Paul M. Sutter, Author at Universe Today

April 17, 2020April 17, 2020 by Paul M. Sutter

Gravity is tested down to a scale smaller than the thickness of a human hair

Gravity was the first force of nature to be realized, and in the centuries since we first cracked the code of that all-pervasive pulling power, scientists have continually come up with clever ways to test our understanding. And it’s no surprise why: the discovery of a new wrinkle in the gravitational force could open up vistas of new physics, and maybe even the nature of reality itself.

April 14, 2020April 15, 2020 by Paul M. Sutter

Thanks to COVID-19, nothing’s moving, and seismologists can tell

As the COVID-19 disease continues to wreak its viral havoc on the human population of Earth, governments around the world have closed their schools, shut down non-essential businesses, and told their citizens to stay at home as much as possible. In other words, there’s a lot less human activity on our planet, and it’s led to a detectable drop in seismic activity.

April 7, 2020April 7, 2020 by Paul M. Sutter

Decaying Dark Matter Should be Visible Here in the Milky Way as a Halo Around the Galaxy

A simulated image of what the X-ray emission from dark matter might be. Image credit: Christopher Dessert, Nicholas L. Rodd, Benjamin R. Safdi, Zosia Rostomian (Berkeley Lab), based on data from the Fermi Large Area Telescope

Astronomers are very sure that dark matter exists, but they’re not sure at all what it’s made of.

The problem is that it isn’t just dark, it’s invisible. As far as we know, dark matter doesn’t emit light, absorb light, reflect light, refract light, scatter light, diffract light, or really have anything to do with light at all. This makes it hard to study. We know that dark matter exists, however, through its gravitational effects. Even though it’s invisible, it still has mass, and so the dark matter in our universe (which, by the way, makes up 85% of all the mass in the cosmos) can affect the motions of normal (or light-interacting) matter, like stars and galaxies.

April 4, 2020April 4, 2020 by Paul M. Sutter

Astronomers are hoping to see the very first stars and galaxies in the Universe

The epoch of reionization was when light from the first stars could travel through the early Universe. At this time, galaxies began assembling, as did black holes. Why did some early galaxies have ancient stars? That's a question JWST will help answer. Credit: Paul Geil & Simon Mutch/The University of Melbourne

Sometimes it’s easy being an astronomer. When your celestial target is something simple and bright, the game can be pretty straightforward: point your telescope at the thing and just wait for all the juicy photons to pour on in.

But sometimes being an astronomer is tough, like when you’re trying to study the first stars to appear in the universe. They’re much too far away and too faint to see directly with telescopes (even the much-hyped James Webb Space Telescope will only be able to see the first galaxies, an accumulation of light from hundreds of billions of stars). To date, we don’t have any observations of the first stars, which is a major bummer.

March 27, 2020March 28, 2020 by Paul M. Sutter

The heliosphere looks a lot weirder than we originally thought

A model of the heliosphere as imagined by new research. Yes, it looks like an ugly croissant. Image courtesy of Merav Opher, et. al

Every second of every day, our sun spits out a stream of tiny high-energy particles, known as the solar wind. This wind blows throughout the solar system, extending far beyond the orbits of the planets and out into interstellar space.

But the farther from the sun the wind gets, the more slowly it streams, changing from the raging torrent that the inner planets experience (strong enough to cause the aurora) into nothing more than an annoying drizzle. And far enough away – about twice the orbit of Neptune – it meets and mingles with all the random bits of energetic junk just floating around amongst the stars.

May 20, 2019May 20, 2019 by Paul M. Sutter

Can You Spot a Planetary Nebula from a Few Blurry Pixels? Astronomers Can – Here’s How

A planetary nebula is one of the most beautiful objects in the universe. Formed from the decaying remnants of a mid-sized star like a sun, no two are alike. Cosmically ephemeral, they last for only about 10,000 years – a blink of a cosmic eye. And yet they are vitally important, as their processed elements spread and intermingle with the interstellar medium in preparation for forming a new generation of stars. So studying them is important for understanding stellar evolution. But unlike their stellar brethren, since no two are alike, it’s hard to efficiently pick them out of astronomical deep-sky surveys. Thankfully, a research team has recently developed a method for doing just that, and their work could open up the door to fully understanding the great circle of stellar life.

