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THE FREE MULTIMEDIA MAGAZINE THAT KEEPS YOU UPDATED ON WHAT IS HAPPENING IN SPACE

Bi-monthly magazine of scientific and technical information ✶ March-April 2018 issue News from the TRAPPIST-1 system ExTrA goes into action

• ESO’s VLT working as 16-metre telescope for first time • Keck Observatory achieves first light with NIRES • Giant bubbles on red giant star’s surface • First ELT main mirror segments successfully cast • SMBHs−host galaxies co-evolution deepened by ALMA AWR star at the origin of the Solar System

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S U M M A R Y

BI-MONTHLY MAGAZINE OF SCIENTIFIC AND TECHNICAL INFORMATION News from the TRAPPIST-1 system FREELY AVAILABLE THROUGH In the last year, many studies dedicated to the extraordinary TRAPPIST-1's planetary system have been THE INTERNET realised and published. Sometimes, works published a short distance from each other have described antithetical scenarios, but as a whole, the efforts made by researchers portrayed that system even... March-April 2018 4

ESO’s VLT working as 16-metre telescope for first time One of the original design goals of ESO’s Very Large Telescope (VLT) was for its four Unit Telescopes (UTs) to work together to create a single giant telescope. With the first light of the ESPRESSO spectrograph 14 using the four-Unit-Telescope mode of the VLT, this milestone has now been reached. After extensive...

Keck Observatory achieves first light with NIRES Astronomers at W. M. Keck Observatory have successfully met a major milestone after capturing the very first science data from Keck Observatory’s newest instrument, the Caltech-built Near-Infrared Echel- 20 lette Spectrometer (NIRES). The Keck Observatory-Caltech NIRES team just completed the instrument’s...

A Wolf-Rayet star at the origin of the Solar System We know the way many structures in the universe evolved following their origin, but in many cases we have not yet understood which phenomenon produced the origin itself. This is the case with our Solar 22 System, for which the dominant thinking is that it was born because of a shock wave from a supernova... English edition of the magazine lA’ STROFILO Researchers catch supermassive black hole burping−twice Astronomers have caught a supermassive black hole in a distant galaxy snacking on gas and then “burp- Editor in chief ing” — not once, but twice. The galaxy under study, called SDSS J1354+1327 (J1354 for short), is about Michele Ferrara 32 800 million light-years from Earth. The team used observations from NASA’s Hubble Space Telescope... Scientific advisor Prof. Enrico Maria Corsini Giant bubbles on red giant star’s surface Publisher Astro Publishing di Pirlo L. Located 530 light-years from Earth in the constellation of Grus (The Crane), π1 Gruis is a cool red giant. Via Bonomelli, 106 It has about the same mass as our Sun, but is 350 times larger and several thousand times as bright. 25049 Iseo - BS - ITALY Our Sun will swell to become a similar red giant star in about five billion years. An international team... email [email protected] 34 Internet Service Provider Aruba S.p.A. ExTrA goes into action Via San Clemente, 53 24036 Ponte San Pietro - BG - ITALY A strategic instrument has become operative in the search for Earth-like planets orbiting red dwarf stars located at relatively short distances from us. Its name is ExTrA. From the ground, it will be able to dis- Copyright cover planets as small as other telescopes can detect from space, and it will help to compile a list of... All material in this magazine is, unless 38 otherwise stated, property of Astro Publishing di Pirlo L. or included with permission of its author. Reproduction or retransmission of the materials, in The archaeology of our Milky Way’s ancient hub probed by Hubble whole or in part, in any manner, with- For many years, astronomers had a simple view of our Milky Way’s central hub, or bulge, as a quiescent out the prior written consent of the place composed of old stars, the earliest homesteaders of our galaxy. However, because the inner Milky copyright holder, is a violation of copy- Way is such a crowded environment, it has always been a challenge to disentangle stellar motions... right law. A single copy of the materi- 46 als available through this course may be made, solely for personal, noncom- mercial use. Users may not distribute such copies to others, whether or not First ELT main mirror segments successfully cast in electronic form, whether or not for The 39-metre-diameter primary mirror of ESO’s Extremely Large Telescope will be by far the largest ever a charge or other consideration, with- made for an optical-infrared telescope. Such a giant is much too large to be made from a single piece out prior written consent of the copy- of glass, so it will consist of 798 individual hexagonal segments, each measuring 1.4 metres across and... right holder of the materials. The 48 publisher makes available itself with having rights for possible not charac- terized iconographic sources. SMBHs−host galaxies co-evolution deepened by ALMA Advertising - Administration Using the Atacama Large Millimeter/submillimeter Array (ALMA) to observe an active galaxy with a strong Astro Publishing di Pirlo L. ionized gas outflow from the galactic center, astronomers have obtained a result making themselves Via Bonomelli, 106 even more puzzled: an unambiguous detection of carbon monoxide (CO) gas associated with the... 25049 Iseo - BS - ITALY 50 email [email protected]

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4 EXOPLANETS

News from the system

by Michele Ferrara

In the last year, many studies dedicated to the extraordinary TRAPPIST-1's planetary system have been realised and published. Sometimes, works published a short distance from one another have described antithetical scenarios, but as a whole, the efforts made by researchers portrayed the system as even more interesting.

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EXOPLANETS 5

TRAPPIST-1

his artist’s impression compares the seven planets orbiting the rom time to time it is unavoidable to go T ultra-cool red dwarf star TRAPPIST-1 to the Earth at the same back to talking about TRAPPIST-1, a decid- scale. New observations, when combined with very sophisticated F edly dwarf and relatively cold star, around analysis, have now yielded good estimates of the densities of all which there are as many as seven planets of a seven of the Earth-sized planets and suggest that they are rich in size comparable to that of Earth’s. We had al- volatile materials, probably water. They are shown to the same ready talked about this system a couple of years scale but not in the correct relative positions. [ESO/M. Kornmesser] ago (2016; 4), on the occasion of the discovery

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of the first three planets. Then again a to give an update on the leading news his infographic year ago (2017; 2), when we reported the concerning the system in the last year, in- T compares the discovery of the other four, and the possi- cluding the most recent and exciting stud- TRAPPIST-1 plane- bility that above some water may exist and ies published in specialised magazines. tary system with therefore an environment perhaps favour- We were left with uncertainties regarding the inner Solar Sys- tem and the four able to life as we know it. Now, we want the distance from the star of the outermost Galilean moons of the planet Jupiter. Left, this diagram compares the masses and energy input of the seven TRAPPIST-1 plan- ets, along with the properties of the four innermost Solar System plan- ets. [NASA/JPL- Caltech]

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his diagram planet, TRAPPIST-1h, a fundamental para- TRAPPIST-1h was found to be 18.76 days, T compares the meter to understand whether liquid water which corresponds to an average distance sizes, masses and can exist in that world (admitted and not from the star of 9.27 million km, too exces- estimated tem- granted that there is water). A team of re- sive to suppose that liquid water can exist peratures of the searchers, led by Rodrigo Luger of the Uni- on that planet. Thus, the Luger team ex- TRAPPIST-1 plan- ets with Solar versity of Washington, intervened to solve cluded the farthest planet from the TRAP- System planets. the problem. In an article published in Na- PIST-1’s habitable zone, after the two The colours indi- ture Astronomy last May, the team reports closest ones, TRAPPIST-1b and TRAPPIST-1c, cate temperatures the results of processing the photometric had already been considered uninhabit- and the black line data of TRAPPIST-1 collected by the Kepler able, not only for the maximum surface matches the den- space telescope between December 2016 temperatures (higher than 100°C), but also sities and compo- and March 2017. because their rotation periods are surely sition of the ter- In this period, known as K2 Campaign 12, synchronized with their revolution peri- restrial planets in Kepler monitored the small star for 74 ods, which leads them to always expose the Solar System. days, providing the longest, nearly contin- the same hemisphere to the star radiation, Planets above the line are less uous set of observations of TRAPPIST-1. with non-positive consequences. dense and plan- This data allowed the researchers to study At that point, many exoplanet specialists ets below are the mutual gravitational interactions be- focused their attention on the four planets denser. [ESO/S. tween planets and to better characterise almost certainly orbiting in the habitable Grimm et al.] the individual orbits. The orbital period of zone: TRAPPIST-1d, TRAPPIST-1e, TRAPPIST-1f

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8 EXOPLANETS

his artist's concept appeared on the Feb. 23, 2017, cover T of the journal Nature announcing that the nearby star TRAPPIST-1, an ultra-cool dwarf, has seven Earth-sized planets orbiting it. Now, astronomers have used NASA's Hubble Space Telescope to conduct the first spectroscopic survey of the Earth-sized planets (d, e, f, and g) within TRAPPIST-1's habitable zone. [Artist's Concept: NASA and JPL/Caltech. Science: NASA, ESA, J. de Wit (MIT), H. Wake- ford (University of Exeter/STScI), and N. Lewis (STScI)]

