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Hubble Glimpses a Glittering Gathering of Stars

Astronomy News - 29 November 2022 - 10:02am
Portal origin URL: Hubble Glimpses a Glittering Gathering of StarsPortal origin nid: 484141Published: Monday, November 28, 2022 - 08:00Featured (stick to top of list): noPortal text teaser: This glittering gathering of stars is Pismis 26, a globular star cluster located about 23,000 light-years away.Portal image: Bright blue-white stars fill the scene with a smattering or bright yellow-white stars

NASA’s Juno Mission Spots Two Jovian Moons

Astronomy News - 29 November 2022 - 10:02am

NASA’s Juno mission completed its 38th close flyby of Jupiter. As the spacecraft sped low over the giant planet’s cloud tops, its JunoCam instrument captured this look at two of Jupiter’s largest moons.

News Article Type: Homepage ArticlesPublished: Monday, November 28, 2022 - 15:58

Non-detection of key signal allows astronomers to determine what the first galaxies were – and weren’t – like

Astronomy News - 29 November 2022 - 9:56am

Using data from India’s SARAS3 radio telescope, researchers led by the University of Cambridge were able to look at the very early Universe – just 200 million years after the Big Bang – and place limits on the mass and energy output of the first stars and galaxies.

Counterintuitively, the researchers were able to place these limits on the earliest galaxies by not finding the signal they had been looking for, known as the 21-centimetre hydrogen line.

This non-detection allowed the researchers to make other determinations about the cosmic dawn, placing restraints on the first galaxies, and enabling them to rule out scenarios including galaxies that were inefficient heaters of cosmic gas and efficient producers of radio emissions.

While we cannot yet directly observe these early galaxies, the results, reported in the journal Nature Astronomy, represent an important step in understanding how our Universe transitioned from mostly empty to one full of stars.

Understanding the early Universe, when the first stars and galaxies formed, is one of the major goals of new observatories. The results obtained using the SARAS3 data are a proof-of-concept study that paves the way to understanding this period in the development of the Universe.

The SKA project – involving two next-generation telescopes due to be completed by the end of the decade – will likely be able to make images of the early Universe, but for current telescopes, the challenge is to detect the cosmological signal of the first stars re-radiated by thick hydrogen clouds.

This signal is known as the 21-centimetre line – a radio signal produced by hydrogen atoms in the early Universe. Unlike the recently launched JWST, which will be able to directly image individual galaxies in the early Universe, studies of the 21-centimetre line, made with radio telescopes such as the Cambridge-led REACH (Radio Experiment for the Analysis of Cosmic Hydrogen), can tell us about entire populations of even earlier galaxies. The first results are expected from REACH early in 2023.

To detect the 21-centimetre line, astronomers look for a radio signal produced by hydrogen atoms in the early Universe, affected by light from the first stars and the radiation behind the hydrogen fog. Earlier this year, the same researchers developed a method that they say will allow them to see through the fog of the early universe and detect light from the first stars. Some of these techniques have been already put to practice in the current study.

In 2018, another research group operating the EDGES experiment published a result that hinted at a possible detection of this earliest light. The reported signal was unusually strong compared to what is expected in the simplest astrophysical picture of the early Universe. Recently, the SARAS3 data disputed this detection: the EDGES result is still awaiting confirmation from independent observations.

In a re-analysis of the SARAS3 data, the Cambridge-led team tested a variety of astrophysical scenarios which could potentially explain the EDGES result, but they did not find a corresponding signal. Instead, the team was able to place some limits on properties of the first stars and galaxies.

The results of the SARAS3 analysis are the first time that radio observations of the averaged 21-centimetre line have been able to provide an insight to the properties of the first galaxies in the form of limits of their main physical properties.

Working with collaborators in India, Australia and Israel, the Cambridge team used data from the SARAS3 experiment to look for signals from cosmic dawn, when the first galaxies formed. Using statistical modelling techniques, the researchers were not able to find a signal in the SARAS3 data.

