Astronomy

GJ 367 b, a planet with an iron heart in an extrasolar system

By ScientifiCult 15 September 2023

GJ 367 b, A PLANET WITH AN IRON HEART IN AN EXTRASOLAR SYSTEM

THE DISCOVERY MADE BY A TEAM AT THE UNIVERSITY OF TURIN ADDS TO THE PUZZLE HOW PLANETS FORM

Researchers at the University of Turin and at the Thüringer Landessternwarte have confirmed that the extrasolar planet GJ 367 b has an ultra-high density – almost twice the density of Earth. The research team also found two more planets that orbit the same star.

Over the past decades, astronomers have found several thousand extrasolar planets. Extrasolar planets orbit stars outside our solar system. The next frontier in this research field is to learn more about their composition and internal structure, in order to develop a better understanding of how planets form.

Elisa Goffo, Ph.D. student at the Physics Department of the University of Turin (Italy) and at the Thüringer Landessternwarte (Germany), together with an international research team, has made a unique discovery about the planet GJ 367 b that raises interesting questions about how planets are born. She is the lead author of the article Company for the ultra-high density, ultra-short period sub-Earth GJ 367 b: discovery of two additional low-mass planets at 11.5 and 34 days published in The Astrophysical Journal Letters.

Elisa Goffo is part of the international KESPRINT collaboration, which confirmed that the ultra-short period exoplanet GJ 367 b, whose orbital period is only 7.7 hours, is also ultra-dense. The density of a planet can be determined from its mass and radius. GJ 367 b is ultra-dense because the researchers found its density to be 10.2 grams per cubic centimeter. That is almost twice the density of Earth, suggesting that this extrasolar planet consists almost entirely of iron.

An unusual composition

Such a composition of a planet is very rare, raising questions about its formation.

“You could compare GJ 367 b to an Earth-like planet with its rocky mantle stripped away. This could have important implications for the formation of GJ 367 b. We believe that the planet might have formed like the Earth, with a dense core made mainly of iron, surrounded by a silicate-rich mantle. A catastrophic event could have stripped away its rocky mantle, leaving the dense core of the planet naked. Alternatively, GJ 367 b was born in an iron-rich region of the protoplanetary disc”,

explains Elisa Goffo. While observing GJ 367 b, the team discovered two additional low-mass planets that orbit around the star GJ 367 in 11.5 days and 34 days, respectively. These three planets and their star comprise an extrasolar system.

GJ 367 b was first found with the Transiting Exoplanet Survey Satellite (TESS), a space telescope operated by NASA. TESS uses the transit method to measure the radii of exoplanets – among other properties. In order to precisely measure the mass of GJ 367 b and confirm that the planet has a very high density, the KESPRINT researchers at the University of Turin and at the Thüringer Landessternwarte acquired nearly 300 radial velocity measurements using the HARPS spectrograph, a high-precision instrument installed at the 3.6 meter telescope operated by the European Southern Observatory (ESO) at La Silla Observatory, Chile.

“Thanks to our intensive observations with the HARPS spectrograph we discovered the presence of two additional low-mass planets with orbital periods of 11.5 and 34 days, which reduce the number of possible scenarios that might have led to the formation of such a dense planet”, says Davide Gandolfi, Professor at the University of Turin. “While GJ 367 b might have formed in an iron-rich environment, we do not exclude a formation scenario involving violent events like giant planet collisions.”

Artie Hatzes, director at the Thüringer Landessternwarte, underscores the relevance of this discovery: “GJ 367 b is an extreme case of an exoplanet. Before we can develop viable theories of its formation, we must precisely measure the planetary mass and radius. We expect an extrasolar system to consist of several planets, so it was important to search for and to find other planets orbiting in the system – to study its architecture.”

MORE INFORMATION

KESPRINT: Consisting of more than 40 members in nine countries (Czech Republic, Denmark, Germany, Italy, Japan, Spain, Sweden, UK, USA), the KESPRINT research consortium is devoted to the confirmation and characterization of transiting exoplanets found by space missions (e.g. Kepler, K2, TESS), with a special emphasis on the characterization of the smallest planets. Its members are from the Dipartimento di Fisica, Università di Torino, Italy, Thüringer Landessternwarte Tautenburg, Germany, Institute of Planetary Research, German Aerospace Center (DLR), Germany, Technische Universität Berlin, Germany, Rheinisches Institut für Umweltforschung an der Universität zu Köln, Germany, Astronomical Institute of the Czech Academy of Sciences, Czech Republic, Chalmers University of Technology, Sweden, Instituto de Astrofísica de Canarias, Spain, Mullard Space Science Laboratory, University College London, UK, University of Oxford, UK, Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark, Astronomy Department and Van Vleck Observatory, Wesleyan University, USA, McDonald Observatory, The University of Texas at Austin, USA, The University of Tokyo, Japan, Astrobiology Center, National Institute of Natural Sciences, Japan.

GJ 367 b and the exoplanet naming convention: Planets are usually named after their host stars, adding a lowercase letter. A planet around the star GJ 367 is called GJ 367 b, c, or d. However, the planet GJ 367 b and its star GJ 367 were named in 2022 during the “NameExoWorlds” project coordinated by the International Astronomical Union. The planet GJ 367 b is called Tahay and its star is called Añañuca, after Chilean wildflowers.

The 7.7 hours period during which GJ 367 b orbits its star stands out even among other ultra-short period planets because it is such a short orbit. One year on this planet is only 7.7 hours long. Its mass is 60 % that of Earth’s mass. Its radius is 70 % that of Earth’s radius. Therefore, it is smaller and less massive than the Earth.

Due to its proximity to the host star, the dayside surface of the planet is expected to have a temperature of almost 1.100 degrees Celsius. The star GJ 367 (Añañuca) is located roughly 31 light years from Earth, i.e., it takes about 31 years for the light to travel this distance.

How the transit method works: NASA’s TESS telescope uses the transit method to search for planets around stars other than the Sun. A transit occurs when a planet moves between its host star and us. Whenever it passes in front of its star, it blocks a small portion of the star’s light. The transit method measures this change in brightness, which yields the orbital period and inclination, the planetary radius, and other parameters.

How the radial velocity method works: The KESPRINT team observes exoplanets with the radial velocity method, which detects the existence of a planet around a star via the Doppler effect. We usually say that planets orbit stars, but that’s not entirely true: planets and stars orbit around their common center of mass! Stars emit light at different colors that become bluer or redder depending on whether the stars are moving toward or away from us while orbiting around the center of mass. When combined with the transit method, radial velocity measurements provide the mass of the planet.

