Saturday, September 30, 2017

Stars and spirals

NGC 1964 (BD-22 1147)
Credit:  ESO/Jean-Christophe Lambry


This spectacular spiral galaxy, known as NGC 1964, resides approximately 70 million light-years away in the constellation of Lepus (The Hare). NGC 1964 has a bright and dense core. This core sits within a mottled oval disc, which is itself encircled by distinct spiral arms speckled with bright starry regions. The brilliant centre of the galaxy caught the eye of the astronomer William Herschel on the night of 20 November 1784, leading to the galaxy’s discovery and subsequent documentation in the New General Catalogue

In addition to containing stars, NGC 1964 lives in a star-sprinkled section of the sky. In this view from the Wide Field Imager (WFI) — an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory, Chile — the star HD 36785 can be seen to the galaxy’s immediate right. Above it reside two other prominent stars named HD 36784 and TYC 5928-368-1 — and the large bright star below NGC 1964 is known as BD-22 1147. 

This view of NGC 1964 also contains an array of galaxies, visible in the background. The WFI is able to observe the light from these distant galaxies, and those up to 40 million times fainter than the human eye can see.



Friday, September 29, 2017

Mapping the nearby Universe

Credit: ESA/Hubble & NASA


The distances to objects in the Universe can differ enormously. The nearest star to us — Proxima Centauri — lies some 4.2 light-years from us, while some incredibly distant galaxies are so far away — 13 billion light-years or more — that they are only visible to us as a result of cosmic tricks of magnification

The subject of this image, a galaxy called ESO 376-16, sits nearly 23 million light-years from Earth — not that great a distance on a cosmic scale. However, given the galaxy’s relative proximity to us, we know surprisingly little about it. Astronomers are still debating about many of the properties of ESO 376-16, including its morphology. Galaxies are divided into types based on their visual appearance and characteristics; spiral galaxies, like the Milky Way, are flattened discs with curved arms sweeping out from a central nucleus, while irregular galaxies lack a distinct structure and look far more chaotic. On the basis of its rather ill-defined morphology, ESO 376-16 is thought to be either a late-type spiral or a dwarf irregular galaxy

Despite its mystique, observations of ESO 376-16 have been useful in several studies, including one made with the NASA/ESA Hubble Space Telescope that aimed to create a 3D map of galaxies lying in the vicinity of Earth. Researchers used Hubble to gauge the distance to galaxies including ESO 376-16 by measuring the luminosities of especially bright red-giant-branch stars sitting within the galaxies. They then used their data to generate and calibrate 3D maps of the distribution of galaxies throughout the nearby cosmos.



Thursday, September 28, 2017

Bursting with Starbirth

Result of a galactic crash 
Credit: ESA/Hubble & NASA
Acknowledgements: D. Calzetti (UMass) and the LEGUS Team, J. Maund (University of Sheffield), and R. Chandar (University of Toledo)



Videos
 
Pan across NGC 4490
Pan across NGC 4490



This image, taken with the NASA/ESA Hubble Space Telescope, shows the galaxy NGC 4490. The scattered and warped appearance of the galaxy are the result of a past cosmic collision with another galaxy, NGC 4485 (not visible in this image).

The extreme tidal forces of the interaction between the two galaxies have carved out the shapes and properties of NGC 4490. Once a barred spiral galaxy, the outlying regions of NGC 4490 have been stretched out, resulting in its nickname of the Cocoon Galaxy.



The Strange Structures of the Saturn Nebula

 
MUSE image of the Saturn Nebula

Three-dimensional MUSE view of the Saturn Nebula 

Annotated image showing features in the Saturn Nebula

The Saturn Nebula in the constellation of Aquarius

The sky around the Saturn Nebula



Videos

ESOcast 129 Light: The Strange Structures of the Saturn Nebula (4K UHD)
ESOcast 129 Light: The Strange Structures of the Saturn Nebula (4K UHD)

Looking at the Saturn Nebula in 3D

Zooming in on the Saturn Nebula



The spectacular planetary nebula NGC 7009, or the Saturn Nebula, emerges from the darkness like a series of oddly-shaped bubbles, lit up in glorious pinks and blues. This colourful image was captured by the powerful MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the dust inside a planetary nebula for the first time. The map — which reveals a wealth of intricate structures in the dust, including shells, a halo and a curious wave-like feature — will help astronomers understand how planetary nebulae develop their strange shapes and symmetries.

The Saturn Nebula is located approximately 5000 light years away in the constellation of Aquarius (The Water Bearer). Its name derives from its odd shape, which resembles everyone’s favourite ringed planet seen edge-on.

But in fact, planetary nebulae have nothing to do with planets. The Saturn Nebula was originally a low-mass star, which expanded into a red giant at the end of its life and began to shed its outer layers. This material was blown out by strong stellar winds and energised by ultraviolet radiation from the hot stellar core left behind, creating a circumstellar nebula of dust and brightly-coloured hot gas. At the heart of the Saturn Nebula lies the doomed star, visible in this image, which is in the process of becoming a white dwarf [1].

In order to better understand how planetary nebulae are moulded into such odd shapes, an international team of astronomers led by Jeremy Walsh from ESO used the Multi Unit Spectroscopic Explorer (MUSE) to peer inside the dusty veils of the Saturn Nebula. MUSE is an instrument installed on one of the four Unit Telescopes of the Very Large Telescope at ESO’s Paranal Observatory in Chile. It is so powerful because it doesn’t just create an image, but also gathers information about the spectrum — or range of colours — of the light from the object at each point in the image.

