Hubble Space Telescope provides a new portrait of Jupiter

Photo: Jupiter as imaged by the Hubble Space Telescope on June 27, 2019.
The NASA/ESA Hubble Space Telescope reveals the intricate, detailed beauty of Jupiter’s clouds in this new image taken on June 27, 2019 by Hubble’s Wide Field Camera 3, when the planet was 644 million kilometers from Earth — its closest distance this year. The image features the planet’s trademark Great Red Spot and a more intense color palette in the clouds swirling in the planet’s turbulent atmosphere than seen in previous years.
Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley) Click here for full-size image!

Among the most striking features in the image are the rich colors of the clouds moving toward the Great Red Spot. This huge anticyclonic storm is roughly the diameter of Earth and is rolling counterclockwise between two bands of clouds that are moving in opposite directions toward it.

As with previous images of Jupiter taken by Hubble, and other observations from telescopes on the ground, the new image confirms that the huge storm which has raged on Jupiter’s surface for at least 150 years continues to shrink. The reason for this is still unknown so Hubble will continue to observe Jupiter in the hope that scientists will be able to solve this stormy riddle. Much smaller storms appear on Jupiter as white or brown ovals that can last as little as a few hours or stretch on for centuries.

The worm-shaped feature located south of the Great Red Spot is a cyclone, a vortex spinning in the opposite direction to that in which the Great Red Spot spins. Researchers have observed cyclones with a wide variety of different appearances across the planet. The two white oval features are anticyclones, similar to small versions of the Great Red Spot.

The Hubble image also highlights Jupiter’s distinct parallel cloud bands. These bands consist of air flowing in opposite directions at various latitudes. They are created by differences in the thickness and height of the ammonia ice clouds; the lighter bands rise higher and have thicker clouds than the darker bands. The different concentrations are kept separate by fast winds which can reach speeds of up to 650 kilometers per hour.

These observations of Jupiter form part of the Outer Planet Atmospheres Legacy (OPAL) program, which began in 2014. This initiative allows Hubble to dedicate time each year to observing the outer planets and provides scientists with access to a collection of maps, which helps them to understand not only the atmospheres of the giant planets in the Solar System, but also the atmosphere of our own planet and of the planets in other planetary systems.


First observation of gravitational wave source, a kilonova: the merger of two neutron stars

Photo: Kilonova observed. Credit: NASA and ESA. Acknowledgment: A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), and A. Fruchter and O. Fox (STScI)
On 17 August 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer both detected gravitational waves from the collision between two neutron stars. Within 12 hours observatories had identified the source of the event within the lenticular galaxy NGC 4993, shown in this image gathered with the NASA/ESA Hubble Space Telescope. The associated stellar flare, a kilonova, is clearly visible in the Hubble observations. This is the first time the optical counterpart of a gravitational wave event was observed. Hubble observed the kilonova gradually fading over the course of six days, as shown in these observations taken in between 22 and 28 August. Credit: NASA and ESA. Acknowledgment: A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), and A. Fruchter and O. Fox (STScI)

On 17 August 2017 the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometerboth alerted astronomical observers all over the globe about the detection of a gravitational wave event named GW170817. About two seconds after the detection of the gravitational wave, ESA’s INTEGRAL telescope and NASA’s Fermi Gamma-ray Space Telescope observed a short gamma-ray burst in the same direction.

In the night following the initial discovery, a fleet of telescopes started their hunt to locate the source of the event. Astronomers found it in the lenticular galaxy NGC 4993, about 130 million light-years away. A point of light was shining where nothing was visible before and this set off one of the largest multi-telescope observing campaigns ever — among these telescopes was the NASA/ESA Hubble Space Telescope.

Several different teams of scientists used Hubble over the two weeks following the gravitational wave event alert to observe NGC 4993. Using Hubble’s high-resolution imaging capabilities they managed to get the first observational proof for a kilonova, the visible counterpart of the merging of two extremely dense objects — most likely two neutron stars. Such mergers were first suggested more than 30 years ago but this marks the first firm observation of such an event. The distance to the merger makes the source both the closest gravitational wave event detected so far and also one of the closest gamma-ray burst sources ever seen.

