Peering inside the birthplaces of planets orbiting the smallest stars

Artistic representation of a planet-forming disk of dust and gas around a very low-mass star (VLMS). The inner dust disk contains a ring structure that indicates the formation of a new planet. The dust disk resides inside a larger gas disk whose thickness increases towards the edge.Image: MPIA graphics department.Hi-res image 

 

Observational data and model of the dust disk around the VLMS MHO6. Left: Image of the dust disk. Middle: The disk model with a 20 au wide central hole, which is consistent with a Saturn-mass planet located at a distance of 7 au from the star, accreting disk material. Right: Radial profile of the model (blue) and after convolving it with the telescope’s angular resolution (red). The black symbols represent the data obtained from the measured brightness distribution. The grey bar corresponds to the angular resolution of the observations. Image: Kurtovic et al./MPI.Hi-res image

 

Astronomers detect ring structures in the planet forming disks of young, very low-mass stars.

Scientists have been finding ring-like structures indicating planet formation in the disks surrounding young Sun-like stars for several years. Astronomers led by Nicolas Kurtovic from the Max Planck Institute for Astronomy in Heidelberg, Germany, have now detected similar signals in disks of young very low-mass stars that are considerably smaller and less massive than their counterparts. Although these stars represent the vast majority of the stellar population, they only host 10% of the known exoplanets to date, including terrestrial and Jupiter-like planets. While theorists have yet to derive a satisfying model that explains the formation of such giant planets inside the rather low-mass disks of the smallest stars, the new results are the beginning of a systematic investigation to solving this mystery.

To date, astronomers have found about 4400 planets in more than 3200 planetary systems around stars other than the Sun. These numbers are biased, because only about 10% of the known exoplanets orbit so-called Red Dwarfs, although these stars make up for roughly three-quarters of the stellar population in the Milky Way. Red Dwarfs are the least massive, smallest and coolest stars that exist. They are extremely faint compared to most known planet harbouring stars, making them very hard to capture and investigate.

For all the same reasons, astronomers only know little about the processes that form planets in the disks made of gas and dust surrounding them at a young age. To improve our understanding, a team led by Nicolas Kurtovic, a PhD student at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, has now mapped and analysed six such disks around young very low-mass stars (VLMS) with unprecedented detail. VLMS are stars with masses of less than 20% of that of our Sun.

“Despite the tremendous progress in understanding planet formation during recent decades, we don’t know much on how the planets of the most common stars form,” Kurtovic points out. Especially the detection of Jupiter-type planets in orbit around VLMS like GJ 3512 (see section “Related articles”) is puzzling and defies the commonly accepted paradigm of planet formation. Their circumstellar disks, from which the planets emerge, only have comparably small amounts of material, making it difficult to form such massive planets.

The researchers used the Atacama Large Millimeter/submillimeter Array (ALMA), currently one of the most powerful radio interferometers. It is jointly operated by the European Southern Observatory (ESO), by the National Radio Astronomy Observatory (NRAO), and by the National Astronomical Observatory of Japan (NAOJ). The astronomers observed the objects at a wavelength of 0.87 millimetres to trace dust and gas at an angular resolution of 0.1 arcseconds. This angle corresponds to the size of a human’s pupil at a distance of around 10 kilometres. Published data complement the investigation. While considering the optical response of the telescope, they modelled the likely correct shape of the disks.

Half of the disks Kurtovic and his colleagues investigated show ring-like dust structures that extend between 50 and 90 times the distance between the Sun and Earth (defined as 1 astronomical unit = 1 au). Their arrangements appear similar to the ones of larger disks of more massive young stars like HL Tau, whose images continue to fascinate astronomers. They commonly explain such rings as giant planets accumulating dust and gas while orbiting the central star. “We explored several alternative physical processes to explain the patterns, such as stellar irradiation evaporating the dust. Still, planet interaction remains to be the most plausible explanation also for our VLMS sample”, Kurtovic says. The sizes of the gaps cleared by such planets around VLMS would require planetary masses similar to Saturn.

The disks around VLMS indeed contain enough material to feed new-born planets. However, this is not the biggest challenge. Confining the dust quickly enough to build planetary embryos on which the gas accumulates to form planets is even more difficult. Time is of the essence because the dust gradually moves inward and eventually evaporates close to the star. This radial migration is about twice as fast as for the more massive stars, leaving little time for the rocky embryos to grow.

“We estimate that the ringed structures we see around the VLMS must have formed within only 200,000 years before the dust would have migrated to the central star”, Dr Paola Pinilla explains. Pinilla leads a research group at MPIA titled “The Genesis of Planets” in which Kurtovic is a member. Once these embryos are present, the gaps they carve while orbiting the star serve as a border that the dust cannot cross. At this stage, the planet can grow steadily by accreting gas and dust. Kurtovic and his colleagues demonstrate that the dust disks are embedded in gas disks four times the size. Initially, they both must have had the same size, which tells us how far the dust had migrated before taking up its current position.

In the remaining three of the six disks observed, the dust appears more centrally concentrated to sizes between 20 and 40 au. They lack an apparent structure, which is probably the result of the inadequate angular resolution. “We think that we will see rings even inside the smaller disks once we obtain better-resolved observations”, Kurtovic predicts.

“This pilot study was a challenging task because the VLMS disks are small and possess relatively little material, resulting in feeble signals that are very hard to detect,” Pinilla admits. However, the investigation has shown that, with the right instrumentation, astronomers can look into planets’ birthplaces even in the faint disks of VLMS. This ability opens a new door that supports the theorists’ efforts to develop an adequate model of planet formation for even the smallest stars, which live longer than any other type of star.

“We still do not know how common planets around Red Dwarf stars are”, Kurtovic concedes. “However, the longevity of Red Dwarf planetary systems is intriguing concerning habitability and hypothetical civilisations”, he adds. In this sense, these faint red stars may be the most interesting ones in the Galaxy.

Source:  Max Planck Institute for Astronomy

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Contact

Nicolas Kurtovic
Phone:+49 6221 528-474
Max Planck Institute for Astronomy, Heidelberg

Dr. Paola Pinilla
Phone:+49 6221 528-263
Max Planck Institute for Astronomy, Heidelberg

Dr. Markus Nielbock
Press and public relations officer
Phone:+49 6221 528-134
Max Planck Institute for Astronomy, Heidelberg

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Original publication

1. Nicolas T. Kurtovic, Paola Pinilla, et al.

Size and Structures of Disks around Very Low Mass Stars in the Taurus Star-Forming Region

Astronomy & Astrophysics, 645, A139 (2021)

Source / DOI

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Related articles

 

When dwarfs give birth to giants

A newly discovered exoplanet challenges current models pertaining to planet formation. [more]

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Links

The Genesis of Planets
Project website of the planet formation working group at MPIA

ALMA – Atacama Large Millimeter/submillimeter Array
Website of the radio interferometer on the Chajnantor plateau in Chile's Atacama Desert

ESO – European Southern Observatory
Website of the European Southern Observatory

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New galaxy sheds light on how stars form

A tidal dwarf galaxy (blue) and a spiral galaxy (greyscale). The Milky Way is an example of a spiral galaxy. (Created from images taken by the Hubble Space Telescope and ALMA.)