The team used MUSE to produce the first detailed optical maps of the gas and dust distributed throughout a planetary nebula [2]. The resulting image of the Saturn Nebula reveals many intricate structures, including an elliptical inner shell, an outer shell, and a halo. It also shows two previously imaged streams extending from either end of the nebula’s long axis, ending in bright ansae (Latin for “handles”).

Intriguingly, the team also found a wave-like feature in the dust, which is not yet fully understood. Dust is distributed throughout the nebula, but there is a significant drop in the amount of dust at the rim of the inner shell, where it seems that it is being destroyed. There are several potential mechanisms for this destruction. The inner shell is essentially an expanding shock wave, so it may be smashing into the dust grains and obliterating them, or producing an extra heating effect that evaporates the dust.

Mapping the gas and dust structures within planetary nebulae will aid in understanding their role in the lives and deaths of low mass stars, and it will also help astronomers understand how planetary nebulae acquire their strange and complex shapes.

But MUSE’s capabilities extend far beyond planetary nebulae. This sensitive instrument can also study the formation of stars and galaxies in the early Universe, as well as map the dark matter distribution in galaxy clusters in the nearby Universe. MUSE has also created the first 3D map of the Pillars of Creation in the Eagle Nebula (eso1518) and imaged a spectacular cosmic crash in a nearby galaxy (eso1437).



Notes

[1] Planetary nebulae are generally short-lived; the Saturn Nebula will last only a few tens of  thousands of years before expanding and cooling to such an extent that it becomes invisible to us. The central star will then fade as it becomes a hot white dwarf.

[2] The NASA/ESA Hubble Space Telescope has previously provided a spectacular image of the Saturn Nebula — but, unlike MUSE, it cannot reveal the spectrum at each point over the whole nebula.



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. 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”.



Links



Contacts

Jeremy Walsh
ESO
Garching bei München, Germany
Email: jwalsh@eso.org

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org


Source: ESO/News

Wednesday, September 27, 2017

The Fastest-Spinning Known Millisecond Pulsar in the Galactic Field

Timing residuals as a function of time and orbital phase are shown in panels (a) and (b) respectively. Folded pulse profiles of PSR J0952-0607 are shown as a function of orbital phase for the orbital phases covered by our observations (panel (c)). Eclipses of the radio signal in black widow systems occur around orbital phase φ=0.25 but are not obvious in PSR J0952-0607. Sloan r´-band light curve of the binary companion of PSR J0952-0607 (panel (d)). The Icarus model fit to the light curve is shown with the solid line. Large format: PNG.


Using observations across the entire electro-magnetic spectrum, astronomers have discovered a radio pulsar spinning 707 times every second, making it the fastest known spinning pulsar in the Galactic field and the second fastest known overall. 

The pulsar emits pulsed electromagnetic radiation at very low radio frequencies and very high gamma-rays, while the low-mass binary companion, heated by the energetic radiation from the pulsar, is detected at optical wavelengths. The discovery of this system at very low radio frequencies suggests there may be an as yet unseen population of fast spinning radio pulsars.

The pulsar, PSR J0952-0607, was discovered with LOFAR, the Low-Frequency Array, a radio telescope consisting of a dense core of antenna stations in the Netherlands, and international stations in Germany, France, Sweden, the United Kingdom, Sweden, Poland and Ireland. Operating at very low radio frequencies of 110 to 150 MHz, the LOFAR telescope targeted unassociated high-energy gamma-ray sources discovered with the space-based Fermi gamma-ray telescope, searching for pulsed radio emission of radio and gamma-ray bright millisecond pulsars.

Radio observations revealed that PSR J0952-0607 is part of a binary system, where the pulsar orbits a very low mass (2% the mass of the Sun) binary companion every 6.42 hours. In these so-called 'black widow' systems, referencing the spider which consumes its mate, the proximity of the companion to the pulsar meant the hemisphere facing the pulsar is heated by the energetic pulsar emission, leading to the evaporation of matter from the companion. This heating leads to large variations in brightness of the companion over the course of an orbit.

"Optical observations with the Isaac Newton Telescope were crucial in accurately pinpointing the location of the pulsar, since both LOFAR and Fermi only provide localizations of a few arcminute accuracy.", says Cees Bassa, lead author of the paper presenting the discovery of PSR J0952-0607. Due to the large variation in optical brightness, modulated at the orbital period of the binary, Bassa was able to quickly identify the companion to PSR J0952-0607 in the time series photometry, obtained with the Isaac Newton Telescope last January in service mode.

The subarcsecond optical localization of the counterpart allowed the astronomers to constrain the spindown rate of the millisecond pulsar, which shows that it has a low magnetic field. Furthermore, modelling the optical light curve reveals that the companion does not fill its Roche lobe. The absence of occasional eclipses of the radio emission is consistent with this, but is contrary to what's found in the majority of black widow systems.

The fast spin period of PSR J0952-0607 makes it a prime candidate for further optical studies, as further modelling of the light curve in multiple filters, combined with optical spectroscopy, may allow for the mass of the pulsar to be determined. Knowledge of the mass of such a rapidly spinning pulsar may provide constraints on the composition of pulsars.



