Hubble snaps close-up of the Tarantula
The Hubble Space Telescope has produced an outstanding image of part of the famous Tarantula Nebula, a vast star-forming cloud of gas and dust in our neighbouring galaxy, the Large Magellanic Cloud. In this picture, we see a close-up of the Tarantula’s central region, glowing brightly with ionised gases and young stars.
The part of the nebula visible in this image from Hubble’s Advanced Camera for Surveys is criss-crossed with tendrils of dust and gas churned up by recent supernovae. These supernova remnants include NGC 2060, visible above and to the left of the centre of this image, which contains the brightest known pulsar. Below and to the right of the nebula, lie the remains of supernova SN 1987a, the closest supernova to Earth to be observed since the invention of telescopes.
Together with dying stars, the Tarantula Nebula is packed with young stars which have recently formed from the nebula’s supply of hydrogen gas. These toddler-stars shine forth with intense ultraviolet light that ionises the gas, making it light up red. The light is so intense that although around 170,000 light-years distant, and outside the Milky Way, the Tarantula Nebula is nevertheless visible without a telescope on a dark night to Earth-bound observers.
A compact and extremely bright star cluster called RMC 136 lies above and to the left of this field of view, providing much of the radiation that powers the multi-coloured glow. Within it lies the star RMC 136a1, which was recently found to be the heaviest ever discovered: the star’s mass when it was born was around 300 times that of the Sun. This heavyweight is challenging astronomers’ theories of star formation, smashing through the upper limit they thought existed on star mass.
Abell 39: the ghost star of the Milky Way
Abell 39, about 7000 light years away, is a ghostly remnant of a Sun-like star and one of the largest existing spheres in the Milky Way. Six light-years across, it was once a sun-like star’s outer atmosphere expelled thousands of years ago. The nearly perfect spherical nature of Abell 39 allows astronomers to accurately estimate how much relative material is actually absorbing and emitting light.
Observations indicate that Abell 39 contains only about half of the oxygen found in the Sun, an intriguing but not surprising confirmation of the chemical differences between stars. The reason why the central star is slightly off center by 0.1 light-years is currently unknown. Several galaxies millions of light years away can be seen through and around the spectral nebula.
NASA’s WISE telescope captured this image of the supergiant star Alpha Camelopardalis (α Cam) speeding through the sky and surrounded on one side by an arc-shaped cloud of dust and gas, colored red in this infrared view. Such fast-moving stars are called runaway stars. Alpha Cam is between 1,600 and 6,900 light-years away and moving at an astonishing rate of somewhere between 680 and 4,200 kilometers per second.
Runaway stars are set into motion either through the supernova explosion of a companion star or through gravitational interactions with other stars in a cluster. Because Alpha Cam is a supergiant star, it gives off a very strong wind. The speed of the wind is boosted in the forward direction the star is moving in space. When this fast-moving wind slams into the slower-moving interstellar material, a bow shock is created. The stellar wind compresses the interstellar gas and dust, causing it to heat up and glow in infrared.
A Dying Star’s Toxic Legacy
The strange and irregular bundle of jets and clouds in this curious image from is the result of a burst of activity late in the life of a star. As its core runs out of nuclear fuel, the star’s unstable outer layers are puffing out a toxic concoction of gases including carbon monoxide and hydrogen cyanide.
The Westbrook Nebula is a protoplanetary nebula, an opaque, dark and relatively short-lived cloud of gas that is ejected by a star as it runs out of nuclear fuel. As the star hidden deep in the centre of the nebula evolves further it will turn into a hot white dwarf and the gas around it will become a glowing planetary nebula, before eventually dispersing.
Protoplanetary nebulae are cool, and so emit little visible light. The picture includes exposures in visible light which shows light reflected from the cloud of gas, combined with other exposures in the near-infrared part of the spectrum, showing us the dim glow, invisible to human eyes, that is coming from different elements deep in the cloud itself.
‘Elephant Trunks’ in Space
NASA’s WISE telescope captured this image of a star-forming cloud of dust and gas, called Sh2-284, located in the constellation of Monoceros. Lining up along the edges of a cosmic hole are several “elephant trunks”—monstrous pillars of dense gas and dust such as the iconic Pillars of Creation in the Eagle nebula.
In this infrared image, the trunks are seen as small columns of gas stretching toward the center of the void in Sh2-284. The most notable one can be seen on the right side at about the 3 o’clock position. It appears as a closed hand with a finger pointing toward the center of the void. That elephant trunk is about 7 light-years long.