"We were looking for a signal with a certain amplitude,” said Harry Bevins, a PhD student from Cambridge’s Cavendish Laboratory and the paper’s lead author. “But by not finding that signal, we can put a limit on its depth. That, in turn, begins to inform us about how bright the first galaxies were.”

“Our analysis showed that the hydrogen signal can inform us about the population of first stars and galaxies,” said co-lead author Dr Anastasia Fialkov from Cambridge’s Institute of Astronomy. “Our analysis places limits on some of the key properties of the first sources of light including the masses of the earliest galaxies and the efficiency with which these galaxies can form stars. We also address the question of how efficiently these sources emit X-ray, radio and ultraviolet radiation.”

“This is an early step for us in what we hope will be a decade of discoveries about how the Universe transitioned from darkness and emptiness to the complex realm of stars, galaxies and other celestial objects we can see from Earth today,” said Dr Eloy de Lera Acedo from Cambridge’s Cavendish Laboratory, who co-led the research.

The observational study, the first of its kind in many respects, excludes scenarios in which the earliest galaxies were both more than a thousand times as bright as present galaxies in their radio-band emission and were poor heaters of hydrogen gas.

“Our data also reveals something which has been hinted at before, which is that the first stars and galaxies could have had a measurable contribution to the background radiation that appeared as a result of the Big Bang and which has been travelling towards us ever since,” said de Lera Acedo, “We are also establishing a limit to that contribution.”

“It’s amazing to be able to look so far back in time – to just 200 million years after the Big Bang- and be able to learn about the early Universe,” said Bevins.

The research was supported in part by the Science and Technology Facilities Council (STFC), part of UK Research & Innovation (UKRI), and the Royal Society. The Cambridge authors are all members of the Kavli Institute for Cosmology in Cambridge.

 

Reference:
H. T. J. Bevins et al. ‘Astrophysical constraints from the SARAS 3 non-detection of the cosmic dawn sky-averaged 21-cm signal.’ Nature Astronomy (2022). DOI: 10.1038/s41550-022-01825-6

Researchers have been able to make some key determinations about the first galaxies to exist, in one of the first astrophysical studies of the period in the early Universe when the first stars and galaxies formed, known as the cosmic dawn.

This is an early step for us in what we hope will be a decade of discoveries about how the Universe transitioned from darkness and emptiness to the complex realm of stars and galaxies we can see todayEloy de Lera AcedoNASA GoddardEarly galaxies capture by the NASA/ESA Hubble Telescope


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Sharper infrared eyes for the VLT: ERIS sees first light

Astronomy News - 28 November 2022 - 10:24am

ESO’s newest scientific instrument, the Enhanced Resolution Imager and Spectrograph (ERIS) has successfully completed its first test observations. One of them exposed the heart of the galaxy NGC 1097 in mesmerising detail. Installed on ESO’s Very Large Telescope (VLT) at Cerro Paranal in northern Chile, this infrared instrument will be able to see further and in finer detail, leading the way in Solar System, exoplanet and galaxy observations.

The versatility of ERIS [1] will lend itself to many fields of astronomical research as it aims to take the sharpest images obtained to date using a single 8.2-metre telescope. It will do so using adaptive optics, a technique that corrects for the blurring effects of Earth’s atmosphere in real time. ERIS will be active for at least ten years and is expected to make significant contributions to a myriad of topics in astronomy, ranging from distant galaxies and black holes through to exoplanets and dwarf planets within our own Solar System.

We expect not only that ERIS will fulfil its main scientific objectives,” says Harald Kuntschner, ESO’s project scientist for ERIS, “but that due to its versatility it will also be used for a wide variety of other science cases, hopefully leading to new and unexpected results.”