“Once I saw that there had been a trigger from LIGO and Virgo at the same time as a gamma-ray burst I was blown away,” recalls Andrew Levan of the University of Warwick, who led the Hubble team that obtained the first observations. “When I realised that it looked like neutron stars were involved, I was even more amazed. We’ve been waiting a long time for an opportunity like this!”

Hubble captured images of the galaxy in visible and infrared light, witnessing a new bright object within NGC 4993 that was brighter than a nova but fainter than a supernova. The images showed that the object faded noticeably over the six days of the Hubble observations. Using Hubble’s spectroscopic capabilities the teams also found indications of material being ejected by the kilonova as fast as one-fifth of the speed of light.

“It was surprising just how closely the behaviour of the kilonova matched the predictions,” said Nial Tanvir, professor at the University of Leicester and leader of another Hubble observing team. “It looked nothing like known supernovae, which this object could have been, and so confidence was soon very high that this was the real deal.”

Connecting kilonovae and short gamma-ray bursts to neutron star mergers has so far been difficult, but the multitude of detailed observations following the detection of the gravitational wave event GW170817 has now finally verified these connections.

“The spectrum of the kilonova looked exactly like how theoretical physicists had predicted the outcome of the merger of two neutron stars would appear,” says Levan. “It ties this object to the gravitational wave source beyond all reasonable doubt.”

The infrared spectra taken with Hubble also showed several broad bumps and wiggles that signal the formation of some of the heaviest elements in nature. These observations may help solve another long-standing question in astronomy: the origin of heavy chemical elements, like gold and platinum. In the merger of two neutron stars, the conditions appear just right for their production.

The implications of these observations are immense. As Tanvir explains: “This discovery has opened up a new approach to astronomical research, where we combine information from both electromagnetic light and from gravitational waves. We call this multi-messenger astronomy — but until now it has just been a dream!”

Levan concludes: “Now, astronomers won’t just look at the light from an object, as we’ve done for hundreds of years, but also listen to it. Gravitational waves provide us with complementary information from objects which are very hard to study using only electromagnetic waves. So pairing gravitational waves with electromagnetic radiation will help astronomers understand some of the most extreme events in the Universe.”

Seven Earth-sized planets discovered around dwarf star 40 light-years distant

Image: Star system with planets. Credit: ESO/M. Kornmesser/
This artist’s impression shows the view from the surface of one of the planets in the TRAPPIST-1 system. At least seven planets orbit this ultra cool dwarf star 40 light-years from Earth and they are all roughly the same size as the Earth. They are at the right distances from their star for liquid water to exist on the surfaces of several of them. This artist’s impression is based on the known physical parameters for the planets and stars seen, and uses a vast database of objects in the Universe. Credit: ESO/M. Kornmesser/

Feb. 22, 2017 — Astronomers have found a system of seven Earth-sized planets just 40 light-years away. Using ground and space telescopes, including ESO’s Very Large Telescope, the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1. According to the paper appearing today in the journal Nature, three of the planets lie in the habitable zone and could harbor oceans of water on their surfaces, increasing the possibility that the star system could play host to life. This system has both the largest number of Earth-sized planets yet found and the largest number of worlds that could support liquid water on their surfaces.

Astronomers using the TRAPPIST–South telescope at ESO’s La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world, have now confirmed the existence of at least seven small planets orbiting the cool red dwarf star TRAPPIST-1. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes similar to Earth.

Dips in the star’s light output caused by each of the seven planets passing in front of it — events known as transits — allowed the astronomers to infer information about their sizes, compositions and orbits. They found that at least the inner six planets are comparable in both size and temperature to the Earth.

Lead author Michaël Gillon of the STAR Institute at the University of Liège in Belgium is delighted by the findings: “This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!”

With just eight percent the mass of the Sun, TRAPPIST-1 is very small in stellar terms — only marginally bigger than the planet Jupiter — and though nearby in the constellation Aquarius (The Water Carrier), it appears very dim. Astronomers expected that such dwarf stars might host many Earth-sized planets in tight orbits, making them promising targets in the hunt for extraterrestrial life, but TRAPPIST-1 is the first such system to be found.