More Information

C. G. Bassa, Z. Pleunis, J. W. T. Hessels, E. C. Ferrara, R. P. Breton, N. V. Gusinskaia, V. I. Kondratiev, S. Sanidas, L. Nieder, C. J. Clark, T. Li, A. S. van Amesfoort, T. H. Burnett, F. Camilo, P. F. Michelson, S. M. Ransom, P. S. Ray, and K. Wood, 2017, "LOFAR Discovery of the Fastest-spinning Millisecond Pulsar in the Galactic Field", ApJL, 846, 20 [ ADS ].

"LOFAR Radio Telescope Discovers Record-Breaking Pulsar", ASTRON press release, 5th September 2017.



Tuesday, September 26, 2017

Mystery solved: rare cosmic high energie particles come from outside our galaxy

Mystery solved: rare cosmic high energie particles come from outside our galaxy


The Pierre Auger Collaboration, in which ASTRON is a partner, reports observational evidence demonstrating that cosmic rays with energies a million times greater than that of the protons accelerated in the Large Hadron Collider come from much further away than from our own Galaxy. These findings

Ever since the existence of cosmic rays with individual energies of several Joules was established in the 1960s, speculation has raged as to whether such particles are created there or in distant extragalactic objects. The 50 year-old mystery has been solved using cosmic particles of mean energy of 2 Joules recorded with the largest cosmic-ray observatory ever built, the Pierre Auger Observatory in Argentina. It is found that at these energies the rate of arrival of cosmic rays is ~6% greater from one side of the sky than from the opposite direction, with the excess lying 120˚ away from the Galactic centre.

In the view of Professor Karl-Heinz Kampert (University of Wuppertal), spokesperson for the Auger Collaboration, which involves over 400 scientists from 18 countries, "We are now considerably closer to solving the mystery of where and how these extraordinary particles are created, a question of great interest to astrophysicists. Our observation provides compelling evidence that the sites of acceleration are outside the Milky Way”. Professor Alan Watson (University of Leeds), emeritus spokesperson, considers this result to be “one of the most exciting that we have obtained and one which solves a problem targeted when the Observatory was conceived by Jim Cronin and myself over 25 years ago”.

Rare particles, gigantic detector

Cosmic rays are the nuclei of elements from hydrogen (the proton) to iron. Above 2 Joules the rate of their arrival at the top of the atmosphere is only about 1 per sq km per year, equivalent to one hitting the area of a football pitch about once per century. Such rare particles are detectable because they create showers of electrons, photons and muons through successive interactions with the nuclei in the atmosphere. These showers spread out, sweeping through the atmosphere at the speed of light in a disc-like structure, similar to a dinner-plate, several kilometres in diameter. They contain over ten billion particles and, at the Auger Observatory, are detected through the Cherenkov light they produce in a few of 1600 detectors, each containing 12 tonnes of water, spread over 3000 km2 of Western Argentina, an area comparable to that of Rhode Island. The times of arrival of the particles at the detectors, measured with GPS receivers, are used to find the arrival directions of events to within ~1˚.

An extragalactic origin

By studying the distribution of the arrival directions of more than 30000 cosmic particles the Auger Collaboration has discovered an anisotropy, significant at 5.2 standard deviations (a chance of about two in ten million), in a direction where the distribution of galaxies is relatively high. Although this discovery clearly indicates an extragalactic origin for the particles, the actual sources have yet to be pinned down. The direction of the excess points to a broad area of sky rather than to specific sources as even particles as energetic as these are deflected by a few 10s of degrees in the magnetic field of our Galaxy. The direction, however, cannot be associated with putative sources in the plane or centre of our Galaxy for any realistic configuration of the Galactic magnetic field.

Cosmic rays of even higher energy than the bulk of those used in this study exist, some even with the kinetic energy of well-struck tennis ball. As the deflections of such particles are expected to be smaller, the arrival directions should point closer to their birthplaces. These cosmic rays are even rarer and further studies are underway using them to try to pin down which extragalactic objects are the sources. Knowledge of the nature of the particles will aid this identification and work on this problem is targeted in the upgrade of the Auger Observatory to be completed in 2018. Source: Radboud University




Monday, September 25, 2017

Fast Radio Bursts May Be Firing Off Every Second


For the first time, two astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) have estimated how many FRBs should occur over the entire observable universe. Their work indicates that at least one FRB is going off somewhere every second.

"If we are right about such a high rate of FRBs happening at any given time, you can imagine the sky is filled with flashes like paparazzi taking photos of a celebrity," said Anastasia Fialkov of the CfA, who led the study. "Instead of the light we can see with our eyes, these flashes come in radio waves."
To make their estimate, Fialkov and co-author Avi Loeb assumed that FRB 121102, a fast radio burst located in a galaxy about 3 billion light years away, is representative of all FRBs. Because this FRB has produced repeated bursts since its discovery in 2002, astronomers have been able to study it in much more detail than other FRBs. Using that information, they projected how many FRBs would exist across the entire sky.

"In the time it takes you to drink a cup of coffee, hundreds of FRBs may have gone off somewhere in the Universe," said Avi Loeb. "If we can study even a fraction of those well enough, we should be able to unravel their origin."

While their exact nature is still unknown, most scientists think FRBs originate in galaxies billions of light years away. One leading idea is that FRBs are the byproducts of young, rapidly spinning neutron stars with extraordinarily strong magnetic fields.

