. Scientific Frontline: Astronomy
Showing posts with label Astronomy. Show all posts
Showing posts with label Astronomy. Show all posts

Thursday, October 13, 2022

Heaviest element yet detected in an exoplanet atmosphere

This artist’s impression shows an ultra-hot exoplanet, a planet beyond our Solar System, as it is about to transit in front of its host star. When the light from the star passes through the planet’s atmosphere, it is filtered by the chemical elements and molecules in the gaseous layer. With sensitive instruments, the signatures of those elements and molecules can be observed from Earth. Using the ESPRESSO instrument of ESO’s Very Large Telescope, astronomers have found the heaviest element yet in an exoplanet's atmosphere, barium, in the two ultra-hot Jupiters WASP-76 b and WASP-121 b. 
Credit: ESO/M. Kornmesser

Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT), astronomers have discovered the heaviest element ever found in an exoplanet atmosphere — barium. They were surprised to discover barium at high altitudes in the atmospheres of the ultra-hot gas giants WASP-76 b and WASP-121 b — two exoplanets, planets which orbit stars outside our Solar System. This unexpected discovery raises questions about what these exotic atmospheres may be like.

“The puzzling and counterintuitive part is: why is there such a heavy element in the upper layers of the atmosphere of these planets?” says Tomás Azevedo Silva, a PhD student at the University of Porto and the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal who led the study published today in Astronomy & Astrophysics.

WASP-76 b and WASP-121 b are not ordinary exoplanets. Both are known as ultra-hot Jupiters as they are comparable in size to Jupiter whilst having extremely high surface temperatures soaring above 1000°C. This is due to their close proximity to their host stars, which also means an orbit around each star takes only one to two days. This gives these planets rather exotic features; in WASP-76 b, for example, astronomers suspect it rains iron.

Wednesday, October 12, 2022

Black Hole Spews Out Material Years After Shredding Star

Artist’s illustration of tidal disruption event AT2019dsg where a supermassive black hole spaghettifies and gobbles down a star. Some of the material is not consumed by the black hole and is flung back out into space. 
Resized Image using AI by SFLORG
Credit: DESY, Science Communication Lab

In October 2018, a small star was ripped to shreds when it wandered too close to a black hole in a galaxy located 665 million light years away from Earth. Though it may sound thrilling, the event did not come as a surprise to astronomers who occasionally witness these violent incidents while scanning the night sky.

But nearly three years after the massacre, the same black hole is lighting up the skies again — and it hasn’t swallowed anything new, scientists say.

“This caught us completely by surprise — no one has ever seen anything like this before,” says Yvette Cendes, a research associate at the Center for Astrophysics | Harvard & Smithsonian (CfA) and lead author of a new study analyzing the phenomenon.

The team concludes that the black hole is now ejecting material traveling at half of the speed of light, but are unsure why the outflow was delayed by several years. The results, described this week in the Astrophysical Journal, may help scientists better understand black holes’ feeding behavior, which Cendes likens to “burping” after a meal.

Thursday, September 29, 2022

Webb and Hubble Capture Detailed Views of DART Impact

For the first time, the NASA/ESA/CSA James Webb Space Telescope and the NASA/ESA Hubble Space Telescope have taken simultaneous observations of the same target.  These images, Hubble on left and Webb on the right, show observations of Dimorphos several hours after NASA’s Double Asteroid Redirection Test (DART) intentionally impacted the moonlet asteroid. It was the world’s first test of the kinetic impact technique using a spacecraft to deflect an asteroid by modifying its orbit.  Both Webb and Hubble observed the asteroid before and after the collision took place.  Scientists will use the combined observations from Hubble and Webb to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, how fast it was ejected, and the distribution of particle sizes in the expanding dust cloud.  In the coming months, scientists will also use Webb’s Mid-Infrared Instrument (MIRI) and Near-Infrared Spectrograph (NIRSpec) to observe Dimorphos further. Spectroscopic data will provide researchers with insight into the asteroid’s composition. Hubble will monitor Dimorphos ten more times over the next three weeks to monitor how the ejecta cloud expands and fades over time.  Hubble observations were conducted in one filter, WFC3/UVIS F350LP (assigned the color blue), while Webb observed at F070W (0.7 microns, assigned the color red). 
Credit: NASA, ESA, CSA, and STScI

Two of the great observatories, the NASA/ESA/CSA James Webb Space Telescope and the NASA/ESA Hubble Space Telescope, have captured views of a unique experiment to smash a spacecraft into a small asteroid. NASA’s Double Asteroid Redirection Test (DART) impact observations mark the first time that Webb and Hubble were used to simultaneously observe the same celestial target.