Detailed observations of molecular gas in a tidal dwarf galaxy have important implications for our understanding of how stars are formed.

A lot is known about galaxies. We know, for instance, that the stars within them are shaped from a blend of old star dust and molecules suspended in gas. What remains a mystery, however, is the process that leads to these simple elements being pulled together to form a new star.

But now an international team of scientists, including astrophysicists from the University of Bath and the National Astronomical Observatory (OAN) in Madrid, Spain have taken a significant step towards understanding how a galaxy’s gaseous content becomes organised into a new generation of stars.

Their findings have important implications for our understanding of how stars formed during the early days of the universe, when galaxy collisions were frequent and dramatic, and star and galaxy formation occurred more actively than it does now.

For this study, the researchers used the Chile-based Atacama Large Millimeter Array (ALMA) – a network of radio telescopes combined to form one, mega telescope – to observe a type of galaxy called a tidal dwarf galaxy (TDG). TDGs emerge from the debris of two older galaxies colliding with great force. They are actively star-forming systems and pristine environments for scientists trying to piece together the early days of other galaxies, including our own – the Milky Way (thought to be 13.6-billion years old).

“The little galaxy we’ve been studying was born in a violent, gas-rich galactic collision and offers us a unique laboratory to study the physics of star formation in extreme environments,” said co-author Professor Carole Mundell, head of Astrophysics at the University of Bath.

From their observations, the researchers learnt that a TDG’s molecular clouds are similar to those found in the Milky Way, both in terms of size and content. This suggests there is a universal star-formation process at play throughout the universe.

Unexpectedly, however, the TDG in the study (labelled TDG J1023+1952) also displayed a profusion of dispersed gas. In the Milky Way, clouds of gas are by far the most prominent star-forming factories.

“The fact that molecular gas appears in both cloud form and as diffuse gas was a surprise,” said Professor Mundell.

Dr Miguel Querejeta from the OAN in Spain and lead author of the study added: "ALMA’s observations were made with great precision so we can say with confidence that the contribution of diffuse gas is much higher in the tidal dwarf galaxy we studied than typically found in normal galaxies."

He added: "This most likely means most of the molecular gas in this tidal dwarf galaxy is not involved in forming stars, which questions popular assumptions about star formation."

Because of the vast distance that separates Earth from TDG J1023+1952 (around 50 million light years), individual clouds of molecular gas appear as tiny regions in the sky when viewed through the naked eye. However, ALMA has the power to distinguish the smallest details.

“We have managed to identify clouds with an apparent size as small as observing a coin placed several kilometres away from us,” said Professor Mundell, adding: “It’s remarkable that we can now study stars and the gas clouds from which they are formed in a violent extragalactic collision with the same detail that we can study those forming in the calm environment of our own Milky Way.”

The paper ALMA Resolves Giant Molecular Clouds in a Tidal Dwarf Galaxy appears in the latest issue of Astronomy & Astrophysics. This research was a collaborative effort of scientists from across the world working remotely. Their expertise covers the physics of stars, dust and gas, and the science of galaxy evolution.

 

Media enquiries

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Source:  University of Bath/Announcements

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Galaxies Hit Single, Doubles, and a Triple (Growing Black Holes)

J1027.0+1749 - J1708+2153
Credit: X-ray: NASA/CXC/Univ. of Michigan/A. Foord et al.; Optical: SDSS & NASA/STScI

JPEG (154.5 kb) -Large JPEG (992.6 kb)- Tiff (62.3 B) - More Images 

Tour: Triple Galaxy Mergers- More Animations

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A new study helps reveal what happens to supermassive black holes when three galaxies merge, as reported in our latest press release. This result, which used data from NASA's Chandra X-ray Observatory and several other telescopes, tells astronomers more about how galaxies and the giant black holes in their centers grow over cosmic time.

While there have been previous studies of mergers between two galaxies, this is one of the first to systematically look at the consequences for supermassive black holes when three galaxies come together. This panel of images contains data from two of seven galactic collisions in the new study containing two supermassive black holes left growing after the collision. The pair of mergers are seen in X-rays from Chandra (left in purple) and optical data (right) from NASA's Hubble Space Telescope and the Sloan Digital Sky Survey (SDSS). Circles in a labeled version of the Chandra image show X-rays from hot gas falling towards each black hole.

These triple galaxy mergers were first identified by sifting through data from the SDSS and NASA's WISE mission and then comparing the results to X-ray data in the Chandra archive. This method identified seven triple galaxy mergers located between 370 million and one billion light years from Earth.

Using specialized software, the team went through Chandra data targeting these systems to detect X-ray sources marking the location of growing supermassive black holes. As material falls toward a black hole, it gets heated to millions of degrees and produces X-rays. The combination of the new software and Chandra's sharp X-ray vision enabled the researchers to identify the black holes despite their close proximity in the images.

Out of seven triple galaxy mergers, there results are: one with a single growing supermassive black hole, four with double growing supermassive black holes (two of which are shown in the main graphics), and one that is a triple. The final merger of three galaxies they studied seems to have no X-ray emission detected from the supermassive black holes. This means that none of the supermassive black holes were left rapidly pulling in matter. In the systems with multiple black holes, the separations between them range between about 10,000 and 30,000 light years.

Once they found evidence for bright X-ray sources as candidates for growing supermassive black holes in the Chandra data, the researchers incorporated archival data from other telescopes such as WISE mission, the Infrared Astronomical Satellite, and the Two Micron All Sky Telescope as another check in the process.

Studies of triple mergers can help scientists understand whether pairs of supermassive black holes can approach so close to each other that they make ripples in spacetime called gravitational waves. The energy lost by these waves will inevitably cause the black holes to merge.

Adi Foord presented the new study, which she worked on as part of her Ph.D. at the University of Michigan, at the 237th meeting of the American Astronomical Society, which is being held virtually from January 11-15, 2021. Two papers describing this work have recently been accepted for publication in The Astrophysical Journal and preprints are available here and here.

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.

A Quick Look at Triple Galaxy Mergers

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Fast Facts for J1027.0+1749:

Scale: Image is about 12.6 arcsec (52,000 light years) across
Category: Black Holes, Groups & Clusters of Galaxies
Coordinates (J2000): RA 10h 27m 00.5s | +17° 49" 00.3'
Constellation: Leo
Observation Dates: Jan 23, 2013
Observation Time: 13 hours 43 minutes
Obs. ID: 14971
Instrument: ACIS
Color Code: X-ray: pink Optical: red, green, blue
Distance Estimate: About 890 million light years

Fast Facts for J1708+2153:

Scale: Image is about 42 arcsec (190,000 light years) across
Category:  Black Holes, Groups & Clusters of Galaxies
Coordinates (J2000): RA 17h 08m 59.12s | Dec +21° 53' 08.08"
Constellation: Hercules
Observation Dates: July 1, 2012
Observation Time: 5 hours 3 minutes
Obs. ID: 13903
Instrument: ACIS
Color Code: X-ray: pink Optical: red, green, blue
Distance Estimate: About 960 million light years

Source: NASA’s Chandra X-ray Observatory

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Puzzling six-exoplanet system with rhythmic movement challenges theories of how planets form

PR Image eso2102a

An artist’s view of the TOI-178 planetary system 

 

PR Image eso2102b

Location of the TOI-178 planetary system in the constellation of Sculptor

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Videos

PR Video eso2102a

ESOcast 233 Light: Six-Exoplanet System with Rhythmic Movement Challenges Theories of How Planets Form 

 

PR Video eso2102b

Artist’s animation of the TOI-178 orbits and resonances (sound on!) 