Fialkov and Loeb point out that FRBs can be used to study the structure and evolution of the Universe whether or not their origin is fully understood. A large population of faraway FRBs could act as probes of material across gigantic distances. This intervening material blurs the signal from the cosmic microwave background (CMB), the left over radiation from the Big Bang. A careful study of this intervening material should give an improved understanding of basic cosmic constituents, such as the relative amounts of ordinary matter, dark matter and dark energy, which affect how rapidly the universe is expanding.

FRBs can also be used to trace what broke down the "fog" of hydrogen atoms that pervaded the early universe into free electrons and protons, when temperatures cooled down after the Big Bang. It is generally thought that ultraviolet (UV) light from the first stars traveled outwards to ionize the hydrogen gas, clearing the fog and allowing this UV light to escape. Studying very distant FRBs will allow scientists to study where, when and how this process of "reionization" occurred.

"FRBs are like incredibly powerful flashlights that we think can penetrate thise fog and be seen over vast distances," said Fialkov. "This could allow us to study the 'dawn' of the universe in a new way."
The authors also examined how successful new radio telescopes – both those already in operation and those planned for the future – may be at discovering large numbers of FRBs. For example, the Square Kilometer Array (SKA) currently being developed will be a powerful instrument for detecting FRBs. The new study suggests that over the whole sky the SKA may be able to detect more than one FRB per minute that originates from the time when reionization occurred.

The Canadian Hydrogen Intensity Mapping Experiment (CHIME), that recently began operating, will also be a powerful machine for detecting FRBs, although its ability to detect the bursts will depend on their spectrum, i.e. how the intensity of the radio waves depends on wavelength. If the spectrum of FRB 121102 is typical then CHIME may struggle to detect FRBs. However, for different types of spectra CHIME will succeed.

The paper by Fialkov and Loeb describing these results was published in the September 10, 2017 issue of The Astrophysical Journal Letters, and is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

Megan Watzke
Harvard-Smithsonian Center for Astrophysics
+1 617-496-7998

mwatzke@cfa.harvard.edu

Peter Edmonds
Harvard-Smithsonian Center for Astrophysics
+1 617-571-7279

pedmonds@cfa.harvard.edu



Sunday, September 24, 2017

Hubble Captures Stars Going Out in Style

He 2-47, NGC 5315,  IC 4593 and NGC 5307
Credits: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)


The colorful, intricate shapes in these NASA Hubble Space Telescope images reveal how the glowing gas ejected by dying Sun-like stars evolves dramatically over time.

These gaseous clouds, called planetary nebulae, are created when stars in the last stages of life cast off their outer layers of material into space. Ultraviolet light from the remnant star makes the material glow. Planetary nebulae last for only 10,000 years, a fleeting episode in the 10-billion-year lifespan of Sun-like stars.

The name planetary nebula has nothing to do with planets. They got their name because their round shapes resembled planets when seen through the small telescopes of the eighteenth century.

The Hubble images show the evolution of planetary nebulae, revealing how they expand in size and change temperature over time. A young planetary nebula, such as He 2-47, at top, left, for example, is small and is dominated by relatively cool, glowing nitrogen gas. In the Hubble images, the red, green, and blue colors represent light emitted by nitrogen, hydrogen, and oxygen, respectively.

Over thousands of years, the clouds of gas expand away and the nebulae become larger. Energetic ultraviolet light from the star penetrates more deeply into the gas, causing the hydrogen and oxygen to glow more prominently, as seen near the center of NGC 5315. In the older nebulae, such as IC 4593, at bottom, left, and NGC 5307, at bottom, right, hydrogen and oxygen appear more extended in these regions, and red knots of nitrogen are still visible.

These four nebulae all lie in our Milky Way Galaxy. Their distances from Earth are all roughly the same, about 7,000 light-years. The snapshots were taken with Hubble's Wide Field Planetary Camera 2 in February 2007. Like snowflakes, planetary nebulae show a wide variety of shapes, indicative of the complex processes that occur at the end of stellar life.

He 2-47, at top, left, is dubbed the "starfish" because of its shape. The six lobes of gas and dust, which resemble the legs of a starfish, suggest that He 2-47 puffed off material at least three times in three different directions. Each time, the star fired off a narrow pair of opposite jets of gas. He 2-47 is in the southern constellation Carina.

NGC 5315, the chaotic-looking nebula at top, right, reveals an x-shaped structure. This shape suggests that the star ejected material in two different outbursts in two distinct directions. Each outburst unleashed a pair of diametrically opposed outflows. NGC 5315 lies in the southern constellation Circinus.

IC 4593, at bottom, left, is in the northern constellation Hercules.

NGC 5307, at bottom, right, displays a spiral pattern, which may have been caused by the dying star wobbling as it expelled jets of gas in different directions. NGC 5307 resides in the southern constellation Centaurus.


For more information, contact:

Donna Weaver/Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4493/4514

dweaver@stsci.edu / villard@stsci.edu

Keith Noll
Space Telescope Science Institute, Baltimore, Md.
410-338-1828

noll@stsci.edu


Source: HubbleSite/News

Saturday, September 23, 2017

More than meets the eye

Credit: ESA/Hubble & NASAAcknowledgement: Judy Schmidt


Despite the advances made in past decades, the process of galaxy formation remains an open question in astronomy. Various theories have been suggested, but since galaxies come in all shapes and sizes — including elliptical, spiral, and irregular — no single theory has so far been able to satisfactorily explain the origins of all the galaxies we see throughout the Universe. 

