Space News and Discussions

[weatheriscool]

Parker solar probe captures its first images of Venus' surface in visible light
https://phys.org/news/2022-02-parker-so ... mages.html
by Mara Johnson-Groh, NASA's Goddard Space Flight Center

NASA's Parker Solar Probe has taken its first visible light images of the surface of Venus from space.

Smothered in thick clouds, Venus' surface is usually shrouded from sight. But in two recent flybys of the planet, Parker used its Wide-Field Imager, or WISPR, to image the entire nightside in wavelengths of the visible spectrum—the type of light that the human eye can see—and extending into the near-infrared.

The images, combined into a video, reveal a faint glow from the surface that shows distinctive features like continental regions, plains, and plateaus. A luminescent halo of oxygen in the atmosphere can also be seen surrounding the planet.

"We're thrilled with the science insights Parker Solar Probe has provided thus far," said Nicola Fox, division director for the Heliophysics Division at NASA Headquarters. "Parker continues to outperform our expectations, and we are excited that these novel observations taken during our gravity assist maneuver can help advance Venus research in unexpected ways."

Such images of the planet, often called Earth's twin, can help scientists learn more about Venus' surface geology, what minerals might be present there, and the planet's evolution. Given the similarities between the planets, this information can help scientists on the quest to understand why Venus became inhospitable and Earth became an oasis.

"Venus is the third brightest thing in the sky, but until recently we have not had much information on what the surface looked like because our view of it is blocked by a thick atmosphere," said Brian Wood, lead author on the new study and physicist at the Naval Research Laboratory in Washington, DC. "Now, we finally are seeing the surface in visible wavelengths for the first time from space."

[wjfox]

Supercomputers Simulated a Black Hole And Found Something We've Never Seen Before

10 FEBRUARY 2022

While black holes might always be black, they do occasionally emit some intense bursts of light from just outside their event horizon. Previously, what exactly caused these flares had been a mystery to science.

That mystery was solved recently by a team of researchers that used a series of supercomputers to model the details of black holes' magnetic fields in far more detail than any previous effort. The simulations point to the breaking and remaking of super-strong magnetic fields as the source of the super-bright flares.

[...]

Simulations showed the breaking and making of magnetic field connections that were invisible at previously available resolutions. Ripperda and his colleagues' image had 1,000 times the resolution of any previously available black hole simulation.

The most accurate simulations in the world can't make up for an incorrect model, so previous simulations ignored basic features of black hole interactions.

With high resolution came greater understanding. The new simulations accurately modeled how the magnetic field process around the event horizon works.

https://www.sciencealert.com/black-hole ... they-do-it

[caltrek]

Distant Galaxies and the True Nature of Dark Matter
February 11, 2022

https://www.eurekalert.org/news-releases/943173

Introduction:

(Eureka Alert) At the centre of spiral galaxies – those near to us but also those billions of light-years away – there is a vast spherical region made up of dark matter particles. This region has two defining characteristics: a density that is constant out to a certain radius that amazingly expands over time, while the density decreases. This suggests the existence of a direct interaction between the elementary particles that make up the dark matter halo and those that make up ordinary matter – protons, electrons, neutrons, and photons. We anticipate that this hypothesis is in direct conflict with the current prevailing theory used to describe the universe – known as Lambda-Cold Dark Matter – which posits that particles of cold dark matter are inert and do not interact with any other particle except gravitationally.

These important findings have been reported in a new study, recently published in the prestigious Astronomy and Astrophysics journal, that studied a large number of distant galaxies, some seven billion light-years away. The study, conducted by Gauri Sharma and Paolo Salucci from SISSA, together with Glen Van de Ven from the University of Vienna, took a new look at one of the greatest mysteries of modern physics. According to the authors, this new research represents a step forward in our understanding of dark matter, the elusive element in our universe which has been theorised based on its demonstrable effects on heavenly bodies, but which is yet to be directly proven. This is despite any number of targeted astrophysical observations and experiments set up for the purpose in dedicated underground laboratories.

Studying dark matter in distant galaxies

Dark matter makes up approximately 84% of the mass in the cosmos: “Its dominant presence throughout the galaxies arises from the fact that the stars and hydrogen gas are moving as if governed by an invisible element” explains Gauri Sharma. Up until now, attempts to study it have focused on galaxies near to our own: “In this study, however,” she explains, “for the first time, we were seeking to observe and determine the distribution of the mass of spiral galaxies with the same morphology of those nearby, but much further away and therefore earlier by some seven billion years.

