Cygnus X-1 was the First Black Hole Ever Found. New Measurements Show it's Much More Massive Than Previously Believed

In 1964 two Aerobee suborbital rockets were launched with the goal of mapping x-ray sources in the sky. Each rocket contained a directed Geiger counter, so that as the rocket rotated at the peak of its trajectory to measure the direction of x-ray sources. The project discovered eight x-ray sources, including a particularly bright one in the constellation Cygnus. It became known as Cygnus X-1.

Cygnus X-1 as imaged by a balloon bourne telescope. Credit: NASA/Marshall Space Flight Center
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A map of 25,000 Supermassive Black Holes Across the Universe

The Low-Frequency Array (LOFAR) is a different kind of radio telescope. Although radio light has the longest wavelengths and lowest frequencies of the electromagnetic spectrum, much of radio astronomy has focused on the higher frequency end. Observatories such as ALMA study radio light at frequencies of hundreds of Gigahertz, and the VLA studies the fifty Gigahertz range, LOFAR captures radio signals below 250 Megahertz, which is in the range of the lowest radio frequencies that can be seen from Earth.

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A new Approach Could Tease out the Connection Between Gravity and Quantum Mechanics

In physics, there are two main ways to model the universe. The first is the classical way. Classical models such as Newton’s laws of motion and Einstein’s theory of relativity assume that the properties of an object such as its position and motion are absolute. There are practical limits to how accurately we can measure an object’s path through space and time, but that’s on us. Nature knows their motion with infinite precision. Quantum models such as atomic physics assume that objects are governed by interactions. These interactions are probabilistic and indefinite. Even if we constrain an interaction to limited outcomes, we can never know the motion of an object with infinite precision, because nature doesn’t allow it.

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A Cluster of Black Holes Found Inside a Globular Cluster of Stars

Black holes come in at least two sizes: small and large. Small black holes are formed from stars. When a large star reaches the end of its life, it typically ends in a supernova. The remnant core then collapses under its own weight, forming a black hole or neutron star. Small stellar-mass black holes are typically tens of solar masses. Large black holes lurk in the centers of galaxies. These supermassive black holes can be millions or billions of solar masses. They formed during the early universe and triggered the formation and evolution of galaxies around them.

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It's Starting to Look Like Super-Earths Really are Just Great big Terrestrial Planets

We’ve learned a thing or two about exoplanets in the past several years. One of the more surprising discoveries is that our solar system is rather unusual. The Sun’s worlds are easily divided into small rocky planets and large gas giants. Exoplanets are much more diverse, both in size and composition.

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If Dark Matter is Made of Sterile Neutrinos, a new Survey has Narrowed Down What to Look for

We don’t know what dark matter is. We do know what it isn’t, and that’s a problem. Matter is made of elementary particles, from the quarks and electrons that make up atoms and molecules, to primordial neutrinos spread throughout the cosmos. But none of the known elementary particles can comprise dark matter, so what is it?

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Black Holes Simulated in a Tank of Water Reveals “Backreaction” for the First Time

It’s hard to make a black hole in the lab. You have to gather up a bunch of mass, squeeze it until it gravitationally collapses on itself, work, work, work. It’s so hard to do that we’ve never done it. We can, however, make a simulated black hole using a tank of water, and it can tell us interesting things about how black holes work.

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In Theory, Supermassive Black Holes Could get Even More Supermassive

Our universe contains some enormous black holes. The supermassive black hole in the center of our galaxy has a mass of 4 million Suns, but it’s rather small as galactic black holes go. Many galactic black holes have a billion solar masses, and the most massive known black hole is estimated to have a mass of nearly 70 billion Suns. But just how big can a black hole get?

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Strange Green Star is the Result of a Merger Between two White Dwarfs

A white dwarf isn’t your typical kind of star. While main sequence stars such as our Sun fuse nuclear material in their cores to keep themselves from collapsing under their own weight, white dwarfs use an effect known as quantum degeneracy. The quantum nature of electrons means that no two electrons can have the same quantum state. When you try to squeeze electrons into the same state, they exert a degeneracy pressure that keeps the white dwarf from collapsing.

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