NASA's Spitzer and Hubble Space Telescopes have teamed up to expose the chaos that baby stars are creating 1,500 light years away in a cosmic cloud called the Orion nebula.
This striking infrared and visible-light composite indicates that four monstrously massive stars at the center of the cloud may be the main culprits in the familiar Orion constellation. The stars are collectively called the "Trapezium." Their community can be identified as the yellow smudge near the center of the image.
Swirls of green in Hubble's ultraviolet and visible-light view reveal hydrogen and sulfur gas that have been heated and ionized by intense ultraviolet radiation from the Trapezium's stars. Meanwhile, Spitzer's infrared view exposes carbon-rich molecules called polycyclic aromatic hydrocarbons in the cloud. These organic molecules have been illuminated by the Trapezium's stars, and are shown in the composite as wisps of red and orange. On Earth, polycyclic aromatic hydrocarbons are found on burnt toast and in automobile exhaust.
Together, the telescopes expose the stars in Orion as a rainbow of dots sprinkled throughout the image. Orange-yellow dots revealed by Spitzer are actually infant stars deeply embedded in a cocoon of dust and gas. Hubble showed less embedded stars as specks of green, and foreground stars as blue spots.
Stellar winds from clusters of newborn stars scattered throughout the cloud etched all of the well-defined ridges and cavities in Orion. The large cavity near the right of the image was most likely carved by winds from the Trapezium's stars.
Located 1,500 light-years away from Earth, the Orion nebula is the brightest spot in the sword of the Orion, or the "Hunter" constellation. The cosmic cloud is also our closest massive star-formation factory, and astronomers believe it contains more than 1,000 young stars.
The Orion constellation is a familiar sight in the fall and winter night sky in the northern hemisphere. The nebula is invisible to the unaided eye, but can be resolved with binoculars or small telescopes.
This image is a false color composite where light detected at wavelengths of 0.43, 0.50, and 0.53 microns is blue. Light at wavelengths of 0.6, 0.65, and 0.91 microns is green. Light at 3.6 microns is orange, and 8.0 microns is red.
Photo credit: NASA/JPL-Caltech/STScI
NASA's Wide-field Infrared Survey Explorer, or WISE, captured this view of a runaway star racing away from its original home. Seen here surrounded by a glowing cloud of gas and dust, the star AE Aurigae appears to be on fire. Appropriately, the cloud is called the Flaming Star Nebula.
A runaway star is one that is hurled into high-speed motion through a supernova explosion or encounter with nearby stars. Like an angry teenager who storms out of the house after a family fight, runaway stars are ejected from their birthplace and race off to other parts of the galaxy.
The runaway star AE Aurigae was likely born in the Trapezium cluster, which is located in the constellation Orion. It formed as a binary-star system with the star Mu Columbae. Approximately 2.5 million years ago, these two stars are thought to have collided with another binary-star system in the Trapezium Cluster. This collision sent both AE Aurigae and Mu Columbae hurtling through space in opposite directions at a speed of 100 kilometers per second (over 200,000 miles per hour). Today, AE Aurigae can be seen in the constellation Auriga hundreds of light-years to the north of its home, while its former companion Mu Columbae is located hundreds of light-years to the south in the constellation Columba.
The wind from AE Aurigae blows away electrons from the gas surrounding it. This ionized gas begins to emit light, creating what is known as an emission nebula. The star also heats up nearby dust, causing it to glow in infrared wavelengths. As seen in visible light, this dust reflects the light of nearby stars, so it is called a reflection nebula.
The colors seen in this image represent specific wavelengths of infrared light. Hot stars scattered throughout the image show up as blue and cyan. Blue represents light emitted at wavelengths of 3.4 microns, while cyan represents 4.6 microns. The gas of the emission nebula appears green, representing 12-micron wavelengths. The dust of the reflection nebula appears primarily red, representing 22-micron light.
One interesting aspect of this image is that the edges of the reflection nebula appear lavender. This is because at its edges the nebula is both emitting light at longer, 22-micron wavelengths, and scattering shorter, 3.4-micron light. Since WISE represents 22-micron light as red and 3.4-micron light as blue, the combination of the two appears in this image as lavender.
Photo credit: NASA/JPL-Caltech/UCLA
This atlas features 30 proplyds, or protoplanetary discs, that were recently discovered in the majestic Orion Nebula. Using the wide field channel on Hubble's Advanced Camera for Surveys (ACS), astronomers discovered a total of 42 new discs that could be the seeds of planetary systems to come.
Within the awe-inspiring, gaseous folds of Orion, researchers have identified two different types of discs around young and forming stars: those that lie close to the brightest star in the cluster (Theta 1 Orionis C) and those farther away from it. The bright star heats up the gas in the nearby discs, causing them to shine brightly. The discs that are farther away do not receive enough of the energetic radiation from the star to set the gas ablaze; thus, they can only be detected as dark silhouettes against the background of the bright nebula, as the dust that surrounds these discs absorbs background visible light. By studying these silhouetted discs, astronomers are better able to characterize the properties of the dust grains that are thought to bind together and possibly form planets like our own.
In the brighter discs the excited material produces many glowing cusps, which all face the bright star, but from our point of view are randomly oriented through the nebula, so we see some edge on, and others face on, for instance. Other interesting features enhance the look of these captivating objects, such as emerging jets of matter and shock waves. The dramatic shock waves are formed when the stellar wind from the nearby massive star collides with the gas in the nebula, sculpting boomerang shapes or arrows or even, in the case of 181-825, a space jellyfish!
It is relatively rare to see visible images of proplyds, but the high resolution and sensitivity of Hubble and the Orion Nebula's proximity to Earth allow for precise views of these potential planetary systems.
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The full set of individual images of the 30 proplyds can be accessed on the dedicated pages at the spacetelescope.org website. See the related link "Proplyd Atlas - Orion Nebula."
Photo credit: NASA/ESA and L. Ricci (ESO)
