Category Astronomy/Space

Thick Lithosphere casts doubt on Plate Tectonics in Venus’s geologically recent past

An image of Mead Crater
Mead crater, the largest impact basin on Venus, is encircled by two rocky rings, which provide valuable information about the planet’s lithosphere. Credit: NASA

At some point between 300 million and 1 billion years ago, a large cosmic object smashed into the planet Venus, leaving a crater more than 170 miles in diameter. A team of Brown University researchers has used that ancient impact scar to explore the possibility that Venus once had Earth-like plate tectonics.

For a study published in Nature Astronomy, the researchers used computer models to recreate the impact that carved out Mead crater, Venus’s largest impact basin. Mead is surrounded by two clifflike faults — rocky ripples frozen in time after the basin-forming impact...

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How Heavy is Dark Matter? Scientists radically narrow the potential mass range for the first time

Credit: Greg Rakozy on Unsplash

Scientists have calculated the mass range for Dark Matter – and it’s tighter than the science world thought. Their findings – due to be published in Physics Letters B in March – radically narrow the range of potential masses for Dark Matter particles, and help to focus the search for future Dark Matter-hunters. The University of Sussex researchers used the established fact that gravity acts on Dark Matter just as it acts on the visible universe to work out the lower and upper limits of Dark Matter’s mass.

The results show that Dark Matter cannot be either ‘ultra-light’ or ‘super-heavy’, as some have theorised, unless an as-yet undiscovered force also acts upon it.

The team used the assumption that the only force acting on Dark Matter is gravity, an...

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New Galaxy Sheds Light on How Stars Form

Image of galaxies
A tidal dwarf galaxy (blue) and a spiral galaxy (greyscale). The Milky Way is an example of a spiral galaxy. (Created from images taken by the Hubble Space Telescope and ALMA.)

A lot is known about galaxies. We know, for instance, that the stars within them are shaped from a blend of old star dust and molecules suspended in gas. What remains a mystery, however, is the process that leads to these simple elements being pulled together to form a new star.

But now an international team of scientists, including astrophysicists from the University of Bath in the UK and the National Astronomical Observatory (OAN) in Madrid, Spain have taken a significant step towards understanding how a galaxy’s gaseous content becomes organised into a new generation of stars.

Their findings have import...

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When Galaxies Collide: Models suggest galactic collisions can starve massive black holes

Eight dark squares, each with a chaotic orange shape
Galaxies collide. Visualizations of the dynamic model simulating two different scenarios. The top row shows a collision reducing core activity, the bottom row shows a collision increasing it. © 2021 Miki et al.

It was previously thought that collisions between galaxies would necessarily add to the activity of the massive black holes at their centers. However, researchers have performed the most accurate simulations of a range of collision scenarios and have found that some collisions can reduce the activity of their central black holes. The reason is that certain head-on collisions may in fact clear the galactic nuclei of the matter which would otherwise fuel the black holes contained within.

When you think about gargantuan phenomena such as the collision of galaxies, it might be t...

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