Co-author Amaury Triaud expands: “The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1!”

The team determined that all the planets in the system are similar in size to Earth and Venus in the Solar System, or slightly smaller. The density measurements suggest that at least the innermost six are probably rocky in composition.

The planetary orbits are not much larger than that of Jupiter’s Galilean moon system, and much smaller than the orbit of Mercury in the Solar System. However, TRAPPIST-1’s small size and low temperature mean that the energy input to its planets is similar to that received by the inner planets in our Solar System; TRAPPIST-1c, d and f receive similar amounts of energy to Venus, Earth and Mars, respectively.

All seven planets discovered in the system could potentially have liquid water on their surfaces, though their orbital distances make some of them more likely candidates than others. Climate models suggest the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water, except maybe on a small fraction of their surfaces. The orbital distance of the system’s outermost planet, TRAPPIST-1h, is unconfirmed, though it is likely to be too distant and cold to harbor liquid water — assuming no alternative heating processes are occurring. TRAPPIST-1e, f, and g, however, represent the holy grail for planet-hunting astronomers, as they orbit in the star’s habitable zone and could host oceans of surface water.

These new discoveries make the TRAPPIST-1 system a very important target for future study. The NASA/ESA Hubble Space Telescope is already being used to search for atmospheres around the planets and team member Emmanuël Jehin is excited about the future possibilities: “With the upcoming generation of telescopes, such as ESO’s European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope, we will soon be able to search for water and perhaps even evidence of life on these worlds.”

Tracing the Milky Way’s magnetic field

Image: Polarized Emission from Milky Way Dust. Credit: ESA and the Planck Collaboration
Polarized Emission from Milky Way Dust

The interaction between interstellar dust in the Milky Way and the structure of our Galaxy’s magnetic field, as detected by the European Space Agency’s Planck satellite over the entire sky.

Planck scanned the sky to detect the most ancient light in the history of the Universe – the cosmic microwave background. It also detected significant foreground emission from diffuse material in our galaxy which, although a nuisance for cosmological studies, is extremely important for studying the birth of stars and other phenomena in the Milky Way.

Among the foreground sources at the wavelengths probed by Planck is cosmic dust, a minor but crucial component of the interstellar medium that pervades the galaxy. Mainly gas, it is the raw material for stars to form.

Interstellar clouds of gas and dust are also threaded by the galaxy’s magnetic field, and dust grains tend to align their longest axis at right angles to the direction of the field. As a result, the light emitted by dust grains is partly ‘polarized’ – it vibrates in a preferred direction – and, as such, could be caught by the polarization-sensitive detectors on Planck.

Scientists in the Planck collaboration are using the polarized emission of interstellar dust to reconstruct the galaxy’s magnetic field and study its role in the build-up of structure in the Milky Way, leading to star formation.

In this image, the color scale represents the total intensity of dust emission, revealing the structure of interstellar clouds in the Milky Way. The texture is based on measurements of the direction of the polarized light emitted by the dust, which in turn indicates the orientation of the magnetic field.

Credit: ESA and the Planck Collaboration

Hubble revisits iconic “Pillars of Creation” image

Photo: Iconic "Pillars of Creation" reimaged. Credit: NASA, ESA/Hubble and the Hubble Heritage Team
New view of the Pillars of Creation — Visible Light. Click to Enlarge.

The NASA/ESA Hubble Space Telescope has captured many breathtaking images of the Universe, but one snapshot stands out from the rest: the Eagle Nebula’s Pillars of Creation. In 1995 Hubble’s iconic image revealed never-before-seen details in the giant columns and now the telescope is kickstarting its 25th year in orbit with an even clearer, and more stunning, image of these beautiful structures.

The three impressive towers of gas and dust captured in this image are part of the Eagle Nebula, otherwise known as Messier 16. Although such features are not uncommon in star-forming regions, the Messier 16 structures are by far the most photogenic and evocative ever captured. The Hubble image of the pillars taken in 1995 is so popular that it has appeared in film and television, on tee-shirts and pillows, and even on postage stamps.

