Herschel Space Telescope Archives

July 1, 2013December 23, 2015 by Nancy Atkinson

Astronomers Capture Images of Herschel Telescope Heading Toward its ‘Graveyard’ Orbit

The dark lines in this image point to the Herschel Space Telescope, which was imaged on June 27, 2013 as it was moving away from its mission orbit around L2 to a heliocentric parking orbit, after the spacecraft was decommissioned. Credit and copyright: Nick Howes and Ernesto Guido, using Faulkes Telescope North in Haleakala, Hawaii.

A pair of astronomers has proved that we haven’t seen the last of the Herschel Space Observatory! On June 17, 2013, engineers for the Herschel space telescope sent final commands to put the decommissioned observatory into its “graveyard” heliocentric parking orbit, after the liquid helium that cooled the observatory’s instruments was depleted. Now, Nick Howes and Ernesto Guido from the Remanzacco Observatory have used the 2 meter Faulkes Telescope North in Hawaii to take a picture of the infrared observatory as it is moving away from its orbit around the L2 LaGrange Point where it spent the entirety of its mission.

Howes told Universe Today that their observations not only improve future chances of it being seen, but also will help astronomers in that the observatory won’t be mistaken for a new asteroid.

“We saw a potential issue here,” Howes said via email, “as the spacecraft would be in a slow tumble, receding from its stable L2 orbit, subjected to solar radiation pressure. And as ESA’s ground stations were no longer communicating with it, so we wanted to basically check the orbits and make sure that for future science, it was not mistakenly detected as an asteroid.”

The Herschel Telescope was imaged by Nick Howes and Ernesto Guido using Faulkes Telescope North in Haleakala, Hawaii, on June 26, 2013.

When Howes and Guido realized that JPL’s Horizons coordinate system — which generates coordinates for objects in space like Herschel — would be suspending coordinates for the observatory from the end of June, they quickly and urgently used the information they had on Herschel’s movements to make their observations.

“The ephemeris from JPL and the Minor Planet Center varied,” Howes said, “and appeared to show quite different long term positions, so we took the initiative to try to help make sure this orbit was better understood. We knew ESA’s scientists had a pretty good handle on the position, but were perplexed by the variance in the coordinates being generated by the two ephemeris systems”

Radiation pressure and a host of other factors would have and will continue to affect the position of the spacecraft, but with it getting fainter by the day, Howes and Guido made the effort by taking two nights of observations to try and find Herschel as it drifted away from L2.

“Imaging a several metre wide spacecraft at over 2.1 million km from Earth in an orbit that was not quite precise, and a tumbling spacecraft is not an easy task, at the faint magnitudes it theoretically could have been at, ” said Guido, who helps manage the Remanzacco Observatory in Italy. “And while we found what we thought could be it on the first night, our calculations would need to be verified by observing it on a second night to validate that it was indeed Herschel.”

The orbit of Herschel during its mission. Credit: ESA.

Howes, who’d written about Herschel when working in science communications for ESA, contacted several of the mission team via emails, who gave valuable advice on the effects of the final orbital burn.

“We effectively had three possible locations to hunt in,” Howes said, “and luckily, as rain at one of our telescope sites stopped our plans for the third run, and nothing showed up in our first coordinates, we managed to get it in the second set of images, exactly where we thought it could be, with the correct data for its motion, position angle and other orbital characteristics. Ernesto worked on the data reduction for these images, and after about 30 minutes of frantic discussion, said ‘I think I’ve found it.’”

The team have filed their data with the Minor Planet Center, and have worked closely with astronomers at Kitt Peak, who also imaged the Observatory, further refining the observing arc, passing their coordinates even on to astronomers in Chile, with significantly larger telescopes to get even more images of it.

The Faulkes Telescope Project is based at the University of South Wales, and the telescopes are operated by the Las Cumbres Observatory Global Telescope Network. The telescopes are also used for educational purposes, and schools using the Faulkes Telescope will be able to follow Herschel as she leaves her orbit to wander around the Sun. It will return to our neck of the Solar System around 2027/2028 (astrometry measured by Howes and Guido is factoring in radiation pressure, so the values are approximate), when it will return at around magnitude 21.7.

“We’ve engaged schools in this project as it’s great for learning astrometry, and photometry as well as a fun thing to do, and they’ve also been making animations from our data.”