The very first test observations with ERIS were obtained in February of this year, with further observations conducted in August and November to test the limits of the instrument. One of these observations features the inner ring of the galaxy NGC 1097, located 45 million light-years away from Earth, in the constellation Fornax. This gaseous and dusty ring lies at the very centre of the galaxy; the bright spots in it are stellar nurseries, shown here in unprecedented detail. The glowing centre shows the active heart of the galaxy, a supermassive black hole that feeds off its surroundings. To put ERIS’s resolution in perspective, this image shows, in detail, a portion of the sky less than 0.03% the size of the full Moon.

Mounted on the VLT's Unit Telescope 4, ERIS will take over the role of the very successful NACO and SINFONI instruments, providing some essential improvements to the facility for the coming decade. 

ERIS boasts a state-of-the-art infrared imager, the Near Infrared Camera System — or NIX — which was used to image the inner ring in NGC 1097. NIX will offer a new and unique view of many different astronomical objects, such as exoplanets and the discs of gas and dust around young stars. It can use a technique called coronagraphy, which blocks light from stars similarly to a solar eclipse, allowing us to observe the faint planets around them.

ERIS also features a 3D spectrograph named SPIFFIER, an upgrade of SINFONI’s SPIFFI (SPectrometer for Infrared Faint Field Imaging). SPIFFIER collects a spectrum from each individual pixel within its field of view. This will allow astronomers to study, for instance, the dynamics of distant galaxies in incredible detail, or to measure the velocities of stars orbiting the supermassive black hole at the centre of the Milky Way, which is key to testing General Relativity and understanding the physics of black holes.

ERIS’s adaptive optics module is equipped with sensors to analyse atmospheric turbulence on the fly, by monitoring either a real astronomical source or an artificial laser guide star. It sends this information up to a thousand times per second to the VLT’s deformable secondary mirror, which then corrects for the blurring in real time, thus creating more detailed images. 

ERIS breathes new life into the fundamental adaptive optics imaging and spectroscopy capability of the VLT,” says Ric Davies, the Principal Investigator of the ERIS consortium and researcher at the Max Planck Institute for Extraterrestrial Physics. “Thanks to the efforts of all those involved in the project over the years, many science projects are now able to benefit from the exquisite resolution and sensitivity the instrument can achieve.

Notes

[1] ERIS was designed and built under the leadership of the Max Planck Institute for Extraterrestrial Physics (Germany) by a consortium including the National Institute for Astrophysics (INAF, Italy), the UK Astronomy Technology Centre (UK), ETH Zürich (Switzerland), and NOVA (the Netherlands), together with ESO.

Travel to ESO’s observatories in Chile on a special virtual tour

Astronomy News - 28 November 2022 - 10:24am

On 2 December, at 19.00 CET, join a special, live virtual guided tour of our sites. Get to see what goes on behind the scenes at our observatories in Chile, located in one of the most remote places on Earth. Discover what it takes to operate a telescope in the middle of the Atacama Desert and what astronomers are looking to find out there. Join us in the integration hall of the ESO Headquarters in Germany and much more.

The event will be broadcasted in English, on ESO’s YouTube channel and Facebook page. It will last one hour and it includes a Q&A session at the end. During the tour our team will also answer your astronomy questions via social media.

The ESO Supernova Planetarium & Visitor Centre in Garching near Munich, Germany will host a free public event on the same day, streaming the virtual tour, with ESO astronomers and engineers available in the exhibition to engage with visitors and answer their questions. To book a free place, please go here

This virtual tour is part of a campaign to mark ESO’s 60th anniversary. Under the motto „Feet on the ground, eyes on the sky” we have been organising several activities that focus on how we are building on our legacy to continue the success story of international collaboration in astronomy. Among them, a series of social media messages published with the hashtag #ESO60Years that are exploring our plans for the future: from the discoveries we expect to enable in the next decades, technologies being developed at ESO that have applications in other areas, to how we are contributing to society in broader terms and building a more sustainable future, from an environmental perspective as well as socially and economically. 