[caltrek]

Largest And Most Accurate Simulation of the Universe Created Using Supercomputers
by Benjamin Taub
February 11, 2022

https://www.iflscience.com/space/larges ... computers/

Introduction:

(IFL Science) The entire evolution of the cosmos, covering the 13.7 billion years since the Big Bang, has been accurately simulated by a supercomputer.

Describing this leviathan achievement in the Monthly Notices of the Royal Astronomical Society, researchers say that the model accurately positions the galaxies and other structures in our local universe, thereby indicating that our understanding of the forces that drive the evolution of the universe is correct.

According to the accepted model of cosmology, all astronomical events can be explained by the behavior of dark matter, which condenses into clumps known as haloes. Referred to as the Cold Dark Matter (CDM) model, this paradigm assumes that the accumulation of gases and other material around these haloes eventually leads to the formation of stars and galaxies, and has been used to explain several properties of the observable universe.

However, the study authors point out that most previous simulations using the CDM hypothesis have focused on random patches of sky rather than our own cosmic neighborhood – so they set out to determine whether or not the model could be used to accurately recreate the area of space surrounding the Milky Way galaxy.

They fed the complex physical equations that underpin the CDM model into a supercomputer called DiRAC COSmology MAchine (COSMA), located at Durham University. Based on these equations, the machine then proceeded to simulate the entire history of a patch of sky extending 600 million lightyears from our Solar System, represented by over 130 billion simulated particles.

[caltrek]

University of California - Irvine Scientists Discover How Galaxies Can Exist Without Dark Matter
February 14, 2022

https://www.eurekalert.org/news-releases/943369

Introduction:

(Eureka Alert) Irvine, Calif., Feb. 14, 2022 — In a new Nature Astronomy study (see also abstract below), an international team led by astrophysicists from the University of California, Irvine and Pomona College report how, when tiny galaxies collide with bigger ones, the bigger galaxies can strip the smaller galaxies of their dark matter — matter that we can’t see directly, but which astrophysicists think must exist because, without its gravitational effects, they couldn’t explain things like the motions of a galaxy’s stars.

It’s a mechanism that has the potential to explain how galaxies might be able to exist without dark matter – something once thought impossible.

https://www.nature.com/articles/s41550-021-01598-4

Abstract:

(Nature Astronomy) The standard cold dark matter plus cosmological constant model predicts that galaxies form within dark-matter haloes, and that low-mass galaxies are more dark-matter dominated than massive ones. The unexpected discovery of two low-mass galaxies lacking dark matter immediately provoked concerns about the standard cosmology and ignited explorations of alternatives, including self-interacting dark matter and modified gravity. Apprehension grew after several cosmological simulations using the conventional model failed to form adequate numerical analogues with comparable internal characteristics (stellar masses, sizes, velocity dispersions and morphologies). Here we show that the standard paradigm naturally produces galaxies lacking dark matter with internal characteristics in agreement with observations. Using a state-of-the-art cosmological simulation and a meticulous galaxy-identification technique, we find that extreme close encounters with massive neighbours can be responsible for this. We predict that ~30% of massive central galaxies (with at least 1011 solar masses in stars) harbour at least one dark-matter-deficient satellite (with 108–109 solar masses in stars). This distinctive class of galaxies provides an additional layer in our understanding of the role of interactions in shaping galactic properties. Future observations surveying galaxies in the aforementioned regime will provide a crucial test of this scenario.

[wjfox]

[weatheriscool]

Astronomers discover widest separation of brown dwarf pair to date
https://phys.org/news/2022-02-astronome ... -pair.html
by W. M. Keck Observatory

A team of astronomers has discovered a rare pair of brown dwarfs that has the widest separation of any brown dwarf binary system found to date.

"Because of their small size, brown dwarf binary systems are usually very close together," said Emma Softich, an undergraduate astrophysics student at the Arizona State University (ASU) School of Earth and Space Exploration and lead author of the study. "Finding such a widely separated pair is very exciting."

The gravitational force between a pair of brown dwarfs is lower than for a pair of stars with the same separation, so wide brown dwarf binaries are more likely to break up over time, making this pair of brown dwarfs an exceptional find.

