il Gioiello Galactic Cluster

il Gioiello Cluster: A galaxy cluster located about 9.6 billion light years from Earth.

The most massive cluster of galaxies with an age of 800 million years or younger has been discovered and studied. X-ray data from Chandra allowed astronomers to accurately determine the mass and other properties of this cluster, nicknamed the "Gioiello" (Italian for "Jewel") cluster. This composite image of the Gioiello Cluster contains X-rays from Chandra (purple), infrared data from Herschel (red), and an optical image from Subaru (red, green, and blue). Results like this help
astronomers better understand how galaxy clusters, the largest structures in the Universe held together by gravity, have evolved over time.

Scale: Image is 3.7 arcmin across (about 6.2 million light years).

Image credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel

Note: For more information, see il Gioiello Cluster: NASA's Chandra Weighs Most Massive Galaxy Cluster in Distant Universe.

Galaxy Cluster XDCPJ0044.0-2033

This multi-telescope composite combines X-ray, infrared and optical data of the galaxy cluster XDCPJ0044.0-2033.

The purple/pink in the image corresponds to infrared emission measured by Herschel and X-ray emission detected with NASA's Chandra telescope.

Infrared data from ESA's Herschel telescope has revealed where interstellar dust in the cluster's core is being heated by young, hot, stars. This is the first time that star formation has been found in the core of a cluster of this size and age.

The X-ray data were used to map the mass of this giant cluster.

These data have been combined with optical and near-infrared images of the cluster captured by the National Astronomical Observatory of Japan's Subaru telescope and the European Southern Observatory Very Large Telescope, the data from which are colored red, green and blue in this image.

XDCPJ0044.0-2033 is a massive galaxy cluster with an estimated mass of about four hundred thousand billion times that of our Sun. It lies at a redshift of almost 1.6, meaning that we see it as it was 9.6 billion years ago.

Image credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel/J. Santos, et al.

Note: For more information, see Herschel's View of the Early Universe Reveals Galaxy Cluster Fireworks

Sextans A

A small galaxy, called Sextans A, is shown here in a multi-wavelength mosaic captured by the European Space Agency's Herschel mission, in which NASA is a partner, along with NASA's Galaxy Evolution Explorer (GALEX) and the National Radio Astronomy Observatory's Jansky Very Large Array observatory near Socorro, New Mexico. The galaxy is located 4.5 million light-years from Earth in the Sextans constellation.

The environment in this galaxy is similar to that of our infant universe because it lacks in heavy metals, or elements heavier than hydrogen and helium. Heavy metals act in some ways like fertilizers for stars, helping them form and grow. Scientists study galaxies like Sextans A to learn how stars still manage to slowly bloom under these poor-growing conditions. The research provides a better understanding of how the very first stars in our universe came to be.

In this image, the purple shows gas; blue shows young stars and the orange and yellow dots are newly formed stars heating up dust.

Image credit: ESA/NASA/JPL-Caltech/NRAO

Messier 33 - The Triangulum Galaxy

The spiral galaxy M33, also known as the Triangulum Galaxy, is one of our closest cosmic neighbors, just three million light-years away. Home to some forty billion stars, it is the third largest in the Local Group of galaxies after the Andromeda Galaxy (M31) and our own Milky Way.

M33 is popular with astrophotographers and from exceptionally dark sites it can even be seen with the naked eye. Thanks to its orientation, we can enjoy a face-on view of the beautiful spiral structure of the galaxy's disc.

This image, from ESA's Herschel space observatory, shows M33 in far-infrared light, revealing the glow of cosmic dust in the interstellar medium that permeates the galaxy. The patchy, disorganized structure of M33's spiral arms resembles a tuft of wool, leading astronomers to classify it as a flocculent spiral galaxy.

The brightest spots sprinkled along the spiral arms are dense pockets of gas and dust where massive stars are born. The most prominent of these is NGC 604, visible in the upper left spiral arm. This is an enormous star-forming region where hundreds of thousands of stars are taking shape.

