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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 ✶ January-February 2018 issue TThhee ffiirrsstt iinntteerrsstteellllaarr aasstteerrooiidd
Chicxulub: perfect timing… for us! Fake images in astronomy
• First light for ESPRESSO • ALMA discovers cold dust around nearest star • ESA: crossing drones with satellite • Closest temperate world orbiting quiet star discovered
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S U M M A R Y
BI-MONTHLY MAGAZINE OF SCIENTIFIC AND TECHNICAL INFORMATION The first interstellar asteroid FREELY AVAILABLE THROUGH Our current technology does not allow us to reach other planetary systems, and this limitation will remain THE INTERNET for a long time. This will not prevent us, however, from closely studying asteroids and comets born light years away around stars other than the Sun. The first of those objects has already been discovered a short... January-February 2018 4
Movement of light echo around SN 2014J in M82 Voices reverberating off mountains and the sound of footsteps bouncing off walls are examples of an echo. Echoes happen when sound waves ricochet off surfaces and return to the listener. Space has its 14 own version of an echo. It’s not made with sound but with light, and occurs when light bounces off...
Hubble observes exoplanet that snows sunscreen NASA’s Hubble Space Telescope has found a blistering hot planet outside our solar system where it “snows” sunscreen. The problem is the sunscreen (titanium dioxide) precipitation only happens on the 20 planet’s permanent nighttime side. Any possible visitors to the exoplanet, called Kepler-13Ab, would...
First light for ESPRESSO ESPRESSO has achieved first light on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile. ESPRESSO was designed and built by a consortium consisting of: the Astronomical Observatory of 22 the University of Geneva and University of Bern, Switzerland; INAF–Osservatorio Astronomico di Trieste... English edition of the magazine lA’ STROFILO Chicxulub: perfect timing... for us! Two Japanese researchers have concluded that the evolution of mammals from the Cretaceous to today Editor in chief would have been entirely different if the asteroid which put an end to that period, 79 million years Michele Ferrara 24 long and dominated by dinosaurs, had fallen on areas with different petrological properties. The mass... Scientific advisor Prof. Enrico Maria Corsini ALMA discovers cold dust around nearest star Publisher Astro Publishing di Pirlo L. Proxima Centauri is the closest star to the Sun. It is a faint red dwarf lying just four light-years away in Via Bonomelli, 106 the southern constellation of Centaurus (The Centaur). It is orbited by the Earth-sized temperate world 25049 Iseo - BS - ITALY Proxima b, discovered in 2016 and the closest planet to the Solar System. But there is more to this... email [email protected] 34 Internet Service Provider Aruba S.p.A. Closest temperate world orbiting quiet star discovered Via San Clemente, 53 24036 Ponte San Pietro - BG - ITALY A team working with ESO’s High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Obser- vatory in Chile has found that the red dwarf star Ross 128 is orbited by a low-mass exoplanet every 9.9 Copyright days. This Earth-sized world is expected to be temperate, with a surface temperature that may also be... 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 NASA’s JWST early science observations revealed whole or in part, in any manner, with- Astronomers around the world will have immediate access to early data from specific science observa- out the prior written consent of the tions from NASA’s James Webb Space Telescope, which will be completed within the first five months copyright holder, is a violation of copy- of Webb’s science operations. These observing programs were chosen from a Space Telescope Science... right law. A single copy of the materi- 40 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 Ozone ups and downs in electronic form, whether or not for Climate scientists studying three decades of ozone measurements from seven satellites see a positive a charge or other consideration, with- trend in global recovery thanks to international efforts to curb ozone-depleting substances. The part of out prior written consent of the copy- Earth’s atmosphere with high concentrations of ozone gas protects life on Earth from the Sun’s ultra... right holder of the materials. The 42 publisher makes available itself with having rights for possible not charac- terized iconographic sources. Fake images in astronomy Advertising - Administration 2017 has emphasized the theme of fake news as if that phenomenon had never existed before, whereas Astro Publishing di Pirlo L. it is ancient as humanity itself. Likewise remote is the origin of fake images, representations or altered Via Bonomelli, 106 interpretations of reality, which can be used for different purposes. This phenomenon is also widespread... 25049 Iseo - BS - ITALY 44 email [email protected]
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4 SOLAR SYSTEM The first inte asteroid
by Michele Ferrara
Our current technology does not allow us to reach other planetary systems, and this limitation will remain for a long time. This will not prevent us, however, from closely studying asteroids and comets born light years away around stars other than the Sun. The first of those objects has already been discovered a short distance from our planet, and we are thinking about how to intercept the next one.
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SOLAR SYSTEM 5 tteerstellar
his artist’s im- n astronomy, each discovery adds a piece on several occasions, someone hypothe- T pression shows to the great puzzle of the universe. A cen- sized the existence of numerous dark bod- the first interstellar tury ago, we thought our galaxy repre- ies of various sizes in free movement in the asteroid: Oumua- I sented the whole cosmos. Thirty years ago, empty spaces separating the stars. Verifying mua. This unique we could only imagine there were planets the hypothesis seemed difficult, as these object was discov- ered by the Pan- around other stars, and interstellar space bodies did not emit enough radiation to STARRS 1 telescope was always considered empty or, at best, be distinguished from the black background in Hawaii. [ESO/M. just filled with a few atoms of gas per cubic of the night sky. In the last twenty years, Kornmesser] meter. To tell the truth, as early as the 1930s, however, exploitation of what is called
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6 SOLAR SYSTEM
microlensing (an increase in the light from large objects is hugely dispersed. While it is a background star following the transit of true that, when it comes to sub-stellar and a dark body in front of it) has allowed us to planetary sized objects, interstellar space is close that gap, revealing the existence of essentially empty, the same conclusion may sub-stellar and planet-sized objects wan- not be valid for smaller bodies, the num- dering the galaxy. About fifteen of these ber of which increases ex- bodies are known today, and the presence ponentially of many others is suspected. Conserva- tive assessments indicate that their total number is twice the num- ber of stars in the Milky Way, and thus some hun- dreds of billions. De- spite this enormous amount, the galaxy is so gigantic that the population of
he Pan-STARRS1 Observatory T on Halealakala, Maui, opens at sunset to begin a night of map- ping the sky. [Rob Ratkowski]
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SOLAR SYSTEM 7
as the size decreases. In this case, we refer tems, it goes without saying that there is a to asteroids and comets, whose presence in multitude of objects around the galaxy interstellar space is also indicated by the whose presence could only be revealed if most reliable models of planetary system they were close enough to be within reach formation. These models predict that the of our most efficient photographic tele- stages of formation and migration of plan- scopes. Researchers have calculated how ets within each system are responsible for many asteroids or comets expelled from the expulsion of countless billions of rocky other planetary systems we should be able and icy bodies, which in escaping the grav- to discover every year, and the result is 0.2, itational attraction of their stars would end or one every five years on average. This as- up wandering through the galaxy indefi- sessment is inevitably approximate since nitely. It is estimated that, on average, any the variables in the equation are so numer- existing planetary system may have ejected ous that this calculation seems a mere the equivalent of approximately 20 Earth probabilistic exercise. Nevertheless, a sur- masses in the form of asteroids and comets. prising thing happened last October, which Considering that, as far as we know today, in all respects appears to confirm that hy- the majority of stars possess planetary sys- pothetical scenario. Here are the facts.