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stronomers used AHubble to ana- lyze light from the nearby star TRAP- PIST-1 that passed through the atmo- spheres of four Earth-sized planets in the star’s habit- able zone. This zone is a region at a dis- tance from the star where liquid water, the key to life as we know it, could exist on the planet's sur- faces. The astrono- mers were looking for the signatures of certain gases, includ- ing hydrogen, in the atmospheres that were imprinted on the starlight. The graphic at the top shows a model spec- trum containing the signatures of gases the astronomers would expect to see if the exoplanets’ atmospheres were puffy and dominated by primordial hydrogen from the distant worlds’ formation. The Hubble Space Telescope observations, however, revealed that the planets do not have hydrogen-dominated atmospheres. The flat spectrum shown in the illustration at the bottom indicates that Hubble did not spot any traces of water or methane, which are abundant in hydrogen-rich atmospheres. The researchers concluded that the atmospheres are composed of heavier ele- ments residing at much lower altitudes than could be measured by the Hubble observations. [NASA, ESA, and Z. Levy (STScI)]

and TRAPPIST-1g, about 3 to 7 million km away from date life. Indeed, CfA researchers estimate that under the star. The enthusiasm generated by these poten- those conditions, life has less than a 1% chance of ap- tially Earth-like planets, however, was somewhat lack- pearing compared to the Earth. ing in the following months. Indeed, in June and July, The second CfA team, led by Cecilia Garraffo, and also two teams of researchers from Harvard-Smithsonian attended by the University of Massachusetts, high- Center for Astrophysics (CfA) announced the results of lighted another deadly threat to those planets. Like two independent studies on the effects of red dwarf’s the Sun, even TRAPPIST-1 pours copious amounts of stellar activity in the surrounding environment and high-energy particles into the surrounding space, but therefore on the planets. as the dwarf is much closer to its worlds, the stellar One of the two teams of researchers, led by Manasvi wind pressure that invests them is 1000 to 100,000 Lingam, focused on the consequences of TRAPPIST-1’s times greater than that exerted on the Earth by the ultraviolet radiation on the planetary system. As that solar wind. As the stellar wind carries with it the mag- radiation is much more intense than that from the Sun netic field associated with the particles, researchers which hits the Earth, researchers came to the conclu- claim (in an article in The Astrophysical Journal Let- sion that the atmospheres of those worlds could be ters) that this specific magnetic field can be directly destroyed in a short time, astronomically speaking. connected to the magnetic fields of the individual This scenario, described in the International Journal of planets. If this is the case, the flux of particles emitted Astrobiology, obviously clashes with the possibility all around by TRAPPIST-1 would continuously affect that the dwarf star’s planetary system can accommo- the atmospheres, which would gradually be eroded

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until complete evaporation. In short, the to life. To obtain a reliable estimate, the rtist’s im- two CfA studies warn against easy enthu- two researchers took into account some Apression of siasm, even if, as researchers themselves key parameters, such as the speed at which the TRAPPIST-1 point out, their conclusions do not entirely the dwarf orbits around the galactic centre system, showcas- ing all seven exclude the possibility that life forms may (a speed that increases with age), its atmo- planets in various exist around TRAPPIST-1 or other red spheric composition (also the quantity of phases. When a dwarfs. Shortly after the publication of metals increases with age), and the num- planet transits these works, near the middle of August last ber of harsh flares that occurred during the across the disk of year, the results of another study con- observation periods. All of the parameters the red dwarf ducted by Adam Burgasser (University of considered indicate that the age of TRAP- host star, as two California, San Diego) and Eric Mamajek PIST-1 is significantly higher than that of of the planets (NASA / JPL) were published in The Astro- the Sun and is likely between 5.4 and 9.8 here are shown to do, it creates a physical Journal. The goal was to establish billion years old. Such an advanced age af- dip in the star’s the TRAPPIST-1’s age, a fundamental datum fects both negatively and positively the light that can be to understand the extent to which its plan- possible habitability of those worlds. On detected from etary system can be hostile or favourable the negative side, in such a long period of Earth. [NASA]

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hese spectra show the chemical makeup of the atmospheres of four Earth-size planets orbiting within or near the habitable T zone of the nearby star TRAPPIST-1. The habitable zone is a region at a distance from the star where liquid water, the key to life as we know it, could exist on the planets’ surfaces. To obtain the spectra, astronomers used the Hubble Space Telescope to collect light from TRAPPIST-1 that passed through the exoplanets’ atmospheres as the alien worlds crossed the face of the star. The purple curves show the predicted signatures of gases such as water and methane that absorb certain wavelengths of light. These gases would be found in a puffy hydrogen-dominated atmosphere similar to gaseous planets such as Neptune. The Hubble results, noted by the green crosses, reveal no evidence of an extended atmosphere in three of the exoplanets (TRAPPIST-1d, f, and e). Additional observations are needed to rule out a hydrogen-dominated atmosphere for the fourth planet (TRAPPIST-1g). The evidence indicates that the atmospheres are more compact than could be measured by the Hubble observations. [NASA, ESA, and Z. Levy (STScI)]

time the mass of the star has surely managed to syn- spheric winds that situation can generate). On the pos- chronise the rotation periods of all of the planets with itive side, however, an old red dwarf produces less their respective revolution periods, making the hemi- flares than a younger one, and it’s, therefore, less dev- spheres facing the star too hot, and those in the shade astating for any possible life forms living in the system. too cold (without considering the powerful atmo- Moreover, if the planets are still where we see them

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after billions of years (they have migrated site seems to be true, and this is because his infographic there in remote times from more external despite those planets sizes being compara- T lists the main orbits), it means that the system is stable, ble to that of Earth’s, they have lower av- properties of the and we know well how stability is neces- erage densities, which means that a seven TRAPPIST-1 sary for life to appear and evolve. How- significant part of their mass could be in a planets, along ever, the advanced TRAPPIST-1’s age raises gaseous state. In other words, those plan- with the four in- some doubts about the actual existence of ets are more than likely surrounded by a nermost planets in the Solar System atmospheres around its planets. Indeed, rather thick atmosphere. at the same scale. even neglecting the fateful scenario of Assuming that this scenario is realistic, we [NASA/JPL-Cal- magnetic fields, the extreme proximity of would have at least a couple of very posi- tech/R. Hurt, T. the whole system to the star and the expo- tive effects: the dense atmospheres would Pyle (IPAC)] Left, sure for several billion years to its radiation be able to shield a relevant part of the harm- this video takes could have led to the boiling of the atmo- ful stellar radiation; furthermore, they the viewer on a sphere. Researchers calculated that each of would favour the global redistribution of quick trip from the five innermost Earth to TRAPPIST- planets might have 1 and its seven lost, through evapo- planets. The stars ration, an average in the animation amount of water (if are accurately po- any) equivalent to a sitioned as in real- terrestrial ocean. ity. The artist’s Only the two outer impression in this video is based on planets would have the known physi- escaped that fate, cal parameters but for other rea- for the planets sons, they are not and stars seen, less hostile. To be and uses a vast precise, there is no database of evidence to confirm objects in the the evaporation of Universe. [ESO/ atmospheres. On the L. Calçada/ contrary, the oppo- spaceengine.org]

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his video tional. In the mean- T shows the time, we can try to TRAPPIST-1 sys- understand which of tem from the the planets is less hos- most distant tile to life. A large planet (TRAPPIST- team of researchers, 1h). In the video, the transits of led by Simon Grimm two inner planets (Universität Bern), can be seen, with went in this direction, the large disc of and applied very com- TRAPPIST-1g plex models to all of transiting last. the available data of The artist’s im- TRAPPIST-1’s planets, pression in this to define their densi- video is based on ties with a precision the known phys- never reached before. ical parameters The results of this for the planets study, recently pub- and stars seen, and uses a vast lished on Astronomy database of ob- the heat accumulated in the hemispheres & Astrophysics, suggest that all those plan- jects in the Uni- perpetually exposed towards the star. On ets may have retained water reserves verse. [ESO/L. the contrary, however, very dense atmo- equal to 5% of their mass, a huge amount Calçada/spaceeng spheres could easily trigger an irreversible if we consider that in the case of the Earth ine.org. Music: greenhouse effect, similar to the one pre- only 0.02% of the mass comes in the form Johan B. Monell] sent on Venus. of water. In the scenario that takes shape Correct characterisation of the atmo- from Grimm’s team’s study, if TRAPPIST-1b spheres is therefore essential to under- and TRAPPIST-1c still have an atmosphere, stand how much those planets can re- water should be present in a vapour state, semble ours, rather than Venus’ or, con- which would help make those worlds in- versely, Mars’. In this regard, the results of hospitable. The outer planets, “f”, “g” and the first spectroscopic analysis of the plan- “h”, are perhaps a little too far from the ets “d”, “e”, “f” and “g”, i.e. those that star to ensure liquid water on the surface. orbit in the TRAPPIST-1’s habitable zone, The planets “d” and “e” are more interest- were published in Nature Astronomy on 5 ing. The former is the lightest of the sys- February. This new study, led by a team of tem, it has indeed only 30% of Earth’s astronomers from the Space Telescope Sci- mass, and we do not know in what state ence Institute (STScI), revealed that at least the water (perhaps) present on it is. TRAP- the first three of those four planets are not PIST-1e is instead the most promising surrounded by a puffy, particularly hydro- planet: it is just a little smaller than the gen-rich atmosphere, like that of a mini- Earth, but it is slightly denser, features Neptune. This is a good sign, as hydrogen compatible with the presence of an iron is a greenhouse gas that makes the planets core, a rocky surface alternating with ex- inhospitable. If in the atmospheres there is panses of water, and an atmosphere that so little hydrogen not to be easily de- is not necessarily thick. tectable, this increases the likelihood that In addition to the size, density and per- heavier atoms and molecules are prepon- haps the consistency of the atmosphere, derant, like some potential biomarkers − TRAPPIST-1e is comparable to Earth also for more interesting for researchers − that the amount of radiation it receives from its could reveal the presence of life on those star. All of this, of course, does not mean planets. But to confirm this, we have to habitability or presence of life, but we can wait until next year, when NASA’s James bet that this planet will be one of Webb’s Webb Space Telescope will become opera- first targets. !