On 26 September 2022 at 13:14 CEST, DART intentionally crashed into Dimorphos, the asteroid moonlet in the double-asteroid system of Didymos. It was the world’s first test of the kinetic impact technique using a spacecraft to deflect an asteroid by modifying the object’s orbit. DART is a test for defending Earth against potential asteroid or comet hazards.

The observations are more than just an operational milestone for each telescope—there are also key science questions relating to the makeup and history of our solar system that researchers can explore when combining the capabilities of these observatories.

Thursday, September 22, 2022

Star Light, Star Bright … But Exactly How Bright?

Astronomers use the brightness of a type of exploding star known as a supernova type IA (seen here as bright blue dot to the left of a remote spiral galaxy) to determine the age and expansion rate of the universe. New calibrations of the luminosity of nearby stars, observed by NIST researchers, could help astronomers refine their measurements.
Credit: NASA, ESA, J. DePasquale (STScI), M. Kornmesser and M. Zamani (ESA/Hubble), A. Riess (STScI/JHU) and the SH0ES team, and the Digitized Sky Survey

A picture may be worth a thousand words, but for astronomers, simply recording images of stars and galaxies isn’t enough. To measure the true size and absolute brightness (luminosity) of heavenly bodies, astronomers need to accurately gauge the distance to these objects. To do so, the researchers rely on “standard candles” -- stars whose luminosities are so well known that they act like light bulbs of known wattage. One way to determine a star’s distance from Earth is to compare how bright the star appears in the sky to its luminosity.

But even standard candles need to be calibrated. For more than a decade, scientists at the National Institute of Standards and Technology (NIST) have been working to improve the methods for calibrating standard stars. They observed two nearby bright stars, Vega and Sirius, in order to calibrate their luminosity over a range of visible-light wavelengths. The researchers are now completing their analysis and plan to release the calibration data to astronomers within the next 12 months.

Astronomers detect hot gas bubble swirling around the Milky Way’s supermassive black hole

This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modelling of the ALMA data predicts the hot spot to be and its orbit around the black hole. 
Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus)

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the black hole at the centre of our galaxy. The finding helps us better understand the enigmatic and dynamic environment of our supermassive black hole.

“We think we're looking at a hot bubble of gas zipping around Sagittarius A* on an orbit similar in size to that of the planet Mercury, but making a full loop in just around 70 minutes. This requires a mind-blowing velocity of about 30% of the speed of light!” says Maciek Wielgus of the Max Planck Institute for Radio Astronomy in Bonn, Germany, who led the study published today in Astronomy & Astrophysics.

The observations were made with ALMA in the Chilean Andes — a radio telescope co-owned by the European Southern Observatory (ESO) — during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first ever image of Sagittarius A. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A. To the team's surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements.

How global warming affects astronomical observations

The VLT's Laser Guide Star: A laser beam launched from VLT´s 8.2-metre Yepun telescope crosses the majestic southern sky and creates an artificial star at 90 km altitude in the high Earth´s mesosphere. The Laser Guide Star (LGS) is part of the VLT´s Adaptive Optics system and it is used as reference to correct images from the blurring effect of the atmosphere.
Credit: ESO / G. Hüdepohl atacamaphoto.com

Astronomical observations from ground-based telescopes are sensitive to local atmospheric conditions. Anthropogenic climate change will negatively affect some of these conditions at observation sites around the globe, as a team of researchers led by the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS reports.

The quality of ground-based astronomical observations delicately depends on the clarity of the atmosphere above the location from which they are made. Sites for telescopes are therefore very carefully selected. They are often high above sea level, so that less atmosphere stands between them and their targets. Many telescopes are also built in deserts, as clouds and even water vapor hinder a clear view of the night sky.

A team of researchers led by the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS shows in a study, published in the journal Astronomy & Astrophysics and presented at the Europlanet Science Congress 2022 in Granada, how one of the major challenges of our time – anthropogenic climate change – now even affects our view of the cosmos.