Howes and Guido hope that the updated information will help others keep an eye on the telescope in the future. “It’s been an exciting week, and we wanted to say thank you to ESA for building such a magnificent telescope,” Howes said. “We just wanted to give it a good send off!”

June 17, 2013December 23, 2015 by Nancy Atkinson

Final Command Shuts Down Herschel Telescope

Screens in ESOC's Main Control Room on the day the last command was sent to the Herschel Space Telescope, shutting the observatory off. Credit: ESA.

We knew it was coming, but it is still sad to see the end of a mission. Controllers for the Herschel space telescope sent final commands today to put the observatory into a heliocentric parking orbit. Commands were sent at 12:25 GMT on June 17, 2013, marking the official end of operations for Herschel. But expect more news from this spacecraft’s observations, as there is still a treasure trove of data that that will keep astronomers busy for many years to come. Additionally, maneuvers done by the spacecraft allowed engineers to test out control techniques that can’t normally be tested in-flight during a mission.

You can watch a video of Herschel’s final “live” moments below:

Herschel’s science mission had already ended in April when the liquid helium that cooled the observatory’s instruments ran out.

Herschel will now be parked indefinitely in a heliocentric orbit, as a way of “disposing” of the spacecraft. It should be stable for hundreds of years, but perhaps scientists will figure out another use for it in the future. One original idea for disposing of the spacecraft was to have it impact the Moon, a la the LCROSS mission that slammed into the Moon in 2009, and it would kick up volatiles at one of the lunar poles for observation by another spacecraft, such as the Lunar Reconnaissance Orbiter. But that idea has been nixed in favor of the parking orbit.

Some of the maneuvers that were tested before the spacecraft was put into its final orbit were some in-orbit validations and analysis of hardware and software.

ESA's Herschel telescope used liquid helium to keep cool while it observed heat from the early Universe. Credit: ESA — ESA’s Herschel telescope used liquid helium to keep cool while it observed heat from the early Universe. Credit: ESA

“Normally, our top goal is to maximise scientific return, and we never do anything that might interrupt observations or put the satellite at risk,” says Micha Schmidt, Herschel’s Spacecraft Operations Manager at the European Space Operations Center. “But the end of science meant we had a sophisticated spacecraft at our disposal on which we could conduct technical testing and validate techniques, software and the functionality of systems that are going to be reused on future spacecraft. This was a major bonus for us.”

The test requests came from other missions. For example, the ExoMars team requested doing some validations using Herschel’s Visual Monitoring Camera since ExoMars will have a similar camera, and the Euclid spacecraft team asked for some reaction wheel tests.
On May 13-14, engineers commanded Herschel to fire its thrusters for a record 7-hours and 45-minutes. This ensured the satellite was boosted away from its operational orbit around the L2 Sun–Earth Lagrange Point and into a heliocentric orbit, further out and slower than Earth’s orbit. This depleted most of the fuel, and the final thruster command today used up all of the remaining fuel. Today’s final command was the last step in a complex series of flight control activities and thruster maneuvers designed to take Herschel into a safe disposal orbit around the Sun; additionally all its systems were turned off.

“Herschel has not only been an immensely successful scientific mission, it has also served as a valuable flight operations test platform in its final weeks of flight. This will help us increase the robustness and flexibility of future missions operations,” said Paolo Ferri, ESA’s Head of Mission Operations. “Europe really received excellent value from this magnificent satellite.”

Source: ESA

May 7, 2013December 23, 2015 by Elizabeth Howell

Milky Way’s Black Hole Munches On Supercooked Gas

Artist's concept of a supermassive black hole at the center of a galaxy. Credit: NASA/JPL-Caltech

It’s a simple menu, but smoking hot. The black hole at the center of the Milky Way galaxy is sucking in ultra-hot molecular gas, as seen through the eyes of the Herschel space telescope.

“The biggest surprise was quite how hot the molecular gas in the innermost central region of the galaxy gets. At least some of it is around 1000ºC [1832º F], much hotter than typical interstellar clouds, which are usually only a few tens of degrees above the –273ºC [-460ºF] of absolute zero,” stated the European Space Agency.

Herschel, which is out of coolant and winding down its scientific operations, will continue producing results in the next few years as scientists crunch the results. The telescope has found a bunch of basic molecules in the Milky Way that include water vapour and carbon monoxide, and has been engaged in looking to learn more about the gas that surrounds the massive black hole at our galaxy’s center.