To determine which formation model is correct (if any), astronomers hunt for the telltale signs of various physical processes. One example of this is galactic coronas, which are huge, invisible regions of hot gas that surround a galaxy’s visible bulk, forming a spheroidal shape. They are so hot that they can be detected by their X-ray emission, far beyond  the optical radius of the galaxy. Because they are so wispy, these coronas are extremely difficult to detect. In 2013, astronomers highlighted NGC 6753, imaged here by the NASA/ESA Hubble Space Telescope, as one of only two known spiral galaxies that were both massive enough and close enough to permit detailed observations of their coronas. Of course, NGC 6753 is only close in astronomical terms — the galaxy is nearly 150 million light-years from Earth.

NGC 6753 is a whirl of colour in this image — the bursts of blue throughout the spiral arms are regions filled with young stars glowing brightly in ultraviolet light, while redder areas are filled with older stars emitting in the cooler near-infrared.



Friday, September 22, 2017

Hubble discovers a unique type of object in the Solar System

 PR Image heic1715a
The binary asteroid 288P (artist’s impression)

Image of binary asteroid system 288P

PR Image heic1715c
Asteroid belt



Videos

Fly towards 288P (artist’s impression)
Fly towards 288P (artist’s impression) 

Time-lapse video of 288P
Time-lapse video of 288P



With the help of the NASA/ESA Hubble Space Telescope, a German-led group of astronomers have observed the intriguing characteristics of an unusual type of object in the asteroid belt between Mars and Jupiter: two asteroids orbiting each other and exhibiting comet-like features, including a bright coma and a long tail. This is the first known binary asteroid also classified as a comet. The research is presented in a paper published in the journal Nature this week.

In September 2016, just before the asteroid 288P made its closest approach to the Sun, it was close enough to Earth to allow astronomers a detailed look at it using the NASA/ESA Hubble Space Telescope [1].

The images of 288P, which is located in the asteroid belt between Mars and Jupiter, revealed that it was actually not a single object, but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. That discovery was in itself an important find; because they orbit each other, the masses of the objects in such systems can be measured.

But the observations also revealed ongoing activity in the binary system. “We detected strong indications of the sublimation of water ice due to the increased solar heating — similar to how the tail of a comet is created,” explains Jessica Agarwal (Max Planck Institute for Solar System Research, Germany), the team leader and main author of the research paper. This makes 288P the first known binary asteroid that is also classified as a main-belt comet.

Understanding the origin and evolution of main-belt comets — asteroids orbiting between Mars and Jupiter that show comet-like activity — is a crucial element in our understanding of the formation and evolution of the whole Solar System. Among the questions main-belt comets can help to answer is how water came to Earth [2]. Since only a few objects of this type are known, 288P presents itself as an extremely important system for future studies.

The various features of 288P — wide separation of the two components, near-equal component size, high eccentricity and comet-like activity — also make it unique among the few known wide asteroid binaries in the Solar System. The observed activity of 288P also reveals information about its past, notes Agarwal: “Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick.”

From this, the team concluded that 288P has existed as a binary system  for only about 5000 years. Agarwal elaborates on the formation scenario: “The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the two fragments may have been moved further apart by sublimation torques.”

The fact that 288P is so different from all other known binary asteroids raises some questions about whether it is not just a coincidence that it presents such unique properties. As finding 288P included a lot of luck, it is likely to remain the only example of its kind for a long time. “We need more theoretical and observational work, as well as more objects similar to 288P, to find an answer to this question,” concludes Agarwal.



Notes

[1] Like any object orbiting the Sun, 288P travels along an elliptical path, bringing it closer and further away to the Sun during the course of one orbit. 

[2] Current research indicates that water came to Earth not via comets, as long thought, but via icy asteroids.



More Information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The international team of astronomers in this study consists of Jessica Agarwal (Max Planck Institute for Solar System Research, Göttingen, Germany), David Jewitt (Department of Earth, Planetary and Space Sciences and Department of Physics and Astronomy, University of California at Los Angeles, USA), Max Mutchler (Space Telescope Science Institute, Baltimore, USA), Harold Weaver (The Johns Hopkins University Applied Physics Laboratory, Maryland, USA) and Stephen Larson (Lunar and Planetary Laboratory, University of Arizona, Tucson, USA).

The results were released in the paper “A binary main belt comet” to be published in Nature.

Image credit: NASA, ESA






Contacts

Jessica Agarwal
Max Planck Institute for Solar-System Research
Göttingen, Germany
Tel: +49 551 384 979 438
Email: agarwal@mps.mpg.de

Lauren Fuge
ESA/Hubble, Public Information Officer
Garching bei München, Germany
Email: lfuge@partner.eso.org


Thursday, September 21, 2017

Ageing Star Blows Off Smoky Bubble

Delicate bubble of expelled material around the cool red star U Antliae

The star U Ant in the constellation of Antlia (The Air Pump)

Wide-field image of the sky around U Antliae

PR Image eso1730d
ALMA view of the motions of material in the shell around U Antliae



Videos

ESOcast 127 Light: Ageing Star Blows Off Smoky Bubble
ESOcast 127 Light: Ageing Star Blows Off Smoky Bubble

Flying from the Earth to the star U Antliae
Flying from the Earth to the star U Antliae

Tomography of a cosmic bubble
Tomography of a cosmic bubble




Astronomers have used ALMA to capture a strikingly beautiful view of a delicate bubble of expelled material around the exotic red star U Antliae. These observations will help astronomers to better understand how stars evolve during the later stages of their life-cycles.

