Friday, March 16, 2018

Spirals and supernovae

Credit: ESA/Hubble & NASA, A. Riess (STScl/JHU)

This stunning image from Hubble shows the majestic galaxy NGC 1015, found nestled within the constellation of Cetus (The Whale) 118 million light-years from Earth. In this image, we see NGC 1015 face-on, with its beautifully symmetrical swirling arms and bright central bulge creating a scene akin to a sparkling Catherine wheel firework.

NGC 1015 has a bright, fairly large centre and smooth, tightly wound spiral arms and a central “bar” of gas and stars. This shape leads NGC 1015 to be classified as a barred spiral galaxy — just like our home, the Milky Way. Bars are found in around two-thirds of all spiral galaxies, and the arms of this galaxy swirl outwards from a pale yellow ring encircling the bar itself. Scientists believe that any hungry black holes lurking at the centre of barred spirals funnel gas and energy from the outer arms into the core via these glowing bars, feeding the black hole, fueling star birth at the centre and building up the galaxy’s central bulge.

In 2009, a Type Ia supernova named SN 2009ig was spotted in NGC 1015 — one of the bright dots to the upper right of the galaxy’s centre. These types of supernovae are extremely important: they are all caused by exploding white dwarfs which have companion stars, and always peak at the same brightness — 5 billion times brighter than the Sun. Knowing the true brightness of these events, and comparing this with their apparent brightness, gives astronomers a unique chance to measure distances in the Universe.

Thursday, March 15, 2018

Crab Nebula: A Crab Walks Through Time

 Crab Nebula
Credit  X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech

Next year marks the 20th anniversary of NASA's Chandra X-ray Observatory launch into space. The Crab Nebula was one of the first objects that Chandra examined with its sharp X-ray vision, and it has been a frequent target of the telescope ever since.

There are many reasons that the Crab Nebula is such a well-studied object. For example, it is one of a handful of cases where there is strong historical evidence for when the star exploded. Having this definitive timeline helps astronomers understand the details of the explosion and its aftermath.

In the case of the Crab, observers in several countries reported the appearance of a "new star" in 1054 A.D. in the direction of the constellation Taurus. Much has been learned about the Crab in the centuries since then. Today, astronomers know that the Crab Nebula is powered by a quickly spinning, highly magnetized neutron star called a pulsar, which was formed when a massive star ran out of its nuclear fuel and collapsed. The combination of rapid rotation and a strong magnetic field in the Crab generates an intense electromagnetic field that creates jets of matter and anti-matter moving away from both the north and south poles of the pulsar, and an intense wind flowing out in the equatorial direction.

The latest image of the Crab is a composite with X-rays from Chandra (blue and white), NASA's Hubble Space Telescope (purple) and NASA's Spitzer Space Telescope (pink). The extent of the X-ray image is smaller than the others because extremely energetic electrons emitting X-rays radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light.

This new composite adds to a scientific legacy, spanning nearly two decades, between Chandra and the Crab Nebula. Here is a sample of the many insights astronomers have gained about this famous object using Chandra and other telescopes.

1999: Within weeks of being deployed into orbit from the Space Shuttle Columbia during the summer of 1999, Chandra observed the Crab Nebula. The Chandra data revealed features in the Crab never seen before, including a bright ring of high-energy particles around the heart of the nebula.

2002: The dynamic nature of the Crab Nebula was vividly revealed in 2002 when scientists produced videos based on coordinated Chandra and Hubble observations made over several months. The bright ring seen earlier consists of about two dozen knots that form, brighten and fade, jitter around, and occasionally undergo outbursts that give rise to expanding clouds of particles, but remain in roughly the same location.

These knots are caused by a shock wave, similar to a sonic boom, where fast-moving particles from the pulsar are slamming into surrounding gas. Bright wisps originating in this ring are moving outward at half the speed of light to form a second expanding ring further away from the pulsar.

2006: In 2003, the Spitzer Space Telescope was launched and the space-based infrared telescope joined Hubble, Chandra, and the Compton Gamma-ray Observatory and completed the development of NASA's "Great Observatory" program. A few years later, the first composite of the Crab with data from Chandra (light blue), Hubble (green and dark blue), and Spitzer (red) was released. 

2008: As Chandra continued to take observations of the Crab, the data provided a clearer picture of what was happening in this dynamic object. In 2008, scientists first reported a view of the faint boundary of the Crab Nebula's pulsar wind nebula (i.e., a cocoon of high-energy particles surrounding the pulsar).

The data showed structures that astronomers referred to as "fingers", "loops", and "bays". These features indicated that the magnetic field of the nebula and filaments of cooler matter are controlling the motion of the electrons and positrons. The particles can move rapidly along the magnetic field and travel several light years before radiating away their energy. In contrast, they move much more slowly perpendicular to the magnetic field, and travel only a short distance before losing their energy.

2011: Time-lapse movies of Chandra data of the Crab have been powerful tools in showing the dramatic variations in the X-ray emission near the pulsar. In 2011, Chandra observations, obtained between September 2010 and April 2011, were obtained to pinpoint the location of remarkable gamma-ray flares observed by NASA's Fermi Gamma Ray Observatory and Italy's AGILE Satellite. The gamma-ray observatories were not able to locate the source of the flares within the nebula, but astronomers hoped that Chandra, with its high-resolution images, would.

Two Chandra observations were made when strong gamma-ray flares occurred, but no clear evidence was seen for correlated flares in the Chandra images.

Despite this lack of correlation, the Chandra observations helped scientists to home in on an explanation of the gamma-ray flares. Though other possibilities remain, Chandra provided evidence that accelerated particles produced the gamma-ray flares.

2014: To celebrate the 15th anniversary of Chandra's launch, several new images of supernova remnants were released, including the Crab Nebula. This was a "three color" image of the Crab Nebula, where the X-ray data were split into three different energy bands. In this image, the lowest-energy X-rays Chandra detects are red, the medium range are green, and the highest-energy X-rays from the Crab are colored blue. Note that the extent of the higher energy X-rays in the image is smaller than the others. This is because the most energetic electrons responsible for the highest energy X-rays radiate away their energy more quickly than the lower-energy electrons.