The image is a composite of the wavelengths: 70 microns (blue), 100 microns (green) and 160 microns (red). At the shortest wavelengths, astronomers trace warmer dust, revealing individual regions of star formation and parent clouds. At longer wavelengths, they detect emission from colder dust, outlining some of the cool dust reservoir along the galaxy’s winding spiral arms. This is where stars may be born in the future.

The image spans about one degree on each side; north is up and east is to the left. The data were collected with Herschel's PACS instrument as part of the Herschel M33 extended survey (HerM33es) Key Programme to study the star formation in the Triangulum Galaxy.

Image credit: ESA/Herschel/PACS/HerM33es Key Programme/C. Kramer/M. Boquien

Messier 106's Anomalous Spiral Arms

A galaxy about 23 million light-years away is the site of impressive, ongoing, fireworks. Rather than paper, powder, and fire, this galactic light show involves a giant black hole, shock waves, and vast reservoirs of gas.

This galactic fireworks display is taking place in NGC 4258 (also known as M106), a spiral galaxy like the Milky Way. This galaxy is famous, however, for something that our galaxy doesn't have -- two extra spiral arms that glow in X-ray, optical, and radio light. These features, or anomalous arms, are not aligned with the plane of the galaxy, but instead intersect with it.

The anomalous arms are seen in this new composite image of NGC 4258, where X-rays from NASA's Chandra X-ray Observatory are blue, radio data from the NSF's Karl Jansky Very Large Array are purple, optical data from NASA's Hubble Space Telescope are yellow and blue, and infrared data from NASA's Spitzer Space Telescope are red.

A new study of these anomalous arms made with Spitzer shows that shock waves, similar to sonic booms from supersonic planes, are heating large amounts of gas -- equivalent to about 10 million suns. What is generating these shock waves? Radio data shows that the supermassive black hole at the center of NGC 4258 is producing powerful jets of high-energy particles. Researchers think that these jets strike the disk of the galaxy and generate shock waves. These shock waves, in turn, heat some of the gas -- composed mainly of hydrogen molecules -- to thousands of degrees. As shown in our additional, composite image, part of the evidence for this heating process comes from the similarity in location between the hydrogen and X-ray emission, both thought to be caused by shocks, and the radio jets.

The Chandra X-ray image reveals huge bubbles of hot gas above and below the plane of the galaxy. These bubbles indicate that much of the gas that was originally in the disk of the galaxy has been heated to millions of degrees and ejected into the outer regions by the jets from the black hole.

The ejection of gas from the disk by the jets has important implications for the fate of this galaxy. Researchers estimate that all of the remaining gas will be ejected within the next 300 million years -- very soon on cosmic time scales -- unless it is somehow replenished. Because most of the gas in the disk has already been ejected, less gas is available for new stars to form. Indeed, the researchers used Spitzer data to estimate that stars are forming in the central regions of NGC 4258, at a rate which is about ten times less than in the Milky Way galaxy.

The European Space Agency's Herschel Space Observatory, for which NASA plays an important role, was used to confirm the estimate from Spitzer data of the low star-formation rate in the central regions of NGC 4258. Herschel was also used to make an independent estimate of how much gas remains in the center of the galaxy. After allowing for the large boost in infrared emission caused by the shocks, the researchers found that the gas mass is ten times smaller than had been previously estimated.

Because NGC 4258 is relatively close to Earth, astronomers can study how this black hole is affecting its galaxy in great detail. The supermassive black hole at the center of NGC 4258 is about ten times larger than the one in the Milky Way, and is also consuming material at a faster rate, potentially increasing its impact on the evolution of its host galaxy.

Image credit: NASA/CXC/JPL-Caltech/STScI/NSF/NRAO/VLA

Note: For more information, see PIA18462: Black Hole Jets Make Shock Waves, NGC 4258 (M106): Galactic Pyrotechnics On Display and Black Hole Fireworks in Nearby Galaxy.