The Physics Department at the University of Turin. Over the past decade, the Exoplanet group at the Physics Department of the University of Turin has focused on the detection and characterization of planets orbiting stars other than the Sun, especially those transiting their host stars, combining space-based observations with high-precision spectroscopy. The group at the University of Turin has led and coordinated the observations of GJ 367 carried out with the HARPS spectrograph.

Press release from the University of Turin.

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Astronomy

Webb snaps supersonic outflow of young star from HH 211

By ScientifiCult 14 September 2023

Webb snaps supersonic outflow of young star from HH 211

This new image from the NASA/ESA/CSA James Webb Space Telescope features Herbig-Haro 211 (HH 211), a bipolar jet travelling through interstellar space at supersonic speeds. At roughly 1,000 light-years away from Earth in the constellation Perseus, the object is one of the youngest and nearest protostellar outflows, making it an ideal target for Webb.

Featured in this image from the NASA/ESA/CSA James Webb Space Telescope is Herbig-Haro 211 (HH 211), a bipolar jet travelling through interstellar space at supersonic speeds. At roughly 1,000 light-years away from Earth in the constellation Perseus, the object is one of the youngest and nearest protostellar outflows, making it an ideal target for Webb.
Herbig-Haro objects are luminous regions surrounding newborn stars, and are formed when stellar winds or jets of gas spewing from these newborn stars form shockwaves colliding with nearby gas and dust at high speeds. This spectacular image of HH 211 reveals an outflow from a Class 0 protostar, an infantile analogue of our Sun when it was no more than a few tens of thousands of years old and with a mass only 8% of the present-day Sun (it will eventually grow into a star like the Sun).
Infrared imaging is powerful in studying newborn stars and their outflows, because such stars are invariably still embedded within the gas from the molecular cloud in which they formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making a Herbig-Haro object like HH 211 ideal for observation with Webb’s sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide and silicon monoxide, emit infrared light that Webb can collect to map out the structure of the outflows.
The image showcases a series of bow shocks to the southeast (lower-left) and northwest (upper-right) as well as the narrow bipolar jet that powers them in unprecedented detail — roughly 5 to 10 times higher spatial resolution than any previous images of HH 211. The inner jet is seen to “wiggle” with mirror symmetry on either side of the central protostar. This is in agreement with observations on smaller scales and suggests that the protostar may in fact be an unresolved binary star.
Credit:
ESA/Webb, NASA, CSA, T. Ray (Dublin Institute for Advanced Studies)

Herbig-Haro objects are luminous regions surrounding newborn stars, and are formed when stellar winds or jets of gas spewing from these newborn stars form shockwaves colliding with nearby gas and dust at high speeds. This spectacular image of HH 211 reveals an outflow from a Class 0 protostar, an infantile analogue of our Sun when it was no more than a few tens of thousands of years old and with a mass only 8% of the present-day Sun (it will eventually grow into a star like the Sun).

Infrared imaging is powerful in studying newborn stars and their outflows, because such stars are invariably still embedded within the gas from the molecular cloud in which they formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making a Herbig-Haro object like HH 211 ideal for observation with Webb’s sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide and silicon monoxide, emit infrared light that Webb can collect to map out the structure of the outflows.

The image showcases a series of bow shocks to the southeast (lower-left) and northwest (upper-right) as well as the narrow bipolar jet that powers them. Webb reveals this scene in unprecedented detail — roughly 5 to 10 times higher spatial resolution than any previous images of HH 211. The inner jet is seen to “wiggle” with mirror symmetry on either side of the central protostar. This is in agreement with observations on smaller scales and suggests that the protostar may in fact be an unresolved binary star.

Earlier observations of HH 211 with ground-based telescopes revealed giant bow shocks moving away from us (northwest) and moving towards us (southeast) and cavity-like structures in shocked hydrogen and carbon monoxide respectively, as well as a knotty and wiggling bipolar jet in silicon monoxide. Researchers have used these new observations to determine that the object’s outflow is relatively slow in comparison to more evolved protostars with similar types of outflows.

The team measured the velocities of the innermost outflow structures to be roughly 80 to 100 kilometres per second. However, the difference in velocity between these sections of the outflow and the leading material that they’re colliding with — the velocity of the shockwave — is much smaller. The researchers concluded that outflows from the youngest stars, like that in the center of HH 211, are mostly made up of molecules, because the comparatively low shock wave velocities are not energetic enough to break the molecules apart into simpler atoms and ions.

You can learn more about this research here.

This image was captured as part of the Webb Cycle One programme #1257.

Bibliographic information:

Ray, T.P., McCaughrean, M.J., Caratti o Garatti, A. et al. Outflows from the Youngest Stars are Mostly Molecular, Nature (2023). https://doi.org/10.1038/s41586-023-06551-1

Young star HH 211 Herbig-Haro 211 — Featured in this image from the NASA/ESA/CSA James Webb Space Telescope is Herbig-Haro 211 (HH 211), a bipolar jet travelling through interstellar space at supersonic speeds. At roughly 1,000 light-years away from Earth in the constellation Perseus, the object is one of the youngest and nearest protostellar outflows, making it an ideal target for Webb.
Herbig-Haro objects are luminous regions surrounding newborn stars, and are formed when stellar winds or jets of gas spewing from these newborn stars form shockwaves colliding with nearby gas and dust at high speeds. This spectacular image of HH 211 reveals an outflow from a Class 0 protostar, an infantile analogue of our Sun when it was no more than a few tens of thousands of years old and with a mass only 8% of the present-day Sun (it will eventually grow into a star like the Sun).
Infrared imaging is powerful in studying newborn stars and their outflows, because such stars are invariably still embedded within the gas from the molecular cloud in which they formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making a Herbig-Haro object like HH 211 ideal for observation with Webb’s sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide and silicon monoxide, emit infrared light that Webb can collect to map out the structure of the outflows.
The image showcases a series of bow shocks to the southeast (lower-left) and northwest (upper-right) as well as the narrow bipolar jet that powers them in unprecedented detail — roughly 5 to 10 times higher spatial resolution than any previous images of HH 211. The inner jet is seen to “wiggle” with mirror symmetry on either side of the central protostar. This is in agreement with observations on smaller scales and suggests that the protostar may in fact be an unresolved binary star.
Credit:
ESA/Webb, NASA, CSA, T. Ray (Dublin Institute for Advanced Studies)

Press release from ESA Webb.