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ESO’s VLT workingas16-m for first time

by ESO

ne of the original design goals of OESO’s Very Large Telescope (VLT) was for its four Unit Tele- scopes (UTs) to work together to create a sin- gle giant tele- scope. With the first light of the ESPRESSO spec- trograph using the four-Unit- Telescope mode of the VLT, this milestone has now been reached. After extensive prepara- tions by the ESPRESSO con- sortium (led by the Astronomical Observatory of the University of her- Geneva, with the participation of re- ent focus search centres from Italy, Portugal, to feed a single Spain and Switzerland) and ESO instrument!” When staff, ESO’s Director General Xavier all four 8.2-metre Unit Barcons initiated this historic astro- Telescopes combine their light-col- nomical observation with the push lecting power to feed a single instru- ular require the of a button in the control room. ment, the VLT effectively becomes observation of distant and faint ESPRESSO instrument scientist at the largest optical telescope in the quasars, and this science goal will ESO, Gaspare Lo Curto, explains the world in terms of collecting area. benefit the most from combining historical significance of this event: Two of the main scientific goals of the light from all four Unit Tele- “ESO has realised a dream that dates ESPRESSO are the discovery and char- scopes in ESPRESSO. Both rely on back to the time when the VLT was acterisation of Earth-like planets and the ultra-high stability of the instru- conceived in the 1980s: bringing the the search for possible variability of ment and an extremely stable refer- light from all four Unit Telescopes the fundamental constants of phys- ence light source. Due to the com- on Cerro Paranal together at an inco- ics. The latter experiments in partic- plexity involved, the combination of

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either collect the light from up to all four Unit Telescopes together, in- 6-metre telescope creasing its light-gathering power, or alternatively receive light from any one of the Unit Telescopes inde- pendently, allowing for more flexi- ble usage of observing time. ESPRESSO was specially developed to exploit this infrastructure. Light from the four Unit Telescopes is routinely brought together in the VLT Interferom- eter for the study of extremely fine detail in compar- atively bright ob- jects. Project Scientist Paolo Molaro com- ments: “This im- pressive milestone is the culmination of work by a large team of scientists and engi- neers over many years. It is wonderful to see ESPRESSO working with all four Unit Telescopes and I look forward to the exciting sci- ence results to come.” Feeding the combined light into a single instru- ment will give astronomers access to information never previously avail- able. This new facility is a game changer for astronomy with high- resolution spectrographs. l i g h t It makes use of novel concepts, such from all four as wavelength calibration aided by Unit Telescopes in a laser frequency comb, providing this way, at what is unprecedented precision and re- known as an “incoherent peatability, and now the capability focus”, had not been implemented to join together the light-collecting until now. However, space for it was power of the four individual Unit built into the telescopes and the un- Telescopes. “ESPRESSO working derground structure of the moun- with all four Unit Telescopes gives his picture taintop from the start. A system of us an enticing foretaste of what T shows in highly mirrors, prisms and lenses transmits the next generation of telescopes, simplified form how the the light from each VLT Unit Tele- light collected by all four VLT such as ESO’s Extremely Large Tele- Unit Telescopes is combined in the scope to the ESPRESSO spectrograph scope, will offer in a few years,” ESPRESSO instrument, located under up to 69 metres away. Thanks to concludes ESO’s Director General, the VLT platform. [ESO/L. Calçada] these complex optics, ESPRESSO can Xavier Barcons. !

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16 SPACE CHRONICLES

Earliest galaxies spun like the Milky Way

by ALMA Observatory

n international team led by Light from distant objects takes time Dr Renske Smit from the to reach Earth, so observing objects A Kavli Institute of Cosmology that are billions of light years away at the University of Cambridge used enables us to look back in time and the Atacama Large Millimeter/sub- directly observe the formation of millimeter Array (ALMA) in Chile to the earliest galaxies. The Universe at open a new window onto the dis- that time, however, was filled with tant Universe, and have for the first an obscuring ‘haze’ of neutral hy- time been able to identify normal drogen gas, which makes it difficult star-forming galaxies at a very early to see the formation of the very first stage in cosmic history with this tele- galaxies with optical telescopes. scope. The results are reported in Smit and her colleagues used ALMA the journal Nature, and were pre- to observe two small newborn gal- sented at the 231st meeting of the axies, as they existed just 800 million American Astronomical Society. years after the Big Bang. By analyz- ing the spectral ‘fin- gerprint’ of the far- infrared light col- lected by ALMA, they were able to estab- lish the distance to the galaxies and, for the first time, see the internal motion of the gas that fueled their growth. “Until ALMA, we’ve never been able to video simulation of rotating disc. [R. Crain (LJMU) and J. Geach (U.Herts)] see the formation of A galaxies in such de-

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ata visualization – Hubble Tele- Dscope image of the night sky where the galaxies were found and two zoomed in panels of the ALMA data. [Hubble (NASA/ESA), ALMA (ESO/NAOJ/NRAO), P. Oesch (Uni- versity of Geneva) and R. Smit (Uni- versity of Cambridge)]

tail, and we’ve never been able to measure the movement of gas in galaxies so early in the Universe’s history,” said co-author Dr Stefano Carniani, from Cambridge’s Caven- dish Laboratory and Kavli Institute of Cosmology. The researchers found that the gas in these newborn galaxies swirled and rotated in a whirlpool motion, similar to our own galaxy and other, more mature galaxies much later in the Universe’s history. Despite their relatively small size – about five times smaller than the Milky Way – these galaxies were forming stars at a higher rate than other young galaxies, but the researchers were surprised to discover that the galax- ies were not as chaotic as expected. “In the early Universe, gravity caused gas to flow rapidly into the galaxies, stirring them up and form- ing lots of new stars – violent super- nova explosions from these stars also made the gas turbulent,” said Smit, who is a Rubicon Fellow at Cambridge, sponsored by the Netherlands Organization for Scien- tific Research. “We expected that young galaxies would be dynam- ically ‘messy’, due to the havoc caused by exploding young stars, but these mini-galaxies show the ability to retain order and appear well regulated. Despite their small size, they are already rapidly grow- ing to become one of the ‘adult’ galaxies like we live in today.” The data from this project on small galaxies paves the way for larger studies of galaxies during the first billion years of cosmic time. !

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3D journey through the Orion Nebula

by NASA/ESA

stronomers and visualization his image showcases both the visible-light and the infrared-light visualizations specialists from NASA’s Uni- T of the Orion Nebula. This view from the movie sequence looks down the “val- A verse of Learning program ley” leading to the star cluster at the far end. The left side of the image shows the have combined visible and infrared visible-light visualization, which fades to the infrared visualization on the right. vision of the Hubble and Spitzer These two contrasting models derive from observations by the Hubble and Spitzer space telescopes. [NASA, ESA, F. Summers, G. Bacon, Z. Levay, J. DePasquale, space telescopes to create an un- L. Frattare, M. Robberto and M. Gennaro (STScI), and R. Hurt (Caltech/IPAC)] precedented, three-dimensional, fly- through view of the picturesque The three-minute movie, which “Looking at the universe in infrared Orion Nebula, a nearby star-form- shows the Orion Nebula in both vis- light gives striking context for the ing region. Viewers experience this ible and infrared light, was released more familiar visible-light views. nearby stellar nursery “close up and to the public Thursday, Jan. 11. It is This movie provides a uniquely im- personally” as the new digital visu- available to planetariums and other mersive chance to see how new alization ferries them among new- centers of informal learning world- features appear as we shift to born stars, glowing clouds heated wide to help audiences explore fun- wavelengths of light normally in- by intense radiation, and tadpole- damental questions in science such visible to our eyes,” said Robert shaped gaseous envelopes sur- as, “How did we get here?” Hurt, lead visualization scientist at rounding protoplanetary disks. “Being able to fly through the neb- IPAC. One of the sky’s brightest Using actual scientific imagery and ula’s tapestry in three dimensions nebulas, the Orion Nebula is visible other data, combined with Holly- gives people a much better sense of to the naked eye. It appears as the wood techniques, a team at the what the universe is really like,” ex- middle “star” in the sword of the Space Telescope Science Institute in plained the Space Telescope Science constellation Orion, the Hunter, Baltimore, Maryland, and the Cal- Institute’s visualization scientist and is located about 1,350 light- tech/IPAC in Pasadena, California, Frank Summers, who led the team years away. At only 2 million years has created the best and most de- that developed the movie. “By ad- old, the nebula is an ideal labora- tailed multi-wavelength visualiza- ding depth and structure to the tory for studying young stars and tion yet of this photogenic nebula. amazing images, this fly-through stars that are still forming. It offers The fly-through enables people to helps elucidate the universe for the a glimpse of what might have hap- experience and learn about the uni- public, both educating and inspir- pened when the Sun was born 4.6 verse in an exciting new way. ing,” added Summers. billion years ago.

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his visu- Hubble and Spitzer images, Sum- T alization mers and Hurt worked with experts is an excerpt to analyze the structure inside the from a longer nebula. They first created a visible- sequence light surface, and then an underly- that explores ing structure of the infrared fea- the Orion tures. Nebula using both visible To give the nebula its ethereal feel, and infrared Summers wrote a special rendering light. Two code for efficiently combining the correlated tens of millions of semi-transparent computer elements of the gas. The custom- models were ized code allows Summers to run created this and other visualizations on based on vis- desktop workstations, rather than ible-light observations from the Hubble Space Telescope and infrared-light obser- on a supercomputing cluster. vations from the Spitzer Space Telescope. [NASA, ESA, F. Summers, G. Bacon, The other components of the neb- Z. Levay, J. DePasquale, L. Hustak, L. Frattare, M. Robberto and M. Gennaro (STScI), ula were isolated into image layers and R. Hurt (Caltech/IPAC) - Acknowledgement: R. Gendler] and modeled separately. These ele- ments included stars, protoplane- tary disks, bow shocks, and the thin gas in front of the nebula called “the veil.” After rendering, these The three-dimensional video pro- temperatures of just hundreds of layers and the gaseous nebula are vides a look at the fantastic topog- degrees. Spitzer’s infrared vision brought back together to create the raphy of the nebula. A torrent of pierces through obscuring dust to visualization. ultraviolet radiation and stellar see stars embedded deep into the The three-dimensional structures winds from the massive, central nebula, as well as fainter and less serve as scientifically reasonable stars of the Trapezium star cluster massive stars, which are brighter in approximations for imagining the have carved out a cavernous bowl- the infrared than in visible light. nebula. “The main thing is to give like cavity in the wall of a giant The new visualization helps people the viewer an experiential under- cloud of cold molecular hydrogen experience how the two telescopes standing, so that they have a way laced with dust. Astronomers and provide a more complex and com- to interpret the images from tele- visualizers worked together to plete picture of the nebula. scopes,” explained Summers. “It’s a make a three-dimensional model of The visualization is one of a new really wonderful thing when they the depths of this cavernous re- generation of products and experi- can build a mental model in their gion, like plotting mountains and ences being developed by the head to transform the two-dimen- valleys on the ocean floor. Colorful NASA’s Universe of Learning pro- sional image into a three-dimen- Hubble and Spitzer images were gram. The effort combines a direct sional scene.” then overlaid on the terrain. connection to the science and sci- This movie demonstrates the power The scientific visualization video entists of NASA’s Astrophysics mis- of multi-wavelength astronomy. It takes the viewer on a breathtaking sions with attention to audience helps audiences understand how flight through the nebula, follow- needs to enable youth, families, science is done — how and why as- ing the contours of the gas and and lifelong learners to explore tronomers use multiple regions of dust. By toggling between the Hub- fundamental questions in science, the electromagnetic spectrum to ble and Spitzer’s views, the movie experience how science is done, explore and learn about our uni- shows strikingly different details of and discover the universe for them- verse. It is also whetting astrono- the Orion Nebula. selves. mers’ appetites for what they will Hubble sees objects that glow in The three-dimensional interpreta- see with NASA’s James Webb Space visible light, which are typically in tion is guided by scientific knowl- Telescope, which will show much the thousands of degrees. Spitzer edge and scientific intuition. finer details of the deeper, infrared is sensitive to cooler objects with Starting with the two-dimensional features. !

