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Andromeda’s once and future stars

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Two ESA observatories have combined forces to show the Andromeda Galaxy in a new light. Herschel sees rings of star formation in this, the most detailed image of the Andromeda Galaxy ever taken at infrared wavelengths, and XMM-Newton shows dying stars shining X-rays into space.

During Christmas 2010, ESA’s Herschel and XMM-Newton space observatories targeted the nearest large spiral galaxy M31. This is a galaxy similar to our own Milky Way – both contain several hundred billion stars. This is the most detailed far-infrared image of the Andromeda Galaxy ever taken and shows clearly that more stars are on their way.

Sensitive to far-infrared light, Herschel sees clouds of cool dust and gas where stars can form. Inside these clouds are many dusty cocoons containing forming stars, each star pulling itself together in a slow gravitational process that can last for hundreds of millions of years. Once a star reaches a high enough density, it will begin to shine at optical wavelengths. It will emerge from its birth cloud and become visible to ordinary telescopes.

Many galaxies are spiral in shape but Andromeda is interesting because it shows a large ring of dust about 75 000 [...]

Herschel finds a hole in space

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ESA’s Herschel infrared space telescope has made an unexpected discovery: a hole in space. The hole has provided astronomers with a surprising glimpse into the end of the star-forming process.

Stars are born in dense clouds of dust and gas that can now be studied in unprecedented detail with Herschel. Although jets and winds of gas have been seen coming from young stars in the past, it has always been a mystery exactly how a star uses these to blow away its surroundings and emerge from its birth cloud. Now, for the first time, Herschel may be seeing an unexpected step in this process. A cloud of bright reflective gas known to astronomers as NGC 1999 sits next to a black patch of sky. For most of the 20th century, such black patches have been known to be dense clouds of dust and gas that block light from passing through.

When Herschel looked in its direction to study nearby young stars, the cloud continued to look black. But wait! That should not be the case. Herschel’s infrared eyes are designed to see into such clouds. Either the cloud was immensely dense or something was wrong.

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Herschel reveals the hidden side of star birth

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The first scientific results from ESA’s Herschel infrared space observatory are revealing previously hidden details of star formation. New images show thousands of distant galaxies furiously building stars and beautiful star-forming clouds draped across the Milky Way. One picture even catches an ‘impossible’ star in the act of formation.

Presented today during a major scientific symposium held at the European Space Agency (ESA), the results challenge old ideas of star birth, and open new roads for future research.

Herschel’s observation of the star-forming cloud RCW 120 has revealed an embryonic star which looks set to turn into one of the biggest and brightest stars in our Galaxy within the next few hundred thousand years. It already contains eight to ten times the mass of the Sun and is still surrounded by an additional 2000 solar masses of gas and dust from which it can feed further.

“This star can only grow bigger,” says Annie Zavagno, Laboratoire d’Astrophysique de Marseille. Massive stars are rare and short-lived. To catch one during formation presents a golden opportunity to solve a long-standing paradox in astronomy. “According to our current understanding, you should not be able to form stars larger than eight [...]

Inside the dark heart of the Eagle

Inside the dark heart of the Eagle

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Herschel has peered inside an unseen stellar nursery and revealed surprising amounts of activity. Some 700 newly-forming stars are estimated to be crowded into filaments of dust stretching through the image. The image is the first new release of ‘OSHI’, ESA’s Online Showcase of Herschel Images.

This image shows a dark cloud 1000 light-years away in the constellation Aquila, the Eagle. It covers an area 65 light-years across and is so shrouded in dust that no previous infrared satellite has been able to see into it. Now, thanks to Herschel’s superior sensitivity at the longest wavelengths of the infrared, astronomers have their first picture of the interior of this cloud.

It was taken on 24 October using two of Herschel’s instruments: the Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE). The two bright regions are areas where large newborn stars are causing hydrogen gas to shine.

The new OSHI website that goes live today will become the library of Herschel’s best images. Stunning views of the infrared sky will be made available as the mission progresses. Each will be captioned in a way to make them accessible to media representatives, educators and [...]

Herschel views deep-space pearls on a cosmic string

Herschel views deep-space pearls on a cosmic string

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Herschel has delivered spectacular vistas of cold gas clouds lying near the plane of the Milky Way, revealing intense, unexpected activity. The dark, cool region is dotted with stellar factories, like pearls on a cosmic string.

On 3 September, Herschel aimed its telescope at a reservoir of cold gas in the constellation of the Southern Cross near the Galactic Plane. As the telescope scanned the sky, the spacecraft’s Spectral and Photometric Imaging REceiver, SPIRE, and Photoconductor Array Camera and Spectrometer, PACS instruments snapped the pictures. The region is located about 60° from the Galactic Centre, thousands of light-years from Earth.

The five original infrared wavelengths have been colour-coded to allow scientists to differentiate extremely cold material (red) from the surrounding, slightly warmer stuff (blue).

The images reveal structure in cold material in our Galaxy, as we have never seen it before, and even before a detailed analysis, scientists have gleaned information on the quantity of the material, its mass, temperature, composition and whether it is collapsing to form new stars.

That a dark, cool area such as this would be bustling with activity, was unexpected. But the images reveal a surprising amount of turmoil: the interstellar material [...]

Herschel images promise bright future

Herschel images promise bright future

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Herschel has carried out the first test observations with all its instruments, with spectacular results. Galaxies, star-forming regions and dying stars comprised the telescope’s first targets. The instruments provided spectacular data on their first attempt, finding water and carbon and revealing dozens of distant galaxies.

These observations show that Herschel’s instruments are working beyond expectations. They promise a mission of rich discoveries for waiting astronomers.

On 24 June, Herschel’s Spectral and Photometric Imaging Receiver (SPIRE) was trained on two galaxies for its first look at the Universe. The galaxies showed up prominently, providing astronomers with their best images yet at these wavelengths, and revealing other, more distant galaxies in the background of the images.

The pictures below show galaxies M66 and M74 at a wavelength of 250 microns, longer than any previous infrared space observatory, but still the shortest SPIRE wavelength.

SPIRE is designed to look at star formation in our own Galaxy and in nearby galaxies. It will also search for star-forming galaxies in the very distant Universe. Because these galaxies are so far away, their light has taken a very long time to reach us, so by detecting them we are looking into the past [...]

Herschel’s daring test: a glimpse of things to come

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Herschel opened its ‘eyes’ on 14 June and the Photoconductor Array Camera and Spectrometer obtained images of M51, ‘the whirlpool galaxy’ for a first test observation. Scientists obtained images in three colours which clearly demonstrate the superiority of Herschel, the largest infrared space telescope ever flown.

This image shows the famous ‘whirlpool galaxy’, first observed by Charles Messier in 1773, who provided the designation Messier 51 (M51). This spiral galaxy lies relatively nearby, about 35 million light-years away, in the constellation Canes Venatici. M51 was the first galaxy discovered to harbour a spiral structure.

The image is a composite of three observations taken at 70, 100 and 160 microns, taken by Herschel’s Photoconductor Array Camera and Spectrometer (PACS) on 14 and 15 June, immediately after the satellite’s cryocover was opened on 14 June.

Herschel, launched only a month ago, is still being commissioned and the first images from its instruments were planned to arrive only in a few weeks. But engineers and scientists were challenged to try to plan and execute daring test observations as part of a ‘sneak preview’ immediately after the cryocover was opened. The objective was to produce a very early image that gives [...]

Herschel cryocover is open

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At 12:53 CEST yesterday, the cryocover of the Herschel satellite was opened after the spacecraft received a command to fire pyrotechnic bolts holding it down. This crucial step brings ESA’s newest space telescope one step closer to starting its scientific mission.

The cryocover is the Herschel telescope’s ‘lens cap’: it provides a high-vacuum tight closure of the cryostat on ground and during the early orbit phase, and preserves the cryogenic environment of the instrument focal plane units during activities on ground.

With the cryocover on, the instruments and the telescope cannot ‘see’.

As Herschel is now in the vacuum of space and the first few weeks of out-gassing have passed, the cryocover could be opened safely. The command to open the cryocover was issued manually by spacecraft controllers at ESOC, ESA’s European Space Operations Centre, in Darmstadt, Germany. Telemetry received just afterwards from the spacecraft indicated that the cryocover had reached the open position.

“The cryocover swung back and forth several times, pushing the satellite somewhat, and there were changes in temperature measured at several points close to the focal plane units, as expected. All this is consistent with the cryocover opening successfully. The final positive confirmation [...]