Om nom nom: a black hole ate a star and left crumbs for us to see

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A Black Hole Ate A Star And Left Crumbs Of Light For Astronomers To Discover

colliding galaxies Arp 299

The colliding galaxies Arp 299, as seen in visible light (the background) and X-rays (red, green, and blue foreground). [Credit: NASA, JPL-Caltech, GSFC, Hubble, NuSTAR]

For Forbes:

Astronomers captured the last moments of an unlucky star that got too close to a black hole. However, they didn’t know that’s what we were seeing right away, because the whole scene of carnage was hidden by clouds of gas and dust. Now, with multiple types of observations and more than ten years of data, we have new insights into the way black holes shred stars, as reported in a new paper in Science.

Black holes, like Cookie Monster, are notoriously messy eaters. That’s good for astronomers, though, because the cosmic crumbs a black hole spills during its meal emit a lot of light. If a star gets too close to a black hole, the gravity tears it to pieces in an act known as “tidal disruption”, but only part of the star’s material actually falls in. (This is a more extreme version of the same forces that raise tides on Earth, and which destroyed a small moon to create Saturn’s rings.) The rest of the star gets channeled into a powerful jet that streams away from the black hole back into space.

[Read the rest at Forbes…]

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How to find newborn planets without seeing them

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Astronomers Use The Doppler Effect To Find Three Newborn Planets

For Forbes:

We can’t witness the birth of our own Solar System, but the Atacama Large Millimeter/submillimeter Array (ALMA) is providing a picture of how it may have happened. ALMA spotted signs of three giant planets forming around a young star in our cosmic neighborhood. The technique astronomers used to study these planets is one that can be used to find other newborn worlds, and see exactly how clouds of gas and dust turn into something like the Solar System.

The star, which astronomers gave the memorable name HD 163296, is only about 4 million years old, which in cosmic terms makes it a baby. Researchers used ALMA to take detailed images of the disk of dust and gas surrounding the star, which showed three gaps. By studying the motion of carbon monoxide gas within the disk, the astronomers showed it was being moved by massive objects living in those gaps — a telltale sign of newborn planets. These findings were published in a pair of articles in Astrophysical Journal Letters.

[Read the rest at Forbes…]

Planet Nine or Planet Nein? The quest to understand the weird outer Solar System

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One Big Planet Nine, Or A Swarm Of Small Icy Worlds?

For Forbes:

The outermost Solar System is a confusing and complicated place. Once you get Neptune, the comets, Kuiper belt objects, and other small icy worlds orbit the Sun in odd patterns. A few of those, including the very distant world known as Sedna, have orbits that make very little sense compared with other Solar System inhabitants. For that reason, some astronomers think there’s a Planet Nine hiding far beyond Pluto’s orbit: a giant world roughly 10 times the mass of Earth.

But a new study by University of Colorado researchers proposed an alternative explanation. Astronomer Ann-Marie Madigan and her student Jacob Fleisig realized they could reproduce the strange orbits of icy worlds just by the way they interact with each other: no Planet Nine necessary. The idea is they sometimes swarm (in a broad sense) during their orbits, and when multiple Moon-sized bodies are in the same general region, it’s enough to kick other worlds like Sedna into their wild trajectories. It’s an eminently sensible explanation, and since two years of hunting for Planet Nine haven’t turned up anything, the hypothesis is definitely worth pondering more. However, we haven’t seen enough of these small worlds yet either, so the race is now on to see which explanation is correct.

[Read the rest at Forbes…]

Earth is a freeeeee faaaallin’ laboratory for testing general relativity

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Scientists Check Einstein’s Predictions Using Earth Itself As The Laboratory

For Forbes:

The modern description of gravity, Albert Einstein’s general relativity, is one of the most successful and best-tested theories we have. The core of that theory is a set of principles that say basically “physics is physics, wherever you are and no matter how fast you’re moving”. In particular, an experiment performed under the influence of gravity alone should work exactly the same as if you’re performing the same experiment deep in space without any gravity at all.

That’s a tricky concept to verify, but scientists at the National Institute of Standards and Technology (NIST) in Colorado have provided the best test for it yet, using Earth itself as the laboratory. They performed precision experiments in atomic physics (one of NIST’s specialties) and compared those results to those obtained at labs around the world, with data taken over a period of 14 years. The result: general relativity’s predictions were upheld once again.

[Read the rest at Forbes…]

The ice must flow to make Pluto’s dunes, but how?

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The Wrinkles On Pluto’s Heart Could Be Methane-Ice Dunes

possible dunes on Pluto

In this high-resolution image of Pluto’s heart, you can see wrinkles in the nitrogen ice. Those are possibly dunes made of methane, which raises an interesting question: how can such dunes form? [Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute]

For Forbes:

Sand dunes are found all over Earth: along the shores of lakes or oceans, deserts like the Sahara in Africa, and even underwater. Robotic space probes have also found dunes on Venus, Mars, and Saturn’s giant moon Titan.

Now researchers think they have found dunes on Pluto, which presents a huge (and fun) mystery. How can dunes form on a world where the atmosphere is a bare wisp, not enough to create the kind of winds responsible for making dunes elsewhere in the Solar System?

[Read the rest at Forbes…]

Strange asteroid may have been born in another star system

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Strange Asteroid May Be A Permanent Alien Guest

strange asteroid 2015 BZ509

The strange asteroid 2015 BZ509 (circled), which may have been born orbiting another star before getting kicked out and joining our Solar System. [Credit: C. Veillet/LBTO]

For Forbes:

Last fall, an asteroid we named ʻOumuamua passed through the Solar System. Its visit marked the first time we’ve identified an object inside the Solar System that definitely came from outside. However, a new study argues that we might have a more permanent interstellar guest: a weird asteroid called 2015 BZ509.

Thousands of asteroids swarm around Jupiter’s orbit, but they all orbit the same direction as the giant planet except 2015 BZ509. This weirdo orbits the opposite direction — “retrograde” in technical terms — at a highly tilted angle. Fathi Namouni and Helena Morais performed a computer simulation which demonstrates that 2015 BZ509 could stay in its orbit for billions of years, but it’s unlikely it formed there when the rest of the Solar System was born. Instead, the authors argue, it probably originated outside the Solar System and drifted in, where it was captured by gravity.

[Read the rest at Forbes]

An astronomical saga of star births, pancakes, and Kylo Ren

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The Hidden Depths Of The Dark Cloud Hiding Newborn Stars

For Forbes:

The third dimension is one of the biggest obstacles in astronomy. We see the stars, but we don’t know how far away they are without some additional information, which requires scientific cleverness. And when the object we’re studying is a nebula — a cloud of gas or dust — we only see its profile, not its full three-dimensional shape. But a new paper shows that, in some cases, we might be able to deduce the full shape of a nebula by how it vibrates: a kind of magnetic nebulaquake.

Astrophysicists Aris Tritsis and Konstantinos Tassis compared a sophisticated computer simulation to observational data on an object called the “Musca molecular cloud”, also known as the “Dark Doodad”. (“Musca” is the name of the constellation where it’s found, which means “the fly”. It’s only visible in the Southern Hemisphere.) They found that even though the Doodad looks like a filament, it’s actually more like a pancake that we’re seeing edge-on. Beyond the curiosity aspect (who wouldn’t want to study the Dark Doodad?), this result is important for understanding how stars are born.

[Read the rest at Forbes…]