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Astronomy

Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

By ScientifiCult 11 September 2023

Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

A new investigation by an international team of astronomers using data from the NASA/ESA/CSA James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

methane carbon dioxide K2-18 b — This artist’s concept shows what exoplanet K2-18 b could look like based on science data. K2-18 b, an exoplanet 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth. A new investigation with the NASA/ESA/CSA James Webb Space Telescope into K2-18 b has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere in K2-18 b.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The first insight into the atmospheric properties of this habitable-zone exoplanet came from observations with the NASA/ESA Hubble Space Telescope, which prompted further studies that have since changed our understanding of the system.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of equivalent nearby planets means that these ‘sub-Neptunes’ are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of analogous nearby planets means that these ‘sub-Neptunes’ are poorly understood and the nature of their atmospheres is a matter of active debate between astronomers. The suggestion that the sub-Neptune K2-18 b could be a Hycean exoplanet is intriguing, as some astronomers believe that these worlds are promising environments to search for evidence for life on exoplanets.

“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,”

explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results.

“Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.“

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere on K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulphide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

The inference of DMS is less robust and requires further validation.

“Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” explained Madhusudhan.

While K2-18 b lies in the habitable zone and is now known to harbour carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet’s large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface. Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

“Although this kind of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy,” explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Characterising the atmospheres of exoplanets like K2-18 b — meaning identifying their gases and physical conditions — is a very active area in astronomy. However, these planets are outshone — literally — by the glare of their much larger parent stars, which makes exploring exoplanet atmospheres particularly challenging.

The team sidestepped this challenge by analysing light from K2-18 b’s parent star as it passed through the exoplanet’s atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star. This is how the exoplanet was first discovered. This means that during transits a tiny fraction of starlight will pass through the exoplanet’s atmosphere before reaching telescopes like Webb. The starlight’s passage through the exoplanet atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet’s atmosphere.

“This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits,” continued Madhusudhan. “For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years and in a relatively narrow wavelength range.”

“These results are the product of just two observations of K2-18 b, with many more on the way,” explained team member Savvas Constantinou of the University of Cambridge. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

The team now intends to conduct follow-up research with the telescope’s Mid-InfraRed Instrument (MIRI) spectrograph that they hope will further validate their findings and provide new insights into the environmental conditions on K2-18 b.

“Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the Universe,” concluded Madhusudhan. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest.”

Spectrum of K2-18 b, obtained with Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph), displays an abundance of methane and carbon dioxide in the exoplanet’s atmosphere, as well as a possible detection of a molecule called dimethyl sulfide (DMS). The detection of methane and carbon dioxide, and shortage of ammonia, are consistent with the presence of an ocean underneath a hydrogen-rich atmosphere in K2-18 b. K2-18 b, 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The team’s results are accepted for publication in The Astrophysical Journal Letters.

Notes

[1] The Habitable Zone is the region around a star where the conditions could potentially be suitable to sustain life on a planet within this region, for example allowing the presence of liquid water on its surface.

Press release from ESA Webb

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Astronomy

Hubble dispels dust to see the glittering globular cluster Terzan 12

By ScientifiCult 7 September 2023

The glittering globular cluster Terzan 12 — a vast, tightly bound collection of stars — fills the frame of this image from the NASA/ESA Hubble Space Telescope. The location of this globular cluster, deep in the Milky Way galaxy in the constellation Sagittarius, means that it is shrouded in gas and dust which absorb and alter the starlight emanating from Terzan 12.

This star-studded stellar census comes from a string of observations that aim to systematically explore the relatively few globular clusters located towards the centre of our galaxy, such as Terzan 12, which is located about 15 000 light-years from Earth. Globular clusters are not uncommon in the Milky Way galaxy. Around 150 are known, mostly in its outer halo, and Hubble has revolutionised their study since its launch in 1990. However, examining clusters like Terzan 12, highly obscured by interstellar dust, is complicated by the resulting reddening of the light.

Terzan 12 Hubble — The glittering globular cluster Terzan 12 — a vast, tightly bound collection of stars — fills the frame of this image from the NASA/ESA Hubble Space Telescope. This star-studded stellar census comes from a string of observations that aim to systematically explore globular clusters located towards the centre of our galaxy, such as this one in the constellation Sagittarius. The locations of these globular clusters — deep in the Milky Way galaxy — mean that they are shrouded in gas and dust, which can block or alter the wavelengths of starlight emanating from the clusters.
Here, astronomers were able to sidestep the effect of gas and dust by comparing the new observations made with the razor-sharp vision of Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 with pre-existing images. Their observations should shed light on the relation between age and composition in the Milky Way’s innermost globular clusters.
Credit:
ESA/Hubble & NASA, R. Cohen (Rutgers University)

When starlight passes through an interstellar cloud it can be absorbed and scattered by particles of dust. The strength of this scattering depends on the wavelength of the light, with shorter wavelengths being scattered and absorbed more strongly. This means that the blue wavelengths of light from stars are less likely to make it through a cloud, making background stars appear redder than they actually are.

Astronomers refer to the colour change caused by the scattering and absorption of starlight — appropriately — as reddening, and it is responsible for the vibrant range of colours in this image. Relatively unobscured stars shine brightly in white and blue, whereas creeping tendrils of gas and dust blanket other large portions of Terzan 12, giving stars a sinister red hue. The more dust that lies along our line of sight to the cluster, the more the light of the stars is reddened.

A similar effect is responsible for the spectacular rosy hues of sunsets here on Earth. The atmosphere preferentially scatters shorter wavelengths of light, which is why the sky overhead appears blue. As the sun sinks lower in the sky, sunlight has to pass through more of the atmosphere, which means more and more blue light is scattered and sunlight takes on a characteristically golden red hue.

Some of the stars in the photo appear starkly different in colour to their near neighbours. The brightest red stars are bloated, ageing giants, many times larger than our Sun. They lie between Earth and the cluster. Only a few may actually be members of the cluster. The very brightest hot, blue stars are also along the line of sight and not inside the cluster, which only contains ageing stars.

The reddening of stars usually poses problems for astronomers, but the scientists behind this observation of Terzan 12 were able to sidestep the effect of gas and dust by comparing the new observations made with the razor-sharp vision of Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 with pre-existing images. Their observations should shed light on the relation between age and composition in the Milky Way’s galaxy’s innermost globular clusters, comparable to astronomers’ understanding of the clusters spread throughout the rest of our galaxy.