2017: Building on the multiwavelength images of the Crab from the past, a highly detailed view of the Crab Nebula was created in 2017 using data from telescopes spanning nearly the entire breadth of the electromagnetic spectrum. Radio waves from the Karl G. Jansky Very Large Array (red), Hubble optical data (green), infrared data from Spitzer (yellow), and X-ray data from XMM-Newton (blue) and Chandra (purple) produced a spectacular new image of the Crab.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Fast Facts for Crab Nebula:

Scale: Image is about 5 arcmin (10 light years) across
Category: Supernovas & Supernova Remnants, Neutron Stars/X-ray Binaries
Coordinates (J2000): RA 05h 34m 32s | Dec +22° 0.0' 52.00"
Constellation: Taurus
Observation Date: 48 pointings between March 2000 and Nov 2013
Observation Time: 25 hours 28 min (1 day 1 hour 28 min)
Obs. ID 769-773, 1994-2001, 4607, 13139, 13146, 13147, 13150-13154, 13204-13210, 13750-13752, 13754-13757, 14416, 14458, 14678-14682, 14685, 16245, 16257, 16357, 16358
Instrument: ACIS
Also Known As: NGC 1952
Color Code: X-ray (Blue), Optical (Purple), Infrared (Pink)

Wednesday, March 14, 2018

Stephen Hawking, 8 January 1942 – 14 March 2018

 Stephen Hawking (1942-2018)

On 14th January 2018 Professor Stephen Hawking died peacefully at his home in Cambridge at the age of 76.

Stephen Hawking is widely recognised as one of the most influential theoretical physicists in modern times. He has made seminal contributions to several areas of astrophysics. In particular, his studies have provided some of the pillars of our understanding of black holes, including the concept that black holes must have a temperature and must generate radiation (known as Hawking radiation). More broadly, his studies have resulted in major fundamental advances in areas of cosmology and general relativity.

He was the Lucasian Professor of Mathematics at the University of Cambridge (the same chair held by Isaac Newton) from 1979 to 2009. In 2007 he founded the Centre for Theoretical Cosmology, of which he was Director of Research until 2014 and then he was the Dennis Stanton Avery and Sally Tsui Wong-Avery Director of Research. He received many awards and honours, including the Hughes and Copley Medals of the Royal Society, the US Presidential Medal of Freedom, and the Fundamental Physics prize.

Stephen Hawking wrote milestone research papers and well known scientific books. He also wrote several popular science books, such as the famous "A Brief History of Time".

Within the context of the Kavli Institute, Stephen supported the creation of the Institute and most recently has helped us to expand our research in Gravitational Waves, an area in which he has been a pioneer.

Stephen was a source of inspiration for all of us and we will greatly miss him.

Stephen Hawking (centre), together with Roberto Maiolino (Director of the Kavli Institute, left) and members of the Kavli Foundation Board of Directors and Staff during their visit in November 2017.

Jupiter's Great Red Spot Getting Taller as it Shrinks, NASA Team Finds

Scientists have noticed that Jupiter's Great Red Spot has been getting smaller over time. Now, there's evidence the storm is actually growing taller as it shrinks. Credits: NASA's Goddard Space Flight Center. This video is public domain and can be downloaded from NASA's Scientific Visualization Studio.

Though once big enough to swallow three Earths with room to spare, Jupiter’s Great Red Spot has been shrinking for a century and a half. Nobody is sure how long the storm will continue to contract or whether it will disappear altogether.

A new study suggests that it hasn’t all been downhill, though. The storm seems to have increased in area at least once along the way, and it’s growing taller as it gets smaller.

“Storms are dynamic, and that’s what we see with the Great Red Spot. It’s constantly changing in size and shape, and its winds shift, as well,” said Amy Simon, an expert in planetary atmospheres at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the new paper, published in the Astronomical Journal.

Observations of Jupiter date back centuries, but the first confirmed sighting of the Great Red Spot was in 1831. (Researchers aren’t certain whether earlier observers who saw a red spot on Jupiter were looking at the same storm.)

Keen observers have long been able to measure the size and drift of the Great Red Spot by fitting their telescopes with an eyepiece scored with crosshairs. A continuous record of at least one observation of this kind per year dates back to 1878.

Simon and her colleagues drew on this rich archive of historical observations and combined them with data from NASA spacecraft, starting with the two Voyager missions in 1979. In particular, the group relied on a series of annual observations of Jupiter that team members have been conducting with NASA’s Hubble Space Telescope as part of the Outer Planets Atmospheres Legacy, or OPAL, project. The OPAL team scientists are based at Goddard, the University of California at Berkeley, and NASA’s Jet Propulsion Laboratory in Pasadena, California.

The team traced the evolution of the Great Red Spot, analyzing its size, shape, color  and drift rate. They also looked at the storm’s internal wind speeds, when that information was available from spacecraft.

The new findings indicate that the Great Red Spot recently started to drift westward faster than before. The storm always stays at the same latitude, held there by jet streams to the north and south, but it circles the globe in the opposite direction relative to the planet’s eastward rotation. Historically, it’s been assumed that this drift is more or less constant, but in recent observations, the team found the spot is zooming along much faster.

The study confirms that the storm has been decreasing in length overall since 1878 and is big enough to accommodate just over one Earth at this point. But the historical record indicates the area of the spot grew temporarily in the 1920s.

“There is evidence in the archived observations that the Great Red Spot has grown and shrunk over time,” said co-author Reta Beebe, an emeritus professor at New Mexico State University in Las Cruces. “However, the storm is quite small now, and it’s been a long time since it last grew.”

Because the storm has been contracting, the researchers expected to find the already-powerful internal winds becoming even stronger, like an ice skater who spins faster as she pulls in her arms.
Instead of spinning faster, the storm appears to be forced to stretch up. It’s almost like clay being shaped on a potter’s wheel. As the wheel spins, an artist can transform a short, round lump into a tall, thin vase by pushing inward with his hands. The smaller he makes the base, the taller the vessel will grow.

In the case of the Great Red Spot, the change in height is small relative to the area that the storm covers, but it’s still noticeable.

The Great Red Spot’s color has been deepening, too, becoming intensely orange since 2014. Researchers aren’t sure why that’s happening, but it’s possible that the chemicals which color the storm are being carried higher into the atmosphere as the spot stretches up. At higher altitudes, the chemicals would be subjected to more UV radiation and would take on a deeper color.