 

PR Video eso2102c

Animated artist’s impression of the six-exoplanet system 

 

PR Video eso2102a

ESOcast 233 Light: Six-Exoplanet System with Rhythmic Movement Challenges Theories of How Planets Form 

 

PR Video eso2102b

Artist’s animation of the TOI-178 orbits and resonances (sound on!) 

 

PR Video eso2102c

Animated artist’s impression of the six-exoplanet system

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Using a combination of telescopes, including the Very Large Telescope of the European Southern Observatory (ESO’s VLT), astronomers have revealed a system consisting of six exoplanets, five of which are locked in a rare rhythm around their central star. The researchers believe the system could provide important clues about how planets, including those in the Solar System, form and evolve.

The first time the team observed TOI-178, a star some 200 light-years away in the constellation of Sculptor, they thought they had spotted two planets going around it in the same orbit. However, a closer look revealed something entirely different. “Through further observations we realised that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration,” says Adrien Leleu from the Université de Genève and the University of Bern, Switzerland, who led a new study of the system published today in Astronomy & Astrophysics.

The new research has revealed that the system boasts six exoplanets and that all but the one closest to the star are locked in a rhythmic dance as they move in their orbits. In other words, they are in resonance. This means that there are patterns that repeat themselves as the planets go around the star, with some planets aligning every few orbits. A similar resonance is observed in the orbits of three of Jupiter’s moons: Io, Europa and Ganymede. Io, the closest of the three to Jupiter, completes four full orbits around Jupiter for every orbit that Ganymede, the furthest away, makes, and two full orbits for every orbit Europa makes.

The five outer exoplanets of the TOI-178 system follow a much more complex chain of resonance, one of the longest yet discovered in a system of planets. While the three Jupiter moons are in a 4:2:1 resonance, the five outer planets in the TOI-178 system follow a 18:9:6:4:3 chain: while the second planet from the star (the first in the resonance chain) completes 18 orbits, the third planet from the star (second in the chain) completes 9 orbits, and so on. In fact, the scientists initially only found five planets in the system, but by following this resonant rhythm they calculated where in its orbit an additional planet would be when they next had a window to observe the system.

More than just an orbital curiosity, this dance of resonant planets provides clues about the system’s past. “The orbits in this system are very well ordered, which tells us that this system has evolved quite gently since its birth,” explains co-author Yann Alibert from the University of Bern. If the system had been significantly disturbed earlier in its life, for example by a giant impact, this fragile configuration of orbits would not have survived.

Disorder in the rhythmic system

But even if the arrangement of the orbits is neat and well-ordered, the densities of the planets “are much more disorderly,” says Nathan Hara from the Université de Genève, Switzerland, who was also involved in the study. “It appears there is a planet as dense as the Earth right next to a very fluffy planet with half the density of Neptune, followed by a planet with the density of Neptune. It is not what we are used to.” In our Solar System, for example, the planets are neatly arranged, with the rocky, denser planets closer to the central star and the fluffy, low-density gas planets farther out.

“This contrast between the rhythmic harmony of the orbital motion and the disorderly densities certainly challenges our understanding of the formation and evolution of planetary systems,” says Leleu.

Combining techniques

To investigate the system’s unusual architecture, the team used data from the European Space Agency’s CHEOPS satellite, alongside the ground-based ESPRESSO instrument on ESO’s VLT and the NGTS and SPECULOOS, both sited at ESO’s Paranal Observatory in Chile. Since exoplanets are extremely tricky to spot directly with telescopes, astronomers must instead rely on other techniques to detect them. The main methods used are imaging transits — observing the light emitted by the central star, which dims as an exoplanet passes in front of it when observed from the Earth — and radial velocities — observing the star’s light spectrum for small signs of wobbles which happen as the exoplanets move in their orbits. The team used both methods to observe the system: CHEOPS, NGTS and SPECULOOS for transits and ESPRESSO for radial velocities. 

By combining the two techniques, astronomers were able to gather key information about the system and its planets, which orbit their central star much closer and much faster than the Earth orbits the Sun. The fastest (the innermost planet) completes an orbit in just a couple of days, while the slowest takes about ten times longer. The six planets have sizes ranging from about one to about three times the size of Earth, while their masses are 1.5 to 30 times the mass of Earth. Some of the planets are rocky, but larger than Earth — these planets are known as Super-Earths. Others are gas planets, like the outer planets in our Solar System, but they are much smaller — these are nicknamed Mini-Neptunes.

Although none of the six exoplanets found lies in the star's habitable zone, the researchers suggest that, by continuing the resonance chain, they might find additional planets that could exist in or very close to this zone. ESO’s Extremely Large Telescope (ELT), which is set to begin operating this decade, will be able to directly image rocky exoplanets in a star’s habitable zone and even characterise their atmospheres, presenting an opportunity to get to know systems like TOI-178 in even greater detail.

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More Information

This research was presented in the paper “Six transiting planets and a chain of Laplace resonances in TOI-178” to appear in Astronomy & Astrophysics (doi: 10.1051/0004-6361/202039767).