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Keck Observatory achieves first light with NIRES

by Keck Observatory

stronomers at W. M. Keck instrument’s first set of commission- said Keck Observatory Director Hil- Observatory have success- ing observations and achieved “first ton Lewis. “NIRES is expected to be A fully met a major milestone light” with a spectral image of the one of the most efficient single-ob- after capturing the very first science planetary nebula NGC 7027. ject, near-infrared spectrographs on data from Keck Observatory’s newest “The Keck Observatory continually an eight to ten-meter telescope, de- instrument, the Caltech-built Near- strives to provide instrumentation signed to study explosive, deep sky Infrared Echellette Spectrometer that meets the high aspirations of phenomena such as supernovae and (NIRES). The Keck Observatory-Cal- our scientific community and re- gamma ray bursts, a capability that tech NIRES team just completed the sponds to changing scientific needs,” is in high demand.”

he “first-light” image from NIRES is of NGC 7027, a planetary nebula. The NIRES “The power of NIRES is that it can T spectrum shows the near-IR spectrum of this nebula dominated by emission cover a whole spectral range simul- lines of hydrogen and helium. The direct image shows NBC 7027 in the K’ filters at taneously with one observation,” 2.2 microns. [W. M. Keck Observatory] said Keith Matthews, the instru-

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be capturing Targets of Opportu- nity (ToO) – astronomical objects that unexpectedly go ‘boom.’ This capability is now more important than ever, especially with the recent discovery, announced October 16, of gravitational waves caused by the collision of two neutron stars. For the first time in history, as- tronomers around the world de- tected both light and gravitational waves of this event, triggering a new era in astronomy. “NIRES will be very useful in this new field of ‘multi-messenger’ as- tronomy,” said Soifer. “NIRES does not have to be taken off of the tele- scope, so it can respond very quickly to transient phenomena. Astrono- mers can easily turn NIRES to the event and literally use it within a IRES arrived at Keck Observatory from Caltech on April 17 and was installed on NKeck II on September 28. This long-awaited instrument is perfectly suited for moment’s notice.” time domain astronomy follow-up observations of targets identified by new surveys With its high-sensitivity, NIRES will that are designed to find transients and exotic objects. [W. M. Keck Observatory] also allow astronomers to observe extremely faint objects found with ment’s principal investigator and a Millikan postdoctoral fellow at Cal- the Spitzer and WISE infrared space chief instrument scientist at Caltech. tech about a decade ago. telescopes. Such ancient objects, like “It’s a cross-dispersed spectrograph Because NIRES will be on the tele- high-redshift galaxies and quasars, that works in the infrared from scope at all times, its specialty will can give clues about what hap- where the visual cuts off pened just after the Big out to 2.4 microns where Bang. “NIRES is yet an- the background from the other revolutionary Keck thermal emission gets se- Observatory instrument vere.” Matthews devel- developed by Keith and oped the instrument with Tom; they built our very the help of Tom Soifer, first instrument, NIRC, the Harold Brown Profes- which was so sensitive it sor of Physics, Emeritus, could detect the equiva- at Caltech and member lent of a single candle of the Keck Observatory flame on the Moon,” said Board of Directors, Jason Lewis. “Keith and Tom Melbourne, a former also developed its succes- postdoctoral scholar at sor, NIRC2, and Keith was Caltech, and University of key to the success of Toronto Department of MOSFIRE. They are instru- Astronomy and Astro- mentation pioneers, and physics Professor Dae-Sik we are grateful to them Moon, who is also associ- and the entire NIRES team ated with Dunlap Insti- IRES Principal Investigator Keith Matthews of Caltech (left) for helping Keck Obser- with W. M. Keck Observatory Director Hilton Lewis (right) tute, and started working N vatory continue to ad- after successfully achieving “first light” with a spectral image vance our technological on NIRES with Matthews of planetary nebula NGC 7027. and Soifer when he was a capabilities.” !

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AA WWoollff--RRaayyeett oorriiggiinn ooff tthhee SS

by Michele Ferrara

We know the way many structures in the universe evolved following their origin, but in many cases we have not yet understood which phenomenon produced the origin itself. This is the case with our Solar System, for which the dominant thinking is that it was born because of a shock wave from a supernova compressing a cloud of dust and gas. A recent study, however, has shown that the triggering cause could be different.

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SOLAR SYSTEM 23 ssttaarr aatt tthhee SSoollaarr SSyysstteemm

he Bubble Neb- e know a lot about the evolution stellar cloud of dust and gas was hit by the T ula (NGC 7635) of the Solar System from its birth shock wave from a supernova, with conse- is about 8000 light Wto today. Some processes we un- quent compression of the material. The years from Earth derstand in detail, others are only broad higher density regions therefore began to and originated outlines, but all in all, we have a suffi- attract other matter gravitationally until from the brilliant ciently clear framework. Conversely, we reaching concentrations and temperature Wolf-Rayet star visible to the left know very little about the mechanism that levels sufficient to trigger thermonuclear of its centre. triggered the formation of the Sun and all reactions. Thus a cluster of stars was born, [NASA, ESA, Hub- the bodies that orbit around it. The pre- one of which was the Sun. Then, the dif- ble Heritage Team] dominant hypothesis has it that an inter- ferent proper motions of individual stars

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helped to disperse the cluster relatively quickly, and the Sun continued alone its path around the centre of the galaxy. That the explosion of a supernova really triggered the birth of the Solar System is not an established truth. Indeed, though that mechanism is effective in destabilizing a cloud of interstellar material, and it is cer- tainly the most widespread mechanism in our galaxy, it is not the only blueprint for powering the formation of new stars. Moreover, in the specific case of our Solar System, a birth due to a supernova is ques- tionable because of a specific peculiarity: the anomalous initial abundance of two specific radioisotopes, aluminium-26 (26Al) and iron-60 (60Fe). These two elements are widespread in the galaxy in constant aver- age ratios with respect to their stable forms, 27Al and 56Fe, and supernova explo- sions are helpful in keeping the ratios con- stant, as they pour these radioisotopes, along with many other elements, into in- terstellar space. These elements, generi- cally called ‘metals’, end up enriching the hydrogen clouds that are mainly scattered in the galactic disk. Whenever new stars and planetary systems form under the im- pulse of a supernova, in a cloud enriched with metals, they inherit from the interstel- lar medium the 26Al/27Al and 60Fe/56Fe ratios typical of the galaxy. When the two radioisotopes combine with other elements to form complex structures, in that specific scenario the ratios with re- spect to the stable isotopes begin to change due to their decay, ending in the complete disappearance of the radioiso- topes. Aluminium-26 has a half-life of about 700,000 years, while iron-60 has a half-life of about 1.5 million years. There- fore, the only way we have to verify their presence and their abundances at the Solar System’s time zero is by studying the iso- topic variations in their decay products. Meteorites are the ideal subjects on which his image of part of the Carina Nebula T shows in its centre a Wolf-Rayet star (WR 22) whose powerful winds are thinning the gases that surround it, up to more than 2 par- secs away. In some cases, WRs can sweep re- gions of space larger than 10 parsecs. [ESO]

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delicate blue A nebula trig- gered around 20,000 years ago by the Wolf-Rayet star (WR 31a) visible at its centre. Our Solar System could have been born in a mass concentration like those distributed in the shell of this bubble. [ESA/Hub- ble & NASA, Judy Schmidt]

to perform that kind of analysis because formation of our Solar System. The progen- their mineralogical structure has remained itor of a supernova, typically a very massive substantially unaltered since the birth of star, produces 26Al in the outer layers and the Solar System. And it is precisely through expels it into space through the powerful studying the decay products of the two ra- winds driven by the pressure of the radia- dioisotopes in question that researchers tion. Radioisotope 60Fe is, however, pro- have on several occasions reached an unex- duced in the innermost regions and re- pected conclusion: the 26Al/27Al ratio, being leased during the supernova phase. 1 atom of the first element to every 20,000 It would, therefore, be reasonable to ex- atoms of the second element, is 17 times pect that, after the explosion of a super- higher than the corresponding average nova, a localised surplus of 26Al would value in the galaxy; but the 60Fe/56Fe ratio coincide with a surplus of 60Fe (with respect is 1 atom of the first element to every 50 to the galactic mean value). Instead, 60Fe million atoms of the second element, a seems to be almost absent at the very be- value much lower than the galactic aver- ginning of the Solar System. age. These differences undermine the su- What if it was not a supernova that trig- pernova hypothesis as a trigger for the gered the birth of the Solar System? Is there