umuamua spotted whizzing through the Solar System in images Otaken with the WIYN telescope. The faint streaks are back- ground stars. The green circles highlight the position of the asteroid in each image. In these images Oumuamua is about 10 million times fainter than the faintest stars visible with the naked eye. [R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF]
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ing datum: the eccentricity of its orbit is close to 1.2. When eccen- tricity is greater than 1, we are dealing with a hyperbolic tra- jectory, that of a body that does not orbit around the Sun. Weryk and Micheli soon realized that that object came from outside our solar system. This unique opportu- nity to study a body formed in umuamua in a 300-second false-colour image another planetary system mobilised nu- Otaken on Oct. 29 from Gemini Observatory on merous researchers, and within a few Mauna Kea, Hawaii. [Gemini Observatory, NSF, hours many telescopes, including larger AURA /M. T. Bannister, R. E. Pike, M. E. Schwamb] ones, were aimed at the ‘visitor’. Below, multiple exposures centered on Oumua- Since it initially appeared to be a cometary mua combined into one image. [R. Kotulla (Uni- nucleus, the object was recorded by the versity of Wisconsin) & WIYN/NOAO/AURA/NSF] Minor Planet Center (MPC, Cambridge, At the end of the day on October 19, Rob Massachusetts) under the name C/2017 U1. Weryk, a postdoctoral researcher at the Uni- However, the most in-depth images taken versity of Hawaii Institute for Astronomy with the ESO's Very Large Telescope (8.2- (IfA), was looking at images taken hours meter) soon showed that there was no earlier by the Panoramic Survey Telescope trace of cometary activity and therefore bove and follow- and Rapid Response System 1 (PanSTARRS the interloper could only be an asteroid, so Aing page, this dia- 1), a 1.8-meter diameter telescope dedi- the designation changed to A/2017 U1. gram shows the orbit of the interstellar as- cated to the search for potentially danger- teroid Oumuamua as ous asteroids. Weryk noticed a luminous it passes through the track in the Pisces constellation made by an Solar System. Unlike object of about magnitude 20. Excited by all other asteroids what he saw, he examined images from the and comets observed previous night and found the track on those before, this body is too, but in an area of the sky so different not bound by gravity to the Sun. It has that it had not been signalled by the auto- come from interstellar matic system detecting moving objects. space and will return At that point, Weryk contacted a specialist there after its brief in the field, Marco Micheli, of the Instituto encounter with our de Astrofísica de Canarias (a former IfA re- star system. Its hyper- searcher), who confirmed the presence of bolic orbit is highly the object through observations conducted inclined and it does not appear to have with the 1-meter telescope at the ESA's Op- come close to any tical Ground Station in Tenerife. other Solar System The preliminary calculation of the mysteri- body on its way in. ous object’s trajectory provided a surpris- [ESO/K. Meech et al.]
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But this designa- tion was al- so destined to last only a short defini- time, because as tive name soon as the astronomers to the object, confirmed the extrasolar ori- Oumuamua − full gin of the object, the MPC decided to name: 1I/`Oumuamua, introduce a new class, the I class (for interstellar), pronounced ‘oh-moo-ah-moo-ah’ and the provisional name of the object became I/2017 and meaning ‘a messenger from afar arriving first’ in U1. Finally, with unprecedented speed, the MPC and Hawaiian. In the first two weeks after the discovery, the Working Group on Small Body Nomenclature of the at least a dozen teams of researchers participated in International Astronomical Union decided to assign a the dynamic, photometric and spectroscopic study of
JANUARY-FEBRUARY 2018 oumuamua EN_l'Astrofilo 29/12/2017 09:30 Page 10
very deep image of Oumuamua created by combining A multiple images from ESO’s Very Large Telescope as well as the Gemini South Telescope. The object is marked with a blue circle and appears to be a point source, with no surrounding dust. [ESO/K. Meech et al.]
Oumuamua. In record time, several articles calculation. Accurate photometric observa- elow, Oumuamua variations were submitted to scientific journals in tions made with the 4.3-meter Discovery Bin brightness during three which the first conclusions were drawn, as Channel Telescope at the Lowell Observa- days in October 2017. The large briefly summarised below. tory (Flagstaff, Arizona), allowed the trac- range of brightness is due to Oumuamua entered the solar system from ing of a light curve with a variability of at the very elongated shape of above, from a very high point on the plane least 1.2 magnitudes and a rotation period this unique object. The differ- ent coloured dots represent of the ecliptic (about 123°); on September of not less than 3 hours, but probably measurements through differ- 2 it dropped below the ecliptic, just inside greater than 5 hours. Assuming that the ent filters, covering the visible the orbit of Mercury, and on September 9 variability is due to the shape of Oumua- and near-infrared part of the it transited to its shortest distance from mua, researchers estimated a ratio of 3:1 spectrum. The dotted line Sun, 37.6 million km, where its surface between its major axis and its minor axis. shows the light curve expected probably reached a temperature higher Different results have come from other re- if Oumuamua were an ellip- than 550 K, assuming an albedo of 5%. Its searchers, led by well-known specialist soid with a 1:10 aspect ratio. travel speed, estimated at 26 km/s, rose to David Jewitt of UCLA. Five nights using the [ESO/K. Meech et al.] 88 km/s during its passage to the periastron, when the Sun’s gravity dramatically al- tered the object’s trajectory. Indeed, Oumuamua’s course bent sharply, climbing to- wards the ecliptic at a less steep angle than during its arrival, leading it in the di- rection of Earth, which it neared on October 14 at a distance of 24 million km and at a speed of 44 km/s. Four days later, Oumuamua was discovered, and once its distance was known, its ap- proximate diameter, 100-300 meters, could be calculated − depending on the surface reflectivity adopted in the
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SOLAR SYSTEM 11
brief over- A view of the discovery of the first interstellar asteroid. [ESO]
e 3.5-meter WIYN Telescope at the Kitt Peak graph) with data produced by other obser- National Observatory and the 2.5-meter vatories, they concluded that Oumuamua Nordic Optical Telescope in La Palma, Ca- is at least 400 meters long and only one-
nary Islands, revealed an 8-hour rotation tenth as wide, that it turns on its axis in 7.3
period and a ratio of 6:1 between the axes, hours and that it has a very dark red sur-
for a real dimension of about 180x30x30 face. This peculiarity is compatible with a meters. Even more extreme is the ratio be- long stay in interstellar space (perhaps bil- tween the axes obtained by a team of as- lions of years) and is virtually the only in- tronomers led by Karen Meech (IfA). formation provided by spectroscopic ob- Combining images taken by the VLT's FORS servations, despite the spectra being ac- (FOcal Reducer and low dispersion Spectro- quired by other big telescopes as well,
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12 SOLAR SYSTEM
such as the 5-meter telescope on Mount star, it is equally likely it would travel at a rtist’s impres- Palomar (the Hale Telescope) and the 4.2- speed of 20 to 30 km/s. Since Oumuamua's Asion of Ou- meter telescope on Roque de los Mucha- arrival speed is almost centred in that muamua. Observa- chos, Canary Islands (the William Herschel range, some researchers have pointed to tions from ESO’s Telescope). some possible asteroid parent stars, all of VLT and other tele- It is interesting to note that Oumuamua which are relatively close star associations, scopes around the world show that entered our solar system from a point in such as the Scorpius-Centaurus association, this unique object space just 6° from what is called the solar the Carina association, the Columba asso- was travelling apex, i.e., the apparent direction in which ciation and the Tucana-Horologium associ- through space for the Sun and its system are moving (at ation. It is actually impossible to establish millions of years about 250 km/s). It is statistically more like- from which planetary system Oumuamua before its chance ly that an extrasolar object would arrive was initially expelled because, before com- encounter with our from that direction and, if it originated ing to us, it may have had previous close star system. [ESO/ with and was expelled by a relatively close transits with other stars, which would have M. Kornmesser]
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SOLAR SYSTEM 13
dramatically changed its Undoubtedly, the discovery of Oumuamua trajectory (there are 357 opens a new research path that will have stars within 10 parsecs significant repercussions on theories on the of the Sun). formation and evolution of planetary sys- If in the future an in- tems, as well as on our knowledge of the habitant of a distant matter they disperse within our galaxy. exoplanet should see It is easy to forecast that in the coming Oumuamua (it is head- years, with the most powerful photographic ing towards the Pegasus telescopes in the world, such as PanSTARRS constellation), it would 1, its recent twin PanSTARRS 2, the Catalina appear to be coming Sky Survey (0.5- to 1.5-meter telescopes), from the direction of the Visible and Infrared Survey Telescope the Sun, but it only for Astronomy (VISTA, 4.1 meters) and the made a brief appear- Large Synoptic Survey Telescope (LSST, 8.4 ance here − though it meters, beginning operation in 2021), as- will take it several years tronomers will be able to discover a grow- to permanently exit the ing number of interstellar visitors. It is solar system. expected that the LSST will allow us to find, Although Oumuamua's on average, one new object per year. origins will remain a When a statistically significant number t the top right, mystery, we know for sure that in astro- have been discovered, we will know Aan animation nomical terms it has passed extremely close whether there are more asteroids or more showing the path of to the Sun, so much so that no one would comets among them. Oumuamua through ever have expected such an event. The Since the giant planets are mainly respon- the solar system. most optimistic predictions indicated that, sible for expelling those objects from plan- Observations made depending on the power of the telescopes etary systems, a predominance of rocky with the ESO VLT used, the first object of that type would and iron-bearing asteroids will mean that and other telescopes probably be discovered at a distance from systems with giant planets very close to have shown that this single object is the Sun of 10 to 30 astronomical units, thus their stars are more common; on the other dark, reddish and in a much larger volume of space. Having hand, a prevalence of icy cometary nuclei very elongated. found it so close to the Sun and the Earth could tell us that the maximum expulsion [ESO, M. Korn- could mean either that there are more of of objects occurs at great distances from messer, L.Calcada. such visitors than expected or that we the stars, where cold volatiles are much Music: Azul Cobalto] were very lucky this time. more abundant and persistent. !