The team is composed of A. Leleu (Observatoire Astronomique de l’Université de Genève, Switzerland [UNIGE], University of Bern, Switzerland [Bern]), Y. Alibert (Bern), N. C. Hara (UNIGE), M. J. Hooton (Bern), T. G. Wilson (Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, UK [St Andrews]), P. Robutel (IMCCE, UMR8028 CNRS, Observatoire de Paris, France [IMCCE]), J.-B Delisle (UNIGE), J. Laskar (IMCCE), S. Hoyer (Aix Marseille Univ, CNRS, CNES, LAM, France [AMU]), C. Lovis (UNIGE), E. M. Bryant (Department of Physics, University of Warwick, UK [Warwick], Centre for Exoplanets and Habitability, University of Warwick [CEH]), E. Ducrot (Astrobiology Research Unit, Université de Liège, Belgium [Liège]), J. Cabrera (Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany [Institute of Planetary Research, DLR]), J. Acton (School of Physics and Astronomy, University of Leicester, UK [Leicester]), V. Adibekyan (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Portugal [IA], Centro de Astrofísica da Universidade do Porto, Departamento de Física e Astronomia, Universidade do Porto [CAUP]), R. Allart (UNIGE), C, Allende Prieto (Instituto de Astrofísica de Canarias, Tenerife [IAC], Departamento de Astrofísica, Universidad de La Laguna, Tenerife [ULL]), R. Alonso (IAC, ULL), D. Alves (Camino El Observatorio 1515, Las Condes, Santiago, Chile), D. R Anderson (Warwick, CEH), D. Angerhausen (ETH Zürich, Institute for Particle Physics and Astrophysics), G. Anglada Escudé (Institut de Ciències de l’Espai [ICE, CSIC], Bellaterra, Spain, Institut d’Estudis Espacials de Catalunya [IEEC], Barcelona, Spain), J. Asquier (ESTEC, ESA, Noordwijk, the Netherlands [ESTEC]), D. Barrado (Depto. de Astrofísica, Centro de Astrobiologia [CSIC-INTA], Madrid, Spain), S.C.C Barros (IA, Departamento de Física e Astronomia, Universidade do Porto), W. Baumjohann (Space Research Institute, Austrian Academy of Sciences, Austria), D. Bayliss (Warwick, CEH), M. Beck (UNIGE), T. Beck (Bern) A. Bekkelien (UNIGE), W. Benz (Bern, Center for Space and Habitability, Bern, Switzerland [CSH]), N. Billot (UNIGE), A. Bonfanti (IWF), X. Bonfils (Université Grenoble Alpes, CNRS, IPAG, Grenoble, France), F. Bouchy (UNIGE), V. Bourrier (UNIGE), G. Boué (IMCCE), A. Brandeker (Department of Astronomy, Stockholm University, Sweden), C. Broeg (Bern), M. Buder (Institute of Optical Sensor Systems, German Aerospace Center (DLR) [Institute of Optical Sensor Systems, DLR]), A. Burdanov (Liège, Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, USA), M. R. Burleigh (Leicester), T. Bárczy (Admatis, Miskok, Hungary), A. C. Cameron (St Andrews), S. Chamberlain (Leicester), S. Charnoz (Université de Paris, Institut de physique du globe de Paris, CNRS, France), B. F. Cooke (Warwick, CEH), C. Corral Van Damme (ESTEC), A. C. M. Correia (CFisUC, Department of Physics, University of Coimbra, Portugal, IMCCE, UMR8028 CNRS, Observatoire de Paris, France), S. Cristiani (INAF - Osservatorio Astronomico di Trieste, Italy [INAF Trieste]), M. Damasso (INAF - Osservatorio Astrofisico di Torino, Italy [INAF Torino]), M. B. Davies (Lund Observatory, Dept. of Astronomy and Theoretical Physics, Lund University, Sweden), M. Deluil (AMU), L. Delrez (AMU, Space sciences, Technologies and Astrophysics Research [STAR] Institute, Université de Liège, Belgium, UNIGE), O. D. S. Demangeon (IA), B.-O. Demory (CSH), P. Di Marcantonio (INAF Trieste), G. Di. Persio (INAF, Istituto di Astrofisica e Planetologia Spaziali, Roma, Italy), X. Dumusque (UNIGE), D. Ehrenreich (UNIGE), A. Erikson (Institute of Planetary Research, DLR), P. Figueira (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, ESO Vitacura), A. Fortier (Bern, CSH), L. Fossato (Space Research Institute, Austrian Academy of Sciences, Graz, Austria [IWF]), M. Fridlund (Leiden Observatory, University of Leiden, The Netherlands, Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Sweden [Chalmers]), D. Futyan (UNIGE), D. Gandolfi (Dipartimento di Fisica, Università degli Studi di Torino, Italy), A. García Muñoz (Center for Astronomy and Astrophysics, Technical University Berlin, Germany), L. Garcia (Liège), S. Gill (Warwick, CEH), E. Gillen (Astronomy Unit, Queen Mary University of London, UK, Cavendish Laboratory, Cambridge, UK [Cavendish Laboratory]), M. Gillon (Liège), M. R. Goad (Leicester), J. I. González Hernández (IAC, ULL), M. Guedel (University of Vienna, Department of Astrophysics, Austria), M. N. Günther (Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, USA), J. Haldemann (Bern), B. Henderson (Leicester), K. Heng (CSH), A. E. Hogan (Leicester), E. Jehin (STAR), J. S. Jenkins (Departamento de Astronomía, Universidad de Chile, Santiago, Chile, Centro de Astrofísica y Tecnologías Afines (CATA), Santiago, Chile), A. Jordán (Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile, Millennium Institute for Astrophysics, Chile), L. Kiss (Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Budapest, Hungary), M. H. Kristiansen (Brorfelde Observatory, Observator Gyldenkernes, Denmark, DTU Space, National Space Institute, Technical University of Denmark, Denmark), K. Lam (Institute of Planetary Research, DLR), B. Lavie (UNIGE), A. Lecavelier des Etangs (Institut d’astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, Paris, France), M. Lendil (UNIGE), J. Lillo-Box (Depto. de Astrofísica, Centro de Astrobiologia (CSIC-INTA),ESAC campus, Madrid, Spain), G. Lo Curto (ESO Vitacura), D. Magrin (INAF, Osservatorio Astronomico di Padova, Italy [INAF Padova]), C. J. A. P. Martins (IA, CAUP), P. F. L. Maxted (Astrophysics Group, Keele University, UK), J. McCormac (Warwick), A. Mehner (ESO Vitacura), G. Micela (INAF - Osservatorio Astronomico di Palermo, Italy), P. Molaro (INAF Trieste, IFPU Trieste), M. Moyano (Instituto de Astronomía, Universidad Católica del Norte, Antofagasta, Chile), C. A. Murray (Cavendish Laboratory), V. Nascimbeni (INAF, Osservatorio Astronomico di Padova, Italy), N. J. Nunes (Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Portugal), G. Olofsson (Department of Astronomy, Stockholm University, Sweden), H. P. Osborn (CSH, Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, USA), M. Oshagh (IAC, ULL), R. Ottensamer (Department of Astrophysics, University of Vienna, Austria), I. Pagano (INAF, Osservatorio Astrofisico di Catania, Italy), E. Pallé (IAC, ULL), P. P. Pedersen  (Cavendish Laboratory), F. A. Pepe (UNIGE), C.M. Persson (Chalmers), G. Peter (Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, Germany), G. Piotto (INAF Padova, Dipartimento di Fisica e Astronomia "Galileo Galilei", Università degli Studi di Padova, Italy), G. Polenta (Space Science Data Center, Roma, Italy), D. Pollacco (Warwick), E. Poretti (Fundación G. Galilei – INAF (Telescopio Nazionale Galileo), La Palma, Spain, INAF - Osservatorio Astronomico di Brera, Merate, Italy), F. J. Pozuelos (Liège, STAR), F. Pozuelos (Liège, STAR), D. Queloz (UNIGE, Cavendish Laboratory), R. Ragazzoni (INAF Padova), N. Rando (ESTEC), F. Ratti (ESTEC), H. Rauer (Institute of Planetary Research, DLR), L. Raynard (Leicester), R. Rebolo (IAC, ULL), C. Reimers (Department of Astrophysics, University of Vienna, Austria), I. Ribas (Institut de Ciències de l’Espai (ICE, CSIC), Spain, Institut d’Estudis Espacials de Catalunya (IEEC), Barcelona, Spain), N. C. Santos (IA, Departamento de Física e Astronomia, Universidade do Porto), G. Scandariato (INAF, Osservatorio Astrofisico di Catania, Italy), J. Schneider (Paris Observatory, France), D. Sebastian (School of Physics Astronomy, University of Birmingham, UK [Birmingham]), M. Sestovic (CSH), A. E. Simon (Bern), A. M. S. Smith (Institute of Planetary Research, DLR), S. G. Sousa (IA), A. Sozzetti (INAF Torino), M. Steller (IWF), A. Suárez Mascareño (IAC, ULL), G. M. Szabó (ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Hungary, MTA-ELTE Exoplanet Research Group, Hungary), D Ségransan (UNIGE), N. Thomas (Bern), S. Thompson (Cavendish Laboratory), R. H. Tilbrook (Leicester), A. Triaud (Birmingham), S. Udry (UNIGE), V. Van Grootel (STAR), H. Venus (Institute of Optical Sensor Systems, DLR), F. Verrecchia (Space Science Data Center, ASI, Roma, Italy, INAF, Osservatorio Astronomico di Roma, Italy), J. I. Vines (Camino El Observatorio 1515, Santiago, Chile), N. A. Walton (Institute of Astronomy, University of Cambridge, UK), R. G. West (Warwick, CEH), P. K. Wheatley (Warwick, CEH), D. Wolter (Institute of Planetary Research, DLR), M. R. Zapatero Osorio (Centro de Astrobiología (CSIC-INTA), Madrid, Spain).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. 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”.