In some ways, the mystery of the Great Red Spot only seems to deepen as the iconic storm contracts. Researchers don’t know whether the spot will shrink a bit more and then stabilize, or break apart completely.

“If the trends we see in the Great Red Spot continue, the next five to 10 years could be very interesting from a dynamical point of view,” said Goddard co-author Rick Cosentino. “We could see rapid changes in the storm’s physical appearance and behavior, and maybe the red spot will end up being not so great after all.”

By Elizabeth Zubritsky
NASA’s Goddard Space Flight Center in Greenbelt, Md.

Editor: Karl Hille

Source: NASA/Jupiter

Tuesday, March 13, 2018

Hubble's Galaxy Full of Cosmic Lighthouses

NGC 3972
Image credit: NASA, ESA, A. Riess (STScI/JHU)
Text: European Space Agency

This enchanting spiral galaxy can be found in the constellation of Ursa Major (the Great Bear). Star-studded NGC 3972 lies about 65 million light-years away from Earth, meaning that the light that we see now left it 65 million years ago, just when the dinosaurs became extinct.

NGC 3972 has had its fair share of dramatic events. In 2011 astronomers observed the explosion of a Type Ia supernova in the galaxy (not visible in this image). These dazzling objects all peak at the same brightness, and are brilliant enough to be seen over large distances.

NGC 3972 also contains many pulsating stars called Cepheid variables. These stars change their brightness at a rate matched closely to their intrinsic luminosity, making them ideal cosmic lighthouses for measuring accurate distances to relatively nearby galaxies.

Astronomers search for Cepheid variables in nearby galaxies that also contain a Type Ia supernova so they can compare the true brightness of both types of stars. That brightness information is used to calibrate the luminosity of Type Ia supernovae in far-flung galaxies so that astronomers can calculate the galaxies' distances from Earth. Once astronomers know accurate distances to galaxies near and far, they can determine and refine the expansion rate of the universe.

This image was taken in 2015 with Hubble's Wide Field Camera 3, as part of a project to improve the precision of the Hubble constant — a figure that describes the expansion rate of the universe.

Editor: Karl Hille

Source: NASA/Hubble

Monday, March 12, 2018

Hubble Finds Relic Galaxy Close to Home

Galaxy NGC 1277
Credit: NASA, ESA, M. Beasley (Instituto de Astrofísica de Canarias), and P. Kehusmaa

Astronomers have put NASA’s Hubble Space Telescope on an Indiana Jones-type quest to uncover an ancient “relic galaxy” in our own cosmic backyard.

The very rare and odd assemblage of stars has remained essentially unchanged for the past 10 billion years. This wayward stellar island provides valuable new insights into the origin and evolution of galaxies billions of years ago.

The galaxy, NGC 1277, started its life with a bang long ago, ferociously churning out stars 1,000 times faster than seen in our own Milky Way today. But it abruptly went quiescent as the baby boomer stars aged and grew ever redder.

The findings are being published online in the March 12 issue of the science journal Nature.

Though Hubble has seen such “red and dead” galaxies in the early universe, one has never been conclusively found nearby. Where the early galaxies are so distant, they are just red dots in Hubble deep-sky images. NGC 1277 offers a unique opportunity to see one up close and personal. “We can explore such original galaxies in full detail and probe the conditions of the early universe,” said Ignacio Trujillo, of the Instituto de Astrofísica de Canarias at the University of La Laguna, Spain.

The researchers learned that the relic galaxy has twice as many stars as our Milky Way, but physically it is as small as one quarter the size of our galaxy. Essentially, NGC 1277 is in a state of “arrested development.” Perhaps like all galaxies it started out as a compact object but failed to accrete more material to grow in size to form a magnificent pinwheel-shaped galaxy.

Approximately one in 1,000 massive galaxies is expected to be a relic (or oddball) galaxy, like NGC 1277, researchers say. They were not surprised to find it, but simply consider that it was in the right place at the right time to evolve — or rather not evolve — the way it did.

The telltale sign of the galaxy’s state lies in the ancient globular clusters of stars that swarm around it. Massive galaxies tend to have both metal-poor (appearing blue) and metal-rich (appearing red) globular clusters. The red clusters are believed to form as the galaxy forms, while the blue clusters are later brought in as smaller satellites are swallowed by the central galaxy. However, NGC 1277 is almost entirely lacking in blue globular clusters. “I’ve been studying globular clusters in galaxies for a long time, and this is the first time I’ve ever seen this,” said Michael Beasley, also of the Instituto de Astrofísica de Canarias.

The red clusters are the strongest evidence that the galaxy went out of the star-making business long ago. However, the lack of blue clusters suggests that NGC 1277 never grew further by gobbling up surrounding galaxies.

By contrast, our Milky Way contains approximately 180 blue and red globular clusters. This is due partly to the fact that our Milky Way continues cannibalizing galaxies that swing too close by in our Local Group of a few dozen small galaxies.

It’s a markedly different environment for NGC 1277. The galaxy lives near the center of the Perseus cluster of over 1,000 galaxies, located 240 million light-years away. But NGC 1277 is moving so fast through the cluster, at 2 million miles per hour, that it cannot merge with other galaxies to collect stars or pull in gas to fuel star formation. In addition, near the galaxy cluster center, intergalactic gas is so hot it cannot cool to condense and form stars.

The team started looking for “arrested development” galaxies in the Sloan Digital Sky Survey and found 50 candidate massive compact galaxies. Using a similar technique, but out of a different sample, NGC 1277 was identified as unique in that it has a central black hole that is much more massive than it should be for a galaxy of that size. This reinforces the scenario that the supermassive black hole and dense hub of the galaxy grew simultaneously, but the galaxy’s stellar population stopped growing and expanding because it was starved of outside material.

“I didn’t believe the ancient galaxy hypothesis initially, but finally I was surprised because it’s not that common to find what you predict in astronomy,” Beasley added. “Typically, the universe always comes up with more surprises that you can think about.”

