Sifting through Dust near Orion’s Belt
A new image of the region surrounding the reflection nebula Messier 78, just to the north of Orion’s Belt, shows clouds of cosmic dust threaded through the nebula like a string of pearls. The observations, made with ESO’s Atacama Pathfinder Experiment (APEX) telescope, use the heat glow of interstellar dust grains to show astronomers where new stars are being formed.
In the centre of the image is Messier 78 (NGC 2068), a reflection nebula with a pale blue glow of starlight reflected from clouds of dust. The APEX observations are overlaid on the visible-light image in orange. Sensitive to longer wavelengths, they reveal the gentle glow of dense cold clumps of dust, some of which are even colder than -250°C, and invisible at other wavelengths.
One filament appears in visible as a dark lane of dust cutting across Messier 78, meaning that the dense dust lies in front of the reflection nebula, blocking its bluish light. Another prominent region of glowing dust overlaps with the visible light from Messier 78 at its lower edge with no visible dark dust lane, meanig that it must lie behind the reflection nebula.
Observations of the gas in these clouds reveal gas flowing at high velocity out of some of the dense clumps. These outflows are ejected from young stars while the star is still forming from the surrounding cloud. Their presence is therefore evidence that these clumps are actively forming stars.
A Cluster Within a Cluster
NGC 6604 is the bright grouping towards to the upper left of the image. It is a young star cluster that is the densest part of a more widely scattered association containing about one hundred brilliant blue-white stars. The picture also shows the cluster’s associated nebula — a cloud of glowing hydrogen gas that is called Sh2-54 — as well as dust clouds.
The cluster’s hot young stars are helping a new generation of stars to form in NGC 6604, by collecting star-making material into a compact region with their strong stellar winds and radiation. This second generation of stars will quickly replace the older generation, as although the brightest young stars are massive, they consume their fuel copiously and live short lives.
NGC 6604 has a strange column of hot ionised gas emanating from it. This particular column (often referred to as a “chimney”) channels outflowing material from the cluster; it is perpendicular to the galactic plane and stretches an incredible 650 light-years in length. Astronomers think that the hot stars within NGC 6604 are responsible for producing the chimney.
NGC 6604 lies about 5500 light-years away in the constellation of Serpens and is located about two degrees north of the Eagle Nebula in the night sky. [video]
Searchlight beams from a preplanetary nebula
The Hubble Space Telescope has been at the cutting edge of research into what happens to stars like our Sun at the ends of their lives. One stage that stars pass through as they run out of nuclear fuel is the protoplanetary nebula. This Hubble image of the Egg Nebula shows one of the best views to date of this brief but dramatic phase in a star’s life.
At the centre of this image, and hidden in a thick cloud of dust, is the nebula’s central star. While we can’t see the star directly, four searchlight beams of light coming from it shine out through the nebula. It is thought that ring-shaped holes in the thick cocoon of dust, carved by jets coming from the star, let the beams of light emerge through the otherwise opaque cloud.
How the stellar jets produce these holes is not known for certain, but one possible explanation is that a binary star system, rather than a single star, exists at the centre of the nebula. The onion-like layered structure of the more diffuse cloud surrounding the central cocoon is caused by bursts of material being ejected from the dying star every few hundred years.
The distance to the Egg Nebula is only known very approximately, the best guess placing it at around 3000 light-years from Earth. This in turn means that astronomers do not have any accurate figures for the size of the nebula (it may be larger and further away, or smaller but nearer).
A new view of the Tarantula Nebula
To celebrate its 22nd anniversary in orbit, the Hubble Space Telescope released a dramatic new image of the star-forming region 30 Doradus, also known as the Tarantula Nebula because its glowing filaments resemble spider legs.
The nebula is located in the neighboring galaxy called the Large Magellanic Cloud, and is one of the largest star-forming regions located close to the Milky Way. At the center of 30 Doradus, thousands of massive stars are blowing off material and producing intense radiation along with powerful winds.
The Chandra X-ray Observatory detects gas that has been heated to millions of degrees by these stellar winds and also by supernova explosions. These X-rays, colored blue in this composite image, come from shock fronts—similar to sonic booms—formed by this high-energy stellar activity.