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Links

• Research paper
• Photos of the VLT
• For scientists: got a story? Pitch your research

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Contacts

Adrien Leleu
Université de Genève
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Email: Adrien.Leleu@unige.ch

Yann Alibert
University of Bern
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Tel: +41 31 631 55 47
Email: yann.alibert@space.unibe.ch

Nathan Hara
Université de Genève
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Email: press@eso.org

Source: ESO/News 

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When galaxies collide: Models suggest galactic collisions can starve massive black holes

Galaxies collide

Visualizations of the dynamic model simulating two different scenarios. The top row shows a collision reducing core activity, the bottom row shows a collision increasing it. © 2021 Miki et al.

 

Cosmic scales

Artist's impression of gas being pulled away from a galactic nucleus. © 2021 Miki et al.

It was previously thought that collisions between galaxies would necessarily add to the activity of the massive black holes at their centers. However, researchers have performed the most accurate simulations of a range of collision scenarios and have found that some collisions can reduce the activity of their central black holes. The reason is that certain head-on collisions may in fact clear the galactic nuclei of the matter which would otherwise fuel the black holes contained within.

When you think about gargantuan phenomena such as the collision of galaxies, it might be tempting to imagine it as some sort of cosmic cataclysm, with stars crashing and exploding, and destruction on an epic scale. But actually it is closer to a pair of clouds combining, usually a larger one absorbing a smaller one. It’s unlikely any stars within them would collide themselves. But that said, when galaxies collide, the consequences can be enormous.

Galaxies collide in different ways. Sometimes a small galaxy will collide with the outer part of a larger one and either pass through or merge, in either case exchanging a lot of stars along the way. But galaxies can also collide head-on, where the smaller of the two will be torn apart by overpowering tidal forces of the larger one. It’s in this scenario that something very interesting can happen within the galactic nucleus.

“At the heart of most galaxies lies a massive black hole, or MBH,” said Research Associate Yohei Miki from the University of Tokyo. “For as long as astronomers have explored galactic collisions, it has been assumed that a collision would always provide fuel for an MBH in the form of matter within the nucleus. And that this fuel would feed the MBH, significantly increasing its activity, which we would see as ultraviolet and X-ray light amongst other things. However, we now have good reason to believe that this sequence of events is not inevitable and that in fact the exact opposite might sometimes be true.”

Galaxies collide (Animation)

Papers:

Yohei Miki, Masao Mori and Toshihiro Kawaguchi, "Destruction of the central black hole gas reservoir through head-on galaxy collisions," Nature Astronomy: January 25, 2021, doi:10.1038/s41550-020-01286-9.

Link (Publication)

 

Source: The University of Tokyo/Press Release

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Search for axions from nearby star Betelgeuse comes up empty

An MIT-led search for axions from nearby star Betelgeuse (pictured here) came up empty, significantly narrowing the search for hypothetical dark matter particle. Credits: Image: Collage by MIT News. Betelgeuse image courtesy of ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella. Hi-res image

Results significantly narrow the range of possible places to find the hypothetical dark matter particles.

The elusive axion particle is many times lighter than an electron, with properties that barely make an impression on ordinary matter. As such, the ghost-like particle is a leading contender as a component of dark matter — a hypothetical, invisible type of matter that is thought to make up 85 percent of the mass in the universe.

Axions have so far evaded detection. Physicists predict that if they do exist, they must be produced within extreme environments, such as the cores of stars at the precipice of a supernova. When these stars spew axions out into the universe, the particles, on encountering any surrounding magnetic fields, should briefly morph into photons and potentially reveal themselves.

Now, MIT physicists have searched for axions in Betelgeuse, a nearby star that is expected to burn out as a supernova soon, at least on astrophysical timescales. Given its imminent demise, Betelgeuse should be a natural factory of axions, constantly churning out the particles as the star burns away.

However, when the team looked for expected signatures of axions, in the form of photons in the X-ray band, their search came up empty. Their results rule out the existence of ultralight axions that can interact with photons over a wide range of energies. The findings set new constraints on the particle’s properties that are three times stronger than any previous laboratory-based axion-detecting experiments.

“What our results say is, if you want to look for these really light particles, which we looked for, they’re not going to talk very much to photons,” says Kerstin Perez, assistant professor of physics at MIT. “We’re basically making everyone’s lives harder because we’re saying, ‘you’re going to have to think of something else that would give you an axion signal.’”

Perez and her colleagues have published their results today in Physical Review Letters. Her MIT co-authors include lead author Mengjiao Xiao, Brandon Roach, and Melaina Nynka, along with Maurizio Giannotti of Barry University, Oscar Straniero of the Abruzzo Astronomical Observatory, Alessandro Mirizzi of the National Institute for Nuclear Physics in Italy, and Brian Grefenstette of Caltech.

A hunt for coupling

Many of the current experiments that search for axions are designed to look for them as a product of the Primakoff effect, a process that describes a theoretical “coupling” between axions and photons. Axions are not normally thought to interact with photons — hence their likelihood of being dark matter. However, the Primakoff effect predicts that, when photons are subjected to intense magnetic fields, such as in stellar cores, they could morph into axions. The center of many stars should therefore be natural axion factories.

When a star explodes in a supernova, it should churn the axions out into the universe. If the invisible particles run into a magnetic field, for instance between the star and Earth, they should turn back into photons, presumably with some detectable energy. Scientists are hunting for axions through this process, for instance from our own sun.

“But the sun also has flares and gives off X-rays all the time, and it’s hard to understand,” says Perez.

She and her colleagues instead looked for axions from Betelgeuse, a star that normally does not emit X-rays. The star is among those nearest to Earth that are expected to explode soon.

“Betelgeuse is at a temperature and lifestage where you don’t expect to see X-rays coming out of it, through standard stellar astrophysics,” Perez explains. “But if axions do exist, and are coming out, we might see an X-ray signature. So that’s why this star is a nice object: If you see X-rays, it’s a smoking gun signal that it’s got to be axions.”

“Data are data”

The researchers looked for X-ray signatures of axions from Betelgeuse, using data taken by NuSTAR, NASA’s space-based telescope that focuses high-energy X-rays from astrophysical sources. The team obtained 50 kiloseconds of data from NuSTAR during the time the telescope was trained on Betelgeuse.

The researchers then modeled a range of X-ray emissions that they might see from Betelgeuse if the star was spewing out axions. They considered a range of masses that an axion might be, as well as a range of likelihoods that the axions would “couple” to and reconvert into a photon, depending on the magnetic field strength between the star and Earth.