Incidentally, the Terzan clusters suffer from something of an astronomical identity crisis: there were actually only 11 clusters discovered by the Turkish-Armenian astronomer Agop Terzan. The mix-up results from an error made by Terzan in 1971, when he rediscovered Terzan 5 — a cluster he had already discovered and reported in 1968 — and named it Terzan 11. Terzan attempted to fix his mistake, but the confusion caused has persisted in scientific studies ever since, astronomers eventually settling on the odd convention that there is no Terzan 11.

Losing and then rediscovering astronomical objects is surprisingly common, even in our own Solar System. Minor planets such as asteroids and dwarf planets are often detected and then subsequently lost because their orbits cannot be determined from only a tiny handful of observations.

Press release from ESA Hubble

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Astronomy

Webb captures detailed beauty of Ring Nebula

By ScientifiCult 21 August 2023

Webb captures detailed beauty of Ring Nebula

The NASA/ESA/CSA James Webb Space Telescope has observed the well-known Ring Nebula with unprecedented detail. Formed by a star throwing off its outer layers as it runs out of fuel, the Ring Nebula is an archetypal planetary nebula. The object is also known as M57 and NGC 6720, and is relatively close to Earth at roughly 2,500 light-years away.

This new NIRCam image provides unprecedented spatial resolution and spectral sensitivity. For example, the intricate details of the filament structure of the inner ring are particularly visible in this dataset.
Credit: ESA/Webb, NASA, CSA, M. Barlow, N. Cox, R. Wesson

The new images provide unprecedented spatial resolution and spectral sensitivity, which also reveal unique details across both infrared observations. For example, the new image from NIRCam (Near-InfraRed Camera) shows the intricate details of the filament structure of the inner ring, while the new image from MIRI (Mid-InfraRed Instrument) reveals particular details in the concentric features in the outer regions of the nebulae’s ring.

Webb’s MIRI (Mid-InfraRed Instrument) reveals particular details in the concentric features in the outer regions of the nebulae’s ring (right).
Credit: ESA/Webb, NASA, CSA, M. Barlow, N. Cox, R. Wesson

There are some 20,000 dense globules in the nebula, which are rich in molecular hydrogen. In contrast, the inner region shows very hot gas. The main shell contains a thin ring of enhanced emission from carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). Roughly ten concentric arcs are located just beyond the outer edge of the main ring. The arcs are thought to originate from the interaction of the central star with a low-mass companion orbiting at a distance comparable to that between the Earth and the dwarf planet Pluto. In this way, nebulae like the Ring Nebula reveal a kind of astronomical archaeology, as astronomers study the nebula to learn about the star that created it.

The nebula is shaped like a distorted doughnut. We are gazing almost directly down one of the poles of this structure, with a brightly coloured barrel of material stretching away from us. Although the centre of this doughnut may look empty, it is actually full of lower density material that stretches both towards and away from us, creating a shape similar to a rugby ball slotted into the doughnut’s central gap.

The colourful main ring is composed of gas thrown off by a dying star at the centre of the nebula. This star is on its way to becoming a white dwarf — a very small, dense, and hot body that is the final evolutionary stage for a star like the Sun.

The Ring Nebula is one of the most notable objects in our skies. It was discovered in 1779 by astronomers Antoine Darquier de Pellepoix and Charles Messier, and was added to the Messier Catalogue. Both astronomers stumbled upon the nebula when trying to follow the path of a comet through the constellation of Lyra, passing very close to the Ring Nebula.

These observations were completed as part of the James Webb Space Telescope observing programme GO 1558. To learn more about the team’s research of these new observations, see the latest NASA Webb blog here.

Webb captures detailed beauty of Ring Nebula (NIRCam and MIRI im — The NASA/ESA/CSA James Webb Space Telescope has observed the well-known Ring Nebula with unprecedented detail. Formed by a star throwing off its outer layers as it runs out of fuel, the Ring Nebula is an archetypal planetary nebula. Also known as M57 and NGC 6720, it is both relatively close to Earth at roughly 2,500 light-years away.
The new images provide unprecedented spatial resolution and spectral sensitivity, which also reveal unique details across both infrared observations. For example, the new image from Webb’s NIRCam (Near-InfraRed Camera) shows the intricate details of the filament structure of the inner ring (left), while the new image from Webb’s MIRI (Mid-InfraRed Instrument) reveals particular details in the concentric features in the outer regions of the nebulae’s ring (right).
There are some 20,000 dense globules in the nebula, which are rich in molecular hydrogen. In contrast, the inner region shows very hot gas. The main shell contains a thin ring of enhanced emission from
carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). Roughly ten concentric arcs are located just beyond the outer edge of the main ring. The arcs are thought to originate from the interaction of the central star with a low-mass companion orbiting at a distance comparable to that between the Earth and the dwarf planet Pluto. In this way, nebulae like the Ring Nebula reveal a kind of astronomical archaeology, as astronomers study the nebula to learn about the star that created it.
Credit:
ESA/Webb, NASA, CSA, M. Barlow, N. Cox, R. Wesson

Press release from ESA Webb.

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Biology

Panagrolaimus kolymaensis, a nematode resurrected from Siberian permafrost laid dormant for 46,000 years

By ScientifiCult 27 July 2023

Panagrolaimus kolymaensis, a nematode resurrected from Siberian permafrost laid dormant for 46,000 years

Genome analysis shows new nematode species shares molecular toolkit for survival with C. elegans

A soil nematode reanimated from Siberian permafrost had laid dormant for approximately 46,000 years, according to a study publishing July 27, 2023 in the open access journal PLOS Genetics by Anastasia Shatilovich at the Institute of Physicochemical and Biological Problems in Soil Science RAS in Russia, Vamshidhar Gade at the Max Planck Institute for Molecular Cell Biology and Genetics in Germany, and colleagues.

Panagrolaimus kolymaensis, a nematode resurrected from Siberian permafrost laid dormant for 46,000 years — General morphology of P. kolymaensis, female. Scanning electron pictures (A, C), light microscopy photographs (E, F) and graphic presentations (B, D, G) of holotype: A, B) entire body, C, D) anterior ends, E) anterior body, F) perivulvar body region, G) tail. Abbreviations: l.f.–lateral field, ov–ovary, pro–procorpus of the pharynx, t.b.–terminal bulb of the pharynx, u–uterus with eggs, v–vulva, v.p.–ventral pore. Scale bars: A, D, E, F, G– 20 μm, B– 100 μm, C– 2 μm. Shatilovich et al, 2023, PLOS Genetics, CC-BY 4.0

Some animals, such as tardigrades, rotifers, and nematodes, can survive harsh conditions by entering a dormant state known as “cryptobiosis”. Previously, nematode individuals were reanimated from samples collected from a fossilized burrow in silt deposits in the northeastern Arctic. In this study, radiocarbon analysis of plant material from the burrow revealed that these frozen deposits, 40 meters below the surface, had not thawed since the late Pleistocene, between 45,839 and 47,769 years ago.