The team has 10 other candidate galaxies to look at with varying degrees of “arrested development.”
The upcoming NASA James Webb Space Telescope (scheduled for launch in 2019) will allow astronomers to measure the motions of the globular clusters in NGC 1277. This will provide the first opportunity to measure how much dark matter the primordial galaxy contains.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Related Links 

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Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Michael Beasley
Instituto de Astrofísica de Canarias, Tenerife, Spain
011-34-922-605-200 x5382

Source: HubbleSite/News

Saturday, March 10, 2018

NASA’s Webb Telescope to Make a Splash in Search for Interstellar Water

Blue light from a newborn star lights up the reflection nebula IC 2631. This nebula is part of the Chamaeleon star-forming region, which Webb will study to learn more about the formation of water and other cosmic ices. CREDIT: European Southern Observatory (ESO)

NASA's Webb Telescope Will Map Cosmic Ices

Water is crucial for life, but how do you make water? Cooking up some H2O takes more than mixing hydrogen and oxygen. It requires the special conditions found deep within frigid molecular clouds, where dust shields against destructive ultraviolet light and aids chemical reactions. NASA's James Webb Space Telescope will peer into these cosmic reservoirs to gain new insights into the origin and evolution of water and other key building blocks for habitable planets.

A molecular cloud is an interstellar cloud of dust, gas, and a variety of molecules ranging from molecular hydrogen (H2) to complex, carbon-containing organics. Molecular clouds hold most of the water in the universe, and serve as nurseries for newborn stars and their planets.

Within these clouds, on the surfaces of tiny dust grains, hydrogen atoms link with oxygen to form water. Carbon joins with hydrogen to make methane. Nitrogen bonds with hydrogen to create ammonia. All of these molecules stick to the surface of dust specks, accumulating icy layers over millions of years. The result is a vast collection of "snowflakes" that are swept up by infant planets, delivering materials needed for life as we know it. "If we can understand the chemical complexity of these ices in the molecular cloud, and how they evolve during the formation of a star and its planets, then we can assess whether the building blocks of life should exist in every star system," said Melissa McClure of the Universiteit van Amsterdam, the principal investigator on a research project to investigate cosmic ices.

In order to understand these processes, one of Webb's Director's Discretionary Early Release Science projects will examine a nearby star-forming region to determine which ices are present where. "We plan to use a variety of Webb's instrument modes and capabilities, not only to investigate this one region, but also to learn how best to study cosmic ices with Webb," said Klaus Pontoppidan of the Space Telescope Science Institute (STScI), an investigator on McClure's project. This project will take advantage of Webb’s high-resolution spectrographs to get the most sensitive and precise observations at wavelengths that specifically measure ices. Webb's spectrographs, NIRSpec and MIRI, will provide up to five times better precision that any previous space telescope at near- and mid-infrared wavelengths.

Infant stars and comet cradles  

The team, led by McClure and co-principal investigators Adwin Boogert (University of Hawaii) and Harold Linnartz (Universiteit Leiden), plans to target the Chamaeleon Complex, a star-forming region visible in the southern sky. It's located about 500 light-years from Earth and contains several hundred protostars, the oldest of which are about 1 million years old. "This region has a bit of everything we're looking for," said Pontoppidan.

The team will use Webb's sensitive infrared detectors to observe stars behind the molecular cloud. As light from those faint, background stars passes through the cloud, ices in the cloud will absorb some of the light. By observing many background stars spread across the sky, astronomers can map ices within the cloud's entire expanse and locate where different ices form. They will also target individual protostars within the cloud itself to learn how ultraviolet light from these nascent stars promotes the creation of more complex molecules.

Astronomers also will examine the birthplaces of planets, rotating disks of gas and dust known as protoplanetary disks that surround newly formed stars. They will be able to measure the amounts and relative abundances of ices as close as 5 billion miles from the infant star, which is about the orbital distance of Pluto in our solar system.

"Comets have been described as dusty snowballs. At least some of the water in Earth's oceans likely was delivered by the impacts of comets early in our solar system's history. We'll be looking at the places where comets form around other stars," explained Pontoppidan.

This simulated spectrum from the Webb telescope illustrates the kinds of molecules that may be detected in star-forming regions like the Eagle Nebula (background). Credit: NASA, ESA, the Hubble Heritage Team, and M. McClure (Universiteit van Amsterdam) and A. Boogert (University of Hawaii)

Laboratory experiments

In order to understand Webb's observations, scientists will need to conduct experiments on Earth. Webb's spectrographs will spread incoming infrared light into a rainbow spectrum. Different molecules absorb light at certain wavelengths, or colors, resulting in dark spectral lines. Laboratories can measure a variety of substances to create a database of molecular "fingerprints." When astronomers see those fingerprints in a spectrum from Webb, they can then identify the molecule or family of molecules that created the absorption lines.

"Laboratory studies will help address two key questions. The first is what molecules are present. But just as important, we'll look at how the ices got there. How did they form? What we find with Webb will help inform our models and allow us to understand the mechanisms for ice formation at very low temperatures," explained Karin Öberg of the Harvard-Smithsonian Center for Astrophysics, an investigator on the program.

"It will take years to fully mine the data that comes out of Webb," Öberg added.

The James Webb Space Telescope is the world's premier infrared space observatory of the next decade. Webb will help humanity solve the mysteries of our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

Additional Resource

Thursday, March 08, 2018

Unprecedentedly Wide and Sharp Dark Matter Map

Figure 1: 2 dimensional dark matter map estimated by weak lensing technique. The dark matter is concentrated in dense clumps. We can identify massive dark matter halos (indicated by oranges circles). The area shown in this figure is approximately 30 square degrees (a total of 160 square degrees were observed this time). The distribution map without the orange circles is available here. (Credit: NAOJ/University of Tokyo)

A research team of multiple institutes, including the National Astronomical Observatory of Japan and University of Tokyo, released an unprecedentedly wide and sharp dark matter map based on the newly obtained imaging data by Hyper Suprime-Cam on the Subaru Telescope. The dark matter distribution is estimated by the weak gravitational lensing technique (Figure 1, Movie). The team located the positions and lensing signals of the dark matter halos and found indications that the number of halos could be inconsistent with what the simplest cosmological model suggests. This could be a new clue to understanding why the expansion of the Universe is accelerating.