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These features place them at the top of the list of the brightest stars in the universe. The very high temperature generates very powerful stellar winds (1000-2000 km/s) which, during the short life of WRs, sweep away their outer layers, leaving uncovered the red-hot innermost layers where helium is abundant. The material blown away by the stellar wind forms a giant bubble (up to tens of light-years long), which over time is enriched by the elements just pro- duced in the outer stellar layers, including 26Al. Researchers have calculated that the impetuous WR stellar winds can expel up to half of the stellar mass over a period of hundreds of thousands of years. By processing observations made by various teams of researchers, Dwarkadas and his colleagues calculated that the average amount of 26Al transferred to the shell of the bubble from a WR is equal to the mass of 3 Earths. They also determined the me- dium that carries the radioisotopes in that external environment. If the atoms of 26Al darted freely through the bubble, they would not be effectively captured by the raphic simula- another scenario that leads to the same re- shell material. For this to happen, the atoms Gtion of the sult but that can also explain the anomaly must ‘cling’ to something more voluminous. evolution of a of the two radioisotopes? Maybe so. In an We have known for decades that WRs can bubble of dust article recently published in The Astrophys- have infrared emissions attributable to the and gases around ical Journal, a team of a WR of 40 solar researchers from the uni- masses, in succes- sive periods, start- versities of Chicago and ing from the up- Clemson led by Vikram per left quadrant Dwarkadas has put for- (t = 1.27 million ward an alternative hy- years from the be- pothesis, which no longer ginning of the sees the Solar System stellar activity). born from a supernova’s Blue represents shock wave crashing into the wind-driven an interstellar cloud, but bubble, and ochre from the gravitational is the region ion- collapse of part of a bub- ised by the star, ble of material ejected by with the thick shell further out. a Wolf-Rayet star (WR). [V. Dwarkadas This type of star is very et al.] rare, gigantic (40-50 times more massive than his animation shows how stellar winds can, over millions of years, the Sun) and has very T produce bubbles inside the envelope of material that surrounds a high surface tempera- giant star. A team from the University of Chicago claims that the Solar tures, from 30,000°C to System could have formed within one of these bubbles. [V. Dwarkadas 200,000°C. and D. Rosenberg]

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his diagram shows T the decay of 26Al: a proton decays into a neutron, releasing a positron and a neu- trino as by-products; 26Al is thus trans- formed into 26Mg*, magnesium with higher energy than in its ground state; finally, the magne- sium is transformed into its stable form, 26Mg, emitting a gamma photon with energy of 1.8 MeV, a frequency that in the galaxy is related to the pres- ence of the most mas- sive stars. [ESA] presence of dust located a relatively short these, after an average journey of about distance from the photosphere. That dust is ten parsecs, travelled in about 20,000 made up of grains with sizes between about years, they reach the densest regions of 0.3 and 2 microns, and the Dwarkadas team the shell, where their speed slows to zero. has shown that larger grains can overcome Since the length of the journey is much the severe environmental conditions that shorter than the half-life of 26Al, we can surround WRs, and can, therefore, reach expect the average velocities of that iso- the shell of the enormous bubble un- tope in the space dominated by WRs to be harmed. In the model proposed by the much lower than those of the stellar team, the 26Al atoms launched into space winds, which would demonstrate the ac- are deposited on the dust grains they in- cumulation of the metal in the shell, and tercept along the way, and together with indeed this is the case. When, due to grav- itational instability, a part of the shell collapses into a centre of mass capable of spawning a new solar system, the system will con- tain more 26Al than the galactic av- erage, but it will certainly not show an excess of 60Fe, an element that remains in the WR’s core and that will not necessarily be re- leased if the star is instantly trans- formed into a black hole without going through the supernova phase. In conclusion, the Sun and our en- tire planetary system (including us) ikram V. Dwarkadas, Research Associate Professor in could be the offspring of a WR. V the Department of Astronomy and Astrophysics at Dwarkadas and his colleagues esti- the University of Chicago, is the first author of the new mate that from 1% to 16% of all study proposing a WR star as a trigger for the birth of solar-type stars could be produced our Solar System. [The University of Chicago] from those giant stars. !

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Odd behaviour of star reveals lonely black hole hiding in giant star cluster

by ESO

lobular star clusters are huge ern constellation of Vela (The Sails), days. Lead author Benjamin Giesers spheres of tens of thousands has now been studied using the (Georg-August-Universität Göttin- Gof stars that orbit most galax- MUSE instrument on ESO’s Very gen, Germany) was intrigued by the ies. They are among the oldest Large Telescope in Chile. An interna- star’s behaviour: “It was orbiting known stellar systems in the Uni- tional team of astronomers has something that was completely in- verse and date back to near the be- found that one of the stars in NGC visible, which had a mass more than ginning of galaxy growth and 3201 is behaving very oddly — it is four times the Sun — this could evolution. More than 150 are cur- being flung backwards and for- only be a black hole! The first one rently known to belong to the Milky wards at speeds of several hundred found in a globular cluster by di- Way. One particular cluster, called thousand kilometres per hour, with rectly observing its gravitational NGC 3201 and situated in the south- the pattern repeating every 167 pull.” The relationship between

ackground and video: astronomers using ESO’s MUSE instru- Bment on the Very Large Telescope in Chile have discovered a star in the cluster NGC 3201 that is behaving very strangely. It ap- pears to be orbiting an invisible black hole with about four times the mass of the Sun — the first such inactive stellar-mass black hole found in a globular cluster. This important discovery impacts on our understanding of the formation of these star clusters, black holes, and the origins of gravitational wave events. This artist’s impression shows how the star and its massive but invisible black hole companion may look, as they orbit each other in the rich heart of the globular star cluster. [ESO/L. Calçada/spaceengine.org]

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black holes and globular clusters is mation, as is the case for globular tached from the rest of the globular an important but mysterious one. clusters, stellar-mass black holes material. Movements at the centre Because of their large masses and soon become the most massive ob- of the cluster are then thought to great ages, these clusters are jects present. Generally, stellar-mass eject the majority of black holes, thought to have produced a large black holes in globular clusters are meaning only a few would survive number of stellar-mass black holes about four times as massive as the after a billion years. — created as massive stars within surrounding low-mass stars. Recent ESO’s MUSE instrument provides as- them exploded and collapsed over theories have concluded that black tronomers with a unique ability to the long lifetime of the cluster. In holes form a dense nucleus within measure the motions of thousands the absence of continuous star for- the cluster, which then becomes de- of far away stars at the same time. With this new finding, the team have for the first time been able to detect an inactive black hole at the heart of a globular cluster — one that is not currently swallowing matter and is not surrounded by a glowing disc of gas. They could es- timate the black hole’s mass through the movements of a star caught up in its enormous gravita- tional pull. From its observed prop- erties the star was determined to be about 0.8 times the mass of our Sun, and the mass of its mysterious counterpart was calculated at around 4.36 times the Sun’s mass — almost certainly a black hole. Recent detections of radio and X- ray sources in globular clusters, as well as the 2016 detection of grav- itational-wave signals produced by the merging of two stellar-mass black holes, suggest that these rel- atively small black holes may be more common in globular clusters than previously thought. Giesers concludes: “Until recently, it was assumed that almost all black holes would disappear from globular clusters after a short time and that systems like this should not even exist! But clearly this is not the case — our discovery is the first direct detection of the gravi- tational effects of a stellar-mass black hole in a globular cluster. This finding helps in understand- ing the formation of globular clus- ters and the evolution of black holes and binary systems — vital in the context of understanding grav- itational wave sources.” !

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Researchers catch supermassive black hole burping − twice

by NASA/ESA

his is an image of T galaxy SDSS J1354 +1327 (lower center) and its companion galaxy SDSS J1354+1328 stronomers have caught a cated in the center of the galaxy, (upper right). The inset panel to the right is a supermassive black hole in a the expected address for such an four-color image that A distant galaxy snacking on object. The X-ray data also provide combines Hubble red, gas and then “burping” — not once, evidence that the supermassive black green and blue filtered but twice. The galaxy under study, hole is embedded in a heavy veil of exposures with Chandra called SDSS J1354+1327 (J1354 for dust and gas. X-ray observations col- short), is about 800 million light- The results indicate that in the past, ored purple. The Hubble years from Earth. The team used the supermassive black hole in image shows the north- observations from NASA’s Hubble J1354 appears to have consumed, or ern bubble of hot ion- Space Telescope, the Chandra X-ray accreted, large amounts of gas ized gas in the vicinity Observatory, as well as the W.M. while blasting off an outflow of of a supermassive Keck Observatory in Mauna Kea, high-energy particles. The outflow black hole. The black hole appears to have Hawaii, and the Apache Point Ob- eventually switched off then turned blasted out jets of servatory (APO) near Sunspot, New back on about 100,000 years later. bright light from gas it’s Mexico. This is strong evidence that accret- accreting from the com- Chandra detected a bright, point- ing black holes can switch their panion galaxy. This like source of X-ray emission from power output off and on again over happened twice in the J1354, a telltale sign of the presence timescales that are short compared past 100,000 years. of a supermassive black hole mil- to the 13.8-billion-year age of the While astronomers have lions or billions of times more mas- universe. “We are seeing this object predicted such objects sive than our Sun. The X-rays are feast, burp, and nap, and then feast can flicker on and off produced by gas heated to millions and burp once again, which theory as a result of gas-feed- of degrees by the enormous gravi- had predicted,” said Julie Comer- ing events, this is the tational and magnetic forces near ford of the University of Colorado first time one has con- vincingly been caught in the black hole. Some of this gas will (CU) at Boulder’s Department of As- the act. The galaxy fall into the black hole, while a por- trophysical and Space Science, who pair is 800 million light- tion will be expelled in a powerful led the study. “Fortunately, we hap- years from Earth. outflow of high-energy particles. pened to observe this galaxy at a [NASA, ESA, and J. By comparing X-ray images from time when we could clearly see evi- Comerford (University Chandra and visible-light (optical) dence for both events.” of Colorado-Boulder)] images from Hubble, the team de- So why did the black hole have two termined that the black hole is lo- separate meals? The answer lies in