Using genome sequencing, assembly, and phylogenetic analysis of the nematode’s relationship to modern species, the researchers determined that it belongs to a previously undescribed species, Panagrolaimus kolymaensis. They compared its genome with the model organism, Caenorhabditis elegans, and identified genes in common that are involved in cryptobiosis. When mildly desiccated in the laboratory, both species increased production of a sugar called trehalose, which may help them to survive harsh desiccation and freezing. They tested the survival capabilities of P. kolymaensis and found that exposure to mild desiccation before freezing helped prepare the worms for cryptobiosis and improved survival at -80°C. This treatment also benefitted C. elegans dauer larvae, which then survived 480 days at -80°C with no reductions in viability or reproduction after thawing.

This study extends the longest reported cryptobiosis in nematodes by tens of thousands of years. By adapting to cope with extreme conditions, such as permafrost, for short periods of time, the nematodes might have gained the potential to remain dormant over geological timescales.

The authors add, “This work also suggests that fluctuations in the environment also determine the time an organism can remain in a cryptobiotic state.”

Bibliographic information:

Shatilovich A, Gade VR, Pippel M, Hoffmeyer TT, Tchesunov AV, Stevens L, et al. (2023) A novel nematode species from the Siberian permafrost shares adaptive mechanisms for cryptobiotic survival with C. elegans dauer larva. PLoS Genet 19(7): e1010798. https://doi.org/10.1371/journal.pgen.1010798

Press release from PLOS Genetics

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Webb snaps highly detailed infrared image of actively forming stars, Herbig-Haro 46/47

By ScientifiCult 26 July 2023

Webb snaps highly detailed infrared image of actively forming stars, known as Herbig-Haro 46/47

The NASA/ESA/CSA James Webb Space Telescope has captured the ‘antics’ of a pair of actively forming young stars, known as Herbig-Haro 46/47, in a high-resolution image in near-infrared light. This is the most detailed portrait of these stars, which reside only 1470 light-years away in the constellation Vela, to date.

Herbig-Haro 46/47 (NIRCam image – annotated). Credit: NASA, ESA, CSA, J. DePasquale (STScI)

To find the pair of young stars, trace the bright pink and red diffraction spikes in the image until you hit the centre: the stars are within the orange-white splotch. They are buried deeply in a disc of gas and dust that feeds their growth as they continue to gain mass. The disc is not visible, but its shadow can be seen in the two dark, conical regions surrounding the central stars.

The pair of actively forming stars has sent out jets in two directions for thousands of years. Although Herbig-Haro 46/47 has been studied by many telescopes, both on the ground and in space, since the 1950s, Webb is the first to capture them at high resolution in near-infrared light. With Webb, we can now understand more of the stars’ activity — past and present — and peer through the dusty blue nebula, which appears black in visible-light images, that surrounds them. Over time, researchers will be able to glean new details about how stars form.

The most striking details are the two-sided lobes that fan out from the actively forming central stars, represented in fiery orange. Much of this material was shot out from those stars as they repeatedly ingest and eject the gas and dust that immediately surround them over thousands of years.

When material from more recent ejections runs into older material, it changes the shape of these lobes. This activity is like a large fountain being turned on and off in rapid, but random succession, leading to billowing patterns in the pool below it. Some jets send out more material and others launch at faster speeds. Why? It’s likely related to how much material fell onto the stars at a particular point in time.

The stars’ more recent ejections appear in a thread-like blue. They run just below the red diagonal diffraction spike at two o’clock. Along the right side, these ejections make clearer wavy patterns. They are disconnected at points, and end in a remarkable uneven light purple circle in the thickest orange area. Lighter blue, curly lines also emerge on the left, near the central stars, but are sometimes overshadowed by the bright red diffraction spike.

All of these jets are crucial to the star formation process itself. Ejections regulate how much mass the stars ultimately gather. (The disc of gas and dust feeding the stars is small. Imagine a band tightly tied around the stars.)

Now, turn your eye to the second most prominent feature: the effervescent blue cloud. This is a region of dense dust and gas, known both as a nebula and more formally as a Bok globule. When viewed in mainly visible light, it appears almost completely black — only a few background stars peek through. In Webb’s crisp near-infrared image, we can see into and through the gauzy layers of this cloud, bringing a lot more of Herbig-Haro 46/47 into focus, while also revealing a wide range of stars and galaxies that lie well beyond it. The nebula’s edges appear in a soft orange outline, like a backward L along the right and bottom of the image.

This nebula is significant — its presence influences the shapes of the jets shot out by the central stars. As ejected material rams into the nebula on the lower left, there is more opportunity for the jets to interact with molecules within the nebula, causing them both to light up.

There are two other areas to look at to compare the asymmetry of the two lobes. Glance toward the upper right to pick out a blobby, almost sponge-shaped ejecta that appears separate from the larger lobe. Only a few threads of the semi-transparent wisps of material point toward the larger lobe. Almost transparent, tentacle-like shapes also appear to be drifting behind it, like streamers in a cosmic wind. In contrast, at lower left, look beyond the hefty lobe to find an arc. Both are made up of material that was pushed the farthest and possibly by earlier ejections. The arcs appear to point in different directions, and may have originated from different outflows.

Take another long look at this image. Although it appears Webb has snapped Herbig-Haro 46/47 edge-on, one side is angled slightly towards Earth. Counterintuitively, it’s the smaller right half. Though the left side is larger and brighter, it is pointing away from us.

Over millions of years, the stars in Herbig-Haro 46/47 will form fully — clearing the scene of these fantastic, multihued ejections and allowing the binary stars to take centre stage against a galaxy-filled background.

Webb can reveal so much detail in Herbig-Haro 46/47 for two reasons. The object is relatively close to Earth, and Webb’s image is made up of several exposures, which adds to its depth.

Press release from ESA Webb.

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Webb detects water vapour in the inner disk of the system PDS 70

By ScientifiCult 24 July 2023

Webb detects water vapour in the inner disk of the system PDS 70, a rocky planet-forming zone

New measurements by the NASA/ESA/CSA James Webb Space Telescope’s Mid-InfraRed Instrument (MIRI) have detected water vapour in the inner disc of the system PDS 70, located 370 light-years away. This is the first detection of water in the terrestrial region of a disc already known to host two or more protoplanets.