Deep inside Sh2-284 resides an open star cluster, called Dolidze 25, which is emitting vast amounts of radiation in all directions, along with stellar winds that are clearing out a cavern inside the surrounding gas and dust, creating the void seen in the center. The bright green wall surrounding the cavern shows how far out the gas has been eroded.
However, some sections of the original gas cloud were much denser than others, and they were able to resist the erosive power of the radiation and stellar winds. These pockets of dense gas remained and protected the gas “downwind” from them, leaving behind the elephant trunks.
Orion’s Lesser-known Nebula
A close-up view of an outer part of the Orion Nebula’s little brother, Messier 43. This nebula is separated from the famous Orion Nebula (Messier 42) by only a dark lane of dust. Both nebulae are part of the massive stellar nursery called the Orion molecular cloud complex, which includes several other nebulae, such as the Horsehead Nebula (Barnard 33) and the Flame Nebula (NGC 2024).
The Orion molecular cloud complex is about 1400 light-years away, making it one of the closest massive star formation regions to Earth. Hubble has therefore studied this extraordinary region extensively over the past two decades, monitoring how stellar winds sculpt the clouds of gas, studying young stars and their surroundings and discovering many elusive objects, such as brown dwarf stars.
This view shows several of the brilliant hot young stars in this less-studied region and it also reveals many of the curious features around even younger stars that are still cocooned by dust.
Beyond the Veil
This large mosaic image from NASA’s WISE telescope, features the wreckage of an exploded star, as well as other stars nearing the end of their lives. Located in the constellation Cygnus, the wispy and colorful emission is the remnant of supernova that ocurred some 5,000 – 8,000 years ago, called the Veil Nebula.
The Veil Nebula is the name that generally refers to the visible sections of the whole supernova remnant that was seen in its entirety in radio light and called the Cygnus Loop. The western portion of the nebula is known as the Witch’s Broom Nebula. It can be seen in this image as a reddish, long, vertical wispy cloud of dust on the right side of the image.
The colors of the Veil Nebula are the result of shock waves energizing the gas and the dust in the region and making it glow across the electromagnetic spectrum. Some astronomers suggest that the Veil Nebula represents not one, but two supernova remnants that are interacting with each other.
Supergiant Star Near Giraffe’s Hind Foot
NASA’s WISE telescope captured this colorful infrared image of the nebula BFS 29 surrounding the star CE-Camelopardalis, found hovering in the band comprising the Milky Way in the night sky.
In visible light, BFS 29 can be seen, but only very slightly. This is because the dust scatters and reflects some of the light from nearby stars, hence its classification as a reflection nebula. The gas in BFS 29 also contains large amounts of ionized hydrogen (H II), hence, the nebula is also classified as an HII region.
Most of the illumination and energy in BFS 29 is likely provided by the star CE-Camelopardalis. Of the three brightest stars in this image, it is the bright pink-colored star nearest to the center of the image. CE-Camelopardalis is a variable supergiant star, which means it will eventually end its life in a supernova, likely leaving behind a black hole.
Messier 78: a reflection nebula in Orion
The reflection nebula Messier 78 takes centre stage in this image taken with the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. It lies about 1,350 light-years away in the constellation of Orion and can be found northeast of the easternmost star of Orion’s belt. The brilliant starlight ricochets off dust particles in the nebula, illuminating it with scattered blue light.
The pale blue tint seen in the nebula in this picture is an accurate representation of its dominant colour. Blue hues are commonly seen in reflection nebulae because of the way the starlight is scattered by the tiny dust particles that they contain.
A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars. In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed.
Two bright stars, HD 38563A and HD 38563B, are the main powerhouses behind Messier 78. However, the nebula is home to many more stars, including a collection of about 45 low mass, young stars (less than 10 million years old) in which the cores are still too cool for hydrogen fusion to start, known as T Tauri stars.
This image shows a composite of the N 70 nebula - a “Super Bubble” in the Large Magellanic Cloud (LMC) satellite galaxy to the Milky Way system, located in the southern sky at a distance of about 160,000 light-years.
N 70 is a luminous bubble of interstellar gas, measuring about 300 light-years in diameter created by winds from hot, massive stars and supernova explosions. The interior is filled with tenuous, hot expanding gas.