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a companion galaxy that is linked to from the galaxy’s center. This strip- off guard,” said CU Boulder doc- J1354 by streams of stars and gas ping was likely caused by a burst of toral student Rebecca Nevin, a produced by a collision between the radiation from the vicinity of the study co-author who used data two galaxies. The team concluded black hole, indicating that a feast- from APO to look at the velocities that clumps of material from the ing event had occurred. and intensities of light from the gas companion galaxy swirled toward To the north they found evidence and stars in J1354. “We were able the center of J1354 and then were for a shock wave, similar to a sonic to show that the gas from the north- eaten by the supermassive black boom, located about 3,000 light- ern part of the galaxy was consis- hole. The team used optical data years from the black hole. This sug- tent with an advancing edge of a from Hubble, Keck, and APO to show gests that a burp occurred after a shock wave, and the gas from the that electrons had been stripped different clump of gas had been south was consistent with an older from atoms in a cone of gas extend- consumed roughly 100,000 years outflow from the black hole.” ing some 30,000 light-years south later. “This galaxy really caught us Our Milky Way galaxy’s supermas- sive black hole has had at least one burp. In 2010, another research team discovered a Milky Way belch using observations from the orbit- ing Fermi Gamma-ray Observatory to look at the galaxy edge on. Astronomers saw gas outflows dubbed “Fermi bubbles” that shine in the gamma-ray, X-ray, and radio wave portion of the electromag- netic spectrum. “These are the kinds of bubbles we see after a black hole feeding event,” said CU postdoctoral fellow Scott Barrows. “Our galaxy’s super- massive black hole is now napping after a big meal, just like J1354’s black hole has in the past. So we also expect our massive black hole to feast again, just as J1354’s has.” Other co-authors on the new study include postdoctoral fellow Fran- cisco Muller-Sanchez of CU Boulder, Jenny Greene of Princeton Univer- sity, David Pooley from Trinity Uni- versity, Daniel Stern from NASA’s Jet Propulsion Laboratory in Pasa- dena, California, and Fiona Harri- son from the California Institute of Technology. A paper on the subject was pub- lished in a recent issue of The As- trophysical Journal and is available online. Comerford presented the team’s findings in a January 11th, 2018 press briefing at the 231st meeting of the American Astro- nomical Society held in Washing- ton D.C. !

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Giant bubbles on red giant star’s surface

by ESO

ocated 530 light- years from Earth in L the constellation of Grus (The Crane), π1 Gruis is a cool red giant. It has about the same mass as our Sun, but is 350 times larger and several thousand times as bright. Our Sun will swell to be- come a similar red giant star in about five billion years. An international team of astronomers led by Claudia Paladini (ESO) used the PIONIER in- strument on ESO’s Very Large Telescope to ob- serve π1 Gruis in greater detail than ever before. They found that the surface of this red giant has just a few convective cells, or granules, that are each about 120 million kilo- his colourful image shows the sky around the bright pair of stars π1 Gruis (centre-right, very metres across — about T red) and π2 Gruis (centre-left, bluish-white). Just right of centre the bright spiral galaxy IC 5201 a quarter of the star’s is also visible and many other fainter galaxies are scattered across this wide-field image from the diameter. Granules are Digitized Sky Survey 2. [ESO/Digitized Sky Survey 2] patterns of convection currents in the plasma of a star. As years and plays a major role in many as photospheres — of many giant plasma heats up at the centre of the astrophysical processes including en- stars are obscured by dust, which star it expands and rises to the sur- ergy transport, pulsation, stellar hinders observations. However, in face, then cools at the outer edges, wind and dust clouds on brown the case of π1 Gruis, although dust becoming darker and more dense, dwarfs. Just one of these granules is present far from the star, it does and descends back to the centre. would extend from the Sun to be- not have a significant effect on the This process continues for billions of yond Venus. The surfaces — known new infrared observations.

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π1 Gruis is one of the brightest members of the rare S class of stars that was first defined by the Ameri- can astronomer Paul W. Merrill to group together stars with similarly unusual spectra. π1 Gruis, R An- dromedae and R Cygni became pro- totypes of this type. Their unusual spectra is now known to be the re- sult of the “s-process” or “slow neu- tron capture process” — responsible for the creation of half the elements heavier than iron. When π1 Gruis ran out of hydrogen to burn long ago, this ancient star ceased the first stage of its nuclear fusion programme. It shrank as it ran out of energy, causing it to heat up to over 100 million degrees. These extreme temperatures fueled the star’s next phase as it began to fuse helium into heavier atoms such as carbon and oxygen. This intensely hot core then expelled the star’s outer layers, causing it to balloon to never before been imaged in detail. stronomers using ESO’s Very hundreds of times larger than its By comparison, the Sun’s photo- ALarge Telescope have directly original size. The star we see today sphere contains about two million observed granulation patterns on is a variable red giant. Until now, the convective cells, with typical diame- the surface of a star outside the surface of one of these stars has ters of just 1500 kilometres. The vast Solar System — the ageing red giant size differ- π1 Gruis. This remarkable new image ences in the from the PIONIER instrument reveals c o n v e c t i v e the convective cells that make up the surface of this huge star. Each cell cells of these covers more than a quarter of the two stars can star’s diameter and measures about be explained 120 million kilometres across. [ESO] in part by their varying than eight solar masses end their surface gravi- lives in dramatic supernovae explo- ties. π1 Gruis sions, less massive stars like this one is just 1.5 gradually expel their outer layers, times the resulting in beautiful planetary neb- mass of the ulae. Previous studies of π1 Gruis Sun but much found a shell of material 0.9 light- larger, result- years away from the central star, ing in a much thought to have been ejected his sequence takes the viewer towards the southern constel- lower surface around 20,000 years ago. This rela- T lation of Grus (The Crane). We zoom in on the pair of stars π1 gravity and tively short period in a star's life lasts Gruis (red) and π2 Gruis (bluish-white), and the bright spiral just a few, ex- just a few tens of thousands of years galaxy IC 5201 is also visible. The final shot shows a very detailed tremely large, – compared to the overall lifetime of view of the surface of the red giant star π1 Gruis from the PIO- granules. several billion – and these observa- NIER instrument on the VLT Interferometer. [ESO/Digitized Sky Survey 2/N. Risinger (skysurvey.org) Music: Astral Electronic] While stars tions reveal a new method for prob- more massive ing this fleeting red giant phase. !

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Outflow in ultraluminous infrared galaxy observed

by ALMA Observatory

stronomers using the Atacama Large Millime- A ter/ submillimeter Array (ALMA) observed for the first time an outflow emerging from one of the nuclei in Arp 220, the closest Ultraluminous Infrared Galaxy to Earth resulting from the collision of two galaxies which are now in the process of merging. Although this object has been extensively studied, its compactness and obscuration have been a challenge for as- tronomers until now: ALMA ob- served the outflow from one of its nuclei in three dimensions (velocity and 2D spatial infor- mation). The results of this re- search appeared in The Astro- physical Journal Letters. The presence of an outflow has been previously detected in Arp 220. However, this is the first time it has been imaged and its kinematics and morphological characteristics determined. The flow is collimated, instead of the wide-angle morphology rp 220 appears to be a single, odd-looking galaxy, but is in fact a nearby example of the that is usually observed. With Aaftermath of a collision between two spiral galaxies. It is the brightest of the three galac- tic mergers closest to Earth, about 250 million light-years away in the constellation of Ser- this discovery, it is possible now pens, the Serpent. [NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collab- to start studying extragalactic oration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)] outflows at 100 pc scales, giv- ing the opportunity to research

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LMA image of Arp A 220 cores over HST image of Arp 220. The two cores (yellow), ob- scured by dust on visi- ble wavelengths, are observed by ALMA. The research team de- tected a bipolar out- flow from the western nucleus and measured its velocity. In red, the North section of the outflow, particles are moving away from Earth. In blue, the South section of the outflow, particles are moving towards Earth. [L. Barcos-Muñoz, N. Lira, J. Pinto – ALMA (NRAO/NAOJ/ESO) / Hubble Space Tele- scope – (NASA/ESA)]

feedback processes in these deeply tion, allowed us to observe inside toral Fellow at ALMA observatory, embedded galaxy nuclei. “ALMA’s this very compact and dust obscured and Principal Investigator of this re- observation wavelength, combined galaxy nucleus,” explained Loreto search. “We confirmed the presence with its high sensitivity and resolu- Barcos-Muñoz, an NRAO Postdoc- of an outflow and obtained a de- tailed image of its morphology and n enlargement of the two nuclei in Arp 220 its velocity at the same time.” A observed with ALMA. [L. Barcos-Muñoz, The new ALMA observations reveal N. Lira, J. Pinto – ALMA (NRAO/NAOJ/ESO)] a bipolar, fast, collimated outflow emerging from the western nucleus of Arp 220. The material transported from the core through the flows has a maximum speed of 840 km/s. According to Loreto Barcos-Muñoz, possible explanations for this out- flow could be energy from super- novae and momentum transfers, radiation pressure feedback, and a central AGN. Another finding that surprised the team of astron-omers is that the outflow is brighter in HCN than in CO, while the opposite is the norm for most extragalactic outflows detected to date. Further observations are needed to determine the origin of this behav- ior, but this discovery challenges the current knowledge about extraga- lactic outflow gas properties. !

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ExTrA goes into action

by Michele Ferrara

his night view shows the three domes of ExTrA under a spectacular T sky where the Orion constellation (just to the right of the centre) and the Pleiades star cluster (to the left) stand out. [ESO/Petr Horálek]

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A strategic instrument has become operative in the search for Earth-like plan- ets orbiting red dwarf stars located at relatively short distances from us. Its name is ExTrA. From the ground, it will be able to discover planets as small as other telescopes can detect from space, and it will help to compile a list of astrobiologically inter- esting atmospheres to be investigated thoroughly using the super telescopes already in an advanced phase of construction.

sign of the great vitality of astronomical research is the Anumber of new instruments that recently became operational. The latest one to have produced its ‘first light’ is called ExTrA, an acronym for Exoplanets in Transit and their Atmo- spheres that leaves no doubt about its mission. This instrument, designed by French researchers from the Université Grenoble Alpes and the French National Centre for Scientific Research (CNRS) and funded by the European Research Council and the Agence National de la Recherche, is composed