Wednesday, September 21, 2022

Astronomers Unveil New – and Puzzling – Features of Mysterious Fast Radio Bursts

Artist's conception of Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China.
Credit: Jingchuan Yu

Fast radio bursts (FRBs) are millisecond-long cosmic explosions that each produce the energy equivalent to the sun’s annual output. More than 15 years after the deep-space pulses of electromagnetic radio waves were first discovered, their perplexing nature continues to surprise scientists – and newly published research only deepens the mystery surrounding them.

In the Sept. 21 issue of the journal Nature, unexpected new observations from a series of cosmic radio bursts by an international team of scientists – including UNLV astrophysicist Bing Zhang – challenge the prevailing understanding of the physical nature and central engine of FRBs.

The cosmic FRB observations were made in late spring 2021 using the massive Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China. The team, led by Heng Xu, Kejia Lee, Subo Dong from Peking University, and Weiwei Zhu from the National Astronomical Observatories of China, along with Zhang, detected 1,863 bursts in 82 hours over 54 days from an active fast radio burst source called FRB 20201124A.

“This is the largest sample of FRB data with polarization information from one single source”, said Lee.

Wednesday, September 14, 2022

New Evidence of Baby Planet in the Making

Artist's illustration of a small Saturn-like planet discovered in the system LkCa 15. The planet resides within dense rings of dust and gas that surround a bright yellow star. Material accumulates in a clump and arc-shape, about 60 degrees away from the planet. Note: This illustration is not to scale.
Credit: M.Weiss/Center for Astrophysics | Harvard & Smithsonian

Astronomers agree that planets are born in protoplanetary disks — rings of dust and gas that surround young, newborn stars. While hundreds of these disks have been spotted throughout the universe, observations of actual planetary birth and formation have proved difficult within these environments.

Now, astronomers at the Center for Astrophysics | Harvard & Smithsonian have developed a new way to detect these elusive newborn planets — and with it, "smoking gun" evidence of a small Neptune or Saturn-like planet lurking in a disk. The results are described today in The Astrophysical Journal Letters.

"Directly detecting young planets is very challenging and has so far only been successful in one or two cases," says Feng Long, a postdoctoral fellow at the Center for Astrophysics who led the new study. "The planets are always too faint for us to see because they’re embedded in thick layers of gas and dust."

Scientists instead must hunt for clues to infer a planet is developing beneath the dust.

Monday, September 12, 2022

First JWST images of Orion Nebula released

The inner region of the Orion Nebula as seen by the James Webb Space Telescope’s NIRCam instrument.
Image credit: NASA, ESA, CSA, Data reduction and analysis: PDRs4All ERS Team; graphical processing S. Fuenmayor

An international research team including University of Michigan researchers has just revealed the first images of the Orion Nebula, the richest and closest star nursery in the solar system, captured by the James Webb Space Telescope.

Located in the constellation of Orion, 1,350 light years from Earth, the Orion Nebula is an area rich in matter where many stars are formed. Its environment is similar to the environment in which our solar system was born more than 4.5 billion years ago. Studying allows researchers to understand the conditions in which our solar system formed.

“Orion Bar is a prototype region for processes that occur throughout our galaxy and the universe as stars continually irradiate nearby material,” said Felipe Alarcon, U-M graduate student and member of the international group. “This amazing picture will be a template image.”

The heart of star nurseries, such as the Orion Nebula, is obscured by large amounts of dust—impossible to observe in visible light with telescopes such as the Hubble Space Telescope. The JWST observes the infrared light of the cosmos, penetrating these layers of dust.

The image reveals many spectacular structures, down to scales of about 40 astronomical units, or about the size of our solar system. These structures include a number of dense filaments of matter, which could launch the birth of a new generation of stars. The image also reveals forming stellar systems. These consist of a central proto-star surrounded by a disc of dust and gas inside which planets form.

Dark Energy Camera Captures Bright, Young Stars Blazing Inside Glowing Nebula

NOIRLab, captures the star-forming nebula NGC 6357, which is located 8000 light-years away in the direction of the constellation Scorpius.
Hi-Res Zoomable Image
Credit: CTIO/NOIRLab/DOE/NSF/AURA  T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), J. Miller (Gemini Observatory/NSF’s NOIRLab), M. Zamani & D. de Martin (NSF’s NOIRLab)

The 570-megapixel US Department of Energy-fabricated Dark Energy Camera at NOIRLab’s Cerro Tololo Inter-American Observatory in Chile is one of the most powerful tools in astronomy and astrophysics. To commemorate its first decade of discovery and exploration, NOIRLab has released a stunning image of the Lobster Nebula, a brilliant star-forming region located 8000 light-years from Earth in the direction of the constellation Scorpius. The image was unveiled at a conference highlighting DECam’s breakthrough science results.

The Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF’s NOIRLab, is celebrating 10 years as one of the highest-performance, wide-field CCD imagers in the world.

To help commemorate DECam’s first decade of operation, NOIRLab has released a breathtaking image of the star-forming Lobster Nebula (NGC 6357), which is located about 8000 light-years from Earth in the direction of the constellation Scorpius. This image reveals bright, young stars surrounded by billowing clouds of dust and gas.

A thousand days of CHEOPS

Artist's impression of CHEOPS
Credit: ESA / ATG medialab

After a thousand days in orbit, the CHEOPS space telescope shows almost no signs of wear. Under these conditions, it could continue to reveal details of some of the most fascinating exoplanets for quite some time. CHEOPS is a joint mission by the European Space Agency (ESA) and Switzerland, under the aegis of the University of Bern in collaboration with the University of Geneva.

Since its launch from Europe's Spaceport in French Guiana, on December 18th, 2019, the CHEOPS telescope in Earth’s orbit has demonstrated its functionality and precision beyond expectations. During this time, it has revealed the characteristics of numerous fascinating planets beyond our Solar System (exoplanets) and has become a key instrument for astronomers in Europe and worldwide.

Wednesday, September 7, 2022

Two new rocky worlds around an ultra-cool star

The telescopes of the SPECULOOS Southern Observatory gaze out into the stunning night sky over the Atacama Desert, Chile.
Credit: ESO/ P. Horålek

An international research team, with the participation of the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS, discovered two "super-Earth" exoplanets. One is located at just the right distance from its star to potentially hold liquid water on its surface.

Most of the planets that have been discovered around other stars – also known as exoplanets – are bad candidates for life as we know it. They are either scorching hot or freezing cold, and the majority consist of nothing but gas. Relatively small terrestrial planets, like our Earth, are difficult to detect. Only a handful are known that receive just the right amount of radiation from their star to allow liquid water on their surface. The reported discovery of a promising candidate for such a world, made by a team of researchers with the participation of the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS, is therefore a significant one. The team published their results in the journal Astronomy & Astrophysics. (As of this posting not yet released)

Thursday, September 1, 2022

Webb takes its first exoplanet image

This image shows the exoplanet HIP 65426 b in different bands of infrared light, as seen from the James Webb Space Telescope: purple shows the NIRCam instrument’s view at 3.00 micrometers, blue shows the NIRCam instrument’s view at 4.44 micrometers, yellow shows the MIRI instrument’s view at 11.4 micrometers, and red shows the MIRI instrument’s view at 15.5 micrometers.
Credit: NASA/ESA/CSA, A Carter (UCSC), the ERS 1386 team and A. Pagan (STScI)

For the first time, astronomers have used the NASA/ESA/CSA James Webb Space Telescope to take a direct image of an exoplanet. The exoplanet is a gas giant, meaning it has no rocky surface and could not be habitable. The image, as seen through four different light filters, shows how Webb’s powerful infrared gaze can easily capture worlds beyond our Solar System, pointing the way to future observations that will reveal more information than ever before about exoplanets.

The exoplanet in Webb’s image, called HIP 65426 b, is about six to eight times the mass of Jupiter. It is young as planets go – about 15 to 20 million years old, compared to our 4.5-billion-year-old Earth.

Astronomers discovered the planet in 2017 using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile and took images of it using short infrared wavelengths of light. The Webb image, taken in mid-infrared light, reveals new details that ground-based telescopes would not be able to detect because of the intrinsic infrared glow of Earth’s atmosphere.

Tuesday, August 30, 2022

X-shaped radio galaxies might form more simply than expected

When astronomers use radio telescopes to gaze into the night sky, they typically see elliptical-shaped galaxies, with twin jets blasting from either side of their central supermassive black hole. But every once in a while, — less than 10% of the time — astronomers might spot something special and rare: An X-shaped radio galaxy, with four jets extending far into space.

Although these mysterious X-shaped radio galaxies have confounded astrophysicists for two decades, a new Northwestern University study sheds new insight into how they form — and its surprisingly simple. The study also found that X-shaped radio galaxies might be more common than previously thought.