Artist's Concept of a Protostar within the Orion A Molecular Cloud

Orion A, a star-forming nebula lying about 1500 light-years from Earth, as viewed by ESA's Herschel space observatory. Orion A is located within the 'sword of Orion' – below the three main stars that form the belt of the Orion constellation.

Embedded in the gaseous and dusty environment of this molecular cloud is the prolific stellar nursery called OMC2 FIR4 (highlighted with a red circle).

Astronomers studying OMC2 FIR4 with Herschel have discovered that at least one of the embryo stars that are taking shape in this protostellar cocoon is gusting a powerful wind of very energetic particles.

The inset shows an illustration of the wind blown by this newborn star. When the energetic particles hit the surrounding material, they may collide with atoms that are present in the star's environment, break them apart and produce new elements.

Our Sun likely gusted a similar wind of particles in its early days; this could explain the origin of a puzzling isotope of beryllium, whose traces are found in meteorites.

Image credit: Herschel image: ESA/Herschel/Ph. André, D. Polychroni, A. Roy, V. Könyves, N. Schneider for the Gould Belt survey Key Programme; inset and layout: ESA/ATG medialab

Note: For more information, see Young Sun's Violent History Solves Meteorite Mystery.

Molecular Cloud W48

Just as children are sorted into age groups at school, so the seeds of new stars can also be found in ‘classes’ of others of similar ages. This is especially true when the birth of stars in a cloud of gas and dust is triggered by an external event, like the explosion of a nearby supernova.

This image from ESA’s Herschel space observatory shows a sequence of star-forming regions in the molecular cloud W48, some 10,000 light-years away in the constellation Aquila (the Eagle).

The blue, jellyfish-shaped cloud at the lower left is the oldest stellar nursery in the image. Young and massive stars embedded within it have shaped it into a bubble and heated the diffuse gas, making it shine at the longest wavelengths probed by Herschel.

To its right, another glowing cloud conceals clumps that will evolve into massive stars. These clumps, some of which are visible as bright blotches of light, are also lined up by their age: the older ones at the lower-left and the younger ones to the upper-right. The youngest in this sequence is the small cyan lump at the center of the image, harboring the seeds of future massive stars.

Astronomers believe that this sequence of stellar birth is the result of dozens of supernovas that exploded over 10 million years ago in a region called Aquila Supershell, beyond the left edge of this image. Compressing the surrounding material, these supernovas may have initiated a wave of star formation that sparked, one by one, these stellar cribs.

The image is a composite of the wavelengths of 70 microns (blue), 160 microns (green) and 250 microns (red) and spans about one degree on the long side. North is to the upper-left and east is to the lower left. The data were acquired with Herschel’s PACS and SPIRE instruments in September 2010, as part of a larger map of the W48 molecular complex in the HOBYS Key Programme. This was first published in a paper by Q. Nguyen Luong, et al. 2011. A more detailed study of the star-forming regions shown in this image is presented in a paper by K.L.J. Rygl, et al. 2014.

Image credit: ESA/Herschel/PACS/SPIRE/HOBYS Key Programme Consortium

Water-Building Molecule in the Ring Nebula

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 micrometers 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.

For more information, see New Molecules Around Old Stars.

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

NGC 7538

The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538. The gigantic ring structure is situated at the center-top of this image. The odd ovoid possesses the mass of 500 suns, with its long axis spanning about 35 light-years and its short axis about 25 light-years.

Astronomers often see ring and bubble-like structures in cosmic dust clouds. The strong winds cast out by the most massive stars, called O-type stars, can generate these expanding puffs, as can their explosive deaths as supernovas. But no energetic source or remnant of a deceased O-type star, such as a neutron star, is apparent within the center of the ring. It is possible that a big star blew the bubble and, because stars are all in motion, subsequently left the scene, escaping detection.