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Movement of light echo around SN 2014J in M82
by NASA
oices reverberating off moun- covered. The “echoing” light looks tains and the sound of foot- like a ripple expanding on a pond. Vsteps bouncing off walls are The supernova, called SN 2014J, examples of an echo. Echoes hap- was discovered on Jan. 21, 2014. A pen when sound waves ricochet off light echo occurs because light from surfaces and return to the listener. the stellar blast travels different Space has its own version of an distances to arrive at Earth. Some echo. It’s not made with sound but light comes to Earth directly from with light, and occurs when light the supernova blast. Other light is bounces off dust clouds. The Hub- delayed because it travels indirectly. ble telescope has just captured one In this case, the light is bouncing off of these cosmic echoes, called a a huge dust cloud that extends 300 “light echo,” in the nearby starburst to 1,600 light-years around the su- galaxy M82, located 11.4 million pernova and is being reflected to- light-years away. A movie assem- ward Earth. So far, astronomers bled from more than two years’ have spotted only 15 light echoes worth of Hubble images reveals around supernovae outside our an expanding shell of light from Milky Way galaxy. Light echo detec- a supernova explosion sweeping tions from supernovae are rarely through interstellar space three seen because they must be nearby years after the stellar blast was dis- for a telescope to resolve them. !
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ight from a supernova explosion in the nearby starburst galaxy M82 Lis reverberating off a huge dust cloud in interstellar space. The su- pernova, called SN 2014J, occurred at the upper right of M82, and is marked by an “X.” The supernova was discovered on Jan. 21, 2014. The inset images at top reveal an expanding shell of light from the stellar explosion sweeping through interstellar space, called a “light echo.” The images were taken 10 months to nearly two years after the violent event (Nov. 6, 2014 to Oct. 12, 2016). The light is bouncing off a giant dust cloud that extends 300 to 1,600 light-years from the supernova and is being reflected toward Earth. The image of M82 reveals a bright blue disk, webs of shredded clouds, and fiery-looking plumes of glow- ing hydrogen blasting out of its central regions. [NASA, ESA, and Y. Yang (Texas A&M University and Weizmann Institute of Science, Israel)]
his video sequence takes the viewer into the nearby starburst T galaxy M82, where a shell of light surrounding an exploding star is moving through interstellar space. [NASA, ESA, G. Bacon, J. De- Pasquale, and Z. Levay (STScI) ]
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16 SPACE CHRONICLES
Fracture swarms on Mars
by ESA were imaged by ESA’s Mars Express deep. Elevated blocks of crust re- in March. They extend for thousands main between the graben when of kilometres in length, far beyond there is a parallel series of fault, as hese striking features on Mars the boundaries of this image. The seen in this scene. The Sirenum Fos- were caused by the planet’s fractures divide the crust into blocks: sae are part of a larger radial frac- Tcrust stretching apart in re- the movement along a pair of faults ture pattern around the Arsia Mons sponse to ancient volcanic activity. causes the centre section to drop volcano in the Tharsis region, which The fractures in the Sirenum Fossae down into ‘graben’ several kilome- is situated some 1800 km to the region in the southern hemisphere tres wide and a few hundred metres northeast. Tharsis is the largest vol-
erspective view of fractures in Sirenum Fossae in the southern hemisphere of Mars. The view shows the movement of P the crust, likely in response to the tectonic stresses linked to volcanic activity of the wider region. In this kind of sce- nario, fractures divide the crust into blocks: movement along a pair of faults causes the centre section to drop down into ‘graben’. The scene is part of the region imaged on 5 March 2017 during Mars Express orbit 16688. The ground resolution is about 14 m/pixel and the images are centred at 28°S / 215°E. North is to the right. [ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO]
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SPACE CHRONICLES 17
canic province on Mars, its far-reach- he region outlined by the larger ing from ancient volcanic activity in ing fracture system testament to the the Tharsis region. For example, the T white box indicates the area powerful influence this impressive imaged during Mars Express orbit graben could either be caused by volcanic province had on the planet. 16688 on 5 March 2017. [NASA the planet’s crust stretching apart as Indeed, the Sirenum Fossae fracture MGS MOLA Science Team, Freie a magma chamber bulges the crust system seen here is thought to be as- Universitaet Berlin] above it, or alternatively as the crust sociated with tectonic stresses aris- collapsed along lines of weakness as
JANUARY-FEBRUARY 2018 chronicles EN_l'Astrofilo 29/12/2017 09:08 Page 18
18 SPACE CHRONICLES
the magma cham-
ber emptied. It is also possible that each graben was associated with an ancient volcanic dike: a steep corri- dor within the rock along which magma from the interior of Mars once propagated upwards, causing cracking along the surface. In this case the graben
could represent a giant ‘dike swarm’
extending from
the volcanic cen- tre. Dike swarms olour view of the Sirenum Fossae fracture system on Mars, located about 1800 km southwest of are also seen on C the vast Tharsis volcanic region. The images were acquired by the High Resolution Stereo Camera Earth, as in Ice- on Mars Express 5 March 2017. The ground resolution is approximately 14 m/pixel and the images are land where they centered at 28°S / 215°E. [ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO]
are observed with surface fractures and graben sets in into the surface of the planet, the They also provide steep surfaces for
the Krafla fissure swarm. As with graben systems make for a good active processes occurring in more any geological feature that cuts window into the subsurface. recent times. For example, NASA’s Mars Reconnais- sance Orbiter iden-
tified gullies on some of the steep
slopes in Sirenum
Fossae, along troughs and in the
rims of impact craters.
What material carves out the small channels is a topic of active re- search: they were
initially thought
to be related to flowing water, but
recent proposals suggest that sea-
sonal frozen car- his image shows the relative heights and depths of a region in the southern hemisphere of Mars bon dioxide – dry showing the Sirenum Fossae fracture system. As indicated in the key at top right, whites and T ice – flowing browns/reds represent the highest terrain, while blue/purple is the lowest (values are marked on the downslope may be scale). [ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO] responsible. !
JANUARY-FEBRUARY 2018
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20 SPACE CHRONICLES
Hubble observes exoplanet that snows sunscreen
by NASA
ASA’s Hubble Space Telescope — six times greater than Jupiter’s — titanium has found a blistering hot pulls the titanium dioxide snow out oxide gas Nplanet outside our solar sys- of the upper atmosphere and traps to absorb in- tem where it “snows” sunscreen. it in the lower atmosphere. coming starlight on The problem is the sunscreen (tita- Astronomers using Hubble didn’t the daytime side, the atmospheric nium dioxide) precipitation only look for titanium oxide specifically. temperature grows colder with in- happens on the planet’s permanent Instead, they observed that the creasing altitude. Normally, titanium nighttime side. Any possible visitors giant planet’s atmosphere is cooler oxide in the atmospheres of hot to the exoplanet, called Kepler- at higher altitudes, which is con- Jupiters absorbs light and reradiates 13Ab, would need to bottle up trary to what was expected. This it as heat, making the atmosphere some of that sunscreen, because finding led the researchers to con- grow warmer at higher altitudes. they won’t find it on the sizzling clude that a light-absorbing gaseous hot, daytime side, which always form of titanium oxide, commonly his illustration shows the seeth- faces its host star. Hubble as- found in this class of star-hugging, T ing hot planet Kepler-13Ab that tronomers suggest that powerful gas giant planet known as a “hot circles very close to its host star, Ke- winds carry the titanium oxide gas Jupiter,” has been removed from the pler-13A. Seen in the background is around to the colder nighttime side, dayside’s atmosphere. The Hubble the star’s binary companion, Kepler- 13B, and the third member of the where it condenses into crystalline observations represent the first time multiple-star system is the orange flakes called titanium dioxide, forms astronomers have detected this pre- dwarf star Kepler-13C. [NASA, ESA, clouds, and precipitates as snow. cipitation process, called a “cold and G. Bacon (STScI)] Kepler-13Ab’s strong surface gravity trap,” on an exoplanet. Without the
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These kinds of observations provide erful gravity. “Presumably, this pre- the distant world traveled behind insight into the complexity of cipitation process is happening on its star, an event called a second- weather and atmospheric composi- most of the observed hot Jupiters, ary eclipse. This type of eclipse tion on exoplanets, and may some- but those gas giants all yields information on the tem- day be applicable to analyzing have lower perature of the con- Earth-size planets for habitability. s u r f a c e stituents in the “In many ways, the atmospheric atmosphere studies we’re doing on hot Jupiters of the ex- now are testbeds for how we’re going to do atmospheric studies on terrestrial, Earth-like planets,” said lead researcher Thomas Beatty of Pennsylvania State University in University Park. “Hot Jupiters provide us with the best views of what climates on other worlds are like. Under- standing the atmo- spheres on these planets and how they work, which is not un- derstood in detail, will help us when we study these smaller planets that are harder to see and have more compli- cated features in their atmospheres.” Beatty’s team selected Ke- pler-13Ab because it is one of the hottest of the known exoplanets, with a dayside temperature of nearly 5,000 °F (near-ly 2,800 °C). Past observa- tions of other hot Jupiters have re- vealed that the upper atmospheres increase in temperature. Even at oplanet’s their much colder temperatures, gravi- d a y s i d e . most of our solar system’s gas gi- ties than “These ob- serva- ants also exhibit this phenomenon. K e p l e r - 1 3 A b , ” tions of Kepler-13Ab are Kepler-13Ab is so close to its parent Beatty explained. “The titanium telling us how condensates and star that it is tidally locked. One side oxide snow doesn’t fall far enough clouds form in the atmospheres of of the planet always faces the star; in those atmospheres, and then it very hot Jupiters, and how gravity the other side is in permanent dark- gets swept back to the hotter day- will affect the composition of an ness. (Similarly, our Moon is tidally side, revaporizes, and returns to a atmosphere,” Beatty explained. locked to Earth; only one hemi- gaseous state.” The researchers “When looking at these planets, sphere is permanently visible from used Hubble’s Wide Field Camera 3 you need to know not only how Earth.) The observations confirm a to conduct spectroscopic observa- hot they are but what their gravity theory from several years ago that tions of the exoplanet’s atmo- is like.” this kind of precipitation could occur sphere in near-infrared light. The Kepler-13 system resides 1,730 on massive, hot planets with pow- Hubble made the observations as light-years from Earth. !