May 17, 2019May 17, 2019 by Paul M. Sutter

Is Dark Matter Made of Axions? Black Holes May Reveal the Answer

The early universe. Credit: Tom Abel & Ralf Kaehler (KIPACSLAC)/ AMNH/NASA

What is dark matter made of? It’s one of the most perplexing questions of modern astronomy. We know that dark matter is out there, since we can see its obvious gravitational influence on everything from galaxies to the evolution of the entire universe, but we don’t know what it is. Our best guess is that it’s some sort of weird new particle that doesn’t like to talk to normal matter very often (otherwise we would have seen it by now). One possibility is that it’s an exotic hypothetical kind of particle known as an axion, and a team of astronomers are using none other than black holes to try to get a glimpse into this strange new cosmic critter.

April 24, 2019April 24, 2019 by Paul M. Sutter

Barfing Neutron Stars Reveal Their Inner Guts

Artist's illustration of two merging neutron stars. The narrow beams represent the gamma-ray burst while the rippling spacetime grid indicates the isotropic gravitational waves that characterize the merger. Swirling clouds of material ejected from the merging stars are a possible source of the light that was seen at lower energies. Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

We don’t really understand neutron stars. Oh, we know that they are – they’re the leftover remnants of some of the most massive stars in the universe – but revealing their inner workings is a little bit tricky, because the physics keeping them alive is only poorly understood.

But every once in a while two neutron stars smash together, and when they do they tend to blow up, spewing their quantum guts all over space. Depending on the internal structure and composition of the neutron stars, the “ejecta” (the polite scientific term for astronomical projectile vomit) will look different to us Earth-bound observers, giving us a gross but potentially powerful way to understand these exotic creatures.

April 19, 2019April 19, 2019 by Paul M. Sutter

What Will the James Webb Space Telescope See? A Whole Bunch of Dust, That’s What

With its helical appearance resembling a snail’s shell, this reflection nebula seems to spiral out from a luminous central star in this new NASA/ESA Hubble Space Telescope image. The star in the centre, known as V1331 Cyg and located in the dark cloud LDN 981 — or, more commonly, Lynds 981 — had previously been defined as a T Tauri star. A T Tauri is a young star — or Young Stellar Object — that is starting to contract to become a main sequence star similar to the Sun. What makes V1331Cyg special is the fact that we look almost exactly at one of its poles. Usually, the view of a young star is obscured by the dust from the circumstellar disc and the envelope that surround it. However, with V1331Cyg we are actually looking in the exact direction of a jet driven by the star that is clearing the dust and giving us this magnificent view. This view provides an almost undisturbed view of the star and its immediate surroundings allowing astronomers to study it in greater detail and look for features that might suggest the formation of a verylow-mass object in the outer circumstellar disc.

When it comes to the first galaxies, the James Webb Space Telescope will attempt to understand the formation of those galaxies and their link to the underlying dark matter. In case you didn’t know, most of the matter in our universe is invisible (a.k.a. “dark”), but its gravity binds everything together, including galaxies. So by studying galaxies – and especially their formation – we can get some hints as to how dark matter works. At least, that’s the hope. It turns out that astronomy is a little bit more complicated than that, and one of the major things we have to deal with when studying these distant galaxies is dust. A lot of dust.

That’s right: good old-fashioned dust. And thanks to some fancy simulations, we’re beginning to clear up the picture.

March 11, 2019March 11, 2019 by Paul M. Sutter

Massive Photons Could Explain Dark Matter, But Don’t

A computer simulation of the distribution of matter in the universe. Orange regions host galaxies; blue structures are gas and dark matter. Credit: TNG Collaboration

I’ll be the first to admit that we don’t understand dark matter. We do know for sure that something funny is going on at large scales in the universe (“large” here meaning at least as big as galaxies). In short, the numbers just aren’t adding up. For example, when we look at a galaxy and count up all the hot glowing bits like stars and gas and dust, we get a certain mass. When we use any other technique at all to measure the mass, we get a much higher number. So the natural conclusion is that not all the matter in the universe is all hot and glowy. Maybe some if it is, you know, dark.

But hold on. First we should check our math. Are we sure we’re not just getting some physics wrong?