Star Formation in the Carina Nebula Complex

This image of the Carina Nebula complex, taken with ESA's Herschel Space Observatory at far-infrared wavelengths, shows the intricate network of clouds that make up this prolific cosmic nursery, where tens of thousands of new stars are being formed.

The complex exhibits a rich assortment of bubbles, filaments and pillars. Partly responsible for creating this tangled structure are the numerous high-mass stars hosted within this star-forming region – in the central region alone, the Carina Nebula boasts a census of more than a hundred very massive stars of type O, B and Wolf-Rayet. These mighty stars, which infuse their surroundings with powerful winds and large amounts of ionizing radiation, not only contribute to shaping the nebula's appearance, but also have a significant impact on the star formation activity that takes place within it.

In the central portion of the image, where several stellar clusters host young, massive stars, feedback effects have cleared out the region, and the diffuse material there shines brightly at the shortest of the wavelengths probed by Herschel (hence the blue-white glow that characterizes this portion of the image). The impact of high-mass stars is revealed also in the upper part of the image, where a series of large bubbles have been carved by winds blown by stars at their center. The most prominent of these bubbles, named Gum 31, is visible at the top right corner of the image; it is the result of feedback from massive stars in the young cluster NGC 3324 hosted within the bubble.

At the lower left part of the image a large number of elongated structures, called the Southern Pillars, can be seen. At the base of these pillars, the mixture of gas and dust is extremely dense, highlighting that in this portion of the nebula the feedback from massive stars has caused the material to concentrate in several compact clumps. New generations of stars will eventually emerge from these dense blobs of matter. A pronounced dark region is adjacent to the right edge of the Southern Pillars: the origin of this bubble-like feature is unclear, as the stars hosted there are not massive enough to have sculpted it with winds. Astronomers believe that it might have been caused by gusts of hot gas leaking from the powerful stars at the center of the nebula.

The image combines data acquired with the PACS instrument at 70 micron (shown in blue) and 160 micron (shown in green) and with the SPIRE instrument at 250 micron (shown in red).

Photo credit: ESA/PACS/SPIRE/Thomas Preibisch, Universitäts-Sternwarte München, Ludwig-Maximilians-Universität München, Germany

Note: For more information, see The Delicate Balance of Star Formation in the Carina Nebula.

NGC 300

ESO has released a spectacular new image of NGC 300, a spiral galaxy similar to the Milky Way, and located in the nearby Sculptor Group of galaxies. Taken with the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile, this 50-hour exposure reveals the structure of the galaxy in exquisite detail. NGC 300 lies about six million light-years away and appears to be about two thirds the size of the full Moon on the sky.

Originally discovered from Australia by the Scottish astronomer James Dunlop early in the nineteenth century, NGC 300 is one of the closest and most prominent spiral galaxies in the southern skies and is bright enough to be seen easily in binoculars. It lies in the inconspicuous constellation of Sculptor, which has few bright stars, but is home to a collection of nearby galaxies that form the Sculptor Group. Other members that have been imaged by ESO telescopes include NGC 55 (eso0914), NGC 253 (eso1025, eso0902) and NGC 7793 (eso0914). Many galaxies have at least some slight peculiarity, but NGC 300 seems to be remarkably normal. This makes it an ideal specimen for astronomers studying the structure and content of spiral galaxies such as our own.

This picture from the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile was assembled from many individual images taken through a large set of different filters with a total exposure time close to 50 hours. The data was acquired over many observing nights, spanning several years. The main purpose of this extensive observational campaign was to take an unusually thorough census of the stars in the galaxy, counting both the number and varieties of the stars, and marking regions, or even individual stars, that warrant deeper and more focused investigation. But such a rich data collection will also have many other uses for years to come. By observing the galaxy with filters that isolate the light coming specifically from hydrogen and oxygen, the many star-forming regions along NGC 300’s spiral arms are shown with particular clarity in this image as red and pink clouds. With its huge field of view, 34 x 34 arcminutes, similar to the apparent size of the full Moon in the sky, the WFI is an ideal tool for astronomers to study large objects such as NGC 300.

NGC 300 is also the home of many interesting astronomical phenomena that have been studied with ESO telescopes. ESO astronomers recently discovered the most distant and one of the most massive stellar-mass black holes yet found (eso1004) in this galaxy, as the partner of a hot and luminous Wolf–Rayet star in a binary system. NGC 300 and another galaxy, NGC 55, are slowly spinning around and towards each other, in the early stages of a lengthy merging process (eso0914). The current best estimate of the distance to the NCG 300 was also determined by astronomers using ESO’s Very Large Telescope at the Paranal Observatory (eso0524), among others.

Photo credit: European Southern Observatory

WR 22 and the Carina Nebula

A spectacular new image from ESO’s Wide Field Imager at the La Silla Observatory in Chile shows the brilliant and unusual star WR 22 and its colorful surroundings. WR 22 is a very hot and bright star that is shedding its atmosphere into space at a rate many millions of times faster than the Sun. It lies in the outer part of the dramatic Carina Nebula from which it formed.