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First light for ESPRESSO
by ESO
SPRESSO has achieved first light do Porto and Universidade de Lis- he Echelle SPectrograph for Rocky Exoplanet on ESO’s Very Large Telescope boa, Portugal; and ESO. The co-prin- T and Stable Spectroscopic Observations Eat the Paranal Observatory in cipal investigators are Francesco (ESPRESSO) successfully made its first observations northern Chile. ESPRESSO was de- Pepe (University of Geneva, Switzer- in November 2017. Installed on ESO’s Very Large signed and built by a consortium land), Stefano Cristiani (INAF–Osser- Telescope (VLT) in Chile, ESPRESSO will search for consisting of: the Astronomical Ob- vatorio Astronomico di Trieste, Italy), exoplanets with unprecedented precision by look- servatory of the University of Rafael Rebolo (IAC, Tenerife, Spain) ing at the minuscule changes in the properties of Geneva and University of Bern, and Nuno Santos (Instituto de As- light coming from their host stars. For the first time Switzerland; INAF–Osservatorio As- trofisica e Ciencias do Espaco, Uni- ever, an instrument will be able to sum up the light tronomico di Trieste and INAF–Os- versidade do Porto, Portugal). from all four VLT telescopes and achieve the light servatorio Astronomico di Brera, This new, third-generation echelle collecting power of a 16-metre telescope. This pic- Italy; Instituto de Astrofísica de Ca- spectrograph is the successor to ture shows a group picture of the happy first light team on the platform at Paranal, with the VLT in narias, Spain; Instituto de Astrofisica ESO’s hugely successful HARPS in- the background. [Giorgio Calderone, INAF Trieste] e Ciências do Espaço, Universidade strument at the La Silla Observatory. chronicles EN_l'Astrofilo 29/12/2017 09:08 Page 23
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HARPS can attain a precision of his colourful image shows around one metre per second T spectral data from the First in velocity measurements, Light of the ESPRESSO instru- whereas ESPRESSO aims to ment on ESO’s Very Large Tele- achieve a precision of just a scope in Chile. The light from a few centimetres per second, star has been dispersed into its due to advances in technology component colours. This view and its placement on a much has been colourised to indicate bigger telescope. how the wavelengths change The lead scientist for ES- across the image, but these are PRESSO, Francesco Pepe from not exactly the colours that the University of Geneva in would be seen visually. Close in- spection shows many dark spec- Switzerland, explains its sig- tral lines in the stellar spectra nificance: “This success is the and also the regular double spots
result of the work of many from a calibration light source.
people over 10 years. ESPRES- The dark gaps are features of
SO isn’t just the evolution of how the data is taken, and are
our previous instruments like not real. [ESO/ESPRESSO team]
HARPS, but it will be transfor-
e mational, with its higher resolution changes in the spectra of stars as a with contributions from an interna- t and higher precision. And unlike planet orbits. This radial velocity tional consortium as well as many earlier instruments it can exploit the method works because a planet’s different groups within ESO: engi- VLT’s full collecting power — it can gravitational pull influences its host neers, astronomers and administra- be used with all four of the VLT Unit star, causing it to “wobble” slightly. tion. They had to not just install the Telescopes at the same time to sim- The less massive the planet, the spectrograph itself, but also the ulate a 16-metre telescope. ES- smaller the wobble, and so for rocky very complex optics that bring the PRESSO will be unsurpassed for at and possibly life-bearing exoplanets light together from the four VLT least a decade — now I am just im- to be detected, an instrument with Unit Telescopes.” patient to find our first rocky very high precision is required. With Although the main goal of ES- planet!” ESPRESSO can detect tiny this method, ESPRESSO will be able PRESSO is to push planet hunting to to detect some of the next level, finding and charac- the lightest planets terising less massive planets and ever found. their atmospheres, it also has many The test observa- other applications. ESPRESSO will tions included ob- also be the world’s most powerful servations of stars tool to test whether the physical and known plane- constants of nature have changed tary systems. Com- since the Universe was young. parisons with exist- Such tiny changes are predicted by ing HARPS data some theories of fundamental phys- showed that ES- ics, but have never been convinc- PRESSO can obtain ingly observed. When ESO’s Ex- similar quality data tremely Large Telescope comes on with dramatically line, the instrument HIRES, which is SPRESSO successfully made its first observations in less exposure time. currently under conceptual design, ENovember 2017. Installed on ESO’s Very Large Telescope Instrument scien- will enable the detection and char- (VLT) in Chile, ESPRESSO will search for exoplanets with un- tist Gaspare Lo acterisation of even smaller and precedented precision by looking at the minuscule changes Curto (ESO) is de- lighter exoplanets, down to Earth- in the properties of light coming from their host stars. For lighted: “Bringing like planets, as well as the study of the first time ever, an instrument will be able to sum up the ESPRESSO this far exoplanet atmospheres with the light from all four VLT telescopes and achieve the light col- lecting power of a 16-metre telescope. [ESO/P. Horálek] has been a great prospect of the detection of signa- accomplishment, tures of life on rocky planets. !
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Chicxulub: perfect timing... for us!
by Michele Ferrara
Two Japanese researchers have concluded that the evolution of mammals from the Cretaceous to today would have been entirely different if the as- teroid which put an end to that period, 79 million years long and dominat- ed by dinosaurs, had fallen on areas with different petrological properties. The mass extinction caused by that event had only a thirteen percent prob- ability of occurring and leading to the appearance of humankind.
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he fires triggered T by the return to Earth of the blazing material thrown into the atmosphere by the impact of Chicxu- lub have until now been considered the critical element in the mass extinction at the end of the Cretaceous. The reality could be different.
ne of the most relevant events in blasting out a crater more than 180 km in the history of life on our planet is diameter. This crater remained hidden un- Othe impact of the asteroid that pro- derground until the ‘70s, before being ran- duced a mass extinction 66 million years domly discovered by two geophysicists ago, sweeping away about 75% of the liv- searching for oil fields. As the epicentre of ing species and putting an end to the dom- the impact was relatively close to the cur- ination of the great reptiles. The asteroid, rent town of Chicxulub, the researchers 9-12 km in diameter, fell into the current agreed to call the crater, the asteroid and Gulf of Mexico, off the Yucatan peninsula, the event by the same name: Chicxulub.