Astronomers study stellar nurseries such as NGC 7538 to better learn how stars come into being. The Herschel observations have revealed numerous clumps of material in NGC 7538, a baker's dozen of which may evolve into O-type stars. Early in the star-formation process, these clumps remain quite cold, just a few tens of degrees above absolute zero. At these temperatures, the clumps emit the bulk of their radiation in the low-energy, sub-millimeter and infrared light that Herschel was specifically designed to detect.

Finding the mysterious ring came as an unexpected bonus during the Herschel observing run.

The blue and green colors in this image represent 70- and 160-micron data, respectively, from Herschel's Photoconductor Array Camera and Spectrometer (PACS) instrument. The red colors are 250-micron observations obtained from Herschel's Spectral and Photometric Imaging Receiver (SPIRE) instrument.

Image credit: ESA/NASA/JPL-Caltech/Whitman College

Note: For more information, see Herschel Sees Budding Stars and a Giant, Strange Ring.

Herschel’s Population of Trans-Neptunian Objects

ESA’s Herschel space observatory has observed 132 of the known 1400 cold worlds that inhabit a region of the Solar System beyond the orbit of Neptune, some 4.5–7.5 billion km from the Sun.

These ‘trans-Neptunian objects’, or TNOs, include worlds such as Pluto, Eris, Haumea and Makemake, and make up a vast population of such objects thought to occupy these far-flung reaches of the Solar System.

TNOs are particularly cold, at around –230ºC, but these low temperatures lend themselves to observations by Herschel, which observes at far-infrared to sub-millimeter wavelengths. Indeed, the space observatory observed the thermal emission from 132 such objects during its nearly four-year lifetime.

These measurements provided their sizes and albedos (the fraction of visible light reflected from the surface), properties that are not otherwise easily accessible. The graphic presented here shows a sample of the population of TNOs observed with Herschel, arranged to showcase these properties.

What is most striking is their diversity. They range from just below 50 km to almost 2400 km in diameter; Pluto and Eris are the largest. Two worlds have distinctly elongated shapes: Haumea (seen in white) and Varuna (brown). Some even host their own moons (not shown).

The albedo measurement implies a variety of surface compositions: low albedo (brown) is an indication of dark surface materials, such as organic material, while higher albedo (white) suggests pure ices.

TNOs are thought to be some of the most primitive remnants of the planet-forming era. Thus the results of the Herschel “TNOs are cool: A survey of the trans-Neptunian region” open key time program are being used to test different models of Solar System formation and evolution.

Image credit: ESA/Herschel/PACS/SPIRE; acknowledgements: M. Rengel and P. Lacerda (Max-Plack-Institute für Sonnensystemforschung, Germany), T. Müller (Max-Planck-Institut für extraterrestrische Physik) and the Herschel “TNOs are Cool” Team.
Description

Red and Dead Elliptical Galaxies

Elliptical Galaxies: Four elliptical galaxies with very low levels of star formation.

This four-panel of images represents a sample of giant elliptical galaxies observed by Chandra and the Hershel Space Observatory in a study to investigate why these objects have such low levels of star formation. In six galaxies, Herschel detected surprisingly large amounts of cold gas – the fuel for star formation. Chandra revealed that the hot gas in the center of these galaxies appears to be much more disturbed than in the cold gas-free systems. This is a sign that material has been ejected from regions close to the central black hole. The energy from these outbursts helps to prevent the cold gas from cooling sufficiently to form stars. In two other galaxies, jets pushing against the hot gas are creating enormous cavities that are observed in the Chandra images. These jets may be heating the hot, X-ray emitting gas, preventing it from cooling and forming cold gas and stars.

Image credit: X-ray: NASA/CXC/Stanford University/N.Werner et al; Optical: DSS

Note: For more information, see Elliptical Galaxies: Chandra Helps Explain "Red and Dead Galaxies".