Water is essential for life as we know it. However, scientists debate how it reached the Earth and whether the same processes could seed rocky exoplanets orbiting distant stars. New insights may come from the system PDS 70, which hosts an inner disc and an outer disc that are separated by a gap of eight billion kilometres, within which are two known gas-giant planets. MIRI has detected water vapour in the system’s inner disc at distances of less than 160 million kilometres from the star — the region where rocky, terrestrial planets may be forming (the Earth orbits 150 million kilometres from our Sun).

“We’ve seen water in other discs, but not so close in and in a system where planets are currently assembling. We couldn’t make this type of measurement before Webb,” said lead author Giulia Perotti of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany.

“This discovery is extremely exciting, as it probes the region where rocky planets similar to Earth typically form,”

added MPIA director Thomas Henning, a co-author of the paper. Henning is co-principal investigator of Webb’s MIRI (Mid-InfraRed Instrument), which made the detection, and the principal investigator of the MINDS (MIRI Mid-Infrared Disk Survey) programme that took the data.

A wet environment for forming planets

PDS 70 is a K-type star, cooler than our Sun, and is estimated to be 5.4 million years old. This is relatively old amongst stars with planet-forming discs, which made the discovery of water vapour surprising.

Over time, the gas and dust content of planet-forming discs declines. Either the central star’s radiation and winds remove such material, or the dust grows into larger objects that eventually form planets. As previous studies failed to detect water in the central regions of similarly aged discs, astronomers suspected it might not survive the harsh stellar radiation, leading to a dry environment for the formation of any rocky planets.

Astronomers haven’t yet detected any planets forming within the inner disc of PDS 70. However, they do see the raw materials for building rocky worlds, in the form of silicates. The detection of water vapour implies that if rocky planets are forming there, they will have water available to them from the beginning.

“We find a relatively large amount of small dust grains. Combined with our detection of water vapour, the inner disc is a very exciting place,” said co-author Rens Waters of Radboud University in the Netherlands.

What is the origin of the water?

The discovery raises the question of where the water came from. The MINDS team considered two different scenarios to explain their finding.

One possibility is that water molecules are forming in place, where we detect them, as hydrogen and oxygen atoms combine. A second possibility is that ice-coated dust particles are being transported from the cool outer disc to the hot inner disc, where the water ice sublimates and turns into vapour. Such a transport system would be surprising, since the dust would have to cross the large gap carved out by the two giant planets.

Another question raised by the discovery is how water could survive so close to the star, where the star’s ultraviolet light should break apart any water molecules. Most likely, surrounding material, such as dust and other water molecules, serves as a protective shield. As a result, the water detected near PDS 70 could survive destruction.

Ultimately, the team will use two of Webb’s other instruments, the Near-InfraRed Camera (NIRCam) and the Near-InfraRed Spectrograph (NIRSpec) to study the PDS 70 system in an effort to glean an even greater understanding.

These observations were made as part of Guaranteed Time Observation program 1282. This finding has been published in the journal Nature.

Water in protoplanetary disc of PDS 70 (MIRI emission spectrum) — New measurements from the NASA/ESA/CSA James Webb Space Telescope’s Mid-InfraRed Instrument (MIRI) have indicated the presence of water vapour in the inner disc of the system PDS 70, located 370 light-years away. This is the first detection of water in the terrestrial region of a disc already known to host two or more protoplanets.
This spectrum of the protoplanetary disk of PDS 70, obtained with Webb’s MIRI instrument, displays a number of emission lines from water vapour.
Credit: NASA, ESA, CSA, J. Olmsted (STScI)

Press release from ESA Webb.

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Hubble sees boulders escaping from asteroid Dimorphos

By ScientifiCult 20 July 2023

Hubble sees boulders escaping from asteroid Dimorphos

Astronomers using the NASA/ESA/ Hubble Space Telescope’s extraordinary sensitivity have discovered a swarm of boulders that were possibly shaken off the asteroid Dimorphos when NASA deliberately slammed the half-tonne DART impactor spacecraft into Dimorphos at approximately 22 500 kilometres per hour. DART intentionally impacted Dimorphos on 26 September 2022, slightly changing the trajectory of its orbit around the larger asteroid Didymos.

Hubble boulders Dimorphos The bright white object at lower left is the asteroid Dimorphos. It has a blue dust tail extending diagonally to the upper right. A cluster of blue dots surrounds the asteroid. These are boulders that were knocked off the asteroid when, on 26 September 2022, NASA deliberately slammed the half-tonne DART impactor spacecraft into the asteroid as a test of what it would take to deflect some future asteroid from hitting Earth. Hubble photographed the slow-moving boulders in December 2022 — This NASA/ESA Hubble Space Telescope image of the asteroid Dimorphos was taken on 19 December 2022, nearly four months after the asteroid was impacted by NASA’s DART (Double Asteroid Redirection Test) mission. Hubble’s sensitivity reveals a few dozen boulders knocked off the asteroid by the force of the collision. These are among the faintest objects Hubble has ever photographed inside the Solar System. The ejected boulders range in size from 1 metre to 6.7 metres across, based on Hubble photometry. They are drifting away from the asteroid at around a kilometre per hour. The discovery yields invaluable insights into the behaviour of a small asteroid when it is hit by a projectile for the purpose of altering its trajectory.
Credit: NASA, ESA, D. Jewitt (UCLA)

The 37 ejected boulders range in size from 1 metre to 6.7 metres across, based on Hubble photometry. They are drifting away from the asteroid at around one kilometre per hour. The total mass in these detected boulders is about 0.1% the mass of Dimorphos. The boulders are some of the faintest objects ever imaged in the Solar System.

This opens up a new dimension for studying the aftermath of the DART experiment using the European Space Agency’s upcoming Hera mission, which is due to launch in 2024. The spacecraft will perform a detailed post-impact survey of the target asteroid Dimorphos. Hera will turn the grand-scale experiment into a well-understood and repeatable planetary defence technique that might one day be used for real [1].

The boulders are most likely not shattered pieces of the diminutive asteroid caused by the impact. They were already scattered across the asteroid’s surface, as evident in the last close-up picture taken by the DART spacecraft just two seconds before collision, when it was only 11 kilometres above the surface.

The science team that observed these boulders with Hubble estimates that the impact shook off two percent of the boulders on the asteroid’s surface. While the boulder observations by Hubble also give an estimate for the size of the DART impact crater, Hera will eventually determine the actual crater size.