The study, which is based on observations the University of California San Diego (UC San Diego) Cool Star Lab conducted with W. M. Keck Observatory on Maunakea, Hawaiʻi Island, is published in today's issue of The Astrophysical Journal Letters.

Using Keck Observatory's Near-Infrared Echellette Spectrometer, or NIRES instrument, members of the UC San Diego Cool Star Lab, including Physics Professor Adam Burgasser and graduate students Christian Aganze and Dino Hsu, obtained infrared spectra of the brown dwarf binary system, called CWISE J014611.20-050850.0AB. The data revealed the two brown dwarfs are about 12 billion miles apart, or three times the separation of Pluto from the sun. This distance confirms the unusual brown dwarf couple breaks the record for having the widest separation from each other.

"Keck's exceptional sensitivity in the infrared with this instrument was critical for our measurements," said co-author Burgasser, who leads the Cool Star Lab. "The secondary brown dwarf of this system is exceptionally faint, but with Keck we were able to obtain good enough spectral data to classify both sources and identify them as members of a rare class of blue L dwarfs."

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New 'black widow' millisecond pulsar discovered
https://phys.org/news/2022-02-black-wid ... ulsar.html
by Tomasz Nowakowski , Phys.org

An international team of astronomers reports the detection of a new millisecond pulsar (MSP) using the Green Bank Telescope (GBT). The newfound pulsar, designated PSR J1555−2908, turns out to be one of the so-called "black widow" MSPs. The finding is detailed in a paper published February 10 on arXiv.org.

The most rapidly rotating pulsars, those with rotation periods below 30 milliseconds, are known as MSPs. Researchers assume that they are formed in binary systems when the initially more massive component turns into a neutron star that is then spun up due to accretion of matter from the secondary star.

A class of extreme binary pulsars with semi-degenerate companion stars is dubbed "spider pulsars." These objects are further categorized as "black widows" if the companion has extremely low mass (less than 0.1 solar masses), while they are called "redbacks" if the secondary star is heavier.

PSR J1555−2908 was initially identified as a gamma-ray point source by NASA's Fermi spacecraft. Given that a large number of point sources in the GeV gamma-ray sky are known to be powered by pulsars, PSR J1555−2908 was perceived as a promising target to search for pulsations. Therefore, a team of astronomers led by Paul S. Ray of the U.S. Naval Research Laboratory in Washington, DC, has investigated this source with GBT, which resulted in the detection of radio pulsations.

[weatheriscool]

New insights into the formation of brown dwarfs
https://phys.org/news/2022-02-insights- ... warfs.html
by Ludwig Maximilian University of Munich

Brown dwarfs are strange celestial bodies, occupying a kind of intermediate position between stars and planets. Astrophysicists sometimes call them "failed stars" because they have insufficient mass to burn hydrogen in their cores and shine like stars. It is continually debated if the formation of brown dwarfs is simply a scaled-down version of the formation of Sun-like stars. Astrophysicists are focusing on the youngest brown dwarfs, also called proto-brown dwarfs. They are only a few thousand years old and are still in the early formation stages. They want to know if the gas and dust in these proto-brown dwarfs resemble the composition of the youngest Sun-like proto-stars.

[weatheriscool]

Scientists reveal 4.4 million galaxies in a new map
https://phys.org/news/2022-02-scientist ... axies.html
by Durham University

Durham University astronomer collaborating with a team of international scientists have mapped more than a quarter of the northern sky using the Low Frequency Array (LOFAR), a pan-European radio telescope.

The map reveals an astonishingly detailed radio image of more than 4.4 million objects and a very dynamic picture of our Universe, which now has been made public for the first time.

The vast majority of these objects are billions of light years away and are either galaxies that harbor massive black holes or are rapidly growing new stars. Rarer objects that have been discovered include colliding groups of distant galaxies and flaring stars within the Milky Way.

To produce the map, scientists deployed state-of-the-art data processing algorithms on high performance computers all over Europe to process 3,500 hours of observations that occupy 8 petabytes of disk space—the equivalent to roughly 20,000 laptops.

This data release, which is by far the largest from the LOFAR Two-metre Sky Survey, presents about a million objects that have never been seen before with any telescope and almost four million objects that are new discoveries at radio wavelengths.