Posted on by Paul M. Sutter

It Looks Like Dark Matter Can be Heated Up and Moved Around

Image credit: NASA & ESA

Look at a galaxy, what do you see? Probably lots of stars. Nebulae too. And that’s probably it. A whole bunch of stars and gas in a variety of colorful assortments; a delight to the eye. And buried among those stars, if you looked carefully enough, you might find planets, black holes, white dwarves, asteroids, and all sorts of assorted chunky odds and ends. The usual galactic milieu.

What you wouldn’t see is what most of that galaxy is really made of. You wouldn’t see the invisible, the hidden. You wouldn’t see the bulk of that galactic mass. You wouldn’t see the dark matter.

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Posted on by Paul M. Sutter

A Guide to Hunting Zombie Stars

R Aquarii is called a symbiotic star system because of their relationship. As the white dwarf draws in material from the Red Giant, it ejects some if it in weird looping patterns, seen in this Hubble image. Image Credit: By Judy Schmidt from USA - Symbiotic System R Aquarii, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=63473035
R Aquarii is called a symbiotic star system because of their relationship. As the white dwarf draws in material from the Red Giant, it ejects some if it in weird looping patterns, seen in this Hubble image. Image Credit: By Judy Schmidt from USA - Symbiotic System R Aquarii, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=63473035

Apparently not all supernovas work. And when they fail, they leave behind a half-chewed remnant, still burning from leftover heat but otherwise lifeless: a zombie star. Astronomers aren’t sure how many of these should-be-dead creatures lurk in the interstellar depths, but with recent simulations scientists are making a list of their telltale signatures so that future surveys can potentially track them down.

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Posted on by Paul M. Sutter

New Research Reveals How Galaxies Stay Hot and Bothered

This visualization uses data from simulations of orbital motions of gas swirling around at about 30% of the speed of light on a circular orbit around the black hole. Credit: ESO/Gravity Consortium/L. Calçada

It’s relatively easy for galaxies to make stars. Start out with a bunch of random blobs of gas and dust. Typically those blobs will be pretty warm. To turn them into stars, you have to cool them off. By dumping all their heat in the form of radiation, they can compress. Dump more heat, compress more. Repeat for a million years or so.

Eventually pieces of the gas cloud shrink and shrink, compressing themselves into a tight little knots. If the densities inside those knots get high enough, they trigger nuclear fusion and voila: stars are born.

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Posted on by Paul M. Sutter

Astronomers Count all the Photons in the Universe. Spoiler Alert: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Photons

The NASA/ESA Hubble Space Telescope offers this delightful view of the crowded stellar encampment called Messier 68, a spherical, star-filled region of space known as a globular cluster. Mutual gravitational attraction amongst a cluster’s hundreds of thousands or even millions of stars keeps stellar members in check, allowing globular clusters to hang together for many billions of years. Astronomers can measure the ages of globular clusters by looking at the light of their constituent stars. The chemical elements leave signatures in this light, and the starlight reveals that globular clusters' stars typically contain fewer heavy elements, such as carbon, oxygen and iron, than stars like the Sun. Since successive generations of stars gradually create these elements through nuclear fusion, stars having fewer of them are relics of earlier epochs in the Universe. Indeed, the stars in globular clusters rank among the oldest on record, dating back more than 10 billion years. More than 150 of these objects surround our Milky Way galaxy. On a galactic scale, globular clusters are indeed not all that big. In Messier 68's case, its constituent stars span a volume of space with a diameter of little more than a hundred light-years. The disc of the Milky Way, on the other hand, extends over some 100 000 light-years or more. Messier 68 is located about 33 000 light-years from Earth in the constellation Hydra (The Female Water Snake). French astronomer Charles Messier notched the object as the sixty-eighth entry in his famous catalogue in 1780. Hubble added Messier 68 to its own impressive list of cosmic targets in this image using the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The image, which combines visible and infrared light, has a field of view of approximately 3.4 by 3.4 arcminutes. Credit: Hubble/NASA/ESA

Imagine yourself in a boat on a great ocean, the water stretching to the distant horizon, with the faintest hints of land just beyond that. It’s morning, just before dawn, and a dense fog has settled along the coast. As the chill grips you on your early watch, you catch out of the corner of your eye a lighthouse, feebly flickering through the fog.

