If You Could See Gravitational Waves, the Universe Would Look Like This

By Brian Koberlein - September 22, 2023 09:00 AM UTC | Physics
Our biology limits our vision. Our eyes can only perceive specific wavelengths of light. But what if we could see the Universe in gravitational waves? A new NASA simulation mapped out hundreds of collisions between dense objects, like white dwarfs, neutron stars, and black holes. These collisions happen within galaxies, sending ripples of gravitational waves across the Universe, and would allow astronomers to recreate the shape of galaxies over time. Upcoming observatories will detect tens of thousands of ultra-compact binary stars, providing even higher resolution—an entirely new way to observe the Universe.
Continue reading

We Can't See the First Stars Yet, but We Can See Their Direct Descendants

By Brian Koberlein - September 21, 2023 09:43 AM UTC | Stars
The first stars in the Universe were enormous, made of primordial hydrogen and helium from the Big Bang. They lived short lives, exploded as supernovae, and seeded nearby nebulae with heavier elements that began the next generation of stars. Our telescopes aren't powerful enough to see them yet, but have astronomers found their direct descendants? The metal-poor stars in the galactic halo seem to show the imprints from those first stars and could offer valuable clues about the first stars in the Universe.
Continue reading

First Contact Could Turn Out Well for Humanity

By Brian Koberlein - September 20, 2023 10:35 AM UTC | Astrobiology
Most science fiction portrays the first contact between humanity and alien civilizations as a disaster. That's probably because our history hasn't turned out so well. But does it have to end poorly for us? A new paper looks at the game theory of first contact. It shows that the rational response to another civilization is to be cautious, with both groups understanding the other before taking decisive action. Communication would be difficult but not impossible. Since we share a physical Universe and have reached a technology level that allows us to detect each other, we could assume some of their characteristics in advance.
Continue reading

Polar Ring Galaxies Are Bizarre and Rare. Astronomers Just Found Two More

By Brian Koberlein - September 19, 2023 10:33 AM UTC | Extragalactic
Many galaxies resemble the Milky Way, with billions of stars organized into a rotating, rotating spiral. There are other irregular galaxies and giant elliptical galaxies with less defined structures, but one of the most bizarre types of galaxies is called "polar rings." In these galaxies, the central core is surrounded by a ring of gas and a star perpendicular to the central spiral disk. It's believed they're formed when a larger galaxy swallows a smaller one, extruding its stars into a ring. A recent survey revealed two previously unknown polar ring galaxies, which could be more common than previously believed.
Continue reading

An Ambitious New Technology Might be Needed to See Other Earths

By Brian Koberlein - September 18, 2023 02:23 PM UTC | Exoplanets
NASA and its partners are starting to develop plans for the Habitable Worlds Observatory flagship mission that's due to launch in the late 2030s or 2040s. Its primary goal will be to observe other Earth-sized worlds orbiting Sun-like stars within the habitable zone. To do this requires blocking the light from the star with an internal coronagraph and a separate starshield. A new paper suggests that NASA should consider a "photonic chronograph" that could be twice as effective in revealing faint planets beside bright stars.
Continue reading

The Milky Way's Disk is Warped. Is That Because our Dark Matter Halo is Tilted?

By Brian Koberlein - September 17, 2023 04:04 PM UTC | Milky Way
Astronomers have measured the Milky Way's shape and found that the disk is warped and not a flat spiral like many of the galaxies we see in the Universe. It was assumed a collision with another galaxy in the ancient past caused this warping. Observations have shown that the galactic stellar halo is tilted concerning the galactic plane, and a new theory proposes that the dark matter halo is tilted, too. This tilt might be torquing the galaxy, causing the warp that astronomers have observed.
Continue reading

A New Observatory Will Spot Core-Collapse Supernovae Before They Explode

By Brian Koberlein - September 17, 2023 08:33 AM UTC | Observing
Although we haven't had a supernova explode nearby in a few hundred years, it's just a matter of time before it happens. Astronomers want to be ready. The Jiangmen Underground Neutrino Observatory is being built in China and should be gathering its first data by the end of 2023. If all goes well, it can detect a burst of neutrinos coming from a core-collapse supernova before we can see the flash of radiation. As the star is imploding, energy piles up inside the star, but the neutrinos can freely escape, arriving seconds earlier than the radiation. It'll have a range of 3,000 light-years for pre-supernova neutrino detections and 1.2 million light-years for post-supernova detection.
Continue reading

A 2022 Gamma Ray Burst Was So Powerful, it was Detected by Spacecraft Across the Solar System

By Brian Koberlein - September 15, 2023 12:14 PM UTC | Solar Astronomy
Gamma-ray bursts are some of the most powerful explosions ever detected, emitting more radiation than the rest of their host galaxy combined. In October 2022, a gamma-ray burst struck the Solar System and interacted with the heliosphere. This set off charged particle detectors in spacecraft, from Mars to Earth, to the Earth-Sun L1 Lagrange Point. These separate detections allowed astronomers to track the motion of the radiation as it moved through the Solar System and allowed them to determine the location of the explosion.
Continue reading

If Neutron Stars Have Mountains, They Should Generate Gravitational Waves

By Brian Koberlein - September 14, 2023 12:03 PM UTC | Stars
Astronomers have discovered the gravitational waves released by colliding black holes, neutron stars, and even the background waves from merging supermassive black holes. A new paper proposes that advanced gravitational wave observatories might be able to detect the presence of "mountains" on spinning neutron stars. Although they're incredibly dense, neutron stars have layers, and as they cool, their solid crusts might deform into regions farther from the central core. This would create a wobble that would release gravitational waves.
Continue reading