“Out of all that modeling, you get a range of what your X-ray signal of axions could possibly look like,” Perez says.

When they searched for these signals in NuSTAR’s data, however, they found nothing above their expected background or outside of any ordinary astrophysical sources of X-rays.

“Betelgeuse is probably in the late stages of evolution and in that case should have a big probability of converting into axions,” Xiao says. “But data are data.”

Given the range of conditions they considered, the team’s null result rules out a large space of possibilities and sets an upper limit that is three times stronger than previous limits, from laboratory-based searches, for what an axion must be. In essence, this means that if axions are ultralight in mass, the team’s results show that the particles must be at least three times less likely to couple to photons and emit any detectable X-rays.

“If axions have ultralight masses, we can definitely tell you their coupling has to be very small, otherwise we would have seen it,” Perez says.

Ultimately, this means that scientists may have to look to other, less detectable energy bands for axion signals. However, Perez says the search for axions from Betelgeuse is not over.

“What would be exciting would be if we see a supernova, which would ignite a huge amount of axions that wouldn’t be in X-rays, but in gamma rays,” Perez says. “If a star explodes and we don’t see axions, then we’ll get really stringent constraints on an axion’s coupling to photons. So everyone’s crossing their fingers for Betelgeuse to go off.”

This research was supported, in part, by NASA.

Jennifer Chu | MIT News Office 

Source: MIT News

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Cosmic brick factory

The reconstructed image of the dusty disk (left) around the young star HD 163296, derived from the MATISSE observations. The false-colour image shows the thermal radiation from the disk at infrared wavelengths. The observations revealed a strong asymmetry which presents itself as a bright clump located at the upper right part in the image. A vortex concentrating material in a horseshoe-shaped region in the inner disk (to the right) could be causing this asymmetry. It orbits the central star at a distance similar to that of Mercury revolving around the Sun.  Credit: Jozsef Varga (Leiden Observatory), Heloise Meheut (CNRS/Lagrange) 

A new instrument reveals the site for planet birth aroud a young star

Studying the formation of planets close to their host stars by observations has been extremely challenging so far. As part of an international collaboration, scientists - among others from the Max Planck Institutes for Astronomy and for Radioastronomy - have employed a new instrument called MATISSE which has now uncovered evidence for a vortex at the inner rim of a planet-forming disk around a young star. It appears to move on an orbit around its star similar to Mercury’s orbit around the Sun. Astronomers think such vortices are sites where small particles converge and grow to form planets’ building blocks. Max Planck researchers contributed considerably to building MATISSE, an infrared imager for ESO’s Very Large Telescope Interferometer.

Astronomers have discovered more than 4000 planets orbiting stars other than the Sun. However, scientists still have to figure out the details of how those planets form from the disks made of dust and gas that surround their parent stars. During recent years, sophisticated instrumentation has provided close-up views on such planet-forming disks. However, they generally lack the angular resolution and sensitivity to probe the disks’ inner regions where terrestrial planets are supposed to emerge from rocky building blocks that eventually grow from tiny dust grains.

An extensive collaboration of scientists led by Jozsef Varga from Leiden Observatory (The Netherlands) have now managed to overcome those limits by utilising a new instrument called MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment). The observations were made with essential contributions by astronomers of the Max Planck Institutes for Astronomy (MPIA) and for Radioastronomy (MPIfR). At infrared wavelengths these observations provide evidence for a vortex embedded inside a ring of hot dust at the inner edge of the protoplanetary disk of the young star HD 163296. The potential vortex revealed itself as a hot spot that produces an asymmetry at the disk’s inner edge. The scientists inferred that it revolves around the star roughly within a month by including published data. Its trajectory resides at a distance from the central star comparable to Mercury’s orbit around the Sun.

Theoretical calculations have predicted the occurrence of vortices in disks, where material swirls around like a tornado and accumulates dust. “The higher dust density induces faster grain growth than anywhere else in the disk, which may render those whirls to be efficient factories to produce the building blocks of future planets,” Roy van Boekel explains. He leads the Protoplanetary Disk Science Group and manages the MATISSE project at MPIA. Some of the newly formed rocky bricks collide under high speeds which causes grinding of the material to tiny grains. They can attain higher temperatures than larger pebbles which is the likely origin of the hot spot found in the data.

Group photo of the MATISSE team next to a MATISSE instrument cryostat.

Credit: Michael Lehmitz (MPIA) 

This spectacular result will appear in the scientific journal Astronomy & Astrophysics as the MATISSE team’s first scientific publication. “MATISSE is a new infrared instrument for the VLTI (Very Large Telescope Interferometer) which the European Southern Observatory (ESO) operates at its Paranal site in Chile,” Michael Lehmitz, an engineer at MPIA says. “MPIA contributed to an international consortium that designed and built MATISSE by integrating the delicate optics into a cryostat that cools them down to -235° C.” Subsequent low-temperature performance tests were also carried out at MPIA. MATISSE combines the light collected from up to four individual VLT units, performing spectroscopic and imaging observations. With such a design, the facility simulates the imaging power of a telescope of up to 200 metres in diameter, capable of producing the most detailed images ever at mid-infrared wavelengths.

“We explicitly designed MATISSE to probe the inner zones of exoplanet-forming disks that have not been accessible before by available astronomical instrumentation,” Thomas Henning, director at MPIA and Co-PI of MATISSE points out. “I am proud and excited that the discovery of a potential vortex in the disk of HD 163296 demonstrates that we can investigate the processes that produce Earth-like planets at small distances from the host star.”

The study presented here belongs to an extensive Guaranteed Time Observation (GTO) program, which investigates the planet-forming mechanisms in the inner zones of protoplanetary disks. Over the next few years, the GTO program will study many more systems like HD 163296. This way, it will improve our understanding of how the formation of Earth-like planets proceeds around a wide variety of young stars.

"This first scientific result marks the starting point for further research. One of the goals is to study stars with dust disks and specifically those in which Earth-like planets can form," says Gerd Weigelt, director at MPIfR, who led a long involvement in the development of MATISSE as head of the Infrared Interferometry Research Group at the institute.

 

Source: Max Planck Institute for Radio Astronomy

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Contact

Dr. Markus Nielbock
Press and public relations officer
Phone:+49 6221 528-134
Max Planck Institute for Astronomy, Heidelberg

Dr. Norbert Junkes
Press and public relations
Phone:+49 2 28525-399
Max Planck Institute for Radio Astronomy, Bonn

Dr. Roy van Boekel
Head of Protoplanetary Disk Science Group
Phone:+49 6221 528-405
Max Planck Institute for Astronomy, Heidelberg

Prof. Dr. Thomas K. Henning
Director
Phone:+49 6221 528-200
Max Planck Institute for Astronomy, Heidelberg

Prof. Dr. Gerd Weigelt
Director
Phone:+49 228 525-243
Max Planck Institute for Radio Astronomy, Bonn

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Original publication

1. J. Varga, M. Hogerheijde, R. van Boekel et al.

The asymmetric inner disk of the Herbig Ae star HD 163296 in the eyes of VLTI/MATISSE: evidence for a vortex?
Astronomy & Astrophysics (2021)
DOI

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MATISSE sees first light at ESO´s Paranal Observatory in Chile
MPIA Institute announcement from 5 March 2018

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Links

MATISSE

Description of the MATISSE-Instrument

MATISSE

Online manual of the MATISSE instrument

Very Large Telescope Interferometer (VLTI)
 

Description of the VLT(I)

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ALMA captures distant colliding galaxy dying out as it loses the ability to form stars

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA  have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression.  Credit: ESO/M. Kornmesser

Galaxies begin to “die” when they stop forming stars, but until now astronomers had never clearly glimpsed the start of this process in a far-away galaxy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have seen a galaxy ejecting nearly half of its star-forming gas. This ejection is happening at a startling rate, equivalent to 10 000 Suns-worth of gas a year — the galaxy is rapidly losing its fuel to make new stars. The team believes that this spectacular event was triggered by a collision with another galaxy, which could lead astronomers to rethink how galaxies stop bringing new stars to life.