Mystery of the accelerated Universe

In the 1930's, Edwin Hubble and his colleagues discovered the expansion of the Universe. This was a big surprise to most of the people who believed that the Universe stayed the same throughout eternity. A formula relating matter and the geometry of space-time was required in order to express the expansion of the Universe mathematically. Coincidentally, Einstein had already developed just such a formula. Modern cosmology is based on Einstein's theory for gravity.

It had been thought that the expansion is decelerating over time (blue and red lines in Figure 2) because the contents of the Universe (matter) attract each other. But in the late 1990's, it was found that the expansion has been accelerating since about 8 Giga years ago. This was another big surprise which earned the astronomers who found the expansion a Nobel Prize in 2011. To explain the acceleration, we have to consider something new in the Universe which repels the space.

The simplest resolution is to put the cosmological constant back into Einstein's equation. The cosmological constant was originally introduced by Einstein to realize a static universe, but was abandoned after the discovery of the expansion of the Universe. The standard cosmological model (called LCDM) incorporates the cosmological constant. The expansion history using LCDM is shown by the green line in Figure 2. LCDM is supported by many observations, but the question of what causes the acceleration still remains. This is one of the biggest problems in modern cosmology.

Figure 2: Expansion history of the Universe. The blue line shows what was believed to be likely in the early days of cosmology. Later this cosmological model fell out of favor because it predicts a higher growth rate and more structures, inconsistent with the observed galaxy distribution. Thus a much lighter Universe model was proposed which is shown by the red line. This light model also solved the so called "age problem," the existence of globular clusters older than the age of the Universe predicted by the blue track. But both the blue and red lines conflict with the inflation cosmology. Later when the acceleration of the Universe was discovered, LCDM represented by the green track, was adopted as the most likely model. Thanks to the addition of the cosmological constant, LCDM becomes consistent with the inflation model. (Credit: NAOJ) 

Wide and deep imaging survey using Hyper Suprime-Cam

The team is leading a large scale imaging survey using Hyper Suprime-Cam (HSC) to probe the mystery of the accelerating Universe. The key here is to examine the expansion history of the Universe very carefully.

In the early Universe, matter was distributed almost but not quite uniformly. There were slight fluctuations in the density which can now be observed through the temperature fluctuations of the cosmic microwave background. These slight matter fluctuations evolved over cosmic time because of the mutual gravitational attraction of matter, and eventually the large scale structure of the present day Universe become visible. It is known that the growth rate of the structure strongly depends on how the Universe expands. For example, if the expansion rate is high, it is hard for matter to contract and the growth rate is suppressed. This means that the expansion history can be probed inversely through the observation of the growth rate.

It is important to note that growth rate cannot be probed well if we only observe visible matter (stars and galaxies). This is because we now know that nearly 80 % of the matter is an invisible substance called dark matter. The team adopted the 'weak gravitation lensing technique.' The images of distant galaxies are slightly distorted by the gravitational field generated by the foreground dark matter distribution. Analysis of the systematic distortion enables us to reconstruct the foreground dark matter distribution.

This technique is observationally very demanding because the distortion of each galaxy is generally very subtle. Precise shape measurements of faint and apparently small galaxies are required. This motivated the team to develop Hyper Suprime-Cam. They have been carrying out a wide field imaging survey using Hyper Suprime-Cam since March 2014. At this writing in February 2018, 60 % of the survey has been completed.

Figure 3: Hyper Suprime-Cam image of a location with a highly significant dark matter halo detected through the weak gravitational lensing technique. This halo is so massive that some of the background (blue) galaxies are stretched tangentially around the center of the halo. This is called strong lensing. (Credit: NAOJ)

Unprecedentedly wide and sharp dark matter map

In this release, the team presents the dark matter map based on the imaging data taken by April 2016 (Figure 1). This is only 11 % of the planned final map, but it is already unprecedentedly wide. There has never been such a sharp dark matter map covering such a wide area.

Imaging observations are made through five different color filters. By combining these color data, it is possible to make a crude estimate of the distances to the faint background galaxies (called photometric redshift). At the same time, the lensing efficiency becomes most prominent when the lens is located directly between the distant galaxy and the observer. Using the photometric redshift information, galaxies are grouped into redshift bins. Using this grouped galaxy sample, dark matter distribution is reconstructed using tomographic methods and thus the 3D distribution can be obtained. Figure 4 shows one such example. Data for 30 square degrees are used to reconstruct the redshift range between 0.1 (~1.3 G light-years) and 1.0 (~8 G light-years). At the redshift of 1.0, the angular span corresponds to 1.0 G x 0.25 G light-years. This 3D dark matter mass map is also quite new. This is the first time the increase in the number of dark matter halos over time can be seen observationally.

Figure 4: An example of 3D distribution of dark matter reconstructed via tomographic methods using the weak lensing technique combined with the redshift estimates of the background galaxies. All of the 3D maps are available here. (Credit: University of Tokyo/NAOJ)

What the dark matter halo count suggests and future prospects

The team counted the number of dark matter halos whose lensing signal is above a certain threshold. This is one of the simplest measurements of the growth rate. The histogram (black line) in Figure 5 shows the observed lensing signal strength versus the number of observed halos whereas the model prediction is shown by the solid red line. The model is based on the standard LCDM model using the observation of cosmic microwave background as the seed of the fluctuations. The figure suggests that the number count of the dark matter halos is less than what is expected from LCDM. This could indicate there is a flaw in LCDM and that we might have to consider an alternative rather than the simple cosmological constant (Note 1).

Figure 5: Number of dark matter halos versus their lensing signal strength (black histogram) and number count expected from LCDM and the most recent CMB observation by the Planck satellite.  (Credit: NAOJ/University of Tokyo) 

The statistical significance is, however, still limited as the large error bars (vertical line on the histogram in Figure 5) suggest. There has been no conclusive evidence to reject LCDM, but many astronomers are interested in testing LCDM because discrepancies can be a useful probe to unlock the mystery of the accelerating Universe. Further observation and analysis are needed to confirm the discrepancy with higher significance. There are some other probes of the growth rate and such analysis are also underway (e.g. angular correlation of galaxy shapes) in the team to check the validity of standard LCDM.