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of three Ritchey-Chrétien telescopes, 60 cm in diameter, f/8, equipped with two-lens field correctors. The telescopes are housed in three independent domes at the Euro- pean Southern Observatory’s La Silla Obser- vatory in Chile. The light collected by the mirrors, rather than being focused directly into a CCD cam- era, is transferred through optical fibre beams to a low-resolution multi-object spec- trograph and then recorded by a sensor. The reasons why French researchers adopted this innovative solution will be clearer after we explain what the ExTrA targets are and the problems involved in studying them. The mission of the new instrument is to monitor hundreds of M-type red dwarf stars, looking for temporary and very slight drops in brightness, typical of planets tran- siting the discs of stars. If the physical properties of a star are known with an excellent amount of confi- dence, a transit can provide information on the planet’s size, its orbit and, if it has an atmosphere, the composition of that atmo- sphere. The atmosphere itself filters a very small portion of starlight, adding the fin- gerprints of the molecules that compose it. Under optimal conditions, it is possible to recognise the nature of those fingerprints using spectroscopy and then to characterise the planet’s atmosphere with reasonable certainty. If the spectrum of a star is known with precision, the planetary atmosphere

can theoretically be studied both when it passes in front of the star’s verview of the ExTrA project. Astronomers now have a disc and when it passes behind it. Onew instrument for searching for potentially habitable In the second case, the very weak worlds. [ESO] spectrum produced by the planet

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he three illuminated domes of ExTrA in the fore- T ground, with numerous other structures belong- ing to the Chilean observatory La Silla in the background. [ESO/Emmanuela Rimbaud]

does not add to that of the star, as happens planet’s atmosphere is its transit across the in all the out-of-transit orbital positions. star’s disc. This is because of the high sig- Using the instruments currently available nal-to-noise ratio (S/N) required for the to researchers, the only configuration that, spectroscopic examination. Per unit of ob- in the most favourable cases, can analyse a serving time and for a given planetary size,

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better S/N ratios are achieved with stars A planet of the same diameter, on the that appear brighter, meaning those that other hand, transiting a larger, solar-type are closer to us (on average). This implies star’s disc produces an eclipse about a that the atmospheres of thousands of ex- hundred times less evident. This is another trasolar planets discovered around very dis- reason we cannot examine in detail the at- tant stars, such as the ones monitored by the Kepler space telescope, are currently out of reach for a detailed spectroscopic in- vestigation. It follows that if we want to discover ter- restrial-like atmospheres and even poten- tial biomarkers inside them, we must look for planets transiting in front of close stars. Because the S/N ratio improves as the star size decreases, our best chance of discover- ing planets is surveys of databases contain- ing M-type red dwarfs, the most common stars in the galaxy and relatively abundant in the part of the galaxy near the Sun. Calculations tell us that Earth-sized planet that passes in front of a red dwarf with a diameter one-tenth that of the Sun will eclipse 0.8% of the star’s surface.

xTrA telescopes at the ESO Observatory E in La Silla, Chile, will search for and study Earth-sized planets in orbit around nearby red dwarfs. The innovative design of ExTrA allows a higher sensitivity than previous tools. Here we see one of the three ExTrA telescopes inside its dome. [ESO/Petr Horálek] extra EN_l'Astrofilo 27/02/2018 17:00 Page 43

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hree short mospheres of most T time-lapse exoplanets discovered video sequences so far; indeed, they of the ExTrA in- were mainly searched strument under around stars similar to the La Silla sky. the Sun because they [ESO/Petr Horálek] are considered (for several good reasons) the most likely to host planets like our own. Nonetheless, an in- creasing number of rocky planets have re- cently been discovered around nearby red dwarfs: our readers will surely remember, for example, the fa- those that will become operational in the mous case of Proxima Centauri b (2016; 5). imminent future, it will finally be possible To ease their discovery, there is not only to accurately characterise that atmosphere. the favourable S/N ratio but also the fre- From the above it is clear that if we want, quency with which the planets transit. In- within a few years, to throw the first deed, the lesse massive the star, the smaller glimpse into an exoatmosphere potentially the stable orbits, and therefore the higher conducive to life as we know it, we must the chances of observing transits, including necessarily focus on the nearest red dwarfs, those of planets orbiting in the habitable discovering new Earth-sized rocky planets zone of those dwarf stars. It is estimated and drawing up a list of possible candi- that, compared to a dates for follow-up atmospheric analysis. solar-type star, plane- This is exactly the task entrusted to ExTrA. tary transits on a red Although ExTrA is certainly not the first in- dwarf are 4 to 10 strument used in this type of research, it is times more frequent. the first one with optical and electronic so- Also, at an equal dis- lutions that allow it to counteract the main tance from the star, a limitations afflicting telescopes operating planet of mass ‘x’ on the ground. produces larger varia- As mentioned, the photometric variations tions in the radial ve- produced by a planetary transit in the locity of a red dwarf light curve of a red dwarf are, in the most than in a star similar favourable cases, measurable in fractions to the Sun, and the of one-hundredth of a magnitude. chance of calculating One can therefore easily imagine how ‘x’ depends on the detrimental the movements of air masses magnitude of those in our atmosphere are to measurements. variations. When the But it’s not just a matter of seeing because mass of a planet is when the signal you want to highlight is so known, you may then small, any inaccuracy in the instruments have a rough idea of can produce ‘noise’ greater than the signal the kind of atmo- sought. It is no coincidence that no ground- sphere that sur- based instrument has yet been able to dis- rounds it. cover exoplanets with diameters less than With the most pow- twice that of the Earth. erful ground-based Even given an instrument that does not in- telescopes, especially troduce noise into the measurements and extra EN_l'Astrofilo 27/02/2018 17:00 Page 44

that does not disperse any of the useful sig- developed a new method that, in a sense, n the fore- nal, all the limitations imposed by our atmo- assigns the task of narrow band-pass filters I ground, one of sphere remain. The two most significant of to the aforementioned low-resolution multi- the domes hous- these are the efficiency with which humidity object spectrograph (R~200), that covers ing the ExTrA in the air breaks down infrared radiation the range 0.85-1.55 microns of the near in- telescopes. The size of the en- from the red dwarfs (which are particularly frared, in which there is the peak of sensi- trance is a clue to bright in that domain of the electromag- tivity of the CCD camera joined with the the small size of netic spectrum); and the atmosphere’s chro- instrument. This solution offers the double these structures: matic absorption, which unpredictably advantage of collecting much more incom- the telescope unbalances the colours of the comparison ing radiation and of being able to tune the inside takes up stars with respect to the target star, distort- colours of the target star and its comparison almost all the ing the photometric measurements. stars in specific spectral channels, solving available space. So far, researchers have tackled these prob- the problem of stellar chromatism. By suit- [ESO/Petr lems by making observations from particu- ably managing individual channels, the Horálek] larly dry sites with low air humidity, and by bandwidth, the focusing of stars and the using narrow band-pass filters. If the first recording of the signal via CCD, the French solution helps in some way, the second one team can produce light curves with a pho- thwarts it, because in this specific case the tometric accuracy of 0.02% for measure- quality of the photometry improves with ment, and with a high S/N ratio. the reduction of the filter bandwidth. In theory, ExTrA should allow the discovery But the more you tighten the band, the of planets with a minimum diameter ap- more the light signal weakens, and the proximately the same as the Earth’s radius. larger the telescope diameter must be to This new method of research also has the obtain a readable S/N ratio. To get around great advantage of being much cheaper all these obstacles, the ExTrA designers have than the classical methods. !

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The archaeology of our Milky Way’s ancient hub probedbyHubble

by NASA/ESA

or many years, astronomers inner Milky Way is such a crowded bulge reveals that our galaxy’s hub had a simple view of our Milky environment, it has always been a is a dynamic environment of stars of FWay’s central hub, or bulge, as challenge to disentangle stellar mo- various ages zipping around at dif- a quiescent place composed of old tions to probe the bulge in detail. ferent speeds, like travelers bustling stars, the earliest homesteaders of Now, a new analysis of about about a busy airport. This conclu- our galaxy. However, because the 10,000 normal Sun-like stars in the sion is based on nine years’ worth

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Search. Sets of spectra from the Eu- revious page: the vast edge-on stretch of our home galaxy, the Milky Way, ropean Southern Observatory’s Very P is seen intersecting the night sky above the silhouetted Rocky Mountains in this photograph. The Milky Way noticeably widens at lower right. This wider Large Telescope in Chile were used area is the central hub, or bulge, of our galaxy. Peering into a very narrow re- to help estimate the chemical com- gion of the core, astronomers used the Hubble Space Telescope to study the positions of stars. compositions and motions of 10,000 Sun-like stars, as seen in the inset Hubble Currently, only Hubble has sharp image. The analysis reveals that our galaxy’s bulge is an unexpectedly dynamic enough resolution to simultaneously environment of stars of various ages zipping around at different speeds, like measure the motions of thousands travelers bustling about a busy airport. The study yields important new clues of Sun-like stars at the the galaxy to the complexity of the central bulge and our Milky Way’s evolution over bil- bulge’s distance from Earth. lions of years. The Hubble image is a composite of exposures taken in near- The center of our galaxy is about infrared and visible light with Hubble’s Wide Field Camera 3. The observations 26,000 light-years away. “Before this are part of two Hubble surveys: the Galactic Bulge Treasury Program and analysis, the motions of these stars the Sagittarius Window Eclipsing Extrasolar Planet Search. The center of our was not known,” said team member galaxy is 26,000 light-years away. [NASA, ESA, and Z. Levay (STScI)] Kailash Sahu of the Space Telescope Science Institute. “You need a long of archival data from NASA’s Hubble tions of stars, and they should show time baseline to accurately measure Space Telescope. The Hubble study a different motion compared to the the positions and the motions of of this complicated, chaotic heart of older stars. The stars in our study these faint stars.” our Milky Way may provide new are showing characteristics of both The team studied Sun-like stars be- clues to the evolution of our galaxy, models. Therefore, this analysis can cause they are so abundant and eas- said researchers. help us in understanding the bulge’s ily within Hubble’s reach. Previous The research team, led by Will Clark- origin.” observations looked at brighter, son of the University of Michigan- The astronomers divided the stars aging red giant stars, which are not Dearborn, found that the motions by their chemical compositions and as plentiful because they represent of bulge stars are different, depend- then compared the motions of each a brief episode in a star’s lifetime. ing on a star’s chemical composition. group. They determined the stars’ “Hubble gave us a narrow, pencil- Stars richer in elements heavier than chemical content by studying their beam view of the galaxy’s core, but hydrogen and helium have less dis- colors and divided them in two main we are seeing thousands more stars ordered motions, but are orbiting groups according to their heavy-ele- than those spotted in earlier stud- around the galactic center faster ment (iron) abundance. The chemi- ies,” Calamida said. The Milky Way’s than older stars that are deficient in cally enriched stars are moving twice bulge is roughly one-tenth the di- heavier elements. as fast as the other population. ameter of our pancake-shaped gal- “There are many theories describing “By analyzing nine years’ worth of axy. “We next plan to extend our the formation of our galaxy and data in the archive and improving analysis to do additional observa- central bulge,” said Annalisa Cala- our analysis techniques, we have tions along different sight-lines, mida of the Space Telescope Science made a clear, robust detection of which will allow us to make a three- Institute, Baltimore, Maryland, a the differences in the motion for dimensional probe of the rich com- member of the Hubble research chemically deficient and chemically plexity of the populations in the team. “Some say the bulge formed enriched Sun-like stars,” Clarkson bulge,” Clarkson added. when the galaxy first formed about said. “We hope to continue our anal- The researchers said that this work 13 billion years ago. In this case, all ysis, which will allow us to make a is also an important pathfinder for bulge stars should be old and share three-dimensional chart of the rich NASA’s James Webb Space Telescope a similar motion. But others think chemical and dynamical complexity to probe the archaeology of the the bulge formed later in the gal- of the populations in the bulge.” Milky Way. Scheduled for launch in axy’s lifetime, slowly evolving after The astronomers based their analysis 2019, Webb is expected to more the first generations of stars were on Advanced Camera for Surveys deeply probe stellar populations in born. In this scenario, some of the and Wide Field Camera 3 data from the Milky Way bulge. The research stars in the bulge might be younger, two Hubble surveys: the Wide Field team presented its findings Thurs- with their chemical composition en- Camera 3 Galactic Bulge Treasury day, Jan. 11, at the 231st meeting of riched in heavier elements expelled Program and the Sagittarius Win- the American Astronomical Society from the death of previous genera- dow Eclipsing Extrasolar Planet in Washington, D.C. !