In a region called Sagittarius* (Sgr A*), this huge black hole — four million times the mass of the sun — is thankfully a safe distance from Earth. It’s 26,000 light years away from the solar system.

At left, ionized gas in the galaxy as seen in radio wavelengths; at right, the spectrum at the center seen by Herschel. Credit: Radio-wavelength image: National Radio Astronomy Observatory/Very Large Array (courtesy of C. Lang); spectrum: ESA/Herschel/PACS & SPIRE/J.R. Goicoechea et al. (2013).

Trouble is, there’s a heckuva lot of dust blocking our view to the center of the galaxy. Herschel got around that problem by taking pictures in the far-infrared, seeking heat signatures that can bely intense activity in and around the black hole.

“Herschel has resolved the far-infrared emission within just 1 light-year of the black hole, making it possible for the first time at these wavelengths to separate emission due to the central cavity from that of the surrounding dense molecular disc,” stated Javier Goicoechea of the Centro de Astrobiología, Spain, lead author of a paper reporting the results.

The science team supposes that there are strong shocks within the gas (which is magnetized) that help turn up the heat. The shocks could occur when gas clouds butt up against each other, or material shoots out Fast and Furious-style between stars and protostars (young stars.)

“The observations are also consistent with streamers of hot gas speeding towards Sgr A*, falling towards the very center of the galaxy,” stated Goicoechea. “Our galaxy’s black hole may be cooking its dinner right in front of Herschel’s eyes.”

Source: ESA

April 29, 2013December 23, 2015 by Nancy Atkinson

Herschel Space Telescope Closes Its Eyes on the Universe

ESA’s Herschel space observatory set against a background image of the Vela C star-forming region. Copyright ESA/PACS & SPIRE Consortia, T. Hill, F. Motte, Laboratoire AIM Paris-Saclay, CEA/IRFU – CNRS/INSU – Uni. Paris Diderot, HOBYS Key Programme Consortium.

Sadly – though as expected – the most powerful far-infrared orbital telescope put in orbit has ended mission. The Herschel space observatory has now run out of liquid helium coolant, ending more than three years of pioneering observations of the cool Universe.

The spacecraft needs to be at temperatures as low as 0.3 Kelvin, or minus 459 degrees Fahrenheit to make its observations, and mission scientists and engineers knew since Herschel’s launch on May 14, 2009 that the 2,300 liters of liquid helium would slowly evaporate away.

The Herschel team sent out a notice that the helium was finally exhausted today, noted at the beginning of the spacecraft’s daily communication session with its ground station in Western Australia. The data showed a clear rise in temperatures measured in all of Herschel’s instruments.

“Herschel has exceeded all expectations, providing us with an incredible treasure trove of data that that will keep astronomers busy for many years to come,” said Alvaro Giménez Cañete, ESA’s Director of Science and Robotic Exploration.

The Herschel telescope will be parked indefinitely in a heliocentric orbit, as a way of “disposing” of the spacecraft. It should be stable for 100s of years, but perhaps scientists will figure out another use for it in the future. One original idea for disposing of the spacecraft was to have it impact the Moon, a la the LCROSS mission that slammed into the Moon in 2009, and it would kick up volatiles at one of the lunar poles for observation by another spacecraft, such as the Lunar Reconnaissance Orbiter. But that idea has been nixed in favor of parking Herschel in a heliocentric orbit.

What has Herschel done in its three years of observations? It has made over 35,000 scientific observations, amassing more than 25,000 hours’ worth of science data from about 600 different observing programs. A further 2,000 hours of calibration observations also contribute to the rich dataset, which is based at ESA’s European Space Astronomy Centre, near Madrid in Spain.

But there will be more news the future from Herschel’s observations, as scientists comb through the data. The Herschel team said today that the telescope’s data is expected to provide even more discoveries than have been made during the lifetime of the Herschel mission.

“Herschel’s ground-breaking scientific haul is in no little part down to the excellent work done by European industry, institutions and academia in developing, building and operating the observatory and its instruments,” saids Thomas Passvogel, ESA’s Herschel Program Manager.

“Herschel has offered us a new view of the hitherto hidden Universe, pointing us to a previously unseen process of star birth and galaxy formation, and allowing us to trace water through the Universe from molecular clouds to newborn stars and their planet-forming discs and belts of comets,” said Göran Pilbratt, ESA’s Herschel Project Scientist.