Movie: 2 dimensional dark matter map estimated by weak lensing technique. The dark matter is concentrated in dense clumps. (Credit: NAOJ)

These results were published on January 1, 2018 in the HSC special issue of the Publications of the Astronomical Society of Japan (Miyazaki et al. 2018, "A large sample of shear-selected clusters from the Hyper Suprime-Cam Subaru Strategic Program S16A Wide field mass maps", PASJ, 70, S27; Oguri et al. 2018 "Two- and three-dimensional wide-field weak lensing mass maps from the Hyper Suprime-Cam Subaru Strategic Program S16A data", PASJ, 70, S26). The projects are supported by Grants-In-Aid by MEXT and JSPS JP15H05892, JP15H05887, JP15H05893, JP15K21733, JP26800093, JP15K17600, JP16H01089 as well as JST's CREST JPMJCR1414.

Note 1: Empty space is known to have energy caused by quantum effects and this is one candidate for the source of the cosmological constant. However, the energy density of the cosmological constant is many orders of magnitude weaker than what would be predicted based on this "vacuum energy" and it is hard to reconcile the discrepancy. Astronomers started to consider the existence of some other physical mechanism to explain the energy density, that concept is now called dark energy. The energy density can change over time in this generalization. If the dark energy was stronger in the past, the acceleration would have been more significant and suppressed the growth rate. This would result in fewer dark matter halos.

Wednesday, March 07, 2018

ALMA Reveals Inner Web of Stellar Nursery

ALMA Reveals Inner Web of Stellar Nursery

The jewel in Orion’s sword

ESOcast 154 Light: ALMA Reveals Inner Web of Stellar Nursery (4K UHD)
PR Video eso1809a
ESOcast 154 Light: ALMA Reveals Inner Web of Stellar Nursery (4K UHD) 

Zooming in on ALMA's view of the Orion Nebula
PR Video eso1809b
Zooming in on ALMA's view of the Orion Nebula

Panning across ALMA's view of the Orion Nebula
Panning across ALMA's view of the Orion Nebula

New data from the Atacama Large Millimeter/submillimeter Array (ALMA) and other telescopes have been used to create this stunning image showing a web of filaments in the Orion Nebula. These features appear red-hot and fiery in this dramatic picture, but in reality are so cold that astronomers must use telescopes like ALMA to observe them.

This spectacular and unusual image shows part of the famous Orion Nebula, a star formation region lying about 1350 light-years from Earth. It combines a mosaic of millimetre-wavelength images from the Atacama Large Millimeter/submillimeter Array (ALMA) and the IRAM 30-metre telescope, shown in red, with a more familiar infrared view from the HAWK-I instrument on ESO’s Very Large Telescope, shown in blue. The group of bright blue-white stars at the upper-left is the Trapezium Cluster — made up of hot young stars that are only a few million years old.

The wispy, fibre-like structures seen in this large image are long filaments of cold gas, only visible to telescopes working in the millimetre wavelength range. They are invisible at both optical and infrared wavelengths, making ALMA one of the only instruments available for astronomers to study them. This gas gives rise to newborn stars — it gradually collapses under the force of its own gravity until it is sufficiently compressed to form a protostar — the precursor to a star.

The scientists who gathered the data from which this image was created were studying these filaments to learn more about their structure and make-up. They used ALMA to look for signatures of diazenylium gas, which makes up part of these structures. Through doing this study, the team managed to identify a network of 55 filaments.

The Orion Nebula is the nearest region of massive star formation to Earth, and is therefore studied in great detail by astronomers seeking to better understand how stars form and evolve in their first few million years. ESO’s telescopes have observed this interesting region multiple times, and you can learn more about previous discoveries here, here, and here.

This image combines a total of 296 separate individual datasets from the ALMA and IRAM telescopes, making it one of the largest high-resolution mosaics of a star formation region produced so far at millimetre wavelengths [1].


[1] Earlier mosaics of Orion at millimetre wavelengths had used single-dish telescopes, such as APEX. The new observations from ALMA and IRAM use interferometry to combine the signals from multiple, widely-separated antennas to create images showing much finer detail.

More Information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.



Alvaro Hacar González
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Leiden University, the Netherlands

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Source: ESO/News

Tuesday, March 06, 2018

Hubble Finds Huge System of Dusty Material Enveloping the Young Star HR 4796A

HR 4796A Stellar Dust Disk
This is a Hubble Space Telescope photo of a vast, complex dust structure, about 150 billion miles across, enveloping the young star HR 4796A. A bright, narrow inner ring of dust is already known to encircle the star and may have been corralled by the gravitational pull of an unseen giant planet. This newly discovered huge dust structure around the system may have implications for what this yet-unseen planetary system looks like around the 8-million-year-old star, which is in its formative years of planet construction. The debris field of very fine dust was likely created from collisions among developing infant planets near the star, evidenced by a bright ring of dusty debris seen 7 billion miles from the star. The pressure of starlight from the star, which is 23 times more luminous than the Sun, then expelled the dust far into space.  Credit: NASA, ESA, and G. Schneider (University of Arizona)

Astronomers have used NASA’s Hubble Space Telescope to uncover a vast, complex dust structure, about 150 billion miles across, enveloping the young star HR 4796A. A bright, narrow, inner ring of dust is already known to encircle the star and may have been corralled by the gravitational pull of an unseen giant planet. This newly discovered huge structure around the system may have implications for what this yet-unseen planetary system looks like around the 8-million-year-old star, which is in its formative years of planet construction.

The debris field of very fine dust was likely created from collisions among developing infant planets near the star, evidenced by a bright ring of dusty debris seen 7 billion miles from the star. The pressure of starlight from the star, which is 23 times more luminous than the Sun, then expelled the dust far into space.

But the dynamics don’t stop there. The puffy outer dust structure is like a donut-shaped inner tube that got hit by a truck. It is much more extended in one direction than in the other and so looks squashed on one side even after accounting for its inclined projection on the sky. This may be due to the motion of the host star plowing through the interstellar medium, like the bow wave from a boat crossing a lake. Or it may be influenced by a tidal tug from the star’s red dwarf binary companion (HR 4796B), located at least 54 billion miles from the primary star.