Lensed Galaxy S0901

The young galaxy SDSS090122.37+181432.3, also known as S0901, is seen here as the bright arc to the left of the central bright galaxy. The distorted view of S0901 is caused by gravitational lensing, resulting from one or more galaxies that lie between the observer and S0901. Although one effect of lensing is to distort the image, another effect is to magnify the light of the lensed object. This effect was used to enable scientists to study S0901 with Herschel's Heterodyne Instrument for the Far-Infrared (HIFI).

This image was obtained in May, 2010, using the Wide Field Camera 3 on the NASA/ESA Hubble Space Telescope.

Image credit: NASA/STScI; S. Allam and team; and the Master Lens Database, L. A. Moustakas, K. Stewart, et al (2014)

Note: For more information, see Well-Behaved, Young Galaxy Surprises Astronomers and Herschel Discovers Mature Galaxies in the Young Universe.

The Milky Way in Infrared

The majority of the stars in our Galaxy, the Milky Way, reside in a single huge disc, known as the Galactic Plane, spanning 100,000 light-years across. The Sun also resides in this crowded stellar hub, lying roughly halfway between its center and its outer edges.

This disc is filled with a diffuse mixture of gas and dust – the interstellar medium – that pervades space, filling the large gaps found between stars. Occasionally, these clouds of gas and dust cool, becoming denser and denser until they spark star formation, giving rise to new generations of stars.

This image is part of Hi-GAL, a survey of the Galactic Plane completed with ESA’s Herschel Space Observatory. Peering at the sky in infrared light, Herschel could detect the glow of dust particles dispersed between stars. This minor – but crucial – component of the interstellar medium allows astronomers to investigate how stars are born in the Milky Way, and how they affect their environment as they age.

Nestled in the Milky Way’s disc are pockets of gas and dust that have been heated by nearby newborn stars, causing them to glow brightly like cosmic gems. Through their higher temperatures, these regions glow at shorter infrared wavelengths and are depicted in violet and green, while the colder material in the surroundings – only a few tens of degrees above absolute zero – appears redder.

Laced amongst the stars is an intricate network of filaments sprinkled with tiny white spots: these are denser clumps of gas and dust that will likely evolve and give birth to new stars.

The image combines observations from the PACS and SPIRE instruments on Herschel. It spans about 12º on the longer side, corresponding to some 24 times the diameter of the full Moon. This is 1/30th of the entire Galactic Plane survey.

This image was first published in OSHI, the Online Showcase of Herschel Images, in 2011.

Image credit: ESA/PACS & SPIRE Consortium, S. Molinari, Hi-GAL Project

Cosmic Dust Survey by Herschel and SDSS

Collage of galaxies in the Herschel Reference Survey at infrared/submillimeter wavelengths by Herschel (left) and at visible wavelengths from the Sloan Digital Sky Survey (SDSS, right). The Herschel image is colored with blue representing cold dust and red representing warm dust; the SDSS image shows young stars in blue and old stars in red. Together, the observations plot young, dust-rich spiral/irregular galaxies in the top left, with giant dust-poor elliptical galaxies in the bottom right.

Image credit: ESA/Herschel/HRS-SAG2 and HeViCS Key Programmes/Sloan Digital Sky Survey/ L. Cortese (Swinburne University)

Note: For more information, see Herschel Completes Largest Survey of Cosmic Dust in Local Universe and Herschel Survey in Infrared.

NGC 7538

The billowing clouds portrayed in this image from ESA’s Herschel observatory are part of NGC 7538, a stellar nursery for massive stars. Located around 9000 light-years away, this is one of the few regions of massive-star formation that are relatively close to us, allowing astronomers to investigate this process in great detail.

Star factories like NGC 7538 consist mainly of hydrogen gas, but they also contain small amounts of cosmic dust. It was through this minor – but crucial – component that Herschel could image these star-forming regions, because dust shines brightly at the far-infrared wavelengths that were probed by the observatory.