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First ELT main mirror segments successfully cast

by ESO

he 39-metre-diameter primary much too large to be made from a The segments will work together as mirror of ESO’s Extremely Large single piece of glass, so it will consist a single huge mirror to collect tens TTelescope will be by far the of 798 individual hexagonal seg- of millions of times as much light as largest ever made for an optical- ments, each measuring 1.4 metres the human eye. Marc Cayrel, head of infrared telescope. Such a giant is across and about 5 centimetres thick. ELT optomechanics at ESO, was pre-

he first hexagonal segments for the main mirror of ESO’s Extremely Large Telescope (ELT) are shown being success- T fully cast by the German company SCHOTT at their facility in Mainz. These segments will form parts of the ELT’s 39- metre main mirror, which will have 798 segments in total when completed. The ELT will be the largest optical telescope in the world when it sees first light in 2024. [SCHOTT/ESO]

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he SCHOTT T team that successfully casted the first ELT main mirror segments. [SCHOTT/ESO]

sent at the first castings: “It was a wonderful feel- ing to see the first segments being successfully cast. This is a major milestone for the ELT!” As with the telescope’s sec- ondary mirror blank, the ELT main mirror seg- ments are made from the low-ex- pansion ceramic material Zerodur© from SCHOTT. Zerodur© was originally developed tracts to manufacture the blanks of associated tools and procedures. for astronomical telescopes in the the first four ELT mirrors (known as The casting of the first six segments late 1960s. It has an extremely low M1 to M4, with M1 being the pri- is a major milestone, but the road coefficient of thermal expansion, mary mirror). ahead is long — in total more than meaning that even in the case of The first segment castings are im- 900 segments will need to be cast large temperature fluctuations, the portant as they allow the engineers and polished (798 for the main mir- material does not expand. Chemi- at SCHOTT to validate and optimise ror itself, plus a spare set of 133). cally, Zerodur© is very resistant and the manufacturing process and the When fully up to speed, the pro- can be polished to a high duction rate will be standard of finish. about one segment per The actual reflective layer, day. After casting, the made of aluminium or sil- mirror segment blanks ver, is usually vaporised will go through a slow onto the extremely smooth cooling and heat treat- surface shortly before a ment sequence and will telescope is put into oper- then be ground to the ation and at regular inter- right shape and polished vals afterwards. to a precision of 15 Many well-known tele- nanometres across the scopes with Zerodur© mir- entire optical surface. rors have been operating The shaping and polish- reliably for decades, in- ing will be performed by cluding ESO’s Very Large the French company Telescope in Chile. his video shows the fusion of the first ELT main mirror Safran Reosc, which will ESO has awarded this Ger- T segments. [SCHOTT AG] also be responsible for man company with con- additional testing. !

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SMBHs−host galaxies co-evolution deepened by ALMA

by ALMA Observatory

sing the Atacama Large Millimeter/ this kind of galaxies. That is crucial for un- submillimeter Array (ALMA) to ob- derstanding the full picture of the forma- Userve an active galaxy with a strong tion and evolution of galaxies and super- ionized gas outflow from the galactic cen- massive black holes”. ter, astronomers have obtained a result Answering the question “How did galaxies making themselves even more puzzled: an form and evolve during the 13.8-billion- unambiguous detection of carbon monox- year history of the universe?” has been ide (CO) gas associated with the galactic one top issue in modern astronomy. Stud- disk. However, they have also found that ies already revealed that almost all massive the CO gas which settles in the galaxy is galaxies harbor a supermassive black hole not affected by the strong ionized gas out- at their centers. In recent findings, studies flow launched from the galactic center. further showed the tight correlation be- According to a popular scenario explaining tween the mass of black holes and those the formation and evolution of galaxies of their host galaxies. This correlation sug- and supermassive black holes, radiation gests that supermassive black holes and from galactic centers, where supermassive their host galaxies have evolved together black holes are, can significantly influence and they closely interacted each other as the molecular gas (such as CO) and the star they grew, as known as the co-evolution formation activities of the galaxies. of galaxies and supermassive black holes. ALMA result shows that the ionized gas The gas outflow driven by a supermassive outflow driven by the supermassive black black hole at the galactic cen- hole does not necessarily affect its host ter recently has become the schematic view of the fact that galaxy. This result “has made the co-evo- focus of attention as it possi- A an ionized gas outflow (green) lution of galaxies and supermassive black bly is playing a key role in the driven by the central supermassive holes more puzzling,” explains Dr. Yoshiki co-evolution of galaxies and black hole does not affect the star Toba from the Academia Sinica Institute of black holes. A widely ac- formation of its host galaxy. This sit- Astronomy and Astrophysics (ASIAA, Tai- cepted idea has described this uation may occur if the ionized gas is outflowing perpendicularly to the mo- wan), and main author of this research. phenomenon as the intense lecular gas. [ALMA (ESO/NAOJ/NRAO)] “The next step is looking into more data of radiation from the galactic

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ducted their research by observing the CO and the cold dust of galaxy WISE1029. After detailed analy- sis, surprisingly they found, there is no sign of sig- nificant molecular gas outflow. Furthermore, star- forming activity is neither activated nor suppressed. This indicates that a strong ionized gas outflow launched from the supermassive black hole in WISE1029 neither significantly affect the surround- ing molecular gas nor the star formation. There have been many reports saying that the ion- ized gas outflow driven by the accretion power of a supermassive black hole has an enormous impact on surrounding molecular gas. However, it is a rare case that there is no close interaction between ion- ized and molecular gas as the researchers are re- porting this time. Yoshiki and its team’s result suggests that the radiation from a supermassive black hole does not always affect the molecular gas and star formation of its host galaxy.

mission from carbon monoxide (green) and cold Edust (red) in WISE1029 observed by ALMA. The image size is 3 square arcsecond. [ALMA (ESO/NAOJ/NRAO), Toba et al.]

center in which is the supermassive black hole ion- izes the surrounding gas, even affecting the molec- ular gas that is the ingredient of star formation. The strong radiation activates or suppresses the star for- mation of galaxies. However, “we astronomers do not understand the real relation between the activ- ity of supermassive black holes and star formation in galaxies,” says Tohru Nagao, Professor at Ehime University. “Therefore, many astronomers including us are eager to observe the real scene of the inter- action between the nuclear outflow and the star- forming activities, for revealing the mystery of the co-evolution.” Astronomers believe that DOGs har- bor actively growing supermassive black holes in their nuclei. In particular, one DOG (WISE1029 +0501, hereafter WISE1029) is outflowing gas ionized by While their result is making the co-evolution of galaxies the intense radiation from its supermassive black hole. and supermassive black holes more puzzling, Yoshiki WISE1029 is known as an extreme case concerning ion- and his team are exciting about revealing the full pic- ized gas outflow, and this particular factor has motivated ture of the scenario. He says that “understanding such the researchers to see what happens to its molecular gas. co-evolution is crucial for astronomy. By collecting sta- By making use of ALMA’s outstanding sensitivity which tistical data of this kind of galaxies and continuing in is excellent in investigating properties of molecular gas more follow-up observations using ALMA, we hope to and star-forming activities in galaxies, the team con- reveal the truth.” !

MARCH-APRIL 2018 chronicles EN_l'Astrofilo 27/02/2018 17:05 Page 53

astronomy instruments

Via Fubine, 79 - Felizzano AL - ITALY - Tel. +39 0131772241 nature & didactics [email protected] - [email protected] www.astrobioparcofelizzano.it www.facebook.com/LOasiDiFelizzano http://shop.tecnosky.it www.facebook.com/Tecnosky-146585525428890 cover EN.qxp_l'astrofilo 27/02/2018 17:01 Page 52

Dall Kirkham 350 mm f/20 23% obstruction Supremax 33 precision optics from Schott Carbon structure - 18-point floating cell Motorized Focuser 2.5" Feather Touch Ventilation and suction system of the boundary layer Weight 34 kg.

Also available in the versions Newton f/4.1 with 3" corrector Ritchey Chrétien with f/9 corrector/reducer Cassegrain Classic f/15

www.northek.it - www.facebook.com/northek.it - [email protected] - phone +39 01599521