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meteorites, it trig- isualization gered an exten- V of the aster- sive series of fires oid impact that in forests around 66 million years the globe, produc- ago killed 75% of living species ing huge amounts on Earth. [R. Mi- of soot dispersed chalik, D. Dolak, by atmospheric The Science Insi- circulation and tute Columbia then returning to College, Chicago] the ground in Below, a repre- rainfall. Once the sentation of the soot reached the Chicxulub im- ground, it settled poact seen from in a geological space. [Joe Tuc- layer that tells us ciarone, Science the time of the Source] In addition to the immediate, apocalyptic impact (66,038,000 ±11,000 years ago) aftermath of the impact on a regional and along with other materials, including sig- continental scale, the event also had catas- nificant quantities of iridium from the as- trophic effects on a planetary scale due to teroid. During its stay in the atmosphere, trillions of tons of material of varying con- the soot prevented part of the solar radia- sistencies and sizes thrown into the tropo- tion from reaching the surface, and this sphere, the stratosphere and beyond. triggered a drop in the global average According to the prevailing theory, when temperature, directly causing the mass ex- the heaviest part of that material plunged tinction at a point between the Cretaceous to the ground in the form of burning and Paleogene eras (K-Pg boundary). chicxulub EN_l'Astrofilo 29/12/2017 09:00 Page 27
ramatic scenes This general picture of the Chicxulub event significant global drop in temperature. Dof the end of and its consequences is broadly shared by Moreover, the fires certainly affected every dinosaurs, follow- an overwhelming majority of scientists, al- continent, so the distribution of soot in ing the event of though some specific aspects could be in- the atmosphere had to be fairly uniform, Chicxulub. In the terpreted differently. This is the case with while there is evidence that indicates a view above, a few a study by Kunio Kaiho (Tohoku University, more severe cooling in the northern hemi- days have passed since the impact. Sendai) and Naga Oshima (Meteorological sphere and a faster return to normal in the In the one below, Research Institute, Tsukuba) recently pub- southern one. Above all, forest fires would a few years have lished in Scientific Reports. The two re- have emitted soot only into the tropo- passed, and the searchers claim that the widespread fires sphere, where its stay would have been mass extinction is in vegetation triggered by the burning slightly limited — perhaps weeks — before complete. material falling back to the ground cannot it was totally removed by rainfall. Such a have generated enough soot to create a short period of darkness would not have
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significantly reduced temperatures long gion or, at most, a continent, and the di- rtist's recon- enough to cause a mass extinction. The nosaurs would not have died out. In this Astruction of soot must, therefore, have been in the case, the evolution of life on Earth would Chicxulub crater stratosphere (where it could have persisted soon after im- for years), and only the soot produced and pact, 66 million years ago. ejected as a direct result of the impact [Detlev Van could have gotten so high. Ravenswaay/Sci- By studying this aspect of the Chicxulub ence Source] event through a series of computer simu- On the side, Lift- lations, Kaiho and Oshima discovered that boat Myrtle is a the asteroid, to transfer the necessary drilling platform quantity of elements in suspension into normally used for the stratosphere, must have hit sedimen- oil operations. tary rocks particularly rich in hydrocarbons Since April 2016, and sulfates. By burning at the very high geologists have temperature produced by the impact, been using it in these elements turned into soot and the Gulf of Mex- ico to drill into aerosols. The most surprising aspect is that the crater Chicxu- only about 13% of the Earth’s surface con- lub. [ELeBer/ tains rocks with that composition, and ECORD/ IODP] only by striking those areas could the as- teroid have produced a mass extinction. In other words, if the asteroid had fallen any- where in the remaining 87% of the Earth’s surface, the effects on the biosphere would have been devastating over a re-
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everal samples very probably have taken Sof material a deeply different path taken from the from the one that led to Chicxulub crater the appearance of the using the Liftboat human being. Myrtle platform's Kaiho and Oshima com- auger. They are essentially a mix- ment in more detail be- ture of terrestrial low on the results of their rock and residual simulations in Scientific material from the Reports. Please note that asteroid. the two researchers indi- cate soot with the abbreviation BC, from black carbon, and indicate the quantities in teragrams, Tg (1 Tg = 1 million tons). “We estimated climate changes caused by BC injection due to the Chicxulub asteroid impact for five quantities of BC (20, 200, 500, 1500, and 2600-Tg BC ejection cases) using global climate model calculations. Although BC in the troposphere was effi- ciently removed from the atmosphere by precipitation (within approximately 1 week), BC in the stratosphere had a longer lifetime and was gradually deposited on the surface, on a scale of several years. The stratospheric BC rapidly reduced the sun- light reaching the Earth’s surface, which led to a cooling of the tropospheric atmo- sphere and ocean, and a decrease in pre- cipitation on a global scale. These climate
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piece of the A asteroid that made the Chicxu- lub Crater. [Pho- tograph by Faith Tucker, NASA]
changes were greater for larger BC ejections. Changes in the atmosphere showed a rapid response immediately after the impact: up to 0–0.5 °C, 2–3 °C, 4–6 °C, 8–10 °C, and 8–11 °C cooling of the global mean surface air temperature, 0–1 °C, 4–5 °C, 6–9 °C, 10–16 °C, and 10–18 °C cooling of the global mean surface air tempera- ture on land, and 0–15%, 25–50%, 45–70%, 65–80%, and 75–85% decreases in global mean precipitation on land for 20-, 200-, 500-, 1500-, and 2600-Tg BC ejec- tion cases, respectively, hanerozoic faunal changes with approximately within a few years after the P 13% probability following the Chicxulub aster- impact. Temperature and oid impact. Changes in fauna are based on extinc- precipitation gradually re- tion rates. Changes through the K–Pg boundary covered within the follow- mass extinction are enhanced by a change in the ing 10 years. Seawater main terrestrial fauna from dinosaurs to mammals. temperature changes exhib- [K. Kaiho & N. Oshima, Scientific Reports] ited a slower response fol- lowing the impact, and cooling at shallower water
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n outcrop of rock in Arroyo el AMimbral, Tamaulipas, Mexico, is a good example of the complex deposits of impact debris and other sediment produced by the Chicxulub impact event. The lower portion of the sequence (bottom panel) is composed of altered im- pact melt spherules with an in- terbedded sandy limestone, and overlain with a laminated sand- stone. The base of the laminated sandstone contains plant debris, even though these sediments were deposited on the seafloor beneath ~500 meters of water. The upper portion of the sequence (upper panel) is composed of layers of sandstone, siltstone, and mud- stone. The top of the sequence, where the hammer is resting, con- tains anomalously high concentra- tions of the element iridium, which was produced from the vaporized impactor that produced the Chic- xulub crater. [David A. Kring]
It is interesting to note that global cooling also led to a sig- nificant drop in precipitation, perhaps a drastic one due to high levels of soot emitted into the stratosphere. Less light, more frost and less water can only have been a devastating mixture that damaged vegeta- tion and the terricolous and aquatic organisms at the base of the food chain. It is easy to understand that a few years of that scenario were enough to annihilate many living species, and in particular the dinosaurs, the cold-blooded animals (or lukewarm, as some studies depths (<100 m) was faster and greater would have it) then at the top of the food than cooling at greater water depths (e.g., chain. As the same researchers pointed out up to 0.5 °C, 2 °C, 4 °C, 7 °C, and 9 °C de- in a previous work, a mass extinction crease in global mean seawater tempera- would have required a global drop in the ture at a 2-m water depth for 20-, 200-, surface air temperature of about 8-10 °C, 500-, 1500-, and 2600-Tg BC ejection cases, a value that may only have been reached respectively, within 1–4 years after the im- if the Chicxulub asteroid had hit an area pact, and within 1 °C cooling at a 600-m with a high concentration of hydrocarbons water depth for all cases within >10 years).” and sulfates. This eventuality is confirmed
