Space and astronomy news
In 2019, astronomers observed an unusual gravitational chirp. Known as GW190521, it was the last scream of gravitational waves as a black hole of 66 solar masses merged with a black hole of 85 solar masses to become a 142 solar mass black hole. The data were consistent with all the other black hole mergers we’ve observed. There was just one problem: an 85 solar mass black hole shouldn’t exist.
Continue reading “Building the Black Hole Family Tree”
Binary stars are common throughout the galaxy. Roughly half the stars in the Milky Way are part of a binary or multiple system, so we would expect to find them almost everywhere. However, one place we wouldn’t expect to find a binary is at the center of the galaxy, close to the supermassive black hole Sagittarius A*. And yet, that is precisely where astronomers have recently found one.
Continue reading “A Binary Star Found Surprisingly Close to the Milky Way's Supermassive Black Hole”
Astrophotography is a challenging art. Beyond the usual skill set of understanding things such as light exposure, color balance, and the quirks of your kit, there is the fact that stars are faint and they move.
Continue reading “Astronaut Don Pettit is Serious, He Rigged up Astrophotography Gear on the ISS”
What was the Milky Way like billions of years ago? One way we can find out is by looking at the most distant galaxies in the observable Universe. Seeing those far galaxies is one goal of the James Webb Space Telescope. It has revealed some surprising facts about early galaxies, and now it is starting to reveal the story of our own.
Continue reading “Webb Weighs an Early Twin of the Milky Way”
Neutron stars are so named because in the simplest of models they are made of neutrons. They form when the core of a large star collapses, and the weight of gravity causes atoms to collapse. Electrons are squeezed together with protons so that the core becomes a dense sea of neutrons. But we now know that neutron stars aren’t just gravitationally bound neutrons. For one thing, neutrons are comprised of quarks, which have their own interactions both within and between neutrons. These interactions are extremely complex, so the details of a neutron star’s interior are something we don’t fully understand.
Continue reading “Do the Fastest Spinning Pulsars Contain Quark Matter?”
The Earth and Moon have been locked in a gravitational dance for billions of years. Each day, as the Earth turns, the Moon tugs upon the oceans of the world, causing the rise and fall of tides. As a result, the Earth’s day gets a little bit longer, and the Moon gets a little more distant. The effect is small, but over geologic time it adds up. About 620 million years ago, a day on Earth was only 22 hours long, and the Moon was at least 10,000 km closer than it is now.
Continue reading “Early Earth's Oceans of Magma Accelerated the Moon's Departure”
We know that interstellar objects occasionally visit our solar system. So far, we have only discovered two interstellar objects (ISOs), but that’s mainly because we can only distinguish them from solar system bodies by their orbital motion, and that takes a series of observations over time. The two we have discovered, ?Oumuamua and Borisov, were only noticed because they had highly unusual orbits that moved through the inner solar system. But when sky survey telescopes such as the Vera Rubin Observatory come online, we will likely find new interstellar objects all the time. It’s estimated that several ISOs enter the solar system every year, and there could be hundreds of them passing by at any given time. But that raises an interesting question about how these objects arrive. Do they enter our solar system randomly from all directions, or do they appear in clusters a few at a time?
Continue reading “Tidal Steams of Interstellar Objects May Flow Through the Milky Way Like Braided Rivers”
Sometimes in astronomy, a simple question has a difficult answer. One such question is this: what is the mass of our galaxy?
On Earth, we usually determine the mass of an object by placing it on a scale or balance. The weight of an object in Earth’s gravitational field lets us determine the mass. But we can’t put the Milky Way on a scale. Another difficulty with massing our galaxy is that there are two types of mass. There is the mass of dark matter that makes up most of the Milky Way’s mass, and there is all the regular matter like stars, planets, and us, which is known as baryonic matter.
Continue reading “High Velocity Clouds Comprise Less of the Milky Way’s Mass Than We Thought”
Lots of things out in the Universe can cause a supernova, from the gravitational collapse of a massive star, to the collision of white dwarfs. But most of the supernovae we observe are in other galaxies, too distant for us to see the details of the process. So, instead, we categorize supernovae by observed characteristics such as the light curves of how they brighten and fade and the types of elements identified in their spectra. While this gives us some idea of the underlying cause, there are still things we don’t entirely understand. This is particularly true for one particular kind of supernova known as Type Ia.
Continue reading “Do We Really Know What Becomes a Type Ia Supernova?”
The standard theory of cosmology is based upon four things: the structure of space and time, matter, dark matter, and dark energy. Of these, dark energy is the one we currently understand the least. Within the standard model, dark energy is part of the structure of space and time as described by general relativity. It is uniform throughout the cosmos and expressed as a parameter known as the cosmological constant. But initial observations from the Dark Energy Spectroscopic Instrument (DESI) suggest the rate of comic expansion may vary over time. If further observations reinforce this, it could open up cosmological models to alternatives to general relativity known as modified gravity.
Continue reading “Observations by DESI Open the Door to Modified Gravity Models”