“The dust distribution is a telltale sign of how dynamically interactive the inner system containing the ring is," said Glenn Schneider of the University of Arizona, Tucson, who used Hubble’s Space Telescope Imaging Spectrograph (STIS) to probe and map the small dust particles in the outer reaches of the HR 4796A system, a survey that only Hubble’s sensitivity can accomplish.

“We cannot treat exoplanetary debris systems as simply being in isolation. Environmental effects, such as interactions with the interstellar medium and forces due to stellar companions, may have long-term implications for the evolution of such systems. The gross asymmetries of the outer dust field are telling us there are a lot of forces in play (beyond just host-star radiation pressure) that are moving the material around. We’ve seen effects like this in a few other systems, but here’s a case where we see a bunch of things going on at once,” Schneider further explained.

Though long hypothesized, the first evidence for a debris disk around any star was uncovered in 1983 with NASA’s Infrared Astronomical Satellite. Later photographs revealed an edge-on debris disk around the southern star Beta Pictoris. In the late 1990s, Hubble’s second-generation instruments, which had the capability of blocking out the glare of a central star, allowed many more disks to be photographed. Now, such debris rings are thought to be common around stars. About 40 such systems have been imaged to date, largely by Hubble.

Schneider’s paper appears in the February 2018 Astronomical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

 Releated links


Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Glenn Schneider
The University of Arizona, Tucson, Arizona

Source: HubbleSite

Monday, March 05, 2018

Buoyant bubbles in galaxy clusters and heating of the intracluster medium

Figure 1. Chandra X-ray image of the Perseus cluster. The bubbles appear as dark (X-ray dim) regions in this image. “Active” bubbles (radius ∼ 7 kpc) are marked with black dashed circles. They are surrounded by quasi-spherical weak shocks (radius ∼ 14 kpc), shown by yellow circles. The outer bubble, to the north-west from the centre, has the “horizontal” and “vertical” (radial) sizes L ∼ 25 kpc and h ∼ 7 kpc, respectively. © MPA

Buoyant bubbles of relativistic plasma in galaxy cluster cores plausibly play a key role in conveying the energy from a supermassive black hole to the intracluster medium (ICM). While the amount of energy supplied by the bubbles to the ICM is set by energy conservation, the physical mechanisms involved in coupling the bubbles and the ICM are still being debated. A team of researchers from the Max Planck Institute for Astrophysics (MPA) and the University of Oxford argues that internal waves might be efficient in extracting energy from the bubbles and distributing it over large masses of the ICM.

Galaxy clusters are the most massive gravitational bound structures in the Universe. The temperature of the gas filling the deep potential wells of clusters reaches 10 – 100 million Kelvin, leading to powerful X-ray emission from these objects. While the gas cooling timescales in the cluster cores are much shorter than the Hubble time, there is no evidence that the gas cools below X-ray temperatures. This implies the existence of a powerful heating source that offsets cooling losses of the gas. Supermassive black holes in cluster cores have been widely accepted as a prime candidate for such a heating source.

Observations of clusters provide us with a unique opportunity to study the impact of supermassive black holes on the ambient gas – the process known as active galactic nuclei (AGN) feedback, and in particular its flavour, called radio-mode feedback. In the cluster centre, bubbles of relativistic plasma are inflated by bipolar jets from a supermassive black hole, and subsequently expand until the expansion velocity becomes comparable to their rise velocity driven by the buoyancy force. The bubbles then detach from the jet and buoyantly rise upwards. They finally reach their terminal velocity when the drag force balances the buoyancy force. X-ray and radio observations of nearby clusters show clear signs of the intracluster medium (ICM) interacting with these bubbles (see Fig. 1). Estimates of the power needed to inflate the bubbles based on comparing the inflation and buoyancy time scales show that this power is comparable to the gas cooling losses.

Figure 2. Sketch showing a bubble rising in a stratified medium. The bubble rises at the terminal velocity (Uterm) when the buoyancy force is balanced by the drag force. The grey, black and orange lines schematically show sound waves, turbulence, and internal waves excited by the moving bubble, which can all contribute to the total drag. © MPA

For a bubble rising with terminal velocity, energy conservation arguments imply that much of the energy used by the supermassive black hole to inflate it will be transferred to the ICM once the bubble crosses several pressure scale heights. While this argument guarantees a high coupling efficiency of the bubble-heating process, the particular channels responsible for the energy transfer to the ICM have long been debated. In other words, the nature of the drag force that balances the buoyancy of the bubble is largely unknown. Processes contributing to the drag could be the excitation of sound and internal waves, turbulence in the wake of the bubble, the potential energy of the uplifted gas or others (see Fig. 2).

Astrophysicists have long attempted to explore bubble dynamics and the relevant heating process through numerical simulations. However, these attempts are hindered by uncertainties in the properties of the ICM and the bubbles, especially in the topology and strength of the magnetic field. For instance, ideal hydrodynamic models often lead to a rapid destruction of rising bubbles. However, observations show that some clusters (e.g. Perseus, M87/Virgo) have X-ray cavities with relatively regular shapes even far from the cluster centre (see Fig. 1). As can be seen in this figure, the bubbles are initially almost spherical, but become flattened once they rise buoyantly. Phenomenologically, this can be interpreted as if an effective surface tension acts on the bubble surface and keeps the bubble stable. The flattened bubble shape could result from the combined action of pressure gradients of the flow that squeeze the bubble along the direction of its motion, and surface tension, which prevents the bubble surface from shredding. However, the detailed physical description of this effective surface tension, presumably magnetic, is difficult. To circumvent this difficulty, a team of researchers from MPA and Oxford modelled the bubbles as rigid bodies buoyantly rising in the stratified cluster gas and studied the perturbation induced by such bodies in the gas – a problem that has many applications in atmospheric sciences and oceanology.