“This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to ‘die’ because of a massive cold gas ejection,” says Annagrazia Puglisi, lead researcher on the new study, from the Durham University, UK, and the Saclay Nuclear Research Centre (CEA-Saclay), France. The galaxy, ID2299, is distant enough that its light takes some 9 billion years to reach us; we see it when the Universe was just 4.5 billion years old.

The gas ejection is happening at a rate equivalent to 10 000 Suns per year, and is removing an astonishing 46% of the total cold gas from ID2299. Because the galaxy is also forming stars very rapidly, hundreds of times faster than our Milky Way, the remaining gas will be quickly consumed, shutting down ID2299 in just a few tens of million years.

The event responsible for the spectacular gas loss, the team believes, is a collision between two galaxies, which eventually merged to form ID2299. The elusive clue that pointed the scientists towards this scenario was the association of the ejected gas with a “tidal tail”. Tidal tails are elongated streams of stars and gas extending into interstellar space that result when two galaxies merge, and they are usually too faint to see in distant galaxies. However, the team managed to observe the relatively bright feature just as it was launching into space, and were able to identify it as a tidal tail.

Most astronomers believe that winds caused by star formation and the activity of black holes at the centres of massive galaxies are responsible for launching star-forming material into space, thus ending galaxies’ ability to make new stars. However, the new study published today in Nature Astronomy suggests that galactic mergers can also be responsible for ejecting star-forming fuel into space.

“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” says study co-author Emanuele Daddi of CEA-Saclay. Because of this, some of the teams that previously identified winds from distant galaxies could in fact have been observing tidal tails ejecting gas from them. “This might lead us to revise our understanding of how galaxies ‘die’,” Daddi adds.

Puglisi agrees about the significance of the team’s finding, saying: “I was thrilled to discover such an exceptional galaxy! I was eager to learn more about this weird object because I was convinced that there was some important lesson to be learned about how distant galaxies evolve.“

This surprising discovery was made by chance, while the team were inspecting a survey of galaxies made with ALMA, designed to study the properties of cold gas in more than 100 far-away galaxies. ID2299 had been observed by ALMA for only a few minutes, but the powerful observatory, located in northern Chile, allowed the team to collect enough data to detect the galaxy and its ejection tail. 

“ALMA has shed new light on the mechanisms that can halt the formation of stars in distant galaxies. Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution,” says Chiara Circosta, a researcher at the University College London, UK, who also contributed to the research.

In the future, the team could use ALMA to make higher-resolution and deeper observations of this galaxy, enabling them to better understand the dynamics of the ejected gas. Observations with the future ESO’s Extremely Large Telescope could allow the team to explore the connections between the stars and gas in ID2299, shedding new light on how galaxies evolve.

More Information

This research was presented in the paper “A titanic interstellar medium ejection from a massive starburst galaxy at z=1.4” to appear in Nature Astronomy (doi: 10.1038/s41550-020-01268-x).

The team is composed of A. Puglisi (Centre for Extragalactic Astronomy, Durham University, UK and CEA, IRFU, DAp, AIM, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, CNRS, France [CEA]), E. Daddi (CEA), M. Brusa (Dipartimento di Fisica e Astronomia, Università di Bologna, Italy and INAF-Osservatorio Astronomico di Bologna, Italy), F. Bournaud (CEA), J. Fensch (Univ. Lyon, ENS de Lyon, Univ. Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon, France), D. Liu (Max Planck Institute for Astronomy, Germany), I. Delvecchio (CEA), A. Calabrò (INAF-Osservatorio Astronomico di Roma, Italy), C. Circosta (Department of Physics & Astronomy, University College London, UK), F. Valentino (Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen and DTU-Space, Technical University of Denmark, Denmark), M. Perna (Centro de Astrobiología (CAB, CSIC–INTA), Departamento de Astrofísica, Spain and INAF-Osservatorio Astrofisico di Arcetri, Italy), S. Jin (Instituto de Astrofísica de Canarias and Universidad de La Laguna, Dpto. Astrofísica, Spain), A. Enia (Dipartimento di Fisica e Astronomia, Università di Padova, Italy [Padova]), C. Mancini (Padova) and G. Rodighiero (Padova and INAF-Osservatorio Astronomico di Padova, Italy).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (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 Ministry of Science and Technology (MOST) 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.

The original press release was published by the European Southern Observatory (ESO), an ALMA partner on behalf of Europe.

Source: Atacama Large Millimeter/submillimeter Array (ALMA)/Press Releases

 Contacts

Valeria Foncea
Education and Public Outreach Manager
Joint ALMA Observatory Santiago - Chile
Phone: +56 2 2467 6258
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Email: valeria.foncea@alma.cl

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ESO Public Information Officer
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Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
News and Public Information Manager
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Masaaki Hiramatsu

 Education and Public Outreach Officer, NAOJ Chile
Observatory, Tokyo - Japan
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Email: hiramatsu.masaaki@nao.ac.jp

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Back to the Beginning: Probing the First Galaxies with Webb

A spectacular firestorm of star birth suddenly lit up the heavens and populated the first galaxies when the universe was less than five percent of its current age. This fiery flurry—possibly the cosmos' busiest star-forming period—occurred just a few hundred million years after the big bang. Soon, through the power of NASA's James Webb Space Telescope (JWST), astronomers will look back to that raucous, early period in a deep-sky survey to trace the formation and evolution of the first galaxies.

This is a Hubble Space Telescope view of a portion of GOODS-South, the southern field of a large deep-sky study by several observatories to trace the formation and evolution of galaxies. The image shows a rich tapestry of 7,500 galaxies stretching back through most of the universe's history. The farthest galaxies, a few of the very faint red specks, are seen as they appeared more than 13 billion years ago, or roughly 650 million years after the Big Bang. Soon, the James Webb Space Telescope will peer back even farther into this field to trace the formation and evolution of the very first galaxies. Credits: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, and M. Rutkowski (Arizona State University, Tempe), R. O'Connell (University of Virginia), P. McCarthy (Carnegie Observatories), N. Hathi (University of California, Riverside), R. Ryan (University of California, Davis), H. Yan (Ohio State University), and A. Koekemoer (Space Telescope Science Institute). Hi-res image

Called JADES—the JWST Advanced Deep Extragalactic Survey—this large, ambitious survey totals nearly 800 hours of observing time. The survey takes advantage of Webb's sensitivity to infrared light, which has longer wavelengths than visible light and is invisible to the human eye.