Very massive stars live fast and die young. Some of these stellar beacons have such intense radiation passing through their thick atmospheres late in their lives that they shed material into space many millions of times more quickly than relatively sedate stars such as the Sun. These rare, very hot and massive objects are known as Wolf–Rayet stars, after the two French astronomers who first identified them in the mid-nineteenth century, and one of the most massive ones yet measured is known as WR 22. It appears at the center of this picture, which was created from images taken through red, green and blue filters with the Wide Field Imager on the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile. WR 22 is a member of a double star system and has been measured to have a mass at least 70 times that of the Sun.

WR 22 lies in the southern constellation of Carina, the keel of Jason’s ship Argo in Greek mythology. Although the star lies over 5,000 light-years from the Earth it is so bright that it can just be faintly seen with the unaided eye under good conditions. WR 22 is one of many exceptionally brilliant stars associated with the beautiful Carina Nebula (also known as NGC 3372) and the outer part of this huge region of star formation in the southern Milky Way forms the colorful backdrop to this image.

The subtle colors of the rich background tapestry are a result of the interactions between the intense ultraviolet radiation coming from hot massive stars, including WR 22, and the vast gas clouds, mostly hydrogen, from which they formed. The central part of this enormous complex of gas and dust lies off the left side of this picture as can be seen in image eso1031b. This area includes the remarkable star Eta Carinae and was featured in an earlier press release (eso0905).

Photo credit: European Southern Observatory

V385 Carinae

Some might see a blood-red jellyfish in a forest of seaweed, while others might see a big, red eye or a pair of lips. In fact, the red-colored object in this new infrared image from NASA's Wide-field Infrared Survey Explorer (WISE) is a sphere of stellar innards, blown out from a humongous star.

The star (white dot in center of red ring) is one of the most massive stellar residents of our Milky Way galaxy. Objects like this are called Wolf-Rayet stars, after the astronomers who found the first few, and they make our sun look puny by comparison. Called V385 Carinae, this star is 35 times as massive as our sun, with a diameter nearly 18 times as large. It's hotter, too, and shines with more than one million times the amount of light.

Fiery candles like this burn out quickly, leading short lives of only a few million years. As they age, they blow out more and more of the heavier atoms cooking inside them -- atoms such as oxygen that are needed for life as we know it.

The material is puffed out into clouds like the one that glows brightly in this WISE image. In this case, the hollow sphere showed up prominently only at the longest of four infrared wavelengths detected by WISE. Astronomers speculate this infrared light comes from oxygen atoms, which have been stripped of some of their electrons by ultraviolet radiation from the star. When the electrons join up again with the oxygen atoms, light is produced that WISE can detect with its 22-micron infrared light detector. The process is similar to what happens in fluorescent light bulbs.

Infrared light detected by WISE at 12 microns is colored green, while 3.4- and 4.6-micron light is blue. The green, kelp-looking material is warm dust, and the blue dots are stars in our Milky Way galaxy.

This image mosaic is made up of about 300 overlapping frames, taken as WISE continues its survey of the entire sky -- an expansive search, sure to turn up more fascinating creatures swimming in our cosmic ocean.

V385 Carinae is located in the Carina constellation, about 16,000 light-years from Earth.

Photo credit: NASA/JPL-Caltech/UCLA

NGC 2359, Thor's Helmet, by WISE

This heroic image from WISE is of a special cloud of dust and gas in the constellation Canis Major cataloged as NGC 2359. The nebula is more commonly known as Thor's Helmet due to its remarkable resemblance to depictions of the headwear donned by the famed Norse god of thunder and lightning.

Powering Thor's Helmet is HD 56925, a highly luminous "Wolf-Rayet" star (seen at the center of the helmet). These kinds of stars are massive; from 10 to 80 times the mass of our Sun. Such stars are often associated with bright nebulae, many of which appear to be spherical bubbles with the Wolf-Rayet star at the center. It is thought that the progenitors of these stars are either red supergiants or luminous blue variable stars, both of which slowly shed matter as they age. Once the star enters its Wolf-Rayet phase its strong, fast stellar wind sweeps up the surrounding debris left by the original star and even gathers up interstellar matter from its environment. It literally blows a bubble in space. These hot stars become 200,000 times more luminous than the Sun. They flood the nebula with ultraviolet light that ionizes much of the gaseous material leading to the bright emission in visible light. Interactions with a nearby large molecular cloud are thought to have contributed to the more complex shape and curved bow-shock structure of Thor's Helmet.

NGC 2359 was the first Wolf-Rayet nebula to be discovered. Between 1917 and 1919, Francis Pease studied the nebula at the Mt. Wilson observatory in southern California. He described the bright regions of the nebula as matching the descriptions of early observers such as Sir John Herschel (son of the discoverer of infrared light, William Herschel), who saw a bust rather than a helmet. The object was later found to show nitrogen emission by Edwin Hubble and listed in his 1922 paper, "A General Study of Diffuse Galactic Nebulae." The object has also been of interest to members of the WISE science team during their careers having been studied by Martin Cohen and the WISE Principal Investigator Ned Wright, who co-authored an article in the March 1980 issue of Sky & Telescope, "A Bubble in Space - The Shell of NGC 2359."

Thor's Helmet is about 30 light-years across and its distance from Earth is estimated to be about 15,000 light-years. This image covers an area of sky about 2.5 times the size of the full Moon. All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA