Hersche New molecules around old stars

This image presents the Helix Nebula first at optical wavelengths, as seen by the Hubble Space Telescope, then by Herschel’s SPIRE instrument at wavelengths around 250 micrometres. A spectrum is shown for the region identified on the image, showing the clear signature of CO and OH⁺ emission in the clumpy outer regions of the planetary nebula.

The molecular ion OH⁺ is needed for the formation of water, and ESA’s Herschel space observatory is the first to detect it in planetary nebulas – the product of dying Sun-like stars.

Copyright: Hubble image: NASA/ESA/C.R. O’Dell (Vanderbilt University), M. Meixner & P. McCullough (STScI); Herschel data: ESA/Herschel/SPIRE/MESS Consortium/M. Etxaluze et al.

Using ESA’s Herschel space observatory, astronomers have discovered that a molecule vital for creating water exists in the burning embers of dying Sun-like stars.

When low- to middleweight stars like our Sun approach the end of their lives, they eventually become dense, white dwarf stars. In doing so, they cast off their outer layers of dust and gas into space, creating a kaleidoscope of intricate patterns known as planetary nebulas.

These actually have nothing to do with planets, but were named in the late 18th century by astronomer William Herschel, because they appeared as fuzzy circular objects through his telescope, somewhat like the planets in our Solar System.

Over two centuries later, planetary nebulas studied with William Herschel’s namesake, the Herschel space observatory, have yielded a surprising discovery.

Like the dramatic supernova explosions of weightier stars, the death cries of the stars responsible for planetary nebulas also enrich the local interstellar environment with elements from which the next generations of stars are born.

While supernovas are capable of forging the heaviest elements, planetary nebulas contain a large proportion of the lighter ‘elements of life’ such as carbon, nitrogen, and oxygen, made by nuclear fusion in the parent star.

The Ring Nebula at optical wavelengths as seen by the Hubble Space Telescope, with Herschel data acquired with SPIRE and PACS over a wavelength range of 51–672 micrometres for the region identified. 

The spectra have been cropped and the scales stretched in order to show the OH⁺ emission, a molecular ion important for the formation of water. ESA’s Herschel space observatory is the first to detect this molecule in planetary nebulas – the product of dying Sun-like stars.

Copyright: Hubble image: NASA/ESA/C. Robert O’Dell (Vanderbilt University) Herschel data: ESA/Herschel/PACS & SPIRE/ HerPlaNS survey/I. Aleman et al.

A star like the Sun steadily burns hydrogen in its core for billions of years. But once the fuel begins to run out, the central star swells into a red giant, becoming unstable and shedding its outer layers to form a planetary nebula. 

The remaining core of the star eventually becomes a hot white dwarf pouring out ultraviolet radiation into its surroundings. 

This intense radiation may destroy molecules that had previously been ejected by the star and that are bound up in the clumps or rings of material seen in the periphery of planetary nebulas. 

The harsh radiation was also assumed to restrict the formation of new molecules in those regions. 

But in two separate studies using Herschel astronomers have discovered that a molecule vital to the formation of water seems to rather like this harsh environment, and perhaps even depends upon it to form. The molecule, known as OH+, is a positively charged combination of single oxygen and hydrogen atoms.

 What links the three is that they host the hottest stars, with temperatures exceeding 100 000ºC.

“We think that a critical clue is in the presence of the dense clumps of gas and dust, which are illuminated by UV and X-ray radiation emitted by the hot central star,” says Dr Aleman. 

“This high-energy radiation interacts with the clumps to trigger chemical reactions that leads to the formation of the molecules.”

Herschel observations of Helix Nebula

Copyright: Hubble image: NASA/ESA/C.R. O’Dell (Vanderbilt University), M. Meixner & P. McCullough (STScI); Herschel image: ESA/Herschel/SPIRE/MESS Consortium/M. Etxaluze et al.

Meanwhile, another study, led by Dr Mireya Etxaluze of the Instituto de Ciencia de los Materiales de Madrid, Spain, focused on the Helix Nebula, one of the nearest planetary nebulas to our Solar System, at a distance of 700 light years. 

The central star is about half the mass of our Sun, but has a far higher temperature of about 120 000ºC. The expelled shells of the star, which in optical images appear reminiscent of a human eye, are known to contain a rich variety of molecules. 

Herschel mapped the presence of the crucial molecule across the Helix Nebula, and found it to be most abundant in locations where carbon monoxide molecules, previously ejected by the star, are most likely to be destroyed by the strong UV radiation. 

Once oxygen atoms have been liberated from the carbon monoxide, they are available to make the oxygen–hydrogen molecules, further bolstering the hypothesis that the UV radiation may be promoting their creation.

The two studies are the first to identify in planetary nebulas this critical molecule needed for the formation of water, although it remains to be seen if the conditions would actually allow water formation to proceed. 

“The proximity of the Helix Nebula means we have a natural laboratory on our cosmic doorstep to study in more detail the chemistry of these objects and their role in recycling molecules through the interstellar medium,” says Dr Etxaluze. 

“Herschel has traced water across the Universe, from star-forming clouds to the asteroid belt in our own Solar System,” says Göran Pilbratt, ESA’s Herschel project scientist.  

“Now we have even found that stars like our Sun could contribute to the formation of water in the Universe, even as they are in their death throes.” 

“Herschel planetary nebula survey (HerPlaNS). First detection of OH⁺ in planetary nebulae,” by I. Aleman et al., and “Herschel spectral-mapping of the Helix Nebula (NGC 7293): extended CO photodissociation and OH⁺ emission,” by M. Etxaluze et al., are published in Astronomy & Astrophysics.

 

HerPlaNS (The Herschel Planetary Nebulae Survey) is a survey of 11 planetary nebulas aiming the study the formation and evolution of the circumstellar material by tracing the dust and gas components. The HerPlaNS team is led by Toshiya Ueta from the University of Denver. 

The MESS (Mass loss of Evolved StarS) consortium studies a wide variety of evolved stars (including planetary nebulas) to better understand the mass loss in these objects, the dust and gas chemistry in the ejected material, and the processes shaping the nebulae. The MESS consortium is led by Martin Groenewegen (Royal Observatory of Belgium) and the study of planetary nebulas within the group is led by Peter van Hoof (Royal Observatory of Belgium). 

For further information, please contact:
 
Markus Bauer



ESA Science and Robotic Exploration Communication Officer



Tel: +31 71 565 6799




Mob: +31 61 594 3954




Email: markus.bauer@esa.int

Isabel Aleman
Leiden Observatory, University of Leiden, the Netherlands
Email: aleman@strw.leidenuniv.nl

Mireya Etxaluze
Group of Molecular Astrophysics, Instituto de Ciencias de los Materiales de Madrid, CSIC, Spain
Email: m.etxaluze@icmm.csic.es

Göran Pilbratt

ESA Herschel Project Scientist

Tel: +31 71 565 3621


Email: gpilbratt@rssd.esa.int

 Source: ESA

Herschel links star formation to sonic booms

Dense filaments of gas in the IC5146 interstellar cloud. This image was taken by ESA’s Herschel space observatory at infrared wavelengths 70, 250 and 500 microns. Stars are forming along these filaments.

Credits: ESA/Herschel/SPIRE/PACS/D. Arzoumanian (CEA Saclay) for the “Gould Belt survey” Key Programme Consortium. HI-RES JPEG (Size: 757 kb) - HI-RES TIFF (Size: 14 736 kb)

ESA’s Herschel space observatory has revealed that nearby interstellar clouds contain networks of tangled gaseous filaments. Intriguingly, each filament is approximately the same width, hinting that they may result from interstellar sonic booms throughout our Galaxy.

The filaments are huge, stretching for tens of light years through space and Herschel has shown that newly-born stars are often found in the densest parts of them. One filament imaged by Herschel in the Aquila region contains a cluster of about 100 infant stars.

Such filaments in interstellar clouds have been glimpsed before by other infrared satellites, but they have never been seen clearly enough to have their widths measured. Now, Herschel has shown that, regardless of the length or density of a filament, the width is always roughly the same.

The network of interstellar filaments in Polaris as imaged by ESA’s Herschel space observatory at infrared wavelengths 250, 350 and 500 microns. These filaments are not yet forming stars.

Credits: ESA/Herschel/SPIRE/Ph. André (CEA Saclay) for the Gould Belt survey Key Programme Consortium and A. Abergel (IAS Orsay) for the Evolution of Interstellar Dust Key Programme Consortium. HI-RES JPEG (Size: 2802 kb) - HI-RES TIFF (Size: 5747 kb)

“This is a very big surprise,” says Doris Arzoumanian, Laboratoire AIM Paris-Saclay, CEA/IRFU, the lead author on the paper describing this work. Together with Philippe André from the same institute and other colleagues, she analysed 90 filaments and found they were all about 0.3 light years across, or about 20 000 times the distance of Earth from the Sun. This consistency of the widths demands an explanation.

Comparing the observations with computer models, the astronomers concluded that filaments are probably formed when slow shockwaves dissipate in the interstellar clouds. These shockwaves are mildly supersonic and are a result of the copious amounts of turbulent energy injected into interstellar space by exploding stars. They travel through the dilute sea of gas found in the Galaxy, compressing and sweeping it up into dense filaments as they go.

Interstellar clouds are usually extremely cold, about 10 degrees Kelvin above absolute zero, and this makes the speed of sound in them relatively slow at just 0.2 km/s, as opposed to 0.34 km/s in Earth’s atmosphere at sea-level.

These slow shockwaves are the interstellar equivalent of sonic booms. The team suggests that as the sonic booms travel through the clouds, they lose energy and, where they finally dissipate, they leave these filaments of compressed material.

Herschel telescope mirror at ESTEC

Credit: ESA

“This is not direct proof, but it is strong evidence for a connection between interstellar turbulence and filaments. It provides a very strong constraint on theories of star formation,” says Dr André.

The team made the connection by studying three nearby clouds, known as IC5146, Aquila, and Polaris, using Herschel’s SPIRE and PACS instruments.

“The connection between these filaments and star formation used to be unclear, but now thanks to Herschel, we can actually see stars forming like beads on strings in some of these filaments,” says Göran Pilbratt, the ESA Herschel Project Scientist.

Contact for further information

Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Email: markus.bauer@esa.int
Tel: +31 71 565 6799
Mob: +31 61 594 3 954

Doris Arzoumanian
PhD student at Laboratoire AIM Paris-Saclay, CEA/IRFU
Email: doris.arzoumanian@cea.fr
Mob: +33 6 18 74 36 13

Philippe André
Researcher at Laboratoire AIM Paris-Saclay, CEA/IRFU
PI of the Herschel Gould Belt Survey
Email: pandre@cea.fr
Tel: +33 1 69 08 92 65

Göran Pilbratt
ESA Herschel Project Scientist
Email: gpilbratt@rssd.esa.int
Tel: +31 71 565 3621

Bright galaxies like to stick together

Astronomers using the European Space Agency's Herschel telescope have discovered that the brightest galaxies tend to be in the busiest parts of the Universe. This crucial piece of information will enable theorists to fix up their theories of galaxy formation. For over a decade, astronomers have been puzzled by some strange, bright galaxies in the distant Universe which appear to be forming stars at phenomenal rates. These galaxies are very hard to explain with conventional theories of galaxy formation. One important question has been the environments in which these galaxies are located, such as how close together they are. The Herschel Space Observatory, with its ability for very sensitive mapping over wide areas, has been able to see thousands of these galaxies and identify their location, showing for the first time that these galaxies are packed closely together in the centre of large galaxy clusters.

A project using the UK-led SPIRE instrument on board Herschel has been surveying large areas of the sky, currently totalling 15 square degrees – around 60 times the size of the Full Moon. The two regions mapped so far are in the constellations of Ursa Major and Draco, well away from the confusion of our own Galaxy. Galaxies which are brightest at Herschel’s far-infrared wavelengths are typically seen as they were around 10 billion years ago, the light having been travelling towards us since that time.

Hershcel's view of a patch of sky in the constellation of Ursa Major. Almost every one of the thousands of dots is a distant galaxy. Image credit: ESA / SPIRE / HerMES

The false-colour image above shows a small portion of the sky observed by Herschel. Almost every point of light is an entire galaxy, each containing billions of stars. The colours represent the far-infrared wavelengths measured by Herschel, with redder galaxies either being further away or containing colder dust, while brighter galaxies are forming stars more vigorously. While at a first glance the galaxies look to be scattered randomly over the image, in fact they are not. A closer look will reveals that there are regions which have more galaxies in, and regions that have fewer. This clustering of galaxies through space provides information about the way they have interacted over the history of the Universe.

The Antennae Galaxies as seen in the far-infrared by Herschel (left), and in visible light by the Hubble Space Telescope (right). The areas with most star formation are bright in the Herschel image, but hidden by dust in the Hubble image. Image credit: ESA / PACS / SHINING / U. Klaas & M. Nielbock, MPIA.

Herschel sees material that cannot be seen at visible wavelengths, namely cold gas and dust between the stars. This is well illustrated by looking at much closer galaxies, which can be seen in more detail. The Antennae Galaxies, lying a mere 50 million light years away, are actually two galaxies which are in the process of colliding, and were observed as part of a different observing programme. Herschel does not see the light from stars, but the clouds of dust within which new stars are forming. The collision of these galaxies has caused a surge in star formation, but such collisions are relatively rare in the Universe today. Billions of years ago, however, when galaxies were much more tightly packed, such events were much more common.

Despite the new window on the Universe afforded by the far-infrared light, Herschel is still not seeing the full picture. Three quarters of the matter in our Universe is made up of mysterious “dark matter”, which does not shine at all. Since we cannot see dark matter, we do not yet know what it is made of, but we can measure its effect on the matter around it. Although it does not emit or absorb light, dark matter does interact with the rest of the Universe through gravity, gradually pulling groups of galaxies together into huge clusters over the course of billions of years. While many computer simulations exist of how this occurs, the ability to measure this at different times through the history of the Universe allows astronomers to compare the simulations with real measurements.

These latest results from Herschel, part of the “HerMES” key programme, have shown that the bright galaxies detected with the SPIRE instrument preferentially occupy regions of the Universe that contain more dark matter. This seems to be especially true about 10 billion years ago, when these galaxies were forming stars at a much higher rate than most galaxies are today.

Our Galaxy, the Milky Way, resides on the suburbs of a large supercluster centred about 60 million light years away. The neighbouring supercluster of galaxies to us is around 300 million light years away. By comparison, 10 billion years ago galaxies were only 20 to 30 million light years apart on average. Their proximity means that many of the galaxies will eventually collide with one another. It is these collisions that stirs up the gas and dust in the galaxies and causes the rapid bouts of star formation. Professor Asantha Cooray, of the University of California, is one of the HerMES astronomers leading this investigation, and he commented on the latest HerMES results: "Thanks to the superb resolution and sensitivity of the SPIRE instrument on Herschel, we managed to map in detail the spatial distribution of massively starforming galaxies in the early universe. All indications are that these galaxies are busy. They are crashing, merging, and possibly settling down at centres of large dark matter halos."

It has required the sensitivity and resolution of Herschel to be able to identify the brightest galaxies and establish the way in which they are clustering. Dr Lingyu Wang, of the University of Sussex, said "we have known for a long time that environment plays an important role in shaping galaxies' evolution. With Herschel, we are able to pierce through huge amounts of dust and study the impact of the environment right from the birth of these massive galaxies forming stars at colossal rates. This is allowing us to witness the active past of today's dead elliptical galaxies at times when they were in rich environments."

Professor Seb Oliver, of the University of Sussex, who co-leads the HerMES project, presented this result last week at the Herschel First Results Symposium in the Netherlands. Professor Oliver said "this result from Asantha's team is fantastic, it is just the kind of thing we were hoping for from Herschel and was only possible because we can see so many thousands of galaxies, it will certainly give the theoretician's something to chew over".

This work, conducted as part of the Herschel Multi-tiered Extragalactic Survey (HerMES) Key Project of the Herschel mission, will be published in the international science journal “Astronomy & Astrophysics” in a special issue dedicated to the first science results from Herschel. The project will continue to collect more images over larger areas of the sky in order to build up a more complete picture of how galaxies have evolved and interacted over the past 10-12 billion years.

Herschel finds a hole in space

NGC 1999 is the green tinged cloud towards the top of the image. The dark spot to the right was thought to be a cloud of dense dust and gas until Herschel looked at it. It is in fact a hole that has been blown in the side of NGC 1999 by the jets and winds of gas from the young stellar objects in this region of space.

This image combines Herschel PACS 70 and 160 micron data, and 1.6 and 2.2 micron data with the NEWFIRM camera on the Kitt Peak 4 meter. Credits: ESA/HOPS Consortium

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.

Investigating further using ground-based telescopes, astronomers found the same story however they looked: this patch looks black not because it is a dense pocket of gas but because it is truly empty. Something has blown a hole right through the cloud. “No-one has ever seen a hole like this,” says Tom Megeath, of the University of Toledo, USA. “It’s as surprising as knowing you have worms tunnelling under your lawn, but finding one morning that they have created a huge, yawning pit.”

The astronomers think that the hole must have been opened when the narrow jets of gas from some of the young stars in the region punctured the sheet of dust and gas that forms NGC 1999. The powerful radiation from a nearby mature star may also have helped to clear the hole. Whatever the precise chain of events, it could be an important glimpse into the way newborn stars disperse their birth clouds.

Contacts

Tom Megeath
University of Toledo, Ohio
Tel: +1 419 530 7812
Email: tommegeath @ gmail.com

Herschel's HIFI follows the trail of cosmic water

Herschel's HIFI instrument was especially designed to follow the water trail in the Universe over a wide range of scales, from the Solar System out to extragalactic sources. Early results, presented this week at the Herschel First Results Symposium, demonstrate how HIFI uses water to probe the physical and chemical conditions in different regions of the cosmos.

Water is an extremely important molecule in the Universe, abundant in a large variety of cosmic environments — from our own blue planet and its neighbourhood, the Solar System, through interstellar clouds where new stars and planets are formed, and even beyond the Milky Way, in star-forming galaxies. Due to the large amount of water vapour present in the Earth's atmosphere, however, astronomical observations of water from ground-based facilities are virtually impossible, even from the driest and highest deserts; they need to be carried out with space observatories.

Depicts: Water lines toward low-mass protostars in the NGC 1333 star-forming region

Copyright: ESA and the HIFI consortium; L.E. Kristensen for the WISH Key Programme. Background image: NASA/JPL-Caltech/R. Gutermuth (Harvard-Smithsonian CfA)

Depicts: Water lines toward the intermediate-mass protostar NGC 7129

Copyright: ESA and the HIFI consortium; D. Johnstone for the WISH Key Programme. Background image: NASA/JPL-Caltech/S.T. Megeath (Harvard-Smithsonian CfA)

The presence of water in a celestial object is revealed through its very distinctive fingerprints, or lines, in the object's spectrum at far-infrared and sub-millimetre wavelengths. Only high resolution spectrographs, such as HIFI on board ESA's Herschel Space Observatory, are able to obtain spectra sufficiently precise to track down the abundance of water in great detail.

HIFI, or the Heterodyne Instrument for the Far Infrared, was designed with the quest of water and other molecules very much in mind. Based on the heterodyne detection principle, it basically translates, without loss of information, the high-frequency signal received from astronomical sources to a lower frequency, where measurements are easier to perform. "With its superb spectral resolution, HIFI is ideally suited to detect and characterize molecular lines, and is currently performing a chemical census of the cosmos," says Göran Pilbratt, Herschel Project Scientist.

"Water is an excellent diagnostic tool to probe the chemical and physical structure of the interstellar medium," explains Alexander Tielens from Leiden University. "Early detection of this important molecule on all cosmic scales highlights that HIFI is working extremely well."

With its superb resolution, HIFI can target about 40 different lines, each coming from a different transition of the water molecule and thus sensitive to a different temperature. This plethora of water lines in the spectra is anything but redundant information: it actually helps to overcome one of the natural drawbacks of astronomical observations, which yield two-dimensional images due to the projection on the celestial vault. As each line comes from a slightly different area in the interstellar clouds, putting all the information together gives a three-dimensional view of them. "HIFI data represent a sort of MRI scan through these regions, examining them slice-by-slice in a tomographic approach," explains Frank Helmich, Principal Investigator for Herschel-HIFI.

The role of water is crucial in the processes of star formation, because this molecule contributes to the cooling of the gas and dust mixture from which stars are born. Early results, reported this week at the Herschel First Results Symposium, demonstrate the detection of water in various proto-stellar systems. Along with upcoming data from star-forming clouds throughout the Milky Way, these data will help astronomers understand the mechanisms of star formation in great detail. Beyond our Galaxy, water signatures have been found in nearby galaxies which are known to be undergoing intense bursts of star formation.

Water trails go all the way from vast star-forming clouds down to stars and planets on much smaller scales. In the proto-planetary discs surrounding stars in the process of forming, water vapour may in fact freeze onto dust grains; these cold grains would then condense into icy planetesimals, the seeds of planet formation.

"In our very own planetary system, HIFI has observed a handful of comets, which are dusty conglomerates held together by icy water," notes Tielens. These cosmic 'ice balls' are living fossils in the Solar System, since they spend most of their lifetime at its boundaries and their chemical composition closely reflects the pristine conditions when the planets were formed about 4.5 billion years ago. "Further analysis of these early data collected by HIFI will shed new light on the early history of the Solar System," Tielens adds.

Notes for editors:

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia, with important participation from NASA.

HIFI, a high resolution spectrometer was designed and built by a nationally-funded consortium led by SRON Netherlands Institute for Space Research. The consortium includes institutes from France, Germany, USA, Canada, Ireland, Italy, Poland, Russia, Spain, Sweden, Switzerland, and Taiwan.

The distribution of water and its related species is the primary focus of the Key Programme WISH: Water In Star-forming regions with Herschel, led by Principal Investigator E.F. van Dishoeck. This programme is dedicated to studying the physical and chemical structure of star-forming regions through combined HIFI and PACS spectroscopy.

Other HIFI Key Programmes with a water theme are: HIFISTARS, led by Principal Investigator Valentín Bujarrabal, which studies the role of water in the ejecta from stars in the latest stages of their evolution when they return most of their material back to the interstellar medium; HSSO, led by Principal Investigator Paul Hartogh, which studies the role of water in Solar System objects, in particular Mars, the giant planets and comets; and HEXGAL, led by Principal Investigator Rolf Güsten, which among other things follows the water trail on a galactic scale in nearby galaxies.

Contacts:

Göran Pilbratt, Herschel Project Scientist
Research and Scientific Support Department
Science and Robotic Exploration Directorate, ESA, The Netherlands
Email: gpilbrattr@ssd.esa.int
Phone: +31-71-565-3621

Alexander Tielens, HIFI Project Scientist
Leiden University, The Netherlands
Email: tielens@strw.leidenuniv.nl
Phone: +31-71-527-8465

Ewine van Dishoeck, Principal Investigator of the WISH Key Programme
Leiden University, The Netherlands
Email: ewine@strw.leidenuniv.nl
Phone: +31-71-527-5814

Frank Helmich, Principal Investigator for HIFI
SRON Netherlands Institute for Space Research, The Netherlands
Email: F.P.Helmich@sron.nl
Phone: + 31-50-363-8320
Mobile phone: +31-6-49423644

Herschel unveils rare massive stars in the act of forming

New images from ESA's Herschel space observatory reveal high-mass protostars around two ionised regions in our Galaxy. The detection of these rare stars in an early phase of evolution is key to understanding the mysterious formation of massive stars.

This is one of the many discoveries presented this week at the Herschel First Results Symposium, ESLAB 2010, held at the European Space Research and Technology Centre, Noordwijk, The Netherlands.

Massive stars are the rare birds of astrophysics. With a mass over eight times that of the Sun, these stars are much less common than their lower-mass counterparts. In addition, they are short-lived, consuming their nuclear fuel at a rapid rate before ending their life in spectacular manner as a supernova. Their scarcity means that observations of these rare giants can prove difficult to obtain, but characterising these elusive objects is essential for understanding the chemical and dynamical evolution of galaxies.

The mechanism leading to the formation of massive stars is still largely debated. Detecting these objects in their earliest phases is a highly challenging task, since they are embedded in dusty cocoons that hide them from view. However, the dust that absorbs their light re-emits it at infrared wavelengths, making an infrared observatory such as Herschel a unique tool for locating newborn massive stars in their natal nests.

RCW 120 as seen by Herschel. Credit: ESA, PACS & SPIRE Consortia, A. Zavagno (Laboratoire d'Astrophysique de Marseille) for the Herschel HOBYS and Evolution of Interstellar Dust Key Programmes

One theory that has been put forward predicts that massive stars form at the outskirts of HII regions. An HII region is a bubble of hot hydrogen gas which has been ionised by the powerful radiation emitted by a central massive star formed in a previous generation. Temperature differences between the interior (up to 10 000 Kelvin) and the surrounding material (cooler than 100 Kelvin) cause these bubbles to expand and to reach supersonic speeds. This expanding bubble sweeps up a layer of neutral material around it, which then fragments into the dense seeds of a new generation of high-mass stars.