Now Hubble has revisited the famous pillars, capturing the multi-colored glow of gas clouds, wispy tendrils of dark cosmic dust, and the rust-colored elephants’ trunks with the newer Wide Field Camera 3, installed in 2009. The visible-light image builds on one of the most iconic astronomy images ever taken and provides astronomers with an even sharper and wider view.

In addition to this new visible-light image, Hubble has also produced a bonus image. This image is taken in infrared light, which penetrates much of the obscuring dust and gas and unveils a more unfamiliar view of the pillars, transforming them into wispy silhouettes set against a background peppered with stars. Here newborn stars, hidden in the visible-light view, can be seen forming within the pillars themselves.

Photos: The Pillars of Creation, New and Old. Credit: NASA, ESA/Hubble and the Hubble Heritage Team
The Pillars of Creation – New and Old

Although the original image was dubbed the “Pillars of Creation”, this new image hints that they are also pillars of destruction. The dust and gas in these pillars is seared by intense radiation from the young stars forming within them, and eroded by strong winds from massive nearby stars. The ghostly bluish haze around the dense edges of the pillars in the visible-light view is material that is being heated by bright young stars and evaporating away.

With these new images come better contrast and clearer views of the region. Astronomers can use these new images to study how the physical structure of the pillars is changing over time. The infrared image shows that the reason the pillars exist is because the very ends of them are dense, and they shadow the gas below them, creating the long, pillar-like structures. The gas in between the pillars has long since been blown away by the winds from a nearby star cluster.

At the top edge of the left-hand pillar, a gaseous fragment has been heated up and is flying away from the structure, highlighting the violent nature of star-forming regions.

These massive stars may be slowly destroying the pillars but they are also the reason Hubble sees the structures at all. They radiate enough ultraviolet light to illuminate the area and make the clouds of oxygen, hydrogen and sulphur glow.

Although structures like these exist throughout the Universe, the Pillars of Creation — at a distance of 6,500 light-years away — provide the best, and most dramatic, example. Now, these images have allowed us to see them more clearly than ever, proving that at 25 years of age, Hubble is still going strong.

This image and the associated results were presented today at the 225th meeting of the American Astronomical Society in Seattle, Washington, USA.

Hubble Ultra Deep Field updated … with ultraviolet

Photo: Hubble Ultra Deep Field 2014
The Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken from 2003 to 2012 with Hubble’s Advanced Camera for Surveys and Wide Field Camera 3. Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

Astronomers using the Hubble Space Telescope have captured the most comprehensive picture ever assembled of the evolving Universe — and one of the most colorful. The study is called the Ultraviolet Coverage of the Hubble Ultra Deep Field (UVUDF) project.

Prior to this survey, astronomers were in a curious position. They knew a lot about star formation occurring in nearby galaxies thanks to UV telescope facilities such as NASA’s Galex observatory, which operated from 2003 to 2013. And, thanks to Hubble’s near-infrared and visible capability, they had also studied star birth in the most distant galaxies. We see these distant galaxies in their most primitive stages due to the vast amount of time it takes their light to reach us.

However, between five and 10 billion light-years away from us — corresponding to a time period when most of the stars in the Universe were born — there was a lack of the data needed to fully understand star formation. The hottest, most massive and youngest stars, which emit light in the ultraviolet, were often neglected as subjects of direct observation, leaving a significant gap in our knowledge of the cosmic timeline.

The addition of ultraviolet data to the Hubble Ultra Deep Field using Hubble’s Wide Field Camera 3 gives astronomers access to direct observations of regions of unobscured star formation and may help us to fully understand how stars formed. By observing at these wavelengths, researchers get a direct look at which galaxies are forming stars and, just as importantly, where the stars are forming. This enables astronomers to understand how galaxies like the Milky Way grew in size from small collections of very hot stars to the massive structures they are today.