Several other public events are being organised in ESO’s Member and Partner States, with the list continuously being updated. Check here to see if there are any events near you.

Some of the events will feature an anniversary exhibition, which can be accessed online from this link. Ready-to-print PDF files are available for anyone interested.

JWST reveals first evidence of an exoplanet’s surprising chemistry

Astronomy News - 28 November 2022 - 10:23am

Nature, Published online: 22 November 2022; doi:10.1038/d41586-022-03820-3

Ground-breaking observations by the James Webb Space Telescope reveal clouds and chemical reactions on a world outside our Solar System.

Polarized blazar X-rays imply particle acceleration in shocks

Astronomy News - 28 November 2022 - 10:22am

Nature, Published online: 23 November 2022; doi:10.1038/s41586-022-05338-0

Polarization measurements are reported for the blazar Mk501, revealing a degree of X-ray polarization that is more than twice the optical value and supporting the shock-accelerated energy-stratified electron population scenario.

Shock waves spark blazing light from black holes

Astronomy News - 28 November 2022 - 10:22am

Nature, Published online: 23 November 2022; doi:10.1038/d41586-022-03768-4

Radiation from a jet of ultrafast particles powered by a supermassive black hole suggests that the particles are accelerated by shock waves propagating along the jet, making them shine with the brightness of 100 billion Suns.

Sending Signals Through the Ice on Ocean Worlds

Astronomy News - 28 November 2022 - 10:21am
PROJECT

Ocean Worlds Signals Through the Ice (STI)

SNAPSHOT

The Ocean Worlds Signals Through the Ice (STI) team is developing communication technologies to enable subsurface exploration of ocean worlds where conditions may be conducive to life.

​Figure 1: Artist’s concept of the cross-sectional view of Europa depicting the exciting, potentially habitable environment of the ocean world (Credit: K. Hand et al./NASA/JPL)

Detection of extraterrestrial life would be an incredible discovery, revolutionizing humanity’s perception of life and providing us insight into how life begins and persists in various environments. Exploration of ocean worlds such as Europa and Enceladus—orbiting Jupiter and Saturn, respectively—is particularly intriguing, as they may harbor conditions conducive to life including liquid water, essential chemistry, sources of heat or energy, and long-lived oceans.

To follow up on detections of habitable environments obtained by previous missions (e.g., Cassini), future missions to detect life on icy ocean worlds will require more than only remote observations. Deep subsurface exploration reaching the moons’ oceans and/or water pockets perched in the ice shell could reveal, as well as characterize in detail, any life that may exist there.

Accessing the subsurface ocean or melt pockets perched within an ice shell will pose significant challenges. From a technological perspective, a successful exploration mission will require starting in a vacuum at extreme cold (“cryogenic” temperatures), penetrating tens of kilometers through an ice shell for a few years, and accessing the ocean—all while maintaining communication with assets on the moon’s surface to transmit data back to Earth. The journey through the ice will entail navigating through an ice shell with unknown temperature variations, material strengths, and possible caustic compositions, and will require the capability to survive stress caused by tides and potential fault movement (i.e., ice-quakes).

Figure 2. Artist’s concept of a cryobot at Europa (image credit: Alexander Pawlusik/NASA)

To date, a robust technology concept has emerged for effectively exploring the interior of ice shells: the ice penetrating robot, or “cryobot” (see Figure 2). A cryobot penetrates through ice by melting or excavating ice (and non-ice contaminants) using melting, cutting, or a hybrid method. Terrestrial ice probes have been proposed and/or developed for decades, with laboratory and field testing in Antarctica and Greenland to explore the viability of the concept for future planetary missions. To improve the mission readiness of such an ice-ocean probe, the STI team is developing robust communication technologies that employ optical tethers and free space radio frequency modules capable of transmitting data through multiple kilometers of ice while surviving the extreme conditions found on ocean worlds.