New data from Herschel targeting two distinct HII regions in our Galaxy, namely RCW 120 and N49, yield strong evidence in favour of this scenario. Thanks to its unprecedented resolution and sensitivity over a wide range of infrared wavelengths, ESA's new space observatory has imaged, for the first time, a handful of very young, massive stars on the border of both regions. These objects, which came to life less than a few tens of thousands of years ago, have never before been observed.

"We can finally witness the long-sought-after triggered formation of massive stars," says Annie Zavagno from Laboratoire d'Astrophysique de Marseille. "The high density of the material surrounding these bubbles and the intense motions due to stellar winds might be responsible for this particularly efficient star-forming process, leading to a new population of more massive stars around them."

The 'collect and collapse' model.

Credit: Deharveng & Zavagno

"Exploiting the unique combination of PACS and SPIRE, the two cameras on board Herschel, with a total spectral coverage that extends beyond the far-infrared into the sub-millimetre, the newly released images have refined our view on the birth of stars around expanding HII regions," says Göran Pilbratt, Herschel Project Scientist. "As a result of this new data, astronomers have been able not only to spot previously undetected young stars, but also to characterise their physical properties."

Particularly striking is the discovery, around RCW 120, of a massive protostar with a mass 8-10 times larger than the Sun's. "This object appears to be surrounded by a huge envelope of about 2000 solar masses, and it will continue to grow into an even more massive fully-fledged star," adds Zavagno.

Over the course of the next few months, PACS and SPIRE will target several other galactic HII regions that exhibit evidence of triggered star formation, in order to study this process in greater detail and to shed new light on the mechanisms producing high-mass stars in our Galaxy.

Notes to Editors

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia, with important participation from NASA.

PACS is an imaging photometer and integral field line spectrometer covering wavelengths between 57 and 210 µm. PACS was built by a consortium of institutes and university departments from across Europe, and is led by Albrecht Poglitsch of the Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany. Consortium members are: Austria: UVIE; Belgium: IMEC, KUL, CSL; France: CEA, OAMP; Germany: MPE, MPIA; Italy: IFSI, OAP/OAT, OAA/CAISMI, LENS, SISSA; Spain: IAC.

The SPIRE instrument comprises an imaging photometer (camera) and an imaging spectrometer. The camera operates in three wavelength bands centred on 250, 350 and 500 μm, and so can make images of the sky simultaneously in three submillimetre “colours”. The spectrometer covers the range 200 – 670 μm, allowing the spectral features of atoms and molecules to be measured. SPIRE has been developed by a consortium of institutes led by Cardiff Univ. (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC (UK); and NASA (USA). The SPIRE consortium is led by Prof. Matt Griffin of Cardiff University, United Kingdom.

The results reported here are based on a subset of observations from the following Herschel Key Programmes: HOBYS: the Herschel imaging survey of OB Young Stellar objects, led by Principal Investigator Frédérique Motte (SAp/CEA Saclay, France); Evolution of Interstellar Dust, led by Principal Investigator Alain Abergel (Institut d'Astrophysique Spatiale, IAS, France); and Hi-GAL: the Herschel Infrared Galactic Plane Survey, led by Principal Investigator Sergio Molinari (IFSI-INAF, Italy).

Related publications

Zavagno, A., et al., "Star formation triggered by the Galactic HII region RCW 120", 2010
Zavagno, A., et al., "Star formation triggered by HII regions in our Galaxy", 2010

Both papers will appear in a special issue of the journal Astronomy & Astrophysics dedicated to Herschel's first results.

Contacts

Annie Zavagno
Laboratoire d'Astrophysique de Marseille, France
Email: annie.zavagno@oamp.fr
Phone: +33-4-95-04-41-55

Göran Pilbratt, Herschel Project Scientist
Research and Scientific Support Department
Science and Robotic Exploration Directorate, ESA, The Netherlands
Email: gpilbratt@rssd.esa.int
Phone: +31-71-565-3621

Herschel reveals galaxies in the GOODS fields in a brand new light

The discovery of a previously unresolved population of galaxies in the GOODS fields and the first measurements of properties of galaxies in the almost unexplored far-infrared domain are among the first exciting scientific results achieved by Herschel's PACS and SPIRE instruments. These findings confirm the extraordinary capabilities of ESA's new infrared space observatory to investigate the formation and evolution of galaxies.

These are some of the many discoveries presented this week at the Herschel First Results Symposium, ESLAB 2010, held at the European Space Research and Technology Centre, Noordwijk, The Netherlands.

Understanding the details of how galaxies formed and evolved throughout cosmic history is one of the main goals of current astrophysical research. ESA's Herschel space observatory has begun to address this issue by joining in GOODS - the Great Observatories Origins Deep Survey - an ambitious project conceived to shed new light on this open topic.

Two carefully selected regions of the northern and southern sky, centred on the Hubble Deep Field North and the Chandra Deep Field South, have been the target of deep surveys conducted during the past decade over an extremely broad wavelength range, by means of ESA's and NASA's space observatories and the foremost ground-based telescopes. The GOODS fields, each measuring 10 by 16 arc minutes, are ideal for studying galaxies out to very high redshifts, as they do not contain any bright star and are not contaminated by strong emission coming from the Milky Way.

"Although both GOODS fields have been the object of extensive observations in the past, they have not yet been explored in the far-infrared region of the electromagnetic spectrum," explains Göran Pilbratt, Herschel Project Scientist. "Exploiting Herschel's powerful infrared eye and its broad wavelength coverage, we are now in the process of revealing some of the secrets that have been concealed until now."

Depicts: GOODS-South field

Copyright: ESA/PACS Consortium/PEP Key Programme Consortium

Depicts: PACS composite image of the GOODS-North field

Copyright: ESA/PACS Consortium/PEP Key Programme Consortium

With both the wavelength coverage and the technical characteristics required to resolve this 'cosmic fog' into individual galaxies, Herschel's PACS has isolated the sources of about a half of the CIB in the GOODS fields. "Thanks to the wealth of complementary data available for these fields, we have also studied how many of these galaxies are to be found at various epochs in cosmic history," adds Stefano Berta, who led this study. In fact, most of these galaxies are located at relatively low redshifts, their light having travelled less than 8000 million years before reaching us.

GOODS-N as viewed by SPIRE.

Credit: ESA/SPIRE Consortium/ HerMES Key Programme Consortium

"We know that the energy we receive from galaxies directly is roughly as much as the energy we receive from them after it has been reprocessed by dust," says Seb Oliver from the University of Sussex and leader of the HerMES Key Programme which probes galaxy evolution. "Thanks to SPIRE and PACS, we can finally explore how the population of obscured galaxies has evolved over cosmic time."