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by the fact that the mostly coastal location perature at a 50-m water depth, and mass lobal map of oil fields and other non-renewable en- extinction marked by the extinction of di- Gshowing the ergy sources at the end of the Cretaceous nosaurs. [...] The Chicxulub impact occurred amount of or- period did not differ much from that of in a hydrocarbon-rich, sulfate-dominated ganic matter in today (as shown by maps reconstructed area, and is a rare case of mass extinction sedimentary rocks ejected if through estimates made by Kaiho). In this being caused at such an impact site. [...] The the Chicxulub as- context, the Gulf of Mexico was and still is probability of mass extinction at the K–Pg teroid hit various rich in hydrocarbons. boundary was approximately 13% after the locations at the In addition to the burning of hydrocar- asteroid impacted Earth. The collapse of end of the Creta- bons, a primary role in the cooling of the ecosystems with dinosaurs on land and ceous. Shaded climate was probably played by the sul- large marine reptiles and ammonites in the areas correspond fates present in the rocks impacted by the sea at the top of the food chain was proba- to 0–4 °C, 4–8 °C, asteroid. It is not easy to determine how bly due to soot with possible contributions 8–11 °C, and ≥11 much sulfates affected the mass extinction, by sulfate from the Chicxulub asteroid im- °C cooling. Mass but it has been calculated that by them- pact and led to the subsequent macroevo- extinction could have been caused selves they may have contributed to low- lution and diversification of mammals. by 8–11 °C or ering the global temperature by 14 °C if Therefore, the low probability of mass ex- more cooling there were high concentrations in the tinction indicates the low probability of the when the aster- rocks (1-2% of the terrestrial surface). subsequent macroevolution of mammals.” oid hit an orange Here’s how Kaiho and Oshima summarize The conclusions reached by the two Japan- or magenta area, the scenario in Scientific Reports: ese researchers through their computer sim- which occupied “These results suggest that climate changes ulations make us reflect on how unlucky the approximately (in terms of extinction levels) can be esti- dominant species was at the end of the Cre- 13% of the mated using stratospheric soot amounts. taceous period and, from a different per- Earth’s surface. Soot from hydrocarbon-rich areas (approxi- spective, what a great stroke of luck the The map is based on Courtillot et mately 13%) including high sulfate areas Chicxulub event was for the mammals. How al.; thin lines limited to 1% of the Earth’s surface caused would life on Earth have evolved if that as- indicate continen- 8– ≥ 11 °C global cooling, 13– ≥ 17 °C cooling teroid was a little further ahead or a bit fur- tal crust shelf on land, a decrease in precipitation by ap- ther back in its orbit and had slammed into edges. [K. Kaiho proximately 70– ≥ 85% on land, a decrease our planet a few hundred kilometres away & N. Oshima, Sci- of approximately 5– ≥ 7 °C in seawater tem- from where it fell? ! entific Reports]
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ALMA discovers cold dust around nearest star
by ESO
roxima Centauri is the closest star to the Sun. It is a faint red P dwarf lying just four light- years away in the southern constel- lation of Centaurus (The Centaur). It is orbited by the Earth-sized tem- perate world Proxima b, discovered elaborate planetary system, and not in 2016 and the closest planet to the just a single planet, around the star Solar System. But there is more to closest to our Sun.” this system than just a single planet. Dust belts are the remains of mate- The new ALMA observations reveal rial that did not form into larger emission from clouds of cold cosmic bodies such as planets. The particles dust surrounding the star. of rock and ice in these belts vary in a temperature of about –230 de- The lead author of the new study, size from the tiniest dust grain, grees Celsius, as cold as that of the Guillem Anglada, from the Instituto smaller than a millimetre across, up Kuiper Belt in the outer Solar Sys- de Astrofísica de Andalucía (CSIC), to asteroid-like bodies many kilome- tem. There are also hints in the Granada, Spain, explains the signif- tres in diameter. Dust appears to lie ALMA data of another belt of even icance of this find: “The dust around in a belt that extends a few hundred colder dust about ten times further Proxima is important because, fol- million kilometres from Proxima out. If confirmed, the nature of an lowing the discovery of the terres- Centauri and has a total mass of outer belt is intriguing, given its trial planet Proxima b, it’s the first about one hundredth of the Earth’s very cold environment far from a indication of the presence of an mass. This belt is estimated to have star that is cooler and fainter than
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his artist’s impression shows how T the newly discovered belts of dust around the closest star to the Solar System, Proxima Centauri, may look. ALMA observations revealed the glow coming from cold dust in a re- gion between one to four times as far from Proxima Centauri as the Earth is from the Sun. The data also hint at the presence of an even cooler outer dust belt and indicate the presence of an elaborate planetary system. These structures are similar to the much larger belts in the Solar System and are also expected to be made from particles of rock and ice that failed to form planets. Note that this sketch is not to scale — to make Proxima b clearly visible it has been shown fur- ther from the star and larger than it is in reality. [ESO/M. Kornmesser]
the Sun. Both belts are much further croprobes attached to laser-driven from Proxima Centauri than the sails. A knowledge of the dust envi- planet Proxima b, which orbits at ronment around the star is essential just four million kilometres from its for planning such a mission. parent star. Guillem Anglada ex- Co-author Pedro Amado, also from plains the implications of the discov- the Instituto de Astrofísica de An- ery: “This result suggests that dalucía, explains that this observa- Proxima Centauri may have a tion is just the start: “These first multiple planet system with a results show that ALMA can detect rich history of interactions dust structures orbiting around that resulted in the formation Proxima. Further observations will of a dust belt. Further study give us a more detailed picture of may also provide information Proxima’s planetary system. In that might point to the loca- combination with the study of pro- tions of as yet unidentified toplanetary discs around young additional planets.” stars, many of the details of the Proxima Centauri’s planetary processes that led to the formation system is also particularly in- of the Earth and the Solar System his artist’s video impression shows how teresting because there are about 4600 million years ago will the newly discovered belts of dust around T plans — the Starshot project be unveiled. What we are seeing the closest star to the Solar System, Proxima Centauri, may look. [ESO/M. Kornmesser] — for future direct explo- now is just the appetiser compared ration of the system with mi- to what is coming!” !
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ESA: crossing drones with satellite
by ESA
SA is considering extending its activities to a new region of the Esky via a novel type of aerial ve- hicle, a ‘missing link’ between drones and satellites. High Altitude Pseudo-Satellites, or HAPS, are plat- forms that float or fly at high alti- tude like conventional aircraft but operate more like satellites – except that rather than working from space they can remain in position in- side the atmosphere for weeks or even months, offering continuous coverage of the territory below. The best working altitude is about 20 km, above the clouds and jet streams, and 10 km above commer- cial airliners, where wind speeds are low enough for them to hold posi- tion for long periods. From such a height they can survey igh Altitude Pseudo-Satellites, or HAPS, are platforms that float or fly at high altitude like conventional aircraft but operate more like satellites – ex- the ground to the horizon 500 km H cept that rather than working from space they can remain in position inside away, variously enabling precise the atmosphere for weeks or even months, variously enabling precise monitor- monitoring and surveillance, high- ing and surveillance, high-bandwidth communications or back up to existing bandwidth communications or back satellite navigation services. [ESA Earth Observation Graphics Bureau] up to existing satellite navigation services. bine wide bandwidth with negligi- turised avionics, high-performance Several ESA directorates have ble signal delay. ESA is looking into solar cells, lightweight batteries and teamed up to investigate their po- how these various domains can be harness, miniaturisation of Earth tential, explains future-systems spe- best brought together.” Earth ob- observation sensors and high-band- cialist Antonio Ciccolella: “For Earth servation specialist Thorsten Fehr width communication links that can observation, they could provide pro- explains: “We’ve been looking into deliver competitively priced ser- longed high-resolution coverage for the concept for the last 20 years but vices.” priority regions, while for naviga- now finally it’s becoming reality. Navigation engineer Roberto Prieto tion and telecoms they could shrink That’s come about through the ma- Cerdeira adds: “There’s obvious po- blind spots in coverage and com- turing of key technologies: minia- tential for emergency response.
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he QinetiQ-designed and Airbus-owned Zephyr-7 solar-powered unmanned aircraft holds the world flight endurance T record, having remained aloft from 9 July to 23 July 2010 for a total of 336 hours, 22 minutes and 8 seconds – up- wards of 14 days. The design is part of the Airbus High Altitude Pseudo-Satellite programme, with a larger double-tailed Zephyr-T variant under construction. [Airbus]
They could also be employed semi- satnav coverage into high, narrow European companies have already permanently, perhaps extending valleys and cities.” unveiled product lines. For instance, Airbus has developed the winged, solar-powered Zephyr, which in 2010 achieved a world record 14 days of continuous flight without refuelling. Zephyr-S is designed to fly payloads of a few tens of kilograms for up to three months at a time, with sec- ondary batteries employed to keep it powered and aloft overnight. A larger Zephyr-T version in prepara- tion will support larger payloads and power needs. Thales Alenia Space is meanwhile preparing the lighter-than-air Stra- tobus, with its first flight expected in 2021. The buoyant Stratobus airship can hales Alenia Space’s Stratobus airship can carry up to 250 kg of payload; its carry up to 250 kg; its electric en- T electric engines flying against the breeze to hold itself in position, and rely- ing on fuel cells at night. Its first flight is projected for 2021. [Thales Alenia gines flying against the breeze to Space/Briot] hold itself in position, relying on fuel cells at night. !