With a total mass of almost 400,000 Suns, NGC 7538 is an active factory where stars come to life – especially huge ones that are over eight times more massive than the Sun. Hundreds of seeds of future stellar generations nestle in the mixture of surrounding gas and dust scattered across the image. Once they reach a critical mass, they will ignite as stars. Thirteen of these proto-stars have masses greater than 40 Suns, and are also extremely cold, less than –250ºC.

One group of stellar seeds seem to trace a ring-like structure, visible in the left part of the image. The ring may be the edge of a bubble carved by previous stellar explosions – as stars reach the end of their lives and explode as dramatic supernovas – but astronomers are still investigating the origin of this peculiar arrangement.

The image is a composite of the wavelengths of 70 microns (blue), 160 microns (green) and 250 microns (red) and spans about 50 x 50 arc minutes. North is up and east is to the left. It was first published in the paper Herschel Reveals Massive Cold Clumps in NGC 7538 by Fallscheer et al. 2013.

Image credit: ESA/Herschel/PACS/SPIRE. Acknowledgements: Cassie Fallscheer (University of Victoria), Mike Reid (University of Toronto) and the Herschel HOBYS team

NGC 5044

This image shows a composite view of the giant elliptical galaxy NGC 5044.

The stellar component, as observed at optical wavelengths, is shown in white at the center of the image. The other stars scattered around the image are foreground stars from our own Galaxy.

The galaxy is embedded in a hot atmosphere of ionized hydrogen gas, which is shown in blue. With temperatures up to tens of millions of K, the hot gas shines brightly in X-rays and was observed using NASA's Chandra X-ray Observatory.

Observations show that some of the hot gas cools down and flows towards the center of the galaxy. There, the cold gas may condense and form stars, unless it is reheated or expelled from the galaxy by other agents.

The filamentary network shown in red is warm hydrogen gas, as observed in the H-alpha emission line at a rest wavelength of 656.28 nm with the Southern Observatory for Astrophysical Research (SOAR) telescope in Chile.

When observed in radio wavelengths, this galaxy appears only as the weak source shown in violet at the center of the image, which belies the moderately active black hole sitting at the center of the galaxy. The radio observations were performed with NRAO's Very Large Array (VLA).

A team of astronomers has observed NGC 5044 and other nearby giant elliptical galaxies using ESA's Herschel Space Observatory, to try to figure out why galaxies of this type do not form stars. Spectroscopic observations obtained with Herschel showed that, contrary to previous belief, NGC 5044 contains plenty of cold gas – the raw material to form stars. The same holds true for most of the giant elliptical galaxies that the team observed.

A multi-wavelength study suggests that, while hot gas cools down in these galaxies, stars do not form because of feedback from the central supermassive black hole, which stirs up the gas preventing it from turning into stars.

Image credit: Digitized Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Note: For more information, see Bullying Black Holes Force Galaxies to Stay Red and Dead.

Development of Massive Elliptical Galaxies

This graphic shows the evolutionary sequence in the growth of massive elliptical galaxies over 13 billion years, as gleaned from space-based and ground-based telescopic observations. The growth of this class of galaxies is quickly driven by rapid star formation and mergers with other galaxies.

Astronomers using NASA's Hubble and Spitzer space telescopes, and Europe's Herschel Space Observatory, have pieced together the evolutionary sequence of compact elliptical galaxies that erupted and burned out early in the history of the universe.

Enabled by Hubble's infrared imaging capabilities, astronomers have assembled for the first time a representative spectroscopic sampling of ultra-compact, burned-out elliptical galaxies -- galaxies whose star formation was finished when the universe was only 3 billion years old, less than a quarter of its current estimated age of 13.8 billion years.

The research, supported by several ground-based telescopes, solves a 10-year-old mystery about the growth of the most massive elliptical galaxies we see today. It provides a clear picture of the formation of the most massive galaxies in the universe, from their initial burst of star formation through their development of dense stellar cores, to their ultimate reality as giant ellipticals.