The true power of Herschel is unleashed when the images from both instruments are studied together. As a result of this synergy, observations of galaxies made by SPIRE on the GOODS-North field complement the studies on the CIB performed with PACS data. "A significant fraction of galaxies contributing to the CIB has also been resolved by SPIRE," comments Oliver. "This population of galaxies is dominated by sources at z~1, demonstrating that most of the infrared background radiation is emitted at low redshifts," adds Steve Eales from Cardiff University.

By sampling galaxies at the peak of their far-infrared emission, Herschel allows also a better understanding of the star-forming processes taking place within them. "The properties of galaxies in these new PACS and SPIRE images appear surprisingly uniform over the last 10 billion years of cosmic history, even for those galaxies harbouring an active nucleus," says David Elbaz from Laboratoire AIM-Paris-Saclay. This finding suggests that the history of star formation in the Universe is governed by simple, universal mechanisms. "This is only a first step, since a new window on the GOODS fields has just been opened with the GOODS-Herschel Open Time Key Programme. This will push Herschel to its ultimate limits in terms of depth," adds Elbaz.

And it is clear that much more is in store when placing Herschel data in the broader context of the wider electromagnetic spectrum. Some interesting results have already arisen when comparing Herschel data with radio observations of the GOODS-North field performed by the Very Large Array. "We have revealed tantalising signs of an evolution of the famous (and surprisingly strong) correlation between infrared emission and radio emission," notes Rob Ivison from UK Astronomy Technology Centre at the Royal Observatory in Edinburgh.

Notes to Editors

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia, with important participation from NASA.

PACS is an imaging photometer and integral field line spectrometer covering wavelengths between 57 and 210 µm. PACS was built by a consortium of institutes and university departments from across Europe, and is led by Albrecht Poglitsch of the Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany. Consortium members are: Austria: UVIE; Belgium: IMEC, KUL, CSL; France: CEA, OAMP; Germany: MPE, MPIA; Italy: IFSI, OAP/OAT, OAA/CAISMI, LENS, SISSA; Spain: IAC.

The SPIRE instrument comprises an imaging photometer (camera) and an imaging spectrometer. The camera operates in three wavelength bands centred on 250, 350 and 500 μm, and so can make images of the sky simultaneously in three submillimetre "colours". The spectrometer covers the range 200 – 670 μm, allowing the spectral features of atoms and molecules to be measured. SPIRE has been built by a consortium of 18 institutes in eight countries (UK, France, Italy, Spain, Sweden, USA, and China), and is led by Prof. Matt Griffin of Cardiff University. The instrument was assembled at the STFC's Rutherford Appleton Laboratory in the UK.

The PACS data on the GOODS fields have been obtained within the PACS Evolutionary Probe (PEP) collaboration, a Herschel Guaranteed Time Key Programme extragalactic survey, led by Dieter Lutz (Max Planck Institute for extraterrestrial Physics). PEP aims at studying galaxies up to redshift z~3 over a large total area in the sky, including the COSMOS field, the Lockman Hole and fields centred on lensing galaxy clusters. PEP is coordinated with SPIRE observations of the same fields in the Herschel Multi-tiered Extragalactic Survey (HerMES), another Guaranteed Time Key Programme probing galaxy evolution at high redshift. HerMES is led by Seb Oliver (University of Sussex).

Related publications

Berta, S., et al., "Dissecting the Cosmic Infra-Red Background with Herschel/PEP", 2010

Oliver, S.J., et al., "HerMES: SPIRE galaxy number counts at 250, 350 and 500 µm", 2010

Eales, S., et al."First results from HerMES on the evolution of the submillimetre luminosity function", 2010

Elbaz, D., et al., "Herschel unveils a puzzling uniformity of distant dusty galaxies", 2010

Ivison, R.J., et al., "The far-infrared/radio correlation as probed by Herschel", 2010

These papers will appear in a special issue of the journal Astronomy & Astrophysics dedicated to Herschel's first results.

Contacts

Göran Pilbratt, Herschel Project Scientist
Research and Scientific Support Department
Science and Robotic Exploration Directorate, ESA, The Netherlands
Email: gpilbrattr@ssd.esa.int
Phone: +31-71-565-3621

Dieter Lutz
Max Planck Institute for extraterrestrial Physics, Germany
Phone: +49 89 300003614
Email: lutz@mpe.mpg.de

Stefano Berta
Max Planck Institute for extraterrestrial Physics, Germany
Phone: +49-89-300003616
Email: berta@mpe.mpg.de

Seb Oliver

University of Sussex, United Kingdom

Phone: +44-1273-678852; mobile number: +44-7971-019161

Email: Oliver@sussex.ac.uk

Steve Eales
Cardiff University, United Kingdom
Phone: +44-29-208-76168
Email: Steve Eales@astro.cf.ac.uk

David Elbaz
Laboratoire AIM-Paris-Saclay, France
Phone: + 33-1-69085439
Email: delbaz@cea.fr

Rob Ivison
UK Astronomy Technology Centre at the Royal Observatory Edinburgh, part of the Science and Technology Facilities Council, United Kingdom
Phone: +44-131-668-8361
Email: rji@roe.ac.uk

Baby stars in the Rosette cloud

Infrared image of the Rosette molecular cloud. Herschel collects the infrared light given out by dust and this image is a three-colour composite made of wavelengths at 70 microns (blue), 160 microns (green) and 250 microns (red). It was made with observations from Herschel’s Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE). The bright smudges are dusty cocoons containing massive protostars. The small spots near the centre of the image are lower mass protostars. Credits: ESA/PACS & SPIRE Consortium/HOBYS Key Programme Consortia

HI-RES JPEG (Size: 555 kb) - HI-RES TIFF (Size: 2779 kb)

Herschel’s latest image reveals the formation of previously unseen large stars, each one up to ten times the mass of our Sun. These are the stars that will influence where and how the next generation of stars are formed. The image is a new release of ‘OSHI’, ESA’s Online Showcase of Herschel Images.

The Rosette Nebula resides some 5,000 light years from Earth and is associated with a larger cloud that contains enough dust and gas to make the equivalent of 10,000 Sun-like stars. The Herschel image shows half of the nebula and most of the Rosette cloud. The massive stars powering the nebula lie to the right of the image but are invisible at these wavelengths. Each colour represents a different temperature of dust, from –263ºC (only 10ºC above absolute zero) in the red emission to –233ºC in the blue.