"Galaxies, we think, begin building up in the first billion years after the big bang, and sort of reach adolescence at 1 to 2 billion years. We're trying to investigate those early periods," explained JADES teammate Daniel Eisenstein, a professor of astronomy at Harvard University.   "We must do this with an infrared-optimized telescope because the expansion of the universe causes light to increase in wavelength as it traverses the vast distance to reach us. So even though the stars are emitting light primarily in optical and ultraviolet wavelengths, that light is shifted quite relentlessly out into the infrared. Only Webb can get to the depth and sensitivity that's needed to study these early galaxies."

Joining Forces

The JADES survey is a collaboration of two Webb instrument teams granted Guaranteed Time Observations: the Near Infrared Camera (NIRCam) and the Near Infrared Spectrograph (NIRSpec) teams. The program combines the imaging of NIRCam and the spectroscopic capabilities of NIRSpec with Webb's Mid-Infrared Instrument (MIRI), which boasts both a camera and a spectrograph. Through the use of coordinated, parallel observations, the JADES team will get the best out of all three instruments. 

Scientists will then combine Webb's results with the deepest data from NASA's Hubble Space Telescope, NASA's Chandra X-ray Observatory, and the ground-based Atacama Large Millimeter/submillimeter Array and Jansky Very Large Array radio telescopes to produce an unprecedented view of the universe's very earliest galaxies. By studying galaxies across all these wavelengths, scientists will get a complete picture, allowing them to analyze the light of the galaxies' stars, the dust and the interstellar medium, and the supermassive black holes that are thought to reside within these galaxies. 

Galaxies Through Time 

Discover how telescopes make it possible to look back in time and study the history of the universe, and how NASA’s James Webb Space Telescope will fill in new details on galaxy evolution over time. The earliest pages of cosmic history are blank, but Webb will allow us to look back farther in time than ever before, helping to fill in the lost pages of the universe’s story.  Credits: NASA, ESA, CSA, and L. Hustak and D. Player (STScI).

 

More than 13 billion years ago, during the Era of Reionization, the universe was a very different place. The gas between galaxies was largely opaque to energetic light, making it difficult to observe young galaxies. What allowed the universe to become completely ionized, or transparent, eventually leading to the "clear" conditions detected in much of the universe today? The James Webb Space Telescope will peer deep into space to gather more information about objects that existed during the Era of Reionization to help us understand this major transition in the history of the universe. Credits: NASA, ESA, and J. Kang (STScI). Hi-res image

Studying Familiar Fields

The team chose two, previously well-studied fields from the Great Observatories Origins Deep Survey (GOODS) for their observations. GOODS united extremely deep observations from NASA's Spitzer, Hubble, and Chandra, as well as ESA's Herschel and XMM-Newton space telescopes, and from the most powerful ground-based facilities to survey the faintest light then detectable in the distant universe across the electromagnetic spectrum. The survey covered two large fields, GOODS-North and GOODS-South, which are located in the northern constellation Ursa Major and the southern constellation Fornax, respectively. GOODS-South also contains the Hubble Ultra Deep Field, which is to this day the deepest, most sensitive image of the sky ever taken with Hubble. Now, looking at the same areas, Webb will go even deeper.

"We chose these fields because they have such a great wealth of supporting information. They've been studied at many other wavelengths, so they were the logical ones to do," said Marcia Rieke, who co-leads the JADES Team with Pierre Ferruit of the European Space Agency (ESA). Rieke is also the principal investigator on Webb's NIRCam instrument and a professor of astronomy at the University of Arizona.

The team is also observing the two widely separated fields to study the differences between the number of galaxies at different distances in one field, as compared with the other.

Seeing the Formation of Galaxies, Stars and Black Holes

How rapidly galaxies form and assemble, and how quickly and where they form their stars are still open questions. Several ambitious goals of the JADES program include understanding the distribution of stellar mass in infant galaxies, as well as stellar luminosity, star-formation rates, and stellar age, size and composition. JADES will also analyze galaxies' nuclear activity, determine galaxy structure, and map gas movement over a wide range of distances.

Another goal of the program is understanding the properties of the first generation of black holes. Scientists have measured a tight relationship between the mass of a galaxy's central black hole and the mass of that galaxy's bulge, but how that occurs is currently only the stuff of models and speculation. The JADES team hopes to illuminate the nature of this relationship.

Scientists know these supermassive black holes were already in place with billions of solar masses less than 1 billion years after the big bang, which is less than 10 percent of the universe’s current age. But how such enormous black holes came about so early in the universe is very difficult to understand. 

"We hope to detect the primeval seeds of these monster black holes, the smaller black holes that formed soon after the big bang, and to understand what were their masses, how they were accreting mass, and where they were located," explained JADES teammate Roberto Maiolino, a member of ESA's NIRSpec Instrument Science Team and a professor of experimental astrophysics at the University of Cambridge in the United Kingdom. "For a long time, Webb will be the only facility to possibly detect and understand the processes that later on resulted in these monsters that were already created in the early universe."

Seeking the First Stars

Another mystery involves the gas between the galaxies, which astronomers know today is highly ionized and transparent. But in the first million years, it was not ionized—it was neutral gas that was opaque. How the transition from neutral to ionized gas—from opaque to transparent—occurred is something that scientists have been trying to understand for a long time.

"This transition is a fundamental phase change in the nature of the universe," said JADES teammate Andrew Bunker, another member of the ESA NIRSpec Instrument Science Team and a professor of astrophysics at the University of Oxford in the United Kingdom. "We want to understand what caused it. It could be that it's the light from very early galaxies and the first burst of star formation." 

The JADES team hopes to discover this first population of extremely massive, luminous and hot stars to form after the big bang. "That’s kind of one of the Holy Grails, to find the so-called Population III stars that formed from the hydrogen and helium of the big bang," explained Bunker. "People have been trying to do this for many decades and results have been inconclusive so far." 

Why Webb?

The extremely distant targets of the JADES team appear very small and faint, and their light is often completely shifted beyond optical wavelengths. For these reasons, these objects can only be observed with superlative infrared capability of a large, cold telescope. Webb was built specifically for this purpose; this was one of the major science cases driving its design. 

Because of Webb's sheer size, it will have spatial resolution in the infrared similar to what astronomers have enjoyed with Hubble. Webb will give them a much clearer view at long wavelengths than they have ever had before. 

Webb's ability to get simultaneous spectra of multiple objects at infrared wavelengths is another critical aspect of the JADES program. NIRSpec will be able to target more than 100 galaxies at one time, taking a spectrum of each.

Webb's much larger collecting area, its ability to observe fainter galaxies, and its capacity to simultaneously study multiple objects in a way that scientists have not been able to do before make ambitious, large surveys such as JADES possible for the first time.

"We tend to talk about projects like this in the context of theories and models that we have right now," said Rieke. "But I'm hoping that with Webb we'll find something that we haven't suspected at all—that there will be some new surprise—and that will be great fun!"

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

For more information about Webb, visit www.nasa.gov/webb.

Ann Jenkins / Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland
410-338-4488 / 410-338-4366
jenkins@stsci.edu / cpulliam@stsci.edu

Editor: Lynn Jenner

Source:  NASA/Solar System and Beyond

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