scattered throughout the universe. However, thanks to the distance to them - 6,500 light years, the M16 nebula is the closest and best example.
When Scoven first saw the photograph of the Eagle Nebula he was speechless. "I called Gef Hester to my lab, we placed the photograph on the table and we were excited by the wealth of detail we were seeing for the first time.
The first formation that caught the eyes of the two in 1995 was the gas streams that seem to float out of the columns. Astronomers debated until then what effect the nearby massive stars had on the gas surrounding them in the stellar maternity home.
"Only one thing can light up a neighborhood like this: massive stars that gain enough 'horsepower' in the ultraviolet light range that they can fuel the gas clouds and make them glow," says Scoven. "Nebula regions where stars such as M16 are formed are the interstellar neon lights, which says - massive stars have just been born here." This was the first time we had direct observational evidence of the erosion process, not only for radiation but also for the mechanical tearing of gas from the columns. This is the phenomenon we saw."
By comparing the images from 1995 and 2014, the astronomers noticed a small, long, narrow jet that might have been ejected from a star during its formation. The jet looks like a stream of water in a garden hose. During the 19 years that passed between the two images, the jet stretched and moved away into space another 100 billion kilometers at an estimated speed of 700 thousand km/h.
“Our sun was formed in a turbulent star formation region like this. There is evidence that the young solar system will be carried by a streak of radioactivity from a nearby supernova. This means that our Sun formed as part of a cluster that included stars massive enough to produce strong ionizing radiation like we see in the Eagle Nebula. "This is the only way by which the nebula from which our Sun was formed could be exposed to a supernova so quickly, in the short period that this phenomenon exists because supernovae only occur in massive stars and these only live a few tens of millions of years." Scoven says. This means that when you look at the environment of the Eagle Nebula and star-forming regions like it, you can see the evolving environment in which our Sun was formed."