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Closest temperate world orbiting quiet star discovered
by ESO
team working with ESO’s nearby star to host such a temperate with state-of-the-art data reduction High Accuracy Radial velocity exoplanet. “This discovery is based and analysis techniques. Only HARPS A Planet Searcher (HARPS) at on more than a decade of HARPS in- has demonstrated such a preci- the La Silla Observatory in Chile has tensive monitoring sion and found that the red dwarf star Ross together 128 is orbited by a low-mass exo- planet every 9.9 days. This Earth- sized world is expected to be temperate, with a surface temperature that may also be close to that of the Earth. Ross 128 is the “qui- etest”
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his artist’s impression shows the temperate planet Ross 128 b, with its red T dwarf parent star in the background. This planet, which lies only 11 light- years from Earth, was found by a team using ESO’s unique planet-hunting HARPS instrument. The new world is now the second-closest temperate planet to be detected after Proxima b. It is also the closest planet to be discovered orbiting an inactive red dwarf star, which may increase the likelihood that this planet could potentially sustain life. Ross 128 b will be a prime target for ESO’s Extremely Large Telescope, which will be able to search for biomarkers in the planet’s atmosphere. [ESO/M. Kornmesser]
it remains the best planet hunter 128 b orbits 20 times closer than the of its kind, 15 years after it began Earth orbits the Sun. Despite this operations,” explains Nicola As- proximity, Ross 128 b receives only tudillo-Defru (Geneva Observatory 1.38 times more irradiation than the – University of Geneva, Switzer- Earth. As a result, Ross 128 b’s equi- land), who co-authored the discov- librium temperature is estimated to ery paper. lie between -60 and 20°C, thanks to Red dwarfs are some of the coolest, the cool and faint nature of its small faintest — and most common — red dwarf host star, which has just stars in the Universe. This makes over half the surface temperature them very good targets in the of the Sun. While the scientists in- search for exoplanets and so they volved in this discovery consider are increasingly being studied. In Ross 128b to be a temperate planet, fact, lead author Xavier Bonfils (In- uncertainty remains as to whether stitut de Planétologie et d’Astro- the planet lies inside, outside, or on physique de Grenoble – Université the cusp of the habitable zone, Grenoble-Alpes/CNRS, Grenoble, where liquid water may exist on a France), named their HARPS pro- planet’s surface. gramme The shortcut to happiness, Astronomers are now detecting as it is easier to detect small cool more and more temperate exoplan- siblings of Earth around these stars, ets, and the next stage will be to than around stars more similar to study their atmospheres, composi- the Sun. tion and chemistry in more detail. Many red dwarf stars, including Vitally, the detection of biomarkers Proxima Centauri, are subject to such as oxygen in the very closest flares that occasionally bathe their exoplanet atmospheres will be a orbiting planets in deadly ultravio- huge next step, which ESO’s Ex- let and X-ray radiation. However, it tremely Large Telescope (ELT) is in seems that Ross 128 is a much qui- prime position to take. eter star, and so its planets may be “New facilities at ESO will first play the closest known comfortable a critical role in building the census abode for possible life. of Earth-mass planets amenable to Although it is currently 11 light- characterisation. years from Earth, Ross 128 is moving In particular, NIRPS, the infrared towards us and is expected to be- arm of HARPS, will boost our effi- come our nearest stellar neighbour ciency in observing red dwarfs, in just 79,000 years — a blink of the which emit most of their radiation eye in cosmic terms. Ross 128 b will in the infrared. And then, the ELT by then take the crown from Prox- will provide the opportunity to ob- ima b and become the closest exo- serve and characterise a large frac- planet to Earth! With the data from tion of these planets,” concludes HARPS, the team found that Ross Xavier Bonfils. !
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NASA’s JWST early science observations revealed
by NASA entific community with immediate access to Webb data so they have stronomers around the the opportunity to ana- world will have immediate lyze the data and plan A access to early data from spe- follow-up observations. cific science observations from “We were impressed by NASA’s James Webb Space Tele- the high quality of the scope, which will be completed proposals received,” said within the first five months of Dr. Ken Sembach, Direc- Webb’s science operations. These tor of the Space Tele- observing programs were chosen scope Science Institute from a Space Telescope Science Insti- (STScI) in Baltimore, tute call for early release science Maryland. “These observ- proposals, and include examining ing programs not only Jupiter and its moons, searching for will generate great sci- organic molecules forming around ence, but also will be infant stars, weighing supermassive a unique resource for black holes lurking in galactic cores, demonstrating the inves- and hunting for baby galaxies born tigative capabilities of in the early universe. this extraordinary obser- “I’m thrilled to see the list of as- vatory to the worldwide tronomers’ most fascinating targets scientific community.” for the Webb telescope, and ex- The observations will al- tremely eager to see the results. We so exercise all four of fully expect to be surprised by what Webb’s science instru- we find,” said Dr. John C. Mather, ments, so that the astro- Senior Project Scientist for the Webb nomical community can telescope and Senior Astrophysicist at NASA’s Goddard Space Flight Cen- his artist’s illustration ter, Greenbelt, Maryland. T represents the scien- The resulting observations will com- tific capabilities of NASA’s James Webb Space Tele- prise the Director’s Discretionary scope. Both imaging and Early Release Science (DD-ERS), and spectroscopy will be cover the gamut of Webb science central to the Webb mis- targets, from planets in our solar sys- sion. [NASA, ESA, and tem to the most distant galaxies. A. Feild (STScI)] The program provides the entire sci-
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explore Webb’s full potential. Webb search by Webb is to study planets like WASP-39b and WASP-43b be- has a minimum scientific lifetime of orbiting other stars. When such an cause they are easier targets on five years, so the scientific commu- exoplanet passes in front of its host which to apply this technique. The nity will have to rapidly learn to use star, starlight filters through the results will help guide observing its advanced capabilities. “We want planet’s atmosphere, which absorbs strategies for smaller, mostly rocky the research community to be as sci- certain colors of light depending on and more Earth-like super-Earths, entifically productive as possible, as the chemical composition. Webb will where atmospheric composition early as possible, which is why I am measure this absorption, using its may give hints of a planet’s poten- so pleased to be able to dedicate powerful infrared spectrographs, to tial habitability. nearly 500 hours of director’s discre- look for the chemical fingerprints of Webb also will peer into the distant tionary time to these ERS observa- the atmosphere’s gasses. Astrono- universe, examining galaxies whose tions,” said Sembach. One of the mers initially will train their gaze light has been stretched into in- most widely anticipated areas of re- onto gaseous Jupiter-sized worlds frared wavelengths by the expan- sion of space. This infrared region is be- yond what Hubble can detect. Galaxy clusters are particularly rich sources of targets, since a cluster’s gravity can magnify light from more distant back- ground galaxies. DD-ERS observations will target regions of the sky already examined by Hubble’s Frontier Fields program, such as the galaxy clus- ter MACS J0717.5+3745. Webb data will comple- ment Hubble’s, giving as- tronomers new insights into these cornucopias of galaxies. Since Webb must remain shielded from sunlight, its field of view is limited to specific areas of the sky at certain times of year. As a result, the potential tar- gets listed above may shift depending on the launch date. More than 100 proposals for DD-ERS observations were submitted in August 2017. Of those, 13 pro- grams requesting 460 hours of telescope time were selected following review by panels of sub- ject matter experts and the STScI director. !
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Ozone ups and downs
by ESA egative ozone trends N in the upper strato- sphere before 1997 and limate scientists studying three positive trends after 1997 decades of ozone measure- are observed. Shaded C ments from seven satellites areas show regions where see a positive trend in global recov- the trends are statistically ery thanks to international efforts significant. [FMI] to curb ozone-depleting substances. The part of Earth’s atmosphere with mals, plants and even mi- high concentrations of ozone gas croscopic phytoplankton. protects life on Earth from the Sun’s Starting in the 1970s, ultraviolet radiation. However, pol- ozone in the stratosphere lutants can break down ozone, thin- – some 11–50 km above ning this layer and creating the Earth’s surface – began to infamous ozone hole. decline worldwide. The The depletion of ozone in our atmo- largest drop was in the sphere and subsequent increase in upper stratosphere, at 4– ultraviolet exposure causes skin can- 8% per decade. cer, cataracts and immune system The trend was interrup- damage in humans, and injures ani- ted following interna-
tional agreements on the reduction of ozone-depleting substances and the first signs of ozone recovery were seen by satellites. Satellites provide good coverage but operate for a limited number of years. Meanwhile, climate scientists re-
he ozone layer protects life on T Earth from ultraviolet radiation but it is also a powerful greenhouse gas. Satellites can provide measure- ments of atmospheric ozone and monitor distribution changes with the seasons. [Planetary Visions (credit: ESA/CCI Ozone and Aerosol teams/Planetary Visions)]
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quire readings spanning 30 years or ozone profiles with high vertical NASA’s, we clearly see negative more for analysing trends accu- resolution, meaning the separate ozone trends in the upper atmo- rately. layers can be identified. sphere before 1997 and positive Ozone in particular varies depend- The record relies on five satellite trends after,” said Viktoria Sofieva, ing on the season or solar activity, sensors that provide measurements Senior Research Scientist at the so decades are necessary to sepa- with high vertical resolution. These Finnish Meteorological Institute. rate this natural variability from include the ones on ESA’s former “The upper stratospheric trends be- human-influenced change. Envisat mission, along with current yond the tropics are statistically sig- To tackle this, scientists working information from Canada’s SciSat nificant and indicate an onset of under ESA’s Climate Change Initia- and Sweden’s Odin. ozone recovery.” Ozone measure- tive are harmonising measurements In a new development, measure- ments with high vertical resolution from different satellites to give us a ments from NASA’s Earth Radiation are essential to identify these long-term view of ozone variability. Budget Satellite and Suomi NPP ozone trends. The readings date back to 1995 for satellite have been folded in, fur- The future Altius mission for ESA’s ‘total columns’ – meaning they ther extending coverage back to Earth Watch initiative will provide show the total ozone of all layers of 1984. “By merging the Climate continuing measurements for long- the atmosphere – and to 2001 for Change Initiative’s data with term climate monitoring. !