In the faint southern constellation of Antlia (The Air Pump) the careful observer with binoculars will spot a very red star, which varies slightly in brightness from week to week. This very unusual star is called U Antliae and new observations with the Atacama Large Millimeter/submillimeter Array (ALMA) are revealing a remarkably thin spherical shell around it.

U Antliae [1] is a carbon star, an evolved, cool and luminous star of the asymptotic giant branch type. Around 2700 years ago, U Antliae went through a short period of rapid mass loss. During this period of only a few hundred years, the material making up the shell seen in the new ALMA data was ejected at high speed. Examination of this shell in further detail also shows some evidence of thin, wispy gas clouds known as filamentary substructures.

This spectacular view was only made possible by the unique ability to create sharp images at multiple wavelengths that is provided by the ALMA radio telescope, located on the Chajnantor Plateau in Chile’s Atacama Desert. ALMA can see much finer structure in the U Antliae shell than has previously been possible.

The new ALMA data are not just a single image; ALMA produces a three-dimensional dataset  (a data cube) with each slice being observed at a slightly different wavelength. Because of the Doppler Effect, this means that different slices of the data cube show images of gas moving at different speeds towards or away from the observer. This shell is also remarkable as it is very symmetrically round and also remarkably thin. By displaying the different velocities we can cut this cosmic bubble into virtual slices just as we do in computer tomography of a human body.

Understanding the chemical composition of the shells and atmospheres of these stars, and how these shells form by mass loss, is important to properly understand how stars evolve in the early Universe and also how galaxies evolved. Shells such as the one around U Antliae show a rich variety of chemical compounds based on carbon and other elements. They also help to recycle matter, and contribute up to 70% of the dust between stars.



Notes

[1] The name U Antliae reflects the fact that it is the fourth star that changes its brightness to be found in the constellation of Antlia (The Air Pump). The naming of such variable stars followed a complicated sequence as more and more were found and is explained here . 



More Information

This research was presented in a paper entitled “Rings and filaments. The remarkable detached CO shell of U Antliae”, by F. Kerschbaum et al., to appear in the journal Astronomy & Astrophysics.

The team is composed of F. Kerschbaum (University of Vienna, Austria), M. Maercker (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. Brunner (University of Vienna, Austria), M. Lindqvist (Chalmers University of Technology, Onsala Space Observatory, Sweden), H. Olofsson (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. Mecina (University of Vienna, Austria), E. De Beck (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. A. T. Groenewegen (Koninklijke Sterrenwacht van België, Belgium), E. Lagadec (Observatoire de la Côte d’Azur, CNRS, France), S. Mohamed (University of Cape Town, South Africa), C. Paladini (Université Libre de Bruxelles, Belgium), S. Ramstedt (Uppsala University, Sweden), W. H. T. Vlemmings (Chalmers University of Technology, Onsala Space Observatory, Sweden), and M. Wittkowski (ESO)

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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. 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”.



Links



Contacts

Franz Kerschbaum
University of Vienna
Vienna, Austria
Tel: +43 1 4277-51856
Email:
franz.kerschbaum@univie.ac.at

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email:
rhook@eso.org


Source: ESO/News

Wednesday, September 20, 2017

Size matters in the detection of exoplanet atmospheres

Montage of artist’s impressions of exoplanetary systems
Credit: Alexaldo




Artist’s impressions of exoplanetary system
Credit: Alexaldo



A group-analysis of 30 exoplanets orbiting distant stars suggests that size, not mass, is a key factor in whether a planet’s atmosphere can be detected. The largest population-study of exoplanets to date successfully detected atmospheres around 16 ‘hot Jupiters’, and found that water vapour was present in every case.

The work by a UCL-led team of European researchers has important implications for the comparison and classification of diverse exoplanets. The results will be presented by Angelos Tsiaras at the European Planetary Science Congress (EPSC) 2017 in Riga on Tuesday 19th September.

“More than 3,000 exoplanets have been discovered but, so far, we’ve studied their atmospheres largely on an individual, case-by-case basis. Here, we’ve developed tools to assess the significance of atmospheric detections in catalogues of exoplanets,” said Angelos Tsiaras, the lead author of the study. “

This kind of consistent study is essential for understanding the global population and potential classifications of these foreign worlds.” The researchers used archive data from the ESA/NASA Hubble Space Telescope’s Wide Field Camera 3 (WFC3) to retrieve spectral profiles of 30 exoplanets and analyse them for the characteristic fingerprints of gases that might be present. About half had strongly detectable atmospheres. Results suggest that while atmospheres are most likely to be detected around planets with a large radius, the planet’s mass does not appear to be an important factor. This indicates that a planet’s gravitational pull only has a minor effect on its atmospheric evolution.