Long ago, Dimorphos may have formed from material shed into space by the larger asteroid Didymos. The parent body may have spun up too quickly or could have lost material after a glancing collision with another object, among other scenarios. The ejected material formed a ring that gravitationally coalesced to form Dimorphos. This would make it a flying rubble pile of rocky debris loosely held together by the relatively weak pull of its gravity. Therefore, the interior is probably not solid, but has a structure more like a bunch of grapes.

It’s not clear how the boulders were lifted off the asteroid’s surface. They could be part of an ejecta plume that was photographed by Hubble and other observatories. Or a seismic wave from the impact may have rattled through the asteroid — like hitting a bell with a hammer — shaking loose the surface rubble.

The DART and LICIACube (Light Italian CubeSat for Imaging of Asteroids) teams have also been studying boulders detected in images taken by LICIACube’s LUKE (LICIACube Unit Key Explorer) camera in the minutes immediately following DART’s kinetic impact.

Notes

[1] Just like Hubble and the NASA/ESA/CSA James Webb Space Telescope, NASA’s DART and ESA’s Hera missions are great examples of what international collaboration can achieve; the two missions are supported by the same teams of scientists and astronomers, and operate via an international collaboration called AIDA — the Asteroid Impact and Deflection Assessment.

NASA and ESA worked together in the early 2000s to develop asteroid monitoring systems, but recognised there was a missing link in the chain between asteroid threat identification and ways of addressing that threat. In response NASA oversaw the DART mission while ESA developed the Hera mission to gather additional data on DART’s impact. With the Hera mission, ESA is assuming even greater responsibility for protecting our planet and ensuring that Europe plays a leading role in the common effort to tackle asteroid risks. As Europe’s flagship planetary defender, Hera is supported through the Agency’s Space Safety programme, part of the Operations Directorate.

The bright white object at lower left is the asteroid Dimorphos. It has a blue dust tail extending diagonally to the upper right. A cluster of blue dots surrounds the asteroid. These are boulders that were knocked off the asteroid when, on 26 September 2022, NASA deliberately slammed the half-tonne DART impactor spacecraft into the asteroid as a test of what it would take to deflect some future asteroid from hitting Earth. Hubble photographed the slow-moving boulders in December 2022 — Hubble sees boulders escaping from asteroid Dimorphos: this NASA/ESA Hubble Space Telescope image of the asteroid Dimorphos was taken on 19 December 2022, nearly four months after the asteroid was impacted by NASA’s DART (Double Asteroid Redirection Test) mission. Hubble’s sensitivity reveals a few dozen boulders knocked off the asteroid by the force of the collision. These are among the faintest objects Hubble has ever photographed inside the Solar System. The ejected boulders range in size from 1 metre to 6.7 metres across, based on Hubble photometry. They are drifting away from the asteroid at around a kilometre per hour. The discovery yields invaluable insights into the behaviour of a small asteroid when it is hit by a projectile for the purpose of altering its trajectory.
Credit: NASA, ESA, D. Jewitt (UCLA)

Press release from ESA Hubble

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Webb sees carbon-rich dust grains at redshift, in the first billion years of cosmic time

By ScientifiCult 19 July 2023

Webb sees carbon-rich dust grains at redshift, in the first billion years of cosmic time

For the first time, the NASA/ESA/CSA James Webb Space Telescope has observed the chemical signature of carbon-rich dust grains at redshift ~ 7 [1], which is roughly equivalent to one billion years after the birth of the Universe [2]. Similar observational signatures have been observed in the much more recent Universe, attributed to complex, carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). It is not thought likely, however, that PAHs would have developed within the first billion years of cosmic time. Therefore, this observation suggests the exciting possibility that Webb may have observed a different species of carbon-based molecule: possibly minuscule graphite- or diamond-like grains produced by the earliest stars or supernovae. This observation suggests exciting avenues of investigation into both the production of cosmic dust and the earliest stellar populations in our Universe, and was made possible by Webb’s unprecedented sensitivity.

The seemingly empty spaces in our Universe are in reality often not empty at all, but occupied by clouds of gas and cosmic dust. This dust consists of grains of various sizes and compositions that are formed and ejected into space in a variety of ways, including by supernova events. This material is crucial to the evolution of the Universe, as dust clouds ultimately form the birthplaces for new stars and planets. However, it can also be a hindrance to astronomers: the dust absorbs stellar light at certain wavelengths, making some regions of space very challenging to observe. An upside, however, is that certain molecules will very consistently absorb or otherwise interact with specific wavelengths of light. This means that astronomers can acquire information about the cosmic dust’s composition by observing the wavelengths of light that it blocks. An international team of astronomers used this technique, combined with Webb’s extraordinary sensitivity, to detect the presence of carbon-rich dust grains only a billion years after the birth of the Universe.

Joris Witstok of the University of Cambridge, the lead author of this work, elaborates: “Carbon-rich dust grains can be particularly efficient at absorbing ultraviolet light with a wavelength around 217.5 nanometres, which for the first time we have directly observed in the spectra of very early galaxies.”

This prominent 217.5-nanometre feature has previously been observed in the much more recent and local Universe, both within our own Milky Way galaxy, and in galaxies up to redshift ~ 3 [1]. It has been attributed to two different types of carbon-based species: polycyclic aromatic hydrocarbons (PAHs) or nano-sized graphitic grains. PAHs are complex molecules, and modern models predict that it should take several hundreds of millions of years before they form. It would be surprising, therefore, if the team had observed the chemical signature of a mixture of dust grains that include species that were unlikely to have formed yet. However, according to the science team, this result is the earliest and most distant direct signature for this particular type of carbon-rich dust grain.

The answer may lie in the details of what was observed. As already stated, the feature associated with the cosmic dust mixture of PAHs and tiny graphitic grains is at 217.5 nanometres. However, the feature observed by the team actually peaked at 226.3 nanometres. A nanometre is a millionth of a millimetre, and this discrepancy of less than ten nanometres could be accounted for by measurement error [3]. Equally, it could also indicate a difference in the composition of the early-Universe cosmic dust mixture that the team detected.

“This slight shift in wavelength of where the absorption is strongest suggests we may be seeing a different mix of grains, for example graphite- or diamond-like grains,” adds Witstok. “This could also potentially be produced on short timescales by Wolf-Rayet stars or supernova ejecta.”