It was found that the degree of flattening has dramatic effects on the nature of the drag force generated by rising bubbles. For spherical bubbles, the turbulence in the wake of the bubble dominates the drag, similarly to the case of a homogeneous fluid, while for strongly flattened bubbles, the stratification leads to pronounced changes in the flow. Flattened bubbles move slower and, in particular, clear signs of internal waves are seen in the simulations. Such waves are conceptually similar to the surface waves exited by ships moving in the water. The movie (below) shows how internal waves are excited and propagate horizontally and downwards from the rising bubble, spreading their energy over large volumes of the ICM (see Fig. 3). Attractive features of internal waves, as one of the possible bubble-heating channels, are that: (1) internal waves are trapped in the central region of a cluster, because the Brunt-Väisälä frequency (a.k.a., buoyancy frequency) is a decreasing function of radius, implying that the energy will not leak outside the cluster core; (2) these waves can travel in the tangential direction (azimuthal) and spread energy throughout the cluster core. Another interesting feature is a complex pattern in the wake of the bubble, which reflects the interplay between buoyancy and eddies shed by the flattened bubble.

According to simulations, the expected terminal velocity of the north-west bubble in the Perseus cluster (marked with a white ellipse in Fig. 1) is ∼200 km/s, which broadly agrees with the sole measurements of the gas velocity by the Hitomi satellite. This estimate also agrees with constraints on the velocity from the analysis of the morphology and size of the cool gas filaments trailing the bubble. These results are very encouraging, but of course they only represent the first step towards a comprehensive modelling of bubbles in galaxy clusters and a complete census of all relevant gas heating channels.

Flattened bubble in stratified cluster atmosphere  
Figure 3. Specific kinetic energy of the gas in the simulation with a flattened bubble moving in a stratified cluster atmosphere. Internal waves are excited, revealed by a characteristic “Christmas tree” pattern.


Zhang, Congyao
Phone: 2299

Churazov, Eugene
Scientific Staff
Phone: 2219
Links: personal homepage (the institute is not responsible for the contents of personal homepages)

Original Publication

1. Congyao Zhang, Eugene Churazov, Alexander A. Schekochihin
Generation of Internal Waves by Buoyant Bubbles in Galaxy Clusters and Heating of Intracluster Medium
submitted to MNRASSource

Sunday, March 04, 2018

NASA Finds a Large Amount of Water in an Exoplanet's Atmosphere

Using Hubble and Spitzer space telescopes, scientists studied the "hot Saturn" called WASP-39b - a hot, bloated, Saturn-mass exoplanet located about 700 light-years from Earth. By dissecting starlight filtering through the planet's atmosphere into its component colors, the team found clear evidence for a large amount of water vapor. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers predicted they'd see water, they were surprised by how much they found. This suggests that the planet formed farther out from the star, where it was bombarded by a lot of icy material. Because WASP-39b has so much more water than Saturn, it must have formed differently from our famously ringed neighbor. Credits: NASA, ESA, G. Bacon and A. Feild (STScI), and H. Wakeford (STScI/Univ. of Exeter) .  › Larger view

Using Hubble and Spitzer, astronomers analyzed the atmosphere of the "hot Saturn" exoplanet WASP-39b, and they captured the most complete spectrum of an exoplanet's atmosphere possible with present-day technology. By dissecting starlight filtering through the planet's atmosphere into its component colors, the team found clear evidence for water vapor. Although the researchers predicted they would see water, they were surprised by how much water they found - three times as much water as Saturn has. This suggests that the planet formed farther out from the star, where it was bombarded by icy material. Credits: NASA, ESA, G. Bacon and A. Feild (STScI), and H. Wakeford (STScI/Univ. of Exeter).  › Larger view

Much like detectives who study fingerprints to identify the culprit, scientists used NASA's Hubble and Spitzer space telescopes to find the "fingerprints" of water in the atmosphere of a hot, bloated, Saturn-mass exoplanet some 700 light-years away. And, they found a lot of water. In fact, the planet, known as WASP-39b, has three times as much water as Saturn does.

Though no planet like this resides in our solar system, WASP-39b can provide new insights into how and where planets form around a star, say researchers. This exoplanet is so unique, it underscores the fact that the more astronomers learn about the complexity of other worlds, the more there is to learn about their origins. This latest observation is a significant step toward characterizing these worlds.

Although the researchers predicted they'd see water, they were surprised by how much water they found in this "hot Saturn." Because WASP-39b has so much more water than our famously ringed neighbor, it must have formed differently. The amount of water suggests that the planet actually developed far away from the star, where it was bombarded by a lot of icy material. WASP-39b likely had an interesting evolutionary history as it migrated in, taking an epic journey across its planetary system and perhaps obliterating planetary objects in its path.

"We need to look outward so we can understand our own solar system," explained lead investigator Hannah Wakeford of the Space Telescope Science Institute in Baltimore, and the University of Exeter in Devon, United Kingdom. "But exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that's fantastic!"

Wakeford and her team were able to analyze the atmospheric components of this exoplanet, which is similar in mass to Saturn but profoundly different in many other ways. By dissecting starlight filtering through the planet's atmosphere into its component colors, the team found clear evidence for water. This water is detected as vapor in the atmosphere.

Using Hubble and Spitzer, the team has captured the most complete spectrum of an exoplanet's atmosphere possible with present-day technology. "This spectrum is thus far the most beautiful example we have of what a clear exoplanet atmosphere looks like," said Wakeford.

"WASP-39b shows exoplanets can have much different compositions than those of our solar system," said co-author David Sing of the University of Exeter. "Hopefully, this diversity we see in exoplanets will give us clues in figuring out all the different ways a planet can form and evolve."

Located in the constellation Virgo, WASP-39b whips around a quiet, Sun-like star, called WASP-39, once every four days. The exoplanet is currently positioned more than 20 times closer to its star than Earth is to the Sun. It is tidally locked, meaning it always shows the same face to its star.

Its day-side temperature is a scorching 1,430 degrees Fahrenheit (776.7 degrees Celsius). Powerful winds transport heat from the dayside around the planet, keeping the permanent nightside almost as hot. Although it is called a "hot Saturn," WASP-39b is not known to have rings. Instead, is has a puffy atmosphere that is free of high-altitude clouds, allowing Wakeford and her team to peer down into its depths.

Looking ahead, Wakeford hopes to use NASA's James Webb Space Telescope - scheduled to launch in 2019 - to get an even more complete spectrum of the exoplanet. Webb will be able to give information about the planet's atmospheric carbon, which absorbs light at longer infrared wavelengths than Hubble can see. By understanding the amount of carbon and oxygen in the atmosphere, scientists can learn even more about where and how this planet formed.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

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