Most of the atmospheres detected show evidence for clouds. However, the two hottest planets, where temperatures exceed 1,700 degrees Celsius, appear to have clear skies, at least at high altitudes. Results for these two planets indicate that titanium oxide and vanadium oxide are present in addition to the water vapour features found in all 16 of the atmospheres analysed successfully.

“To understand planets and planet formation we need to look at many planets: at UCL we are implementing statistical tools and models to handle the analysis and interpretation of large sample of planetary atmospheres. 30 planets is just the start,” said Ingo Waldmann, a co-author of the study.

“30 exoplanet atmospheres is a great step forward compared to the handful of planets observed years ago, but not yet big-data. We are working at launching dedicated space missions in the next decade to bring this number up to hundreds or even thousands,” commented Giovanna Tinetti, also UCL.


Source: EuroPlanet




Further information



The research at UCL has been funded by the Science and Technology Facilities Council (STFC) and the ERC projects ExoLights (617119) and ExoMol. Results are summarized by Tsiaras et al. in the paper “A population study of hot Jupiter atmospheres,” which has been submitted to the Astrophysical Journal.

The team of astronomers in this study consists of A. Tsiaras (UCL, UK), I. P. Waldmann (UCL, UK), T. Zingales (UCL, UK/INAF Osservatorio Astronomico di Palermo, Italy), M. Rocchetto (UCL, UK), G. Morello (UCL, UK), M. Damiano (UCL, UK/INAF Osservatorio Astronomico di Palermo, Italy), K. Karpouzas (Aristotle University of Thessaloniki, Greece), G. Tinetti (UCL, UK), L. K. McKemmish (UCL, UK), S. N. Yurchenko (UCL, UK), J. Tennyson (UCL, UK)



Science Contacts

Angelos Tsiaras
University College London
+44 (0)7477 834386
atsiaras@star.ucl.ac.uk

Prof Giovanna Tinetti
University College London
+44 (0) 7912 509617
g.tinetti@ucl.ac.uk



Media Contacts

Anita Heward
Europlanet Media Centre
+44 7756 034243
anita.heward@europlanet-eu.org

Dr Rebecca Caygill
UCL Communications & Marketing
+44 (0)77 3330 7596
r.caygill@ucl.ac.uk



Notes for Editors

About the NASA/ESA Hubble Space Telescope

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.



About UCL (University College London)


UCL was founded in 1826. We were the first English university established after Oxford and Cambridge, the first to open up university education to those previously excluded from it, and the first to provide systematic teaching of law, architecture and medicine. We are among the world’s top universities, as reflected by performance in a range of international rankings and tables. UCL currently has over 39,000 students from 150 countries and over 12,500 staff. Our annual income is more than £1 billion.

www.ucl.ac.uk | Follow us on Twitter @uclnews | Watch our YouTube channel YouTube.com/UCLTV


EPSC 2017


The European Planetary Science Congress (EPSC) 2017 (www.epsc2017.eu) is taking place at the Radisson Blu Latvija in Riga, from Sunday 17 to Friday 22 September 2017. EPSC is the major European annual meeting on planetary science and in 2017 is hosted for the first time in the Baltic States. Around 800 scientists from Europe and around the world will attend the meeting and will give around 1,000 oral and poster presentations about the latest results on our own Solar System and planets orbiting other stars.

EPSC 2017 is organised by Europlanet and Copernicus Meetings. The Local Organising Committee is led by Baltics in Space, a not-for-profit organisation that is supporting 25 members centred around nine Baltic space facilities for the conference. The meeting is sponsored by Investment and Development Agency of Latvia, the Latvian Ministry of Education and Science, Latvijas Mobilais Telefons, Finnish Meteorological Institute, The Estonia-Latvia programme, The Representation of the European Commission in Latvia, the Planetary Science Institute, Latvijas Universitate and The Division for Planetary Sciences of the AAS.

Details of the Congress and a full schedule of EPSC 2017 scientific sessions and events can be found at the official website:  http://www.epsc2017.eu/


Europlanet


Since 2005, the Europlanet project has provided European’s planetary science community with a platform to exchange ideas and personnel, share research tools, data and facilities, define key science goals for the future and engage stakeholders, policy makers and European Citizens with planetary science. Europlanet is the parent organisation of the European Planetary Science Congress (EPSC), and the EPSC Executive Committee is drawn from its membership.

The Europlanet 2020 Research Infrastructure (RI) is a €9.95 million project to address key scientific and technological challenges facing modern planetary science by providing open access to state-of-the-art data, models and facilities across the European Research Area. The project was launched on 1st September 2015 and has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208. Europlanet 2020 RI is led by the Open University, UK, and has 33 beneficiary institutions from 19 European countries.

