Friday, April 7, 2023

Scientists think they know why interstellar object 'Oumuamua moved so strangely


In 2017, 1I/‘Oumuamua was identified as the first known interstellar object in the Solar System1. Although typical cometary activity tracers were not detected, ‘Oumuamua showed a notable non-gravitational acceleration. 

Here we report that the acceleration of ‘Oumuamua is due to the release of entrapped molecular hydrogen that formed through energetic processing of an H2O-rich icy body...We show that this mechanism can explain many of ‘Oumuamua’s peculiar properties without fine-tuning.


But when ‘Oumuamua was discovered, it had no tail and was too small and too far from the sun to capture enough energy to eject much water, which led astronomers to speculate wildly about its composition and what was pushing it outward. Was it a hydrogen iceberg? A large, fluffy snowflake pushed by light pressure from the sun? 

Perhaps, they wondered, its strange acceleration actually came from hydrogen...If so, perhaps the force produced by the hydrogen outgassing could explain ‘Oumuamua’s odd movement.

“For a comet several kilometers across, the outgassing would be from a really thin shell relative to the bulk of the object, so both compositionally and in terms of any acceleration, you wouldn’t necessarily expect that to be a detectable effect,” she said. “But because ‘Oumuamua was so small, we think that it actually produced sufficient force to power this acceleration.”


Scientists have come up with a simple explanation for the strange movements of our solar system's first known visitor from another star.

Oddly, this interstellar object appeared to be slightly accelerating in a way that normally is associated with the outgassing of some kind of material. But astronomers couldn't detect any comet-like tail of dust or gas...Now, though, in the journal Nature, two researchers say the answer might be the release of hydrogen from trapped reserves inside water-rich ice.

"It's an interesting, creative idea," says Karen Meech, with the Institute for Astronomy at the University of Hawaii, who leads the team that initially found and observed 'Oumuamua. "It doesn't require a super-exotic mechanism." But she still thinks it's possible that 'Oumuamua is just a regular, ordinary comet that released enough water, carbon dioxide, and carbon monoxide to account for the acceleration, and astronomers just didn't detect it.

Meech also finds the elongated shape of the object far more intriguing than the odd acceleration, which could be explained by low quantities of ordinary comet ejecta. The currently accepted explanation for the shape is that 'Oumuamua like objects are kicked out during planetary formation.

Scientific American:

Planet formation is a messy process in which worlds emerge from the embryonic disks of gas and dust that give birth to stars themselves. As debris clumps together and grows, whirling around the central star, its gravity pushes and scatters smaller clumps throughout the disk. 

Multiple theories postulate that such processes are responsible for sending ‘Oumuamua our way. Researchers have proposed that the strange object may have been thrown out of its young system after a brush with a giant planet there.


The object, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated—perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike objects seen in our solar system, it may provide new clues into how other solar systems formed. 

Tuesday, April 4, 2023

Global Geomagnetic Perturbation Forecasting Using Deep Learning


Geomagnetically Induced Currents (GICs) arise from spatio-temporal changes to Earth's magnetic field, which arise from the interaction of the solar wind with Earth's magnetosphere, and drive catastrophic destruction to our technologically dependent society. Hence, computational models to forecast GICs globally with large forecast horizon, high spatial resolution and temporal cadence are of increasing importance to perform prompt necessary mitigation.

Our model outperforms, or has consistent performance with state-of-the-practice high time cadence local and low time cadence global models, while also outperforming/having comparable performance with the benchmark models. Such quick inferences at high temporal cadence and arbitrary spatial resolutions may ultimately enable accurate forewarning of dB/dt for any place on Earth, resulting in precautionary measures to be taken in an informed manner.

Like a tornado siren for life-threatening storms in America's heartland, a new computer model that combines artificial intelligence (AI) and NASA satellite data could sound the alarm for dangerous space weather.

The model uses AI to analyze spacecraft measurements of the solar wind (an unrelenting stream of material from the sun) and predict where an impending solar storm will strike, anywhere on Earth, with 30 minutes of advance warning. This could provide just enough time to prepare for these storms and prevent severe impacts on power grids and other critical infrastructure.

To help prepare, an international team of researchers at the Frontier Development Lab—a public-private partnership that includes NASA, the U.S. Geological Survey, and the U.S. Department of Energy—have been using artificial intelligence (AI) to look for connections between the solar wind and geomagnetic disruptions, or perturbations, that cause havoc on our technology. The researchers applied an AI method called "deep learning," which trains computers to recognize patterns based on previous examples. They used this type of AI to identify relationships between solar wind measurements from heliophysics missions (including ACE, Wind, IMP-8, and Geotail) and geomagnetic perturbations observed at ground stations across the planet. 

Previously on this blog:

Using dark matter distribution to test the cosmological model


We present cosmology results from a blinded joint analysis of cosmic shear, ξ±(ϑ), galaxy-galaxy weak lensing, ΔΣ(R), and projected galaxy clustering, wp(R), measured from the Hyper Suprime-Cam three-year (HSC-Y3) shape catalog and the Sloan Digital Sky Survey (SDSS) DR11 spectroscopic galaxy catalog - a 3×2pt cosmology analysis.

We obtain a robust constraint on the cosmological parameters for the flat ΛCDM model: S8=σ8(Ωm/0.3)0.5=0.763+0.040−0.036 (68% C.I.), or the best-constrained parameter given by S′8=σ8(Ωm/0.3)0.22=0.721±0.028, determined with about 4% fractional precision.

An international team of astrophysicists and cosmologists at various institutes including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) have submitted a set of five papers, measuring a value for the "clumpiness" of the universe's dark matter, known to cosmologists as S8, of 0.76, which aligns with values that other gravitational lensing surveys have found in looking at the relatively recent universe, but it does not align with the value of 0.83 derived from the cosmic microwave background, which dates back to the universe's origins when the universe was about 380,000 years old. 

Previously on this blog: 

Webb telescope discovers oldest galaxies ever observed

Nature Astronomy:

Here we identify four galaxies located in the JWST Advanced Deep Extragalactic Survey Near-Infrared Camera imaging with photometric redshifts z of roughly 10–13. These galaxies include the first redshift z > 12 systems discovered with distances spectroscopically confirmed by JWST in a companion paper.

Taken together, these measurements show that the first galaxies contributing to cosmic reionization formed rapidly and with intense internal radiation fields.

The James Webb Space Telescope has discovered the four most distant galaxies ever observed, one of which formed just 320 million years after the Big Bang when the universe was still in its infancy, new research said on Tuesday.

Stephane Charlot, a researcher at the Astrophysics Institute of Paris and co-author of the two new studies, told AFP that the farthest galaxy—called JADES-GS-z13-0—formed 320 million years after the Big Bang. That is the greatest distance ever observed by astronomers, he said.

However in February, the discovery of six massive galaxies from 500-700 million years after the Big Bang led some astronomers to question the standard model.

Those galaxies, also observed by the Webb telescope, were bigger than thought possible so soon after the birth of the universe—if confirmed, the standard model could need updating. 

This analysis does not include even earlier candidates that JWST has discovered that are yet to be confirmed. 

Thermal vacuum testing for the Europa Clipper

NASA (via YouTube ): We'll be back soon. The spacecraft is currently undergoing vacuum testing. I was a huge fan of the livestream for b...