The Hubble data, colored green, reveals the light from these massive stars along with different stages of star birth, including embryonic stars a few thousand years old still wrapped in cocoons of dark gas. Infrared emission data from Spitzer, seen in red, shows cooler gas and dust that have giant bubbles carved into them. These bubbles are sculpted by the same searing radiation and strong winds that comes from the massive stars at the center of 30 Doradus.
Evaporating Blobs of the Carina Nebula
The unusual blobs found in the Carina nebula, some of which are seen floating on the upper right, might best be described as evaporating. Energetic light and winds from nearby stars are breaking apart the dark dust grains that make the iconic forms opaque.
Ironically the blobs, otherwise known as dark molecular clouds, frequently create in their midst the very stars that later destroy them. The floating space mountains pictured above by the orbiting Hubble Space Telescope span a few light months.
The Great Nebula in Carina itself spans about 30 light years, lies about 7,500 light years away, and can be seen with a small telescope toward the constellation of Carina.
M57: The Ring Nebula
Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. Its classic appearance is understood to be due to perspective - our view from planet Earth looks down the center of a roughly barrel-shaped cloud of glowing gas.
But expansive looping structures are seen to extend far beyond the Ring Nebula’s familiar central regions in this intriguing composite of ground based and Hubble Space Telescope images with narrowband image data from Subaru.
Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the gaseous shroud represents outer layers expelled from the dying, once sun-like star at the nebula’s center. Intense ultraviolet light from the hot central star ionizes atoms in the gas.
Ionized oxygen atoms produce the characteristic greenish glow and ionized hydrogen the prominent red emission. The central ring of the Ring Nebula is about one light-year across and 2,000 light-years away. To accompany tonight’s shooting stars it shines in the northen constellation Lyra.
Hubble’s Panoramic View of 30 Doradus
Several million stars are vying for attention in this Hubble Space Telescope image of a raucous stellar breeding ground in 30 Doradus, located in the heart of the Tarantula nebula. The image is being released to celebrate Hubble’s 22nd anniversary.
30 Doradus is the brightest star-forming region in our galactic neighbourhood and home to the most massive stars ever seen. The nebula resides 170,000 light-years away in the Large Magellanic Cloud, a small, satellite galaxy of our Milky Way. No known star-forming region in our galaxy is as large or as prolific as 30 Doradus.
The image is roughly 650 light-years across and comprises one of the largest mosaics ever assembled from Hubble photos and consists of observations taken by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys, combined with observations from ESO’s MPG/ESO 2.2-metre telescope that trace the location of glowing hydrogen and oxygen.
The region’s sparkling centerpiece is a giant, young star cluster named NGC 2070, only 2-3 million years old. Its stellar inhabitants number roughly 500,000. The cluster is a hotbed for young, massive stars. Its dense core, known as RMC 136, is packed with some of the heftiest stars found in the nearby Universe, weighing more than 100 times the mass of our Sun.
The image reveals a fantasy landscape of pillars, ridges, and valleys. The massive stars are carving deep cavities in the surrounding material by unleashing a torrent of ultraviolet light, which is etching away the enveloping hydrogen gas cloud in which they were born. When this radiation hits dense walls of gas, it creates shocks, which may be generating a new wave of star birth.
Images: 1. Hubble’s panoramic view of the 30 Doradus (also known as the Tarantula Nebula) star-forming region. 2. Labelled view of the Tarantula Nebula identifying several prominent features.
The Eagle Nebula from Kitt Peak
From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed.
In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust.
The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of Serpens. This picture combines three specific emitted colors and was taken with the 0.9-meter telescope on Kitt Peak, Arizona, USA.
Hubble Peeks inside a Stellar Cloud
These bright stars shining through what looks like a haze in the night sky are part of a young stellar grouping in one of the largest known star formation regions of the Large Magellanic Cloud (LMC), a dwarf satellite galaxy of the Milky Way. The image was captured by the Hubble Space Telescope’s Wide Field Planetary Camera 2.
The stellar grouping is known as NGC 2040 or LH 88. It is essentially a very loose star cluster whose stars have a common origin and are drifting together through space. NGC 2040 is an OB association, a grouping that usually contains 10–100 stars of type O and B. It is thought that most of the stars in the Milky Way were born in OB associations.