The bright smudges are dusty cocoons hiding massive protostars. These will eventually become stars containing around ten times the mass of the Sun. The small spots near the centre and in the redder regions of the image are lower mass protostars, similar in mass to the Sun.

ESA’s Herschel space observatory collects the infrared light given out by dust. This image is a combination of three infrared wavelengths, colour-coded blue, green and red in the image, though in reality the wavelengths are invisible to our eyes. It was created using observations from Herschel’s Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE).

Herschel is showing astronomers such young, massive protostars for the first time, as part of the ‘Herschel imaging survey of OB Young Stellar objects’. Known as HOBYS, the survey targets young OB class stars, which will become the hottest and brightest stars.

“High-mass star-forming regions are rare and further away than low-mass ones,” says Frédérique Motte, Laboratoire AIM Paris-Saclay, France. So astronomers have had to wait for a space telescope like Herschel to reveal them.

It is important to understand the formation of high-mass stars in our Galaxy because they feed so much light and other forms of energy into their parent cloud they can often trigger the formation of the next generation of stars.

When astronomers look at distant galaxies, the star-forming regions they see are the bright, massive ones. Thus, if they want to compare our Galaxy to distant ones they must first understand high-mass star-formation here.

“Herschel will look at many other high-mass star-forming regions, some of them building stars up to a hundred times the mass of the Sun,” says Dr Motte, who plans to present the first scientific results from HOBYS at ESA’s annual ESLAB symposium to be held in the Netherlands, 4–7 May.

Herschel Finds Possible Life-Enabling Molecules in Space

Data, called a spectrum, showing water and organics in the Orion nebula. The data were taken by the heterodyne instrument for the far infrared, or HIFI, onboard the Herschel Space Observatory, a European Space Agency-led mission with important participation from NASA. Image credit: ESA/NASA/JPL-Caltech. Larger view

The Herschel Space Observatory has revealed the chemical fingerprints of potentially life-enabling organic molecules in the Orion nebula, a nearby stellar nursery in our Milky Way galaxy. Herschel is led by the European Space Agency with important participation from NASA.

The new data, obtained with the telescope's heterodyne instrument for the far infrared -- one of Herschel's three innovative instruments -- demonstrates the gold mine of information that Herschel will provide on how organic molecules form in space.

The Orion nebula is known to be one of the most prolific chemical factories in space, although the full extent of its chemistry and the pathways for molecule formation are not well understood. By sifting through the pattern of spikes in the new data, called a spectrum, astronomers have identified a few common molecules that are precursors to life-enabling molecules, including water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulfur oxide and sulfur dioxide.

Herschel is a European Space Agency cornerstone mission, with science instruments provided by a consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.

More information is online at:

http://www.herschel.caltech.edu/ and http://www.esa.int/SPECIALS/Herschel/index.html

Inside the dark heart of the Eagle

Credits: ESA and the SPIRE & PACS consortia,

P. André (CEA Saclay) for the Gould’s Belt Key Programme Consortia

HI-RES JPEG (Size: 610 kb)

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 the public.

Embedded within the dusty filaments in the Aquila image are 700 condensations of dust and gas that will eventually become stars. Astronomers estimate that about 100 are protostars, celestial objects in the final stages of formation. Each one just needs to ignite nuclear fusion in its core to become a true star. The other 600 objects are insufficiently developed to be considered protostars, but these too will eventually become another generation of stars.

This cloud is part of Gould’s Belt, a giant ring of stars that circles the night sky – the Solar System just happens to lie near the centre of the belt. The first to notice this unexpected alignment, in the mid-19th century, was England’s John Herschel, the son of William, after whom ESA’s Herschel telescope is named. But it was Boston-born Benjamin Gould who brought the ring to wider attention in 1874.

Gould’s Belt supplies bright stars to many constellations such as Orion, Scorpius and Crux, and conveniently provides nearby star-forming locations for astronomers to study. Observing these stellar nurseries is a key programme for Herschel, which aims to uncover the demographics of star formation and its origin, or in other words, the quantities of stars that can form and the range of masses that such newborn stars can possess. Apart from this region of Aquila, Herschel will target 14 other star-forming regions as part of the Gould’s Belt Key Programme.

Notes for editors:

The scientific rights of these Herschel observations are owned by the consortium of the Gould Belt Key Programme, led by P. André (CEA Saclay). A total of 15 nearby star-forming regions such as Aquila will be studied as part of this Programme.

Herschel Takes a Peek at the Ingredients of the Galaxies

The European Space Agency has today (25th Nov) released spectacular new observations from the Herschel Space Observatory, including the UK-led SPIRE instrument. Spectrometers on board all three Hershel instruments have been used to analyse the light from objects inside our galaxy and from other galaxies, producing some of the best measurements yet of atoms and molecules involved in the birth and death of stars.

The SPIRE Fourier Transform Spectrometer (FTS), which covers the whole submillimetre wavelength range between 194 and 672 microns, will be invaluable to astronomers in determining the composition, temperature, density and mass of interstellar material in nearby galaxies and in star-forming clouds in our own galaxy.

Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council (STFC), which provides the UK funding for Herschel, said “Herschel has once again returned some spectacular indications of what is to come. This wealth of new data exists because of the dedication and skill of the scientists working on this project and will vastly expand our knowledge of the life cycle of stars.”

Professor Matt Griffin of Cardiff University, who is the SPIRE Principal Investigator, said: “Some trial observations have been made during initial testing of the spectrometer, and it is clear that the data are of excellent quality, and even these initial results are very exciting scientifically, especially our ability to trace the presence of water throughout the Universe. The spectrometer was technically very challenging to build, and the whole team is delighted that it works so well.”

Professor Glenn White, of the Open University and STFC’s Rutherford Appleton Laboratory, and an expert in the field of molecular astronomy for which the SPIRE spectrometer is designed, said: "The exquisite sensitivity and quality of these early data reveal spectacular spectroscopic signatures that show the diversity and complexity of the birth processes common to the formation of star and planets. Herschel is going to help us trace the evolution and life of stars, to map the chemistry in our galactic neighbourhood, and allow us to detect water and complex molecules in distant galaxies."