Europa: Extreme Cold & Extreme Loads: Submersible robots using hardy fiber optic micro-tethers (diameters ~1-2 mm) that are of sufficient length and mass to support the proposed Europa cryobot architectures have been successfully employed on Earth for terrestrial ocean exploration. However, the ability of these systems to withstand the extreme, in-ice conditions on Europa has not been demonstrated. Therefore, the multi-disciplinary STI team developed new protocols and instrumentation to assess the capabilities of optical communication tethers under the stress and thermal conditions (100 - 260 K) expected in Europa’s icy shell. The team applied shear loading at these temperatures for a range of loads and loading rates to simulate creeping and quick-slip ice-quakes anticipated in the ocean world ice shell environment.

The STI team performed these tests using a cryogenic biaxial deformation apparatus at Lamont Doherty Earth Observatory (LDEO) (see Figure 3a). By testing in a laboratory setting that simulates a relevant ocean world environment, the team characterized two tethers’ shear strengths under conditions similar to ice faults on Europa. The team used a state-of-the-art, three-section die to apply pretension to the tether (see Figure 3b), around which a polycrystalline ice sample was frozen, with two pre-existing plane separations to represent perpendicular faults the tether may cross (dotted lines, in Figure 3b).

This die protocol proved to be a reliable method for creating ice samples with tethers pre-tensioned and fully embedded, and demonstrated a valuable new test preparation technique to the science community. Figure 3c shows one of the tethers tested, the Linden High Strength Strong Tether Fiber Optic Cable (HS-STFOC), and the layers of protective material surrounding the optical fiber through which data is transmitted. The changes in optical integrity and signal strength observed during testing indicate how capable the tether would be in various regions of Europa’s ice shell.

Shear test results demonstrated a surprisingly high level of tether robustness across the range of temperatures and ice fault slip velocities expected on ocean worlds like Europa and Enceladus. The fault slip velocities were controlled by the loading rates applied. Figure 4b shows the peak stress survived by the two particularly robust tethers tested: Linden Photonics Inc. Strong Tether Fiber Optic Cable (STFOC) and Linden HS-STFOC, which survived peak stresses up to 1.5 MPa within the fault slip velocity range of 5x10-7 to 3x10-4 m/s.

However, despite surviving the range of creeping strike-slip and ice-quake shear events at the coldest temperatures (~100 K) and maintaining optical communication throughout the tests, the team noticed some damage to the outer jackets of the tethers and stretching of inner fibers (e.g., Figure 4c), indicating a need for further tether development, which is currently being pursued under the Planetary Science Division’s COLDTech program.

The STI study—with crudely broken and imperfectly planar sliding ice interfaces (likely similar to reactivated faults on Europa) across these fault slip rates, shear loads, and ice shell temperature ranges—provides robust confirmation of how the frictional stability of ice depends on temperature and fault slip velocity. These findings are significant for potential application on Europa, suggesting a variation of sliding behavior with depth. The uppermost and lowest portions of the ice shell slide smoothly (and slowly), whereas at a mid-range in temperature and depth, icy faults could initiate stick-slip, rapid ice-quake events. By characterizing data transmission in these conditions, the tests show that tethers could potentially serve as science instruments to detect ice-quakes and establish the thermal profile of the ice shell. 

These developments and others by the STI team are advancing tethered and free-space communication technologies to retire technical risks for a cryobot mission to access ocean worlds. STI efforts are also improving the ability to probe the temperatures and mechanical and compositional properties of dynamic ice shells, and guiding future technology developments for subsurface exploration of ocean worlds. 