Project website: www.europlanet-2020-ri.eu
Outreach website: www.europlanet-eu.org
Follow @europlanetmedia


Baltics in Space


The philosophy of the nonprofit organization, Baltics in Space, is to “Inventory, Identify, and Integrate” with a sprinkling of Inspiration to build a space product greater than the sum of its parts. The best resource in the space business is people. With an eye to strengthening the triple helix links (Industry, Education, Research), its planned outcomes are integrating Baltic-wide space events, compiling catalogs of skill-sets for prospective users and Baltic space project development with distributed teams and Baltic space education. 

http://www.balticsinspace.eu


Tuesday, September 19, 2017

VLA Begins Huge Project of Cosmic Discovery

The new VLA Sky Survey (VLASS) sharpens the view. Here is the same radio-emitting object as seen, from left to right, with the NRAO VLA Sky Survey (NVSS), the FIRST Survey, and the VLASS. The VLASS image, unlike the others, allows astronomers to positively identify the image as jets of material propelled outward from the center of a galaxy that also is seen in the visible-light Sloan Digital Sky Survey. Technical data: NVSS image at 1.4 GHz in VLA's D configuration; FIRST image at 1.4 GHz in B configuration; VLASS image at 3 GHz in B configuration. Credit: Bill Saxton, NRAO/AUI/NSF. Hi-res images


nrao17df09e from NRAO Outreach on Vimeo
Images of the same celestial object from the NVSS, FIRST, and VLASS surveys, in order, showing increased resolution, or ability to discern detail. Credit: Bill Saxton, NRAO/AUI/NSF.



New sky survey is largest observing project in VLA's history

Astronomers have embarked on the largest observing project in the more than four-decade history of the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) — a huge survey of the sky that promises a rich scientific payoff over many years.

Over the next 7 years, the iconic array of giant dish antennas in the high New Mexico desert will make three complete scans of the sky visible from its latitude — about 80 percent of the entire sky. The survey, called the VLA Sky Survey (VLASS), will produce the sharpest radio view ever made of such a large portion of the sky, and is expected to detect 10 million distinct radio-emitting celestial objects, about four times as many as are now known.

“This survey puts to work the tremendously improved capabilities of the VLA produced by the upgrade project that was completed in 2012. The result will be a unique and extremely valuable tool for frontier research over a diverse range of fields in astrophysics,” said Tony Beasley, Director of the National Radio Astronomy Observatory (NRAO).

Astronomers expect the VLASS to discover powerful cosmic explosions, such as supernovae, gamma ray bursts, and the collisions of neutron stars, that are obscured from visible-light telescopes by thick clouds of dust, or that otherwise have eluded detection. The VLA’s ability to see through dust will make the survey a tool for finding a variety of structures within our own Milky Way that also are obscured by dust.

 The survey will reveal many additional examples of powerful jets of superfast particles propelled by the energy of supermassive black holes at the cores of galaxies. This will yield important new information on how such jets affect the growth of galaxies over time. The VLA’s ability to measure magnetic fields will help scientists gain new understanding of the workings of individual galaxies and of the interactions of giant clusters of galaxies.

“In addition to what we think VLASS will discover, we undoubtedly will be surprised by discoveries we aren’t anticipating now. That is the lesson of scientific history, and perhaps the most exciting part of a project like this,” said Claire Chandler, VLASS Project Director.

The survey began observations on September 7. It plans to complete three scans of the sky, each separated by approximately 32 months. Data from all three scans will be combined to make sensitive radio images, while comparing images from the individual scans will allow discovery of newly-appearing or short-lived objects. For the survey, the VLA will receive cosmic radio emissions at frequencies between 2 and 4 GigaHertz, frequencies also used for satellite communications and microwave ovens.

NRAO will release data products from the survey as quickly as they can be produced. Raw data, which require processing to turn into images, will be released as soon as observations are made. “Quick look” images, produced by an automated processing pipeline, typically will be available within a week of the observations. More sophisticated images, and catalogs of objects detected, will be released on timescales of months, depending on the processing time required.

In addition, other institutions are expected to enhance the VLASS output by performing additional processing for more specialized analysis, and make those products available to the research community. The results of VLASS also will be available to students, educators, and citizen scientists.

Completing the VLASS will require 5,500 hours of observing time. It is the third major sky survey undertaken with the VLA. From 1993-1996, the NRAO VLA Sky Survey (NVSS) used 2932 observing hours to cover the same area of sky as VLASS, but at lower resolution. The FIRST (Faint Images of the Radio Sky at Twenty centimeters) Survey studied a smaller portion of sky in more detail, using 3200 observing hours from 1993 to 2002.

“The NVSS and FIRST surveys have been cited more than 4,500 times in scientific papers, and that number still is growing,” said Project Scientist Mark Lacy. “That’s an excellent indication of the value such surveys provide to the research community,” he added.

Since the NVSS and FIRST surveys were completed, the VLA underwent a complete technical transformation. From 2001-2012, the original electronic systems designed and built during the 1970s were replaced with state-of-the-art technology that vastly expanded the VLA’s capabilities.

“This upgrade made the VLA a completely new scientific tool. We wanted to put that tool to use to produce an all-sky survey that would benefit the entire astronomical community to the maximum extent possible,” Beasley said.

In 2013, NRAO announced that it would consider conducting a large survey, and invited astronomers from around the world to submit ideas and suggestions for the scientific and technical approaches that would best serve the needs of researchers. Ideas were also solicited during scientific meetings, and a Survey Science Group was formed to advise NRAO on the survey’s scientific priorities that includes astronomers from a wide variety of specialties and institutions.

Based on the recommendations from the scientific community, NRAO scientists and engineers devised a design for the survey. In 2016, a pilot survey, using 200 observing hours, was conducted to test and refine the survey’s techniques. The Project Team underwent several design and operational readiness reviews, and finally obtained the go-ahead to begin the full survey earlier this year.

“Astronomy fundamentally is exploring — making images of the sky to see what’s there. The VLASS is a new and powerful resource for exploration,” said Steve Myers, VLASS Technical Lead.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.