Source: ESA

April 23, 2013April 26, 2016 by Elizabeth Howell

Historic Comet Smashup Brought Water to Jupiter’s Stratosphere

Shoemaker-Levy 9 impact site G. The comet collided with Jupiter in 1994. Credit: R. Evans, J. Trauger, H. Hammel and the HST Comet Science Team

A large comet that peppered Jupiter two decades ago brought water into the giant planet’s atmosphere, according to new research from the Herschel space observatory.

Shoemaker-Levy 9 astounded astronomers worldwide when its 21 fragments hit Jupiter in June 1994. The event was predicted and observatories were trained on Jupiter as the impact occurred. The dark splotches the comet left behind were even visible in small telescopes. But apparently, those weren’t the only effects of the collision.

Herschel’s infrared camera revealed there is two to three times more water in the southern hemisphere of the planet, where the comet slammed into the atmosphere, than in the northern hemisphere. Further, the water is concentrated in high altitudes, around the various sites where Shoemaker-Levy 9 left its mark.

It is possible, researchers acknowledged, that water could have come from interplanetary dust striking Jupiter, almost like a “steady rain.” If this were the case, however, scientists expect the water would be evenly distributed and also would have filtered to lower altitudes. Jupiter’s icy moons were also in the wrong locations, researchers said, to have sent water towards the massive planet.

Internal water rising up was ruled out because it cannot penetrate the “cold trap” between Jupiter’s stratosphere and cloud deck, the researchers added.

“According to our models, as much as 95 percent of the water in the stratosphere is due to the comet impact,” said Thibault Cavalié of the Astrophysical Laboratory of Bordeaux, in France, who led the research.

Eight impact sites from Comet Shoemaker-Levy 9 are visible in this 1994 image. Credit: Hubble Space Telescope

While researchers have suspected for years that Jupiter’s water came from the comet — ESA’s Infrared Space Observatory saw the water there years ago — these new observations provide more direct evidence of Shoemaker-Levy 9’s effect. The results were published in Astronomy and Astrophysics.

Herschel’s find provides more fodder for two missions that are scheduled for Jupiter observations in the coming few years. The first goal for NASA’s Juno spacecraft, which is en route and will arrive in 2016, is to figure out how much water is in Jupiter’s atmosphere.

Additionally, ESA’s Jupiter Icy moons Explorer (JUICE) mission is expected to launch in 2022. “It will map the distribution of Jupiter’s atmospheric ingredients in even greater detail,” ESA stated.

While ESA did not link the finding to how water came to be on Earth, some researchers believe that it was comets that delivered the liquid on to our planet early in Earth’s history. Others, however, say that it was outgassing from volcanic rocks that added water to the surface.

Conventional theory dictates ice was in our solar system from when it was formed, and today we know that many planets have water in some form. Last year, for example, water ice and organics were spotted at Mercury’s north pole.

Mars appeared to be full of water in the ancient past, as evidenced by a huge, underground trench recently discovered by scientists. There is frozen water at the Martian poles, and both the Curiosity and Spirit/Opportunity rover missions have found evidence of flowing water on the surface in the past.

The outer solar system also has its share of water, including in all four giant planets (Jupiter, Saturn, Uranus and Neptune) and (in ice form) on various moons. Even some exoplanets have water vapor in their atmospheres.

“All four giant planets in the outer solar system have water in their atmospheres, but there may be four different scenarios for how they got it,” added Cavalié. “For Jupiter, it is clear that Shoemaker-Levy 9 is by far the dominant source, even if other external sources may contribute also.”

Source: European Space Agency

December 4, 2012December 23, 2015 by Jason Major

The Brightest Galaxies in the Universe Were Invisible… Until Now

Hubble images of six of the starburst galaxies first found by ESA’s Herschel Space Observatory (Keck data shown below each in blue)

Many of the brightest, most actively star-forming galaxies in the Universe were actually undetectable by Earth-based observatories, hidden from view by thick clouds of opaque dust and gas. Thanks to ESA’s Herschel space observatory, which views the Universe in infrared, an enormous amount of these “starburst” galaxies have recently been uncovered, allowing astronomers to measure their distances with the twin telescopes of Hawaii’s W.M. Keck Observatory. What they found is quite surprising: at least 767 previously unknown galaxies, many of them generating new stars at incredible rates.