An object like N70 provides astronomers with an excellent opportunity to explore the connection between the life-cycles of stars and the evolution of galaxies. Very massive stars profoundly affect their environment stirring and mixing the interstellar clouds of gas and dust.
Credit: ESO via The Daily Galaxy
The Cosmic ‘Bubble Factory’ Mystery
We don’t know what caused the bubbles and arcs in NGC 2359, but the main culprit is the massive Wolf-Rayet star in the center of one of the bubbles - visible slightly below and to the right of the center.
Wolf-Rayet stars are massive, highly luminous stars that continually shed material in a stellar wind - which commonly form bubbles in the interstellar medium. But the unusual structure of the NGC 2359 arcs indicate something more complex is going on. Experts wonder if the star is moving supersonically? Or, is there another energetic star in the vicinity?
The 200 Wolf-Rayet stars known in the Milky Way are considerably hotter and more luminous than our Sun. All extremely massive stars will eventually evolve though a Wolf-Rayet phase and generate bubbles because they continually eject their outer atmosphere as a stellar wind of particles typically carring away more than the mass of our Earth each year, caused by atmospheric particles absorbing outgoing starlight.
Source: The Daily Galaxy
An Extended Stellar Family
This swirling landscape of stars is known as the North American nebula. In visible light, the region resembles North America, but in this new infrared view from NASA’s Spitzer Space Telescope, the continent disappears.
Where did the continent go? The reason you don’t see it in Spitzer’s view is because infrared light can penetrate dust whereas visible light cannot. Dusty, dark clouds in the visible image become transparent in Spitzer’s view, also revealing the glow of dusty cocoons enveloping baby stars.
Clusters of young stars (about one million years old) can be found throughout the image. Slightly older but still very young stars (about 3 to 5 million years) are also liberally scattered across the complex, with concentrations near the “head” region of the Pelican nebula, which is located to the right of the North American nebula (upper right portion of this picture).
Some areas of this nebula are still very thick with dust and appear dark even in Spitzer’s view. For example, the dark “river” in the lower left-center of the image — in the Gulf of Mexico region — are likely to be the youngest stars in the complex (less than a million years old).
The “eyes” of the Owl Nebula
The Owl Nebula (M97), an interstellar cloud of dust, hydrogen gas, helium and other ionized gases formed roughly 6,000 years ago in the constellation Ursa Major, is regarded as one of the more complex of the planetaries. The object gets it name due to the appearance of owl-like “eyes” when view through a large telescope under dark sky conditions with the aid of a so-called “nebula filter.” The “eyes” are also easily visible through photographs taken of the nebula.
Source: The Daily Galaxy | See also: Gemini Observatory
Fiery Young Stars Wreak Havoc in Stellar Nursery
A violent stellar nursery called NGC 2174, in which stars are born in a first-come-first-served feeding frenzy for survival. Most of the ingredients to make stars are wasted as the cloud of gas and dust, gradually disperses, which is also further speeded up by the presence of hot young stars creating high velocity winds that blow the gas outwards.
These fiery youngsters also bombard the surrounding gas with intense radiation, making it glow brightly, creating the brilliant scene captured here. The nebula is mostly composed of hydrogen gas, which is ionised by the ultraviolet radiation emitted by the hot stars, leading to the nebula’s alternative title as an HII region.
NGC 2174 lies about 6400 light-years away in the constellation of Orion. It is not part of the much more familiar Orion Nebula, which lies much closer to us.
Water Vapor in Space
Water is a critical molecule for human life, and, because it is abundant in the interstellar medium, it also plays an important role in the life of molecular clouds and the stars and planets that form in them. Radiation from water vapor helps to cool a collapsing cloud of material, allowing it to dissipate heat and thereby shrink until a new star can develop.
Water ice acts as a glue on dust grains, helping them coagulate into planetesimals and then into planets. Liquid water transports molecules on planetary surfaces where they can facilitate complex chemistry.
Using data from the Submillimeter Wave Astronomy Satellite (SWAS), CfA astronomers have mapped water vapor along a ridge of warm material in the Orion nebula nearly 18 light-years in length. The Orion ridge is associated with the closest region of massive star formation to the Earth.
The astronomers report that most of the water vapor originates near the surface of the cloud, and that it does not extend into the cloud by more than about one 100th of a light-year, probably because it turns into ice. This result explains why the total abundance estimates of water had been too low. The analysis also helps to resolve what happens when radiation from hot stars impinges on the surface of a molecular cloud.
Source: Harvard-Smithsonian Center for Astrophysics