PROJECT LEADS

Kathleen Craft, JHU Applied Physics Laboratory (JHU APL); Vishaal Singh, Lamont Doherty Earth Observatory (LDEO), Columbia Univ.; Christine McCarthy, LDEO; Michael V. Jakuba, Woods Hole Oceanographic Institute (WHOI); Matthew Silvia, WHOI

SPONSORING ORGANIZATIONS

Planetary Science Division SESAME and COLDTech Programs

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NASA’s Webb Reveals an Exoplanet Atmosphere as Never Seen Before

Astronomy News - 28 November 2022 - 10:20am
Portal origin URL: NASA’s Webb Reveals an Exoplanet Atmosphere as Never Seen BeforePortal origin nid: 484136Published: Tuesday, November 22, 2022 - 11:00Featured (stick to top of list): noPortal text teaser: NASA’s James Webb Space Telescope just scored another first: a molecular and chemical profile of a distant world’s skies.Portal image: A pinkish planet and its star on an empty black background, with a bright white sun in the background.

JWST has spotted chemical reactions in an exoplanet's atmosphere

Astronomy News - 28 November 2022 - 10:20am

Astronomers analysing data from the James Webb Space Telescope have spotted signs of chemical reactions driven by star light in the atmosphere of an exoplanet for the first time

We may finally know how blazars act as cosmic particle accelerators

Astronomy News - 28 November 2022 - 10:19am

Supermassive black holes that beam powerful jets of matter towards Earth, known as blazars, accelerate particles to extraordinarily high energies – and astronomers have finally figured out how

NASA’s Orion capsule captures gorgeous close-up pictures of the moon

Astronomy News - 28 November 2022 - 10:19am

The Orion capsule has made its closest fly-by of the moon and sent back detailed images of its surface and of the spacecraft rounding the far side of the moon

Bluewalker 3 satellite is brighter than 99.8 per cent of visible stars

Astronomy News - 28 November 2022 - 10:18am

Observations of a huge test satellite that launched in September have fuelled concerns about the impact a planned fleet could have on astronomy

Hubble Views a Billowing Cosmic Cloud

Astronomy News - 21 November 2022 - 10:04am
Portal origin URL: Hubble Views a Billowing Cosmic CloudPortal origin nid: 484056Published: Friday, November 18, 2022 - 08:00Featured (stick to top of list): noPortal text teaser: A small, dense cloud of gas and dust called CB 130-3 blots out the center of this image from the NASA/ESA Hubble Space Telescope.Portal image: An irregularly shaped bright orange cloud dense gas and dust, which appears darker and more compact at center and is outlined by thinner gas and dust in light shades of blue. A multitude of bright stars against a black background.

NASA Study: Massive Volcanism May Have Altered Ancient Venus’ Climate

Astronomy News - 21 November 2022 - 10:04am
Portal origin URL: NASA Study: Massive Volcanism May Have Altered Ancient Venus’ ClimatePortal origin nid: 483753Published: Thursday, November 17, 2022 - 10:30Featured (stick to top of list): noPortal text teaser: Volcanic activity lasting hundreds to thousands of centuries and erupting massive amounts of material may have helped transform Venus from a temperate and wet world to the acidic hothouse it is today, a NASA paper suggests.Portal image: Maat Mons volcano on Venus

JWST spots some of the most distant galaxies ever seen

Astronomy News - 19 November 2022 - 7:24pm

Nature, Published online: 17 November 2022; doi:10.1038/d41586-022-03751-z

Premier observatory offers a glimpse of the early Universe.

NASA really, really won’t rename Webb telescope despite community pushback

Astronomy News - 19 November 2022 - 7:23pm

Nature, Published online: 18 November 2022; doi:10.1038/d41586-022-03787-1

Investigation by agency historian finds no evidence explicitly linking former director James Webb with anti-LGBT+ actions.

Early meteorites brought enough water to Mars to create a global ocean

Astronomy News - 17 November 2022 - 11:14am

Meteorites bombarding the Red Planet may have carried so much water that it could have covered the planet in a layer 300 metres deep if spread out, while also depositing molecules essential for life

JWST sees a stunning hourglass of light around a still-forming star

Astronomy News - 17 November 2022 - 11:13am

The James Webb Space Telescope has captured an image of a star that hasn’t yet finished forming, along with a disc of debris that may eventually become planets