Although nearly invisible at optical wavelengths these newly-found galaxies shine brightly in far-infrared, making them visible to Herschel, which can peer through even the densest dust clouds. Once astronomers knew where the galaxies are located, they were able to target them with Hubble and, most importantly, the two 10-meter Keck telescopes — the two largest optical telescopes in the world.

By gathering literally hundreds of hours of spectral data on the galaxies with the Keck telescopes, estimates of their distances could be determined as well as their temperatures and how often new stars are born within them.

“While some of the galaxies are nearby, most are very distant; we even found galaxies that are so far that their light has taken 12 billion years to travel here, so we are seeing them when the Universe was only a ninth of its current age,” said Dr. Caitlin Casey, Hubble fellow at the UH Manoa Institute for Astronomy and lead scientist on the survey. “Now that we have a pretty good idea of how important this type of galaxy is in forming huge numbers of stars in the Universe, the next step is to figure out why and how they formed.”

A representation of the distribution of nearly 300 starbursts in one 1.4 x 1.4 degree field of view.

The galaxies, many of them observed as they were during the early stages of their formation, are producing new stars at a rate of 100 to 500 a year — with a mass equivalent of several thousand Suns — hence the moniker “starburst” galaxy. By comparison the Milky Way galaxy only births one or two Sun-mass stars per year.

The reason behind this explosion of star formation in these galaxies is unknown, but it’s thought that collisions between young galaxies may be the cause.

Another possibility is that galaxies had much more gas and dust during the early Universe, allowing for much higher star formation rates than what’s seen today.

“It’s a hotly debated topic that requires details on the shape and rotation of the galaxies before it can be resolved,” said Dr. Casey.

Still, the discovery of these “hidden” galaxies is a major step forward in understanding the evolution of star formation in the Universe.

“Our study confirms the importance of starburst galaxies in the cosmic history of star formation. Models that try to reproduce the formation and evolution of galaxies will have to take these results into account.”

– Dr. Caitlin Casey, Hubble fellow at the UH Manoa Institute for Astronomy

“For the first time, we have been able to measure distances, star formation rates, and temperatures for a brand new set of 767 previously unidentified galaxies,” said Dr. Scott Chapman, a co-author on the studies. “The previous similar survey of distant infrared starbursts only covered 73 galaxies. This is a huge improvement.”

The papers detailing the results were published today online in the Astrophysical Journal.

Sources: W.M. Keck Observatory article and ESA’s news release.

Image credits: ESA–C. Carreau/C. Casey (University of Hawai’i); COSMOS field: ESA/Herschel/SPIRE/HerMES Key Programme; Hubble images: NASA, ESA. Inset image courtesy W. M. Keck Observatory.

November 25, 2012December 23, 2015 by Jason Major

Orion Revisited: Astronomers Find New Star Cluster in Front of the Orion Nebula

The well-known star-forming region of the Orion Nebula. Credit: Canada-France-Hawaii Telescope / Coelum (J.-C. Cuillandre & G. Anselmi)

Precise distances are difficult to gauge in space, especially within the relatively local regions of the Galaxy. Stars which appear close together in the night sky may actually be separated by many hundreds or thousands of light-years, and since there’s only a limited amount of space here on Earth with which to determine distances using parallax, astronomers have to come up with other ways to figure out how far objects are, and what exactly is in front of or “behind” what.

Recently, astronomers using the 340-megapixel MegaCam on the Canada-France-Hawaii Telescope (CFHT) observed the star-forming region of the famous Orion nebula — located only about 1,500 light-years away — and determined that two massive groupings of the nebula’s stars are actually located in front of the cluster as completely separate structures… a finding that may ultimately force astronomers to rethink how the many benchmark stars located there had formed.

Although the Orion nebula is easily visible with the naked eye (as the hazy center “star” in Orion’s three-star sword, hanging perpendicular below his belt) its true nebulous nature wasn’t identified until 1610. As a vast and active star-forming region of bright dust and gas located a mere 1,500 light-years distant, the various stars within the Orion Nebula Cluster (ONC) has given astronomers invaluable benchmarks for research on many aspects of star formation.