NGC 2040 consists of several high-mass young stars in a large nebula of partially ionised hydrogen gas, and lies in what is known to be a supergiant shell of gas called LMC 4. Over a period of several million years, thousands of stars may form in these supergiant shells, which are the largest interstellar structures in galaxies.
The shells themselves are believed to have been created by strong stellar winds and clustered supernova explosions of massive stars that blow away surrounding dust and gas, and in turn trigger further episodes of star formation.
Cosmic Jet Looks Like Giant Tornado in Space
While examining a region where new stars are forming with NASA’s Spitzer Space Telescope, astronomers found a surprise - an object that looks like a giant tornado in space. The apparent tornado is shaped by a cosmic jet packing a powerful punch as it plows through clouds of interstellar gas and dust.
The “tornado” is actually a shock front created by a jet of material flowing downward through the field of view. A still-forming star located off the upper edge of the image, designated Herbig-Haro 49/50, generates this outflow.
The jet slams into neighboring dust clouds at a speed of more than 100 miles per second, heating the dust to incandescence and causing it to glow with infrared light detectable by Spitzer. The triangular shape results from the wake created by the jet’s motion, similar to the wake behind a speeding boat.
Most striking about the color-coded infrared image is the color gradient from one end of the “tornado” to the other. The blue color at the tornado’s tip results from high molecular excitation at the head of the shock. Those high excitation levels generate more short-wavelength emission, shown as blue. Molecular excitation levels decrease away from the head of the bow shock; therefore the emission is at longer wavelengths, colored red here.
This wide-field view of the star-forming region NGC 281 was taken with the WIYN 0.9-meter telescope at Kitt Peak National Observatory near Tucson, AZ. The iamge shows a centralized cluster of hot blue stars, dust and gas, and lanes of obscuring dust. NGC 281 is about 9,500 light years from Earth in the constellation Cassiopeia.
NGC 7635: The Bubble Nebula
NGC 7635, the Bubble Nebula, is being pushed out by the stellar wind of massive central star BD+602522. Next door, though, lives a giant molecular cloud, visible above to the lower right. At this place in space, an irresistible force meets an immovable object in an interesting way.
The cloud is able to contain the expansion of the bubble gas, but gets blasted by the hot radiation from the bubble’s central star. The radiation heats up dense regions of the molecular cloud causing it to glow.
The Bubble Nebula, pictured above in scientifically mapped colors to bring up contrast, is about 10 light-years across and part of a much larger complex of stars and shells. The Bubble Nebula can be seen with a small telescope towards the constellation of Cassiopeia.
IC 410 in Auriga, the scale in a sky
This zoom in series of photographs of the emission nebula IC 410 was taken by Finnish astrophotographer J-P Metsavainio from his observatory at the city center of Oulu. The images show the actual size of IC 410 in the sky. The white circle in the images show the angular size of the full Moon in the sky. The Moon has an apparent diameter of ~30 arc minutes or 0,5 degrees.
A Fox Fur, a Unicorn, and a Christmas Tree
Pictured above is a star forming region cataloged as NGC 2264, located in the constellation of the unicorn (Monoceros).
The complex jumble of cosmic gas and dust is about 2,700 light-years distant and mixes reddish emission nebulae excited by energetic light from newborn stars with dark interstellar dust clouds. Where the otherwise obscuring dust clouds lie close to the hot, young stars they also reflect starlight, forming blue reflection nebulae.
The above image covers 40 light-years at the distance of NGC 2264. Its cast of cosmic characters includes the Fox Fur Nebula, whose convoluted pelt lies at the upper left, bright variable star S Mon immersed in the blue-tinted haze just below the Fox Fur, and the Cone Nebula near the tree’s top.
The stars of NGC 2264 are also known as the Christmas Tree star cluster. The triangular tree shape traced by the stars appears sideways here, with its apex at the Cone Nebula and its broader base centered near S Mon.
Chaos in Orion
Baby stars are creating chaos 1,500 light-years away in the cosmic cloud of the Orion Nebula. Four massive stars make up the bright yellow area in the center of this false-color image for NASA’s Spitzer Space Telescope. Green indicates hydrogen and sulfur gas in the nebula, which is a cocoon of gas and dust. Red and orange indicate carbon-rich molecules. Infant stars appear as yellow dots embedded in the nebula.