"We at last show how these compact galaxies can form, how it happened, and when it happened. This basically is the missing piece in the understanding of how the most massive galaxies formed, and how they evolved into the giant ellipticals of today," said Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute in Copenhagen, Denmark, who is the leader of this study.

"This had been a great mystery for many years because just 3 billion years after the big bang we see that half of the most massive galaxies have already completed their star formation."

Through the research, astronomers have determined the compact ellipticals voraciously consumed the gas available for star formation, to the point they could not create new stars, and then merged with smaller galaxies to form giant ellipticals. The stars in the burned-out galaxies were packed 10 to 100 times more densely than in equally massive elliptical galaxies seen in the nearby universe today, and that surprised astronomers, according to Toft.

To develop the evolutionary sequence for ultra-compact, burned-out galaxies, Toft's team assembled, for the first time, representative samples of two galaxy populations using the rich dataset in Hubble's COSMOS (Cosmic Evolution Survey) program.

One group of galaxies is the compact ellipticals. The other group contains galaxies that are highly obscured with dust and undergoing rapid star formation at rates thousands of times faster than observed in the Milky Way. Starbursts in these dusty galaxies likely were ignited when two gas-rich galaxies collided. These galaxies are so dusty that they are almost invisible at optical wavelengths, but they shine bright at submillimeter wavelengths, where they were first identified nearly two decades ago by the Submillimeter Common-User Bolometer Array (SCUBA) camera on the James Clerk Maxwell Telescope in Hawaii.

Toft's team started by constructing the first representative sample of compact elliptical galaxies with accurate sizes and spectroscopic redshifts, or distances, measured with Hubble's Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) and 3D-HST (3D-Hubble Space Telescope) programs. 3D-HST is a near-infrared spectroscopic survey to study the physical processes that shape galaxies in the distant universe. The astronomers combined these data with observations from the Subaru telescope in Hawaii, and Spitzer. This allowed for accurate stellar age estimates, from which they concluded compact elliptical galaxies formed in intense starbursts inside the galaxies that preceded them by as long as two billion years.

Next, the team made the first representative sample of the most distant submillimeter galaxies using COSMOS data from the Hubble, Spitzer and Herschel space telescopes, and ground-based telescopes such as Subaru, the James Clerk Maxwell Telescope, and the Submillimeter Array, all located in Hawaii. This multi-spectral information, stretching from optical light through submillimeter wavelengths, yielded a full suite of information about the sizes, stellar masses, star-formation rates, dust content, and precise distances of the dust-enshrouded galaxies that were present early in the universe.

When Toft's team compared the samples of the two galaxy populations, it discovered an evolutionary link between the compact elliptical galaxies and the submillimeter galaxies. The observations show that the violent starbursts in the dusty galaxies had the same characteristics that would have been predicted for progenitors to the compact elliptical galaxies. Toft's team also calculated the intense starburst activity inside the submillimeter galaxies lasted only about 40 million years before the interstellar gas supply was exhausted.

The results appear in the Jan. 29 online issue of The Astrophysical Journal. For related and high resolution imagery, visit: http://hubblesite.org/news/2014/10.

Image credit: NASA, ESA, S. Toft (Niels Bohr Institute), and A. Feild (STScI)

Messier 51 - The Whirlpool Galaxy

The Whirlpool Galaxy, also known as M51 or NGC 5194, is one of the most spectacular examples of a spiral galaxy. With two spiral arms curling into one another in a billowing swirl, this galaxy hosts over a hundred billion stars and is currently merging with its companion, the smaller galaxy NGC 5195.

Around 30 million light-years away, the Whirlpool Galaxy is close enough to be easily spotted even with binoculars. Using the best telescopes available both on the ground and in space, astronomers can scrutinize its population of stars in extraordinary detail.