Now, CFHT observations of the Orion nebula conducted by Dr. Hervé Bouy of the European Space Astronomy Centre (ESAC) and Centre for Astrobiology (CSIC) and Dr. João Alves of the Institut für Astronomie (University of Vienna) have shown that a massive cluster of stars known as NGC 1980 is actually in front of the nebula, and is an older group of approximately 2,000 stars that is separate from the stars found within the ONC… as well as more massive than once thought.

“It is hard to see how these new observations fit into any existing theoretical model of cluster formation, and that is exciting because it suggests we might be missing something fundamental.”

– Dr. João Alves, Institut für Astronomie, University of Vienna

In addition their observations with CFHT — which were combined with previous observations with ESA’s Herschel and XMM-Newton and NASA’s Spitzer and WISE — have led to the discovery of another smaller cluster, L1641W.

According to the team’s paper, “We find that there is a rich stellar population in front of the Orion A cloud, from B-stars to M-stars, with a distinct 1) spatial distribution; 2) luminosity function; and 3) velocity dispersion from the reddened population inside the Orion A cloud. The spatial distribution of this population peaks strongly around NGC 1980 (iota Ori) and is, in all likelihood, the extended stellar content of this poorly studied cluster.”

The findings show that what has been known as Orion Nebula Cluster is actually a combination of older and newer groups of stars, possibly calling for a “revision of most of the observables in the benchmark ONC region (e.g., ages, age spread, cluster size, mass function, disk frequency, etc.)”

“We must untangle these two mixed populations, star by star, if we are to understand the region, and star formation in clusters, and even the early stages of planet formation,” according to co-author Dr. Hervé Bouy.

The team’s article “Orion Revisited” was published in the November 2012 Astronomy & Astrophysics journal. Read the CFHT press release here.

The Canada-France-Hawaii Telescope’s Mauna Kea summit dome in September 2009. Credit: CFHT/Jean-Charles Cuillandre

Inset image: Orion nebula seen in optical – where the molecular cloud is invisible – and infrared, which shows the cloud. Any star detected in the optical in the line of sight over the region highlighted in the right panel must therefore be located in the foreground of the molecular cloud. Credit: J. Alves & H. Bouy.

May 10, 2012December 23, 2015 by Nancy Atkinson

Herschel Telescope Peers into the Glow of Cygnus X

This new view of the Cygnus-X star-formation region by Herschel highlights chaotic networks of dust and gas that point to sites of massive star formation. Credits: ESA/PACS/SPIRE/Martin Hennemann & Frédérique Motte, Laboratoire AIM Paris-Saclay, CEA/Irfu – CNRS/INSU – Univ. Paris Diderot, France.

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In infrared, Cygnus-X is a glowing star nursery, and the Herschel space observatory has captured this beautiful new view showing an extremely active region of big-baby stars. It is located about 4,500 light-years from Earth in the constellation of Cygnus, the Swan. The image highlights the unique capabilities of Herschel to probe the birth of large stars and their influence on the surrounding interstellar material.

The bright white areas are where large stars have recently formed out of turbulent clouds, especially evident in the chaotic network of filaments seen in the right-hand portion of the image. The dense knots of gas and dust collapse to form new stars; the bubble-like structures are carved by the enormous radiation emitted by these stars.

In the center of the image, fierce radiation and powerful stellar winds from stars undetected at Herschel’s wavelengths have partly cleared and heated interstellar material, which then glows blue. The threads of compact red objects scattered throughout the image shows where future generations of stars will be born.

See larger versions of this image at ESA’s website.

April 11, 2012December 23, 2015 by Nancy Atkinson

Frantic Comet Massacre Taking Place at Fomalhaut

Herschel's far-infrared observations of Fomalhaut and its disk. Credit: ESA

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There may be some frantic activity going on in the narrow, dusty disk surrounding a nearby star named Fomalhaut. Scientists have been trying to understand the makeup of the disk, and new observations by the Herschel Space Observatory reveals the disk may come from cometary collisions. But in order to create the amount of dust and debris seen around Fomalhaut, there would have to be collisions destroying thousands of icy comets every day.

“I was really surprised,” said Bram Acke, who led a team on the Herschel observations. “To me this was an extremely large number.”

Fomalhaut is a young star, just a few hundred million years old, about 25.1 light years away and twice as massive as the Sun. It is the brightest star in the constellation Piscis Austrinus and one of the brightest stars in our sky, visible in the southern sky in the northern hemisphere in fall and early winter evenings.