The study was published in the Astrophysical Journal Letters. It marks the first large-scale galaxy accretion simulation that tracks the galactic gas far from the supermassive black hole all the way toward it.

Simple conditions lead to messy result

Using new simulations, the Northwestern astrophysicists implemented simple conditions to model the feeding of a supermassive black hole and the organic formation of its jets and accretion disk. When the researchers ran the simulation, the simple conditions organically and unexpectedly led to the formation of an X-shaped radio galaxy.

Wednesday, August 24, 2022

An extrasolar world covered in water?

Artistic rendition of the exoplanet TOI-1452 b, a small planet that may be entirely covered in a deep ocean.
Credit: Benoit Gougeon, Université de Montréal.

An international team of researchers led by Charles Cadieux, a Ph.D. student at the Université de Montréal and member of the Institute for Research on Exoplanets (iREx), has announced the discovery of TOI-1452 b, an exoplanet orbiting one of two small stars in a binary system located in the Draco constellation about 100 light-years from Earth.

The exoplanet is slightly greater in size and mass than Earth and is located at a distance from its star where its temperature would be neither too hot nor too cold for liquid water to exist on its surface. The astronomers believe it could be an “ocean planet,” a planet completely covered by a thick layer of water, similar to some of Jupiter’s and Saturn’s moons.

In an article published in The Astronomical Journal, Cadieux and his team describe the observations that elucidated the nature and characteristics of this unique exoplanet.

“I’m extremely proud of this discovery because it shows the high caliber of our researchers and instrumentation,” said René Doyon, Université de Montréal Professor and Director of iREx and of the Observatoire du Mont-Mégantic (OMM). “It is thanks to the OMM, a special instrument designed in our labs called SPIRou, and an innovative analytic method developed by our research team that we were able to detect this one-of-a-kind exoplanet.”

Monday, August 22, 2022

Surprising details leap out in sharp new James Webb Space Telescope images of Jupiter

Image 1 This July 27 image of Jupiter taken by the Near-Infrared Camera on the new James Webb Space Telescope is artificially colored to emphasize stunning details of the planet: auroral emission from ionized hydrogen at both the north and south poles (red); high-altitude hazes (green) that swirl around the poles; and light reflected from the deeper main cloud (blue). The Great Red Spot, the equatorial region and compact cloud regions appear white or reddish-white; regions with little cloud cover appear as dark ribbons north of the equatorial region.
Resized Image using AI by SFLORG
Additional Below
Image credit: NASA, European Space Agency, Jupiter Early Release Science team. Image processing: Judy Schmidt

The latest images of Jupiter from the James Webb Space Telescope (JWST) are stunners.

Captured on July 27, the infrared images — artificially colored to make specific features stand out — show fine filigree along the edges of the colored bands and around the Great Red Spot and also provide an unprecedented view of the auroras over the north and south poles.

One wide-field image presents a unique lineup of the planet, its faint rings and two of Jupiter’s smaller satellites — Amalthea and Adrastea — against a background of galaxies.

“We’ve never seen Jupiter like this. It’s all quite incredible,” said planetary astronomer Imke de Pater, professor emerita of the University of California, Berkeley, who led the scientific observations of the planet with Thierry Fouchet, a professor at the Paris Observatory. “We hadn’t really expected it to be this good, to be honest. It’s really remarkable that we can see details on Jupiter together with its rings, tiny satellites and even galaxies in one image.”

De Pater, Fouchet and their team released the images today (Aug. 22) as part of the telescope’s Early Release Science program.

Monday, August 15, 2022

Supernova remnant is source of extreme cosmic particles

Astronomers have long sought the launch sites for some of the highest energy protons in our galaxy. Now, a study using 12 years of data from NASA’s Fermi Gamma-ray Space Telescope confirms that a remnant of a supernova, or star explosion, is just such a place, solving a decade-long cosmic mystery.

Previously, Fermi has shown that the shock waves of exploded stars boost particles to speeds comparable to that of light. Called cosmic rays, these particles mostly take the form of protons, but can include atomic nuclei and electrons. Because they all carry an electric charge, their paths become scrambled as they whisk through our galaxy’s magnetic field, which masks their origins. But when these particles collide with interstellar gas near the supernova remnant, they produce a telltale glow in gamma rays—the highest-energy light there is.