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44 STRANGE IMAGES
FFaakkee iimmaaggeess iinn aassttrroonnoommyy
by M. Ferrara et al.
2017 has emphasized the theme of fake news as if that phenomenon had never existed before, whereas it is ancient as humanity itself. Likewise remote is the origin of fake images, representations or al- tered interpretations of reality, which can be used for different pur- poses. This phenomenon is also widespread in the world of astronomy and often one is deceived by what is seen.
ot always fake images of astronomical nature in a patrol. In this case, we are not in the presence of are undoubtedly artworks like this background a false image or a tendentious interpretation of it, it Nscene, presented in a documentary of the Na- is simply a science-fiction illustration, whose task is to tional Geographic magazine. Although the martian give an idea of what might someday happen. To this landscape represented here is decidedly realistic, we typology of images also belong the representations are certain that human beings have never reached the of other planetary systems, collapsed stars and ob- red planet, and it is therefore pure fantasy to repre- jects or phenomena never photographed from a close sent them descended from a spaceship and engaged distance or in detail. Not always, however, the border
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he starship Daedalus on T Mars. The six astronauts travel to their new home in the rocket, which is based on technology just six years away. [National Geographic]
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Str4a6 nge views of the Sun, the Earth and the Moon
between true and false astronomical photographs is evident, and often in magazines and especially on the web, we find more or less fake images, which if not declared as such they can mislead less expert readers or visitors. Here we present some examples of fake images or artworks which at first sight appear realistic for the simple fact of containing real subjects, but which are instead photomontages. Let's start with images that include the three most familiar subjects: the Sun, the Earth and the Moon. At the top, we see what should be a total eclipse of the Sun taken from high al- titude (stratosphere or beyond). There are two elements that betray the falsity of the image: the shadow projected by the eclipse should be more roun- ded and the diamond ring around the Sun would be more than enough to delete the Milky Way. Above we find a full Moon that rises over a moun- tainous landscape and reflects in a lake. In addition to being unusu- ally detailed, the lunar disk is oversized and its reflection in the water is too sharp when compared to that of the mountain. Below, there is instead an overly large Earth 'seen' by astronauts on an Apollo mission. As Jim Lovell said (Apollo 8 and 13), from the
Moon it is enough to stretch out an arm and to raise the thumb upward to hide the Earth. In this case, the whole hand may not be enough. Above, a pseudo-selfie of an astronaut. If the light that il- luminates him is artificial, the background should definitely be darker. If the astronaut is illuminated by the Sun, one should not see the artificial lights on the ground. Regardless of this, the thickness of the atmosphere is excessive.
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On the right, a rather unnatural view of the Moon photograpShTeRdA NfrGoEm I MhAigGhE Saltitude (troposphere- stratosphere). In this case, the 'counterfeiter' has made several mistakes: the lunar disk is too large and its resolution is much lower than that of the ter- restrial soil; moreover, the inclination of the Moon and its location in the sky compared to the daylight conditions are inconsistent with reality. Below, an obvious false that wants to show the Earth as seen from the Moon. The surface in the fore- ground is very different from that of our satellite, and not even the alleged Earth shows clearly recogniz- able structures. Below, a suggestive scenario called 'sunset at the north pole with the Moon at the perigee'. It is actually a graphic elaboration of the as- trophysics Inga Nielsen, 'stolen' and spread by others on the web as a photography. If it were a real image, the apparent dimensions of the Sun and the Moon would be comparable.
Above, an auroral ring as showed by many photogra- phies from devices in orbit. But this is not very convincing, in- deed, it is definitely false, and you can understand it from at least three important elements. The first is the absence of the at- mosphere, indeed, despite about 1/3 of the globe is shown, there are no cloud formations and not even the typical illuminated bor- der. The second suspicious ele- ment is the wrong position of the auroral ring, centred on the geographic pole rather than on the magnetic pole (in this period the two poles differ by about 400 km). The third suspicious element is the uniformity of the illumina- tion of the ring, which, instead, should be brighter and more de- veloped in the night hemisphere, and, on the contrary, less con- spicuous in the hemisphere illu- minated by the Sun. fakeimages EN_l'Astrofilo 29/12/2017 09:32 Page 48
STRANGE IMAGES Mars’ strange landscapes and ‘animals’
Speaking about fake images, we cannot not dedicate a sec- tion to Mars, the planet that for excellence lends itself to graphic fakes and imagina- tive interpretations of the immense database accumu- lated in almost half a century of automatic missions. Leav- ing aside the sci-fi trash, we have chosen here to repre- sent two well-defined cate- gories: wide martian land- scapes graphically elaborated through an artistic touch, and small structures of the mar- tian surface that resemble petrified animals and that just because of their appear- ance have produced unend- ing speculations. The first category is well represented in the left column, composed of a series of artworks made by Kees Veenenbos on the basis of altimetric data pro- vided by the Mars Orbiter Laser Altimeter (one of the five scientific instruments on board the Mars Global Sur- veyor probe, operating be- tween 1997 and 2006) and processed using the Terra- gen software. In short, these are digital paintings and they should be considered as such, even if in some rare cases they seem a faithful repre- sentation of the reality. On the right and next page, we have instead a selection of improbable 'martian ani- mals' found in the recesses of the surface of the red planet. From top to bottom we can 'recognize' a wary crab climb- ing on a rock, an iguana that turns towards the photo- graphic device, a spider cling- ing to a group of sedimentary rocks, and finally a squirrel hidden between two stones.
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Above we have a marmot watching over its territory, while at the side we see a carapace, what remains of a dead martian tortoise. In the two photographs below you can instead distinguish a toad and, on the right, a little — less defined — penguin. All these curious similarities are fun, but unfortunately, on the web, there are those who used them (and they are not few) to prove the exis- tence of life on Mars. To be- lieve and to affirm that these unusual rocky conformations are living or fossil animals only proves the ignorance of those who believe or affirm it. If such evolved forms of life exist or existed on Mars, we would have evidence of an entire biosphere, not just some isolated specimens. In addition, for billions of years, Mars has been deprived of an atmosphere thick enough to support highly evolved forms of life. Finally, why the alleged martian animals should be identical in shape and evolutionary stage to today's terrestrial animals?
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STRANGE IMAGES Almost true nebular fakes
We conclude this brief digression ➤ on fake images with the deep sky, 4 and in particular with a series of re- markable artworks realized by Jakob
1 ➤ 2➤ ➤ 3 Schiller. They are excel- lent examples of how
➤ real images can be al- 5 tered to create appar- ently natural subjects — as strange as they may seem — but that they are instead pure inventions of the author's imagina- tion: 1 a seal; 2 a but- 6 terfly; 3 an anthropomor- ➤ phic being; 4 a phoenix; 5 and 6 spectral faces; ➤ 7 7 an unusual fish. At this point, it is clear that with regard to astro- nomical images it is not at all easy to distinguish the true from the false. On the web, there are thousands of examples of this type, many of which are shame- less artefacts. But there are also many that effectively simulate reality. To be able to distinguish between a non-ma- nipulated real photography (beyond reasonable processing), a reconstruc- tion of a likely scenario (used to docu- ment) and a deliberately falsified im- age requires some attention. !
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astronomy instruments
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