And – yes – there! Another lighthouse, closer, its light a little stronger. As you scan the horizon more lighthouses signal the dangers of the distant coast.
Continue reading “Astronomers Count all the Photons in the Universe. Spoiler Alert: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Photons”

Posted on by Paul M. Sutter

We May Soon Be Able To See the First, Supergiant Stars in the Universe

An artist's illustration of the first stars to appear in the universe. Credit: N.R. Fuller, National Science Foundation

We need to talk about the dark ages. No, not those dark ages after the fall of the western Roman Empire. The cosmological dark ages. The time in our universe, billions of years ago, before the formation of the first stars. And we need to talk about the cosmic dawn: the birth of those first stars, a tumultuous epoch that completely reshaped the face the cosmos into its modern form.

Those first stars may have been completely unlike anything we see in the present universe. And we may, if we’re lucky, be on the cusp of seeing them for the first time.

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Posted on by Paul M. Sutter

The Power of the Wobble: Finding Exoplanets in the Shifting of Starlight

Artist's concept of the hot Jupiter WASP-121b, which presents the best evidence yet of a stratosphere on an exoplanet - generated using Engine House VFX. Credit: Bristol Science Centre/University of Exeter

They say there’s more than one way to skin an interstellar cat, and in astronomy there’s more than one way to find alien exoplanets orbiting a distant star. With the recent shut-down of NASA’s prolific Kepler mission and its windfall of discoveries, it’s time to look towards the future, and towards alternatives.

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Posted on by Paul M. Sutter

Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves

NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA
NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA

How in the world could you possibly look inside a star? You could break out the scalpels and other tools of the surgical trade, but good luck getting within a few million kilometers of the surface before your skin melts off. The stars of our universe hide their secrets very well, but astronomers can outmatch their cleverness and have found ways to peer into their hearts using, of all things, sound waves. Continue reading “Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves”

Posted on by Paul M. Sutter

This Star Killed its Companion and is now Escaping the Milky Way

Tauris argues that a lopsided supernova explosion may be the source of certain hypervelocity stars (image credit: IsiacDaGraca).

Our universe is capable of some truly frightening scenarios, and in this case we have an apparent tragedy: two stars, lifelong companions, decide to move away from the Milky Way galaxy together. But after millions of years of adventure into intergalactic space, one star murders and consumes the other. It now continues its journey through the universe alone, much brighter than before, surrounded by a shell of leftover remnants.

At least, we think. All we have to go on right now is a crime scene.

Let’s investigate.

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Posted on by Paul M. Sutter

Scary Giant Blue Stars May Unlock Mysteries of Stellar Evolution

Simulation of outburst from blue variable star. by Joseph Insley/Argonne Leadership Computing Facility

Imagine a single star more luminous than a million suns, erupting every few decades in a massive flare that shines as bright as a supernova. But the blast, as ferocious as it is, does not obliterate the tumultuous star. It remains, its surface roiling with violence as spasms rock its inner layers. Soon enough the star will end its suffering in a final titanic blast, but before it does, it must suffer in this state for thousands of years.

This is a rare luminous blue variable star, and it may hold the keys to understanding the link between the lives of stars and their deaths.

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Posted on by Paul M. Sutter

Gravitational waves were only recently observed, and now astronomers are already thinking of ways to use them: like accurately measuring the expansion rate of the Universe

Collisions of neutron stars produce powerful gamma-ray bursts – and heavy elements like gold (Credit: Dana Berry, SkyWorks Digital, Inc.)

Neutron stars scream in waves of spacetime when they die, and astronomers have outlined a plan to use their gravitational  agony to trace the history of the universe. Join us as we explore how to turn their pain into our cosmological profit.

Continue reading “Gravitational waves were only recently observed, and now astronomers are already thinking of ways to use them: like accurately measuring the expansion rate of the Universe”