“Theorists think the highest-energy cosmic ray protons in the Milky Way reach a million billion electron volts, or PeV (for peta-electron-volt) energies,” says Ke Fang, an assistant professor of physics at the University of Wisconsin–Madison’s Wisconsin IceCube Particle Astrophysics Center. “The precise nature of their sources, which we call PeVatrons, has been difficult to pin down.”

Friday, August 12, 2022

Brightest stars in the night sky can strip planets to their rocky cores

Artist’s concept of a Neptune-sized planet, left, around a blue, A-type star. UC Berkeley astronomers have discovered a hard-to-find gas giant around one of these bright, but short-lived, stars, right at the edge of the hot Neptune desert where the star’s strong radiation likely strips any giant planet of its gas.
 Image credit: Steven Giacalone, UC Berkeley

Over the last 25 years, astronomers have found thousands of exoplanets around stars in our galaxy, but more than 99% of them orbit smaller stars — from red dwarfs to stars slightly more massive than our sun, which is considered an average-sized star.

Few have been discovered around even more massive stars, such as A-type stars — bright blue stars twice as large as the sun — and most of the exoplanets that have been observed are the size of Jupiter or larger. Some of the brightest stars in the night sky, such as Sirius and Vega, are A-type stars.

University of California, Berkeley, astronomers now report a new, Neptune-sized planet — called HD 56414 b — around one of these hot-burning, but short-lived, A-type stars and provide a hint about why so few gas giants smaller than Jupiter have been seen around the brightest 1% of stars in our galaxy.

Current exoplanet detection methods most easily find planets with short, rapid orbital periods around their stars, but this newly found planet has a longer orbital period than most discovered to date. The researchers suggest that an easier-to-find Neptune-sized planet sitting closer to a bright A-type star would be rapidly stripped of its gas by the harsh stellar radiation and reduced to an undetectable core.

Sunday, August 7, 2022

No trace of dark matter halos

The dwarf galaxy NGC1427A flies through the Fornax galaxy cluster and undergoes disturbances which would not be possible if this galaxy were surrounded by a heavy and extended dark matter halo, as required by standard cosmology.
Credit: ESO

According to the standard model of cosmology, the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull-on galaxies in the vicinity. A new study led by the University of Bonn and the University of Saint Andrews (Scotland) challenges this view of the Universe. The results suggest that the dwarf galaxies of Earth’s second closest galaxy cluster – known as the Fornax Cluster – are free of such dark matter halos. The study appeared in the journal Monthly Notices of the Royal Astronomical Society.

Dwarf galaxies are small, faint galaxies that can usually be found in galaxy clusters or near larger galaxies. Because of this, they might be affected by the gravitational effects of their larger companions. “We introduce an innovative way of testing the standard model based on how much dwarf galaxies are disturbed by gravitational, tides’ from nearby larger galaxies”, said Elena Asencio, a PhD student at the University of Bonn and the lead author of the story. Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the moon pulls more strongly on the side of Earth which faces the moon.

The Fornax Cluster has a rich population of dwarf galaxies. Recent observations show that some of these dwarfs appear distorted, as if they have been perturbed by the cluster environment. "Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to the standard model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster."

Wednesday, July 6, 2022

Could we eavesdrop on communications that pass through our solar system?

Communications across interstellar distances could take advantage of a star’s ability to focus and magnify communication signals through an effect called gravitational lensing. A signal from—or passing through—a relay probe would bend due to gravity as it passes by the star. The warped space around the object acts somewhat like a lens of a telescope, focusing and magnifying the light. A new study by researchers at Penn State investigated our solar system for communication signals that might be taking advantage of our own sun.
Credit: Dani Zemba / Penn State

Communications across the vastness of interstellar space could be enhanced by taking advantage of a star’s ability to focus and magnify communication signals. A team of graduate students at Penn State is looking for just these sorts of communication signals that might be taking advantage of our own sun if transmissions were passing through our solar system.

A paper describing the technique — explored as part of a graduate course at Penn State covering the Search for Extraterrestrial Intelligence (SETI) — has been accepted for publication in the Astronomical Journal and is available on the preprint server arXiv.

Massive objects like stars and black holes cause light to bend as it passes by due to the object’s gravitational pull, according to Einstein’s Theory of General Relativity. The warped space around the object acts somewhat like a lens of a telescope, focusing and magnifying the light — an effect called gravitational lensing.

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