The detection of this feature in the early Universe is surprising, and allows astronomers to postulate about the mechanisms that could create such a mix of dust grains. This involves drawing on existing knowledge from observations and models. Witstok suggests diamond grains formed in supernova ejecta because models have previously suggested that nano-diamonds could be formed this way. Wolf-Rayet stars are suggested because they are exceptionally hot towards the end of their lives, and very hot stars tend to live fast and die young; giving enough time for generations of stars to have been born, lived, and died, to distribute carbon-rich grains into the surrounding cosmic dust in under a billion years. Models have also shown that carbon-rich grains can be produced by certain types of Wolf-Rayet stars, and just as importantly that those grains can survive the violent deaths of those stars. However, it is still a challenge to fully explain these results with the existing understanding of the early formation of cosmic dust. These results will therefore go on to inform the development of improved models and future observations.

Before Webb, the observations of multiple galaxies had to be combined in order to get signals strong enough to make deductions about the stellar populations in the galaxies, and to learn about how their light was affected by dust absorption. Importantly, astronomers were restricted to studying relatively old and mature galaxies that had had a long time to form stars as well as dust. This limited their ability to really pin down the key sources of cosmic dust. With the advent of Webb, astronomers are now able to make very detailed observations of the light from individual dwarf galaxies, seen in the first billion years of cosmic time. Webb finally permits the study of the origin of cosmic dust and its role in the crucial first stages of galaxy evolution.

“This discovery was made possible by the unparalleled sensitivity improvement in near-infrared spectroscopy provided by Webb, and specifically its Near-Infrared Spectrograph (NIRSpec),” noted team member Roberto Maiolino of the University of Cambridge and University College London. “The increase in sensitivity provided by Webb is equivalent, in the visibile, to instantaneously upgrading Galileo’s 37-millimetre telescope to the 8-metre Very Large Telescope (one of the most powerful modern optical telescopes).”

NIRSpec was built for the European Space Agency by a consortium of European companies led by Airbus Defence and Space (ADS) with NASA’s Goddard Space Flight Centre providing its detector and micro-shutter subsystems. The primary goal of NIRSpec is to enable large spectroscopic surveys of astronomical objects such as stars or distant galaxies. This is made possible by its powerful multi-object spectroscopy mode, which makes use of microshutters. This mode is capable of obtaining spectra of up to nearly 200 objects simultaneously, over a 3.6 × 3.4 arcminute field of view — the first time this capability has been provided from space. This mode makes for very efficient use of Webb’s valuable observing time.

The team is also planning further research into the data and this result.

“We are planning to work further with theorists who model dust production and growth in galaxies,” shares team member Irene Shivaei of the University of Arizona/Centro de Astrobiología (CAB). “This will shed light on the origin of dust and heavy elements in the early Universe.”

These observations were made as part of the JWST Advanced Deep Extragalactic Survey, or JADES, which devoted about 32 days of telescope time to uncovering and characterising faint, distant galaxies. This programme has facilitated the discovery of hundreds of galaxies that existed when the Universe was less than 600 million years old, including some of the farthest galaxies known to date. The sheer number and maturity of these galaxies was far beyond predictions from observations made before Webb’s launch. This new result of early-Universe dust grains contributes to our growing and evolving understanding of the evolution of stellar populations and galaxies during the first billion years of cosmic time.

“This discovery implies that infant galaxies in the early Universe develop much faster than we ever anticipated,” adds team member Renske Smit of the Liverpool John Moores University in the United Kingdom. “Webb shows us a complexity of the earliest birth-places of stars (and planets) that models are yet to explain.“

The results have been published today in Nature.

The infrared image shown here was taken as part of the JADES programme (the JWST Advanced Deep Extragalactic Survey) and shows a portion of an area of the sky known as GOODS-South.
This region was the focus area of Webb study for an international team of astronomers, who observed the chemical signature of carbon-rich dust grains at redshift ~7. This is roughly equivalent to one billion years after the birth of the Universe. Similar observational signatures have been observed in the much more recent Universe, attributed to complex, carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). It is not thought likely, however, that PAHs would have developed within the first billion years of cosmic time. Therefore, this observation suggests the exciting possibility that Webb may have observed a different species of carbon-based molecule: possibly minuscule graphite- or diamond-like grains produced by the earliest stars or supernovae. This observation suggests exciting avenues of investigation into both the production of cosmic dust and the earliest stellar populations in our Universe, and was made possible by Webb’s unprecedented sensitivity.
In this image, blue, green, and red were assigned to Webb’s NIRCam (Near-Infrared Camera) data at 0.9, 1.15, and 1.5 microns; 2.0, 2.77, and 3.55 microns; and 3.56, 4.1, and 4.44 microns (F090W, F115W, and F150W; F200W, F277W, and F335M; and F356W, F410M, and F444W), respectively.
Credit:
ESA/Webb, NASA, ESA, CSA, B. Robertson (UC Santa Cruz), B. Johnson (Center for Astrophysics, Harvard & Smithsonian), S. Tacchella (University of Cambridge, M. Rieke (Univ. of Arizona), D. Eisenstein (Center for Astrophysics, Harvard & Smithsonian), A. Pagan (STScI)

Notes

[1] The Universe is expanding. The expansion is taking place at the fundamental spacetime level, which means that light travelling through the Universe is ‘stretched’ as the Universe expands. The earlier in the Universe the light originated, the more it will have been stretched by now. Practically speaking, this stretching of light means its wavelength becomes longer. This effect is known as cosmological redshift, because the colour red has the longest wavelength of all light visible to human eyes. Because of this, cosmological time is often not measured in years, but is indicated by the redshift of the observed light. The very local Universe — where the light we observe was emitted recently and has not been notably redshifted — has a low redshift. Conversely, redshift 7 corresponds to light that was emitted about 13 billion years ago, in the very early Universe.

[2] Astronomy fundamentally involves the study of light, and light travels at a finite speed (roughly 300 million kilometres per second). Objects can only be observed by humans once light from them has reached Earth. Whilst in some ways providing a limitation, this also provides a direct opportunity to study the early as well as the present Universe. Studying light from the early Universe necessarily entails the observation of regions very distant from Earth from which it takes a huge amount of time for light to travel to us. Thus, probing these early cosmological times (or high redshifts) requires very sensitive telescopes.

[3] All scientific measurements — including those from observations and those predicted by models — will have an associated error. This is because there will always be sources of uncertainty. If a measurement falls within the bounds of the expected error, it means that it could still be accurate: in this context, that means the 226.3 nanometre feature could still account for the same mix of cosmic dust as that represented by the 217.5 nanometre feature.

Press release from ESA Webb

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