Fomalhaut’s toroidal dust belt was discovered in the 1980s by the IRAS satellite. It’s been viewed several times by the Hubble Space Telescope, but Herschel’s new images of the belt show it in much more detail at far-infrared wavelengths than ever before.

The narrow and asymmetrical properties of the disk are thought to be due to the gravity of a possible planet in orbit around the star, but the existence of the planet is still under study.

Hubbles view of the exoplanet Fomalhaut b (NASA/HST) — Hubble's view showing a possible exoplanet Fomalhaut b (NASA/HST)

Acke, from the University of Leuven in Belgium, and his team colleagues analyzed the Herschel observations and found the dust temperatures in the belt to be between –230 and –170 degrees C, and because Fomalhaut is slightly off-center and closer to the southern side of the belt, the southern side is warmer and brighter than the northern side.

Those observations collected starlight scattering off the grains in the belt and showed it to be very faint at Hubble’s visible wavelengths, suggesting that the dust particles are relatively large. But that appears to be incompatible with the temperature of the belt as measured by Herschel in the far-infrared.

While observations with Hubble suggested the grains in the dust disk would be relatively large, the Herschel data show that the dust in the belt has the thermal properties of small solid particles, with sizes of only a few millionths of a meter across. HST observations suggested solid grains more than ten times larger.

To resolve the paradox, Acke and colleagues suggest that the dust grains must be large fluffy aggregates, similar to dust particles released from comets in our own Solar System. These would have both the correct thermal and scattering properties.

However, this leads to another problem.

The bright starlight from Fomalhaut should blow small dust particles out of the belt very rapidly, yet such grains appear to remain abundant there.

So, the only way to explain the contradiction is to resupply the belt through continuous collisions between larger objects in orbit around Fomalhaut, creating new dust.

This isn’t the first time that evidence of cometary collisions have been seen around another star. Last year, astronomers using the Spitzer Space Telescope detected activity resembling a ‘heavy bombardment’ type of event where icy bodies from the outer solar system are possibly pummeling rocky worlds closer to the star.

At Fomalhaut, however, to sustain the belt, the rate of collisions must be remarkable: each day, the equivalent of either two 10 km-sized comets or 2,000 1 km-sized comets must be completely crushed into small, fluffy dust particles.

In order to keep the collision rate so high, scientists say there must be between 260 billion and 83 trillion comets in the belt, depending on their size. This is not unfathomable, the team says, as our own Solar System has a similar number of comets in its Oort Cloud, which formed from objects scattered from a disc surrounding the Sun when it was as young as Fomalhaut.

“These beautiful Herschel images have provided the crucial information needed to model the nature of the dust belt around Fomalhaut,” said Göran Pilbratt, ESA Herschel Project Scientist.

Source: ESA

April 4, 2012December 23, 2015 by Nancy Atkinson

New Image Shows Beautiful Violence in Centaurus A

Centaurus A in Far-infrared and X-rays. Credit: Far-infrared: ESA/Herschel/PACS/SPIRE/C.D. Wilson, MacMaster University, Canada; X-ray: ESA/XMM-Newton/EPIC

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The mysterious galaxy Centaurus A is a great place to study the extreme processes that occur near super-massive black holes, scientists say, and this beautiful new image from the combined forces of the Herschel Space Observatory and the XMM-Newton x-ray satellite reveals energetic processes going on deep in the galaxy’s core. This beautiful image tells a tale of past violence that occurred here.

The twisted disc of dust near the galaxy’s heart shows strong evidence that Centaurus A underwent a cosmic collision with another galaxy in the distant past. The colliding galaxy was ripped apart to form the warped disc, and the formation of young stars heats the dust to cause the infrared glow.

This multi-wavelength view of Centaurus A shows two massive jets of material streaming from a immense black hole in the center. When observed by radio telescopes, the jets stretch for up to a million light years, though the Herschel and XMM-Newton results focus on the inner regions.

At a distance of around 12 million light years from Earth, Centaurus A is the closest large elliptical galaxy to our own Milky Way.

“Centaurus A is the closest example of a galaxy to us with massive jets from its central black hole,” said Christine Wilson of McMaster University, Canada, who is leading the study of Centaurus A with Herschel. “Observations with Herschel, XMM-Newton and telescopes at many other wavelengths allow us to study their effects on the galaxy and its surroundings.”

Find more information on this image at ESA’s website.