The patch of sky in this image has been previously studied by astronomers in a series of visible and near-infrared exposures taken from 2004 to 2009: the Hubble Ultra Deep Field. Now, with the addition of ultraviolet light, they have combined the full range of colors available to Hubble, stretching all the way from ultraviolet to near-infrared light. The resulting image, made from 841 orbits of telescope viewing time, contains approximately 10,000 galaxies, extending back to within a few hundred million years of the Big Bang.

Since the Earth’s atmosphere filters most ultraviolet light, this work can only be accomplished with a space-based telescope like Hubble. Ultraviolet surveys like this are incredibly important in planning for the James Webb Space Telescope (JWST) as Hubble is the only telescope currently able to obtain the ultraviolet data that researchers will need to combine with infrared data from JWST.

Water vapor detected on Ceres

Image Credit: ESA/ATG medialab
Dwarf planet Ceres is located in the asteroid belt, between the orbits of Mars and Jupiter. Observations by ESA’s Herschel space observatory between 2011 and 2013 find that the dwarf planet has a thin water-vapour atmosphere. It is the first unambiguous detection of water vapour around an object in the asteroid belt.
Image Credit: ESA/ATG medialab

Scientists using the Herschel space observatory have made the first definitive detection of water vapor on the largest and roundest object in the asteroid belt, Ceres.

Plumes of water vapor are thought to shoot up periodically from Ceres when portions of its icy surface warm slightly. Ceres is classified as a dwarf planet, a solar system body bigger than an asteroid and smaller than a planet.

Herschel is a European Space Agency (ESA) mission with important NASA contributions.
“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of ESA in Spain, lead author of a paper in the journal Nature.

The results come at the right time for NASA’s Dawn mission, which is on its way to Ceres now after spending more than a year orbiting the large asteroid Vesta. Dawn is scheduled to arrive at Ceres in the spring of 2015, where it will take the closest look ever at its surface.

“We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself,” said Carol Raymond, the deputy principal investigator for Dawn at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “Dawn will map the geology and chemistry of the surface in high-resolution, revealing the processes that drive the outgassing activity.”

For the last century, Ceres was known as the largest asteroid in our solar system. But in 2006, the International Astronomical Union, the governing organization responsible for naming planetary objects, reclassified Ceres as a dwarf planet because of its large size. It is roughly 590 miles (950 kilometers) in diameter. When it first was spotted in 1801, astronomers thought it was a planet orbiting between Mars and Jupiter. Later, other cosmic bodies with similar orbits were found, marking the discovery of our solar system’s main belt of asteroids.

Scientists believe Ceres contains rock in its interior with a thick mantle of ice that, if melted, would amount to more fresh water than is present on all of Earth. The materials making up Ceres likely date from the first few million years of our solar system’s existence and accumulated before the planets formed.

Until now, ice had been theorized to exist on Ceres but had not been detected conclusively. It took Herschel’s far-infrared vision to see, finally, a clear spectral signature of the water vapor. But Herschel did not see water vapor every time it looked. While the telescope spied water vapor four different times, on one occasion there was no signature.

Here is what scientists think is happening: when Ceres swings through the part of its orbit that is closer to the sun, a portion of its icy surface becomes warm enough to cause water vapor to escape in plumes at a rate of about 6 kilograms (13 pounds) per second. When Ceres is in the colder part of its orbit, no water escapes.

The strength of the signal also varied over hours, weeks and months, because of the water vapor plumes rotating in and out of Herschel’s views as the object spun on its axis. This enabled the scientists to localize the source of water to two darker spots on the surface of Ceres, previously seen by NASA’s Hubble Space Telescope and ground-based telescopes. The dark spots might be more likely to outgas because dark material warms faster than light material. When the Dawn spacecraft arrives at Ceres, it will be able to investigate these features.

The results are somewhat unexpected because comets, the icier cousins of asteroids, are known typically to sprout jets and plumes, while objects in the asteroid belt are not.
“The lines are becoming more and more blurred between comets and asteroids,” said Seungwon Lee of JPL, who helped with the water vapor models along with Paul von Allmen, also of JPL. “We knew before about main belt asteroids that show comet-like activity, but this is the first detection of water vapor in an asteroid-like object.”