Professor Mike Barlow of University College London, who will use the SPIRE instrument to study the material ejected into space by stars near the end of their lives, said: “The unprecedented spectral range and the wealth of detail revealed by the SPIRE spectrometer, in a hitherto almost unexplored region of the spectrum, promises to revolutionise our understanding of the formation of molecules and dust particles during the final stages of the lives of stars. These dust particles go on to play a crucial role in the formation of new stars and provide the raw material for the planetesimals and planets that form around them."

Figure 1 shows part of the SPIRE spectrum of VY Canis Majoris (VY CMa), a giant star near the end of its life, which is ejecting huge amounts of gas and dust into interstellar space, including elements such as carbon, oxygen and nitrogen (which form the raw material for future planets, and eventually life). The inset is a SPIRE camera image of VY CMa, in which it appears as a bright point-source near the edge of a large extended cloud. The spectrum is amazingly rich, with prominent features from carbon monoxide (CO) and water (H2O). More than 200 other spectral features have also been identified, many due to water, showing that the star is surrounded by large quantities of hot steam. Observations like these will help to establish a detailed picture of the mass loss from stars and the complex chemistry occurring in their extended envelopes.

Figure 2 is a spectrum of one position on the Orion Bar, part of the Orion nebula in which the gas on the edge of the nebula is partly ionised by intense radiation from nearby hot young stars. The inset shows a near infrared picture from NASA’s Spitzer Space Telescope. The SPIRE spectrum has many features from CO, appearing as the dominating narrow lines, seen here for the first time together in a single spectrum. These mean that the entire spectrum is observed at the same time and calibrated together. The brightness of the spectral features will allow astronomers to estimate the temperature and density of interstellar gas. The spectrum also shows the first detection of an emission feature from the molecular ion methylidynium (CH+), a key building block for larger carbon-bearing molecules. This and similar regions are large, and the SPIRE spectrometer’s will be extremely powerful in characterising how the gas properties vary within such sources.

Figure 3 shows a SPIRE spectrum of Arp 220, a galaxy 250 million light years away from Earthwith very active star formation triggered when two large spiral galaxies collided to produce the complex object we see today. Arp 220 is an important template for understanding even more distant galaxies and galaxy formation in the early universe. The spectrum shows many emission features of CO, and H2O features are seen both in emission and absorption. The inset is an optical image of Arp 220 made with the Hubble Space Telescope.

Figure 4 shows the spectrum of Messier 82 (M82), a nearby galaxy (only 12 million light years away) with very active star formation. It is part of an interacting group of galaxies including the large spiral M81. The accompanying image (inset) is a spectacular three-colour composite picture of the two galaxies made with the SPIRE camera, showing material being stripped from M81 by the gravitational interaction with M82. The SPIRE spectrum of M82 shows strong emission lines from CO over the whole wavelength range, as well as emission lines from atomic carbon and ionized nitrogen.

The SPIRE FTS observations were carried out as part of the performance verification of the observatory. The scientific rights of some of these observations are owned by Key Programme consortia: for Arp 220 and M82, the Nearby Galaxies consortium lead by C. Wilson; for VY CMa the MESS consortium led by M. Groenewegen; for the Orion Bar, the Evolution of Interstellar Dust consortium led by A. Abergel.

Notes for editors

Images (hires) : Figure 1 - Figure 2 - Figure 3 - Figure 4

Further details of the new observations by SPIRE, and by the other two Herschel instruments, may be found at the ESA Herschel Science Centre web site .

UK Herschel site

The SPIRE Fourier Transform Spectrometer covers the submillimetre wavelength range (194–672 microns), and provides a complete survey of the source spectrum over that whole wavelength range in a single observation, something that has never been possible with previous submillimetre instruments.

At the same time as measuring the intensities of narrow spectral features from gas atoms and molecules, the SPIRE spectrometer also accurately measures the broadband emission from dust. With its multi-pixel detector arrays, it can also produce spectral images, allowing astronomers to measure the spatial variation in the interstellar material.

Herschel and SPIRE

The European Space Agency’s Herschel satellite carries the largest telescope to be flown in space and is designed to study the Universe at far infrared wavelengths. It will reveal the early stages of star birth and galaxy formation; it will examine the composition and chemistry of comets and planetary atmospheres in the Solar System; and it will examine the star-dust ejected by dying stars into interstellar space which form the raw material for planets like the Earth.

The SPIRE instrument has been built by a consortium of 18 institutes in eight countries (UK, France, Italy, Spain, Sweden, USA, Canada and China), led by Prof. Matt Griffin of Cardiff University. The instrument was assembled at the STFC’s Rutherford Appleton Laboratory in the UK.

UK Participation in Herschel

The UK contribution to Herschel includes leadership of the international consortium that designed and built the SPIRE instrument. The UK SPIRE team is also responsible for the development of software for instrument control and processing of the scientific data, and leads the in-flight testing and operation of SPIRE. The Herschel programme in the UK is funded by the Science and Technology Facilities Council.

SPIRE comprises a three band imaging photometer and an imaging Fourier transform spectrometer and has been designed and built by a consortium of institutes including a number from the UK (Cardiff University; Imperial College, London; University College London’s Mullard Space Science Laboratory; the University of Sussex; and STFC’s Rutherford Appleton Laboratory and UK Astronomy Technology Centre). The UK is also leading the development of software for controlling the instrument from the ground and processing the data to produce scientific results. The SPIRE Operations Centre, responsible for delivering all instrument software to ESA, and for day-to-day instrument monitoring, operation, and calibration, is located at the Rutherford Appleton Laboratory with contributions from the Imperial College and Cardiff groups. The UK SPIRE institutes, together with astronomers in many other UK universities, are also strongly involved in the Herschel scientific programmes which have already been selected for the first 18 months of Herschel observations, and cover a wide range of science topics from our own solar system to the most distant galaxies.

Contacts

Julia Short
Press Officer
Science and Technology Facilities Council
Tel: +44 (0) 1793 44 2012

Mr. Chris North
UK Herschel Outreach Officer
School of Physics and Astronomy
Cardiff University
Tel: +44 (0)29 208 70537 or 76403

Prof. Matt Griffin
Herschel-SPIRE Principal Investigator
School of Physics and Astronomy
Cardiff University
Tel: +44 (0)29 2087 4203

Prof. Glenn White
Dept. of Physics & Astronomy
The Open University
Walton Hall
Milton Keynes MK7 6AA
Tel: +44 (0)1908 652 735

Prof. Mike Barlow
Department of Physics and Astronomy
University College London
Gower Street
London WC1E 6BT
Tel: +44 (0)20 7679 7160

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