Posted on by Paul M. Sutter

Is the Hubble constant not…Constant?

Image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. Credit: Millennium Simulation Project. Now, the latest FLAMINGO simulation provide more detail about the evolution of the Universe within these structures.
Image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. Who knows how many other civilizations might be out there? Credit: Millennium Simulation Project

Cosmologists have been struggling to understand an apparent tension in their measurements of the present-day expansion rate of the universe, known as the Hubble constant. Observations of the early cosmos – mostly the cosmic microwave background – point to a significantly lower Hubble constant than the value obtained through observations of the late universe, primarily from supernovae. A team of astronomers have dug into the data to find that one possible way to relieve this tension is to allow for the Hubble constant to paradoxically evolve with time. This result could point to either new physics…or just a misunderstanding of the data.

“The point is that there seems to be a tension between the larger values for late universe observations and lower values for early universe observation,” said Enrico Rinaldi, a research fellow in the University of Michigan Department of Physics and coauthor on the study. “The question we asked in this paper is: What if the Hubble constant is not constant? What if it actually changes?”

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Posted on by Paul M. Sutter

Hydroxyl (OH) Seen for the First Time in an Exoplanet Atmosphere

Artist's concept of a hot Jupiter exoplanet orbiting a star similar to tau Boötes (Image used with permission of David Aguilar, Harvard-Smithsonian Center for Astrophysics)

The molecule hydroxyl (HO) is common on Earth, but astronomers have not yet determined how abundant it is on other worlds. For the first time, astronomers have conclusively detected it in the atmosphere of an ultra-hot Jupiter, WASP-33b.

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Posted on by Paul M. Sutter

Exploding Stars are Titanium Factories

Titanium, shaded in blue, superimposed on observations of the supernova Cas A. Image credit: Chandra: NASA/CXC/RIKEN/T. Sato et al.; NuSTAR: NASA/NuSTAR; Hubble: NASA/STScI

If you’re a fan of titanium, you should head to the nearest supernova. You’ll get more than enough of it. And its presence can help astronomers understand how supernovae work.

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Posted on by Paul M. Sutter

Astronomers see a Rare “Double Quasar” in a Pair of Merging Galaxies

Artist's conception of a double quasar. Image credit: ASA, ESA, Joseph Olmsted (STScI)

What’s better than a quasar? That’s right, two quasars. Astronomers have spotted for the first time two rare double-quasars, and the results show us the dynamic, messy consequences of galaxy formation.

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Posted on by Paul M. Sutter

Starlink and OneWeb Have Their First Avoidance Maneuver With Each Other’s Constellations

Two companies, OneWeb and SpaceX, are racing to put fleets of thousands of communication satellites into orbit. In March they had their first near-miss. Avoidance maneuvers were successful, but how many more close calls will they face in the future?

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Posted on by Paul M. Sutter

How can White Dwarfs Produce Such Powerful Magnetic Fields?

Illustration of the internal layers of a white dwarf star. Credit: University of Warwick/Mark Garlick

White dwarfs have some surprisingly strong magnetic fields, and one team of astronomers may have finally found the reason why. When they cool, they can activate a dynamo mechanism similar to what powers the Earth’s magnetic field.

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Posted on by Paul M. Sutter

Both Uranus and Neptune Have Really Bizarre Magnetic Fields

These composite images show Uranian auroras, which scientists caught glimpses of through the Hubble in 2011. In the left image, you can clearly see how the aurora stands high above the planet's denser atmosphere. These photos combine Hubble pictures made in UV and visible light by Hubble with photos of Uranus' disk from the Voyager 2 and a third image of the rings from the Gemini Observatory in Hawaii and Chile. The auroras are located close to the planet's north magnetic pole, making these northern lights. Credit: NASA, ESA, and L. Lamy (Observatory of Paris, CNRS, CNES)

The magnetic fields of Uranus and Neptune are really, seriously messed up. And we don’t know why.

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