In this image, observations performed at three different wavelengths with ESA’s Herschel and XMM-Newton space telescopes are combined to reveal how three generations of stars coexist in the Whirlpool Galaxy.

The infrared light collected by Herschel – shown in red and yellow – reveals the glow of cosmic dust, which is a minor but crucial ingredient in the interstellar material in the galaxy’s spiral arms. This mixture of gas and dust provides the raw material from which the Whirlpool Galaxy’s future generations of stars will take shape.

Observing in visible and ultraviolet light, astronomers can see the current population of stars in the Whirlpool Galaxy, since stars in their prime shine most brightly at shorter wavelengths than infrared. Seen at ultraviolet wavelengths with XMM-Newton and portrayed in green in this composite image are the galaxy’s fiercest stellar inhabitants: young and massive stars pouring powerful winds and radiation into their surroundings.

The image also shows the remains of previous stellar generations, which shine brightly in X-rays and were detected by XMM-Newton. Shown in blue, these sources of X-rays are either the sites where massive stars exploded as supernovae in the past several thousand years, or binary systems that host neutron stars or black holes, the compact objects left behind by supernovae.

Image credit: ESA / Herschel / XMM-Newton. Acknowledgements: "Physical Processes in the Interstellar Medium of Very Nearby Galaxies" Key Programme, Christine Wilson

Water Vapor Around Ceres

Dwarf planet Ceres is located in the main asteroid belt, between the orbits of Mars and Jupiter, as illustrated in this artist's conception. Observations by the Herschel space observatory between 2011 and 2013 find that the dwarf planet has a thin water vapor atmosphere. This is the first unambiguous detection of water vapor around an object in the asteroid belt.

Illustration credit: ESA/ATG medialab

Note: For more information, see PIA17831: Water Detection on Ceres, Herschel Telescope Detects Water on Dwarf Planet, Herschel Discovers Water Vapor Around Dwarf Planet Ceres, and Water Detected on Dwarf Planet Ceres.

Messier 1, The Crab Nebula

Across the Universe, every ending is a new beginning. When a massive star dies, exploding as a spectacular supernova, huge amounts of matter and energy are ejected into surrounding space, and the remnant of the explosion itself remains a hub of fierce activity for thousands of years.

One of the most iconic supernova remnants is the Crab Nebula. A wispy and filamentary cloud of gas and dust, it originated with a supernova explosion that was seen by Chinese astronomers in the year 1054. A spinning neutron star – or pulsar – remains at its center, releasing streams of highly energetic particles into the nebula.

This composite image combines a new infrared view of the Crab Nebula, obtained with ESA’s Herschel Space Observatory, with an optical image from the archives of the NASA/ESA Hubble Space Telescope.

Herschel’s observations are shown in red and reveal the glow from cosmic dust present in the nebula. Hubble’s view, in blue, traces oxygen and sulphur gas in the nebula.

A team of astronomers studying the nebula with Herschel has revealed that this supernova remnant contains much more dust than they had expected – about a quarter of the mass of the Sun.

The new observations also revealed the presence of molecules containing argon, the first time a noble gas-based molecule has been found in space.

Argon is produced in the nuclear reactions that take place during supernova explosions, and astronomers had already detected this element in the Crab Nebula. However, it is surprising that argon bonded with other elements, forming molecules that survived in the hostile environment of a supernova remnant, with hot gas still expanding at high speeds after the explosion.

Image credit: (top) ESA/Herschel/PACS/MESS Key Programme Supernova Remnant Team; NASA, ESA and Allison Loll/Jeff Hester (Arizona State University); (bottom) ESA/Herschel/PACS, SPIRE/MESS Key Programme Supernova Remnant Team

Note: For more information, see PIA17563: Crab Nebula, as Seen by Herschel and Hubble, Herschel Image and Spectrum of the Crab Nebula, Herschel Spies Active Argon in Crab Nebula, and Chemical Surprise Found in Crab Nebula.