Next week’s night sky:
On Thursday, the golden handle appears on the moon. The “Golden Handle” effect is produced by the way the slanted sunlight lights up the prominent mountains of the moon. Best seen through some sort of magnification, the golden handle will appear as a small line trailing from the light side of the moon to the dark side.
How do we detect invisible dark matter?
Dark matter neither absorbs nor gives off light, which is why astronomers have named it dark. But because dark matter has mass, it does interact with normal matter via gravity. This causes an effect called gravitational lensing. This occurs when light from a distant background object passes near a massive object, whose gravity bends it. On Earth, we see that the background object’s image appears distorted. Based on the image we see, astronomers can calculate the amount and distribution of mass it took to create the distortion.
Astronomers can then color the images based on the distortion, leading to “pictures” of dark matter.
A Magnetic Star
When stars collide, the result is often explosive. That’s especially true when those objects are a pair of super dense stellar remnants known as neutron stars. The fireworks show, called a kilonova, unleashes more energy than the Sun will produce during its 10-billion-year lifetime.
Before Hubble, scientists believed that the most likely outcome of two neutron stars merging was a black hole.
However, new evidence shows that the merging could have instead created a magnetar!
Before this, scientists believed that a neutron star merger formed an unstable, heavy neutron star that only lasted for a handful of milliseconds before collapsing into a black hole. But a black hole wouldn’t explain the extra energy Hubble saw during this kilonova. However, a magnetar would create the perfect storm of energy!
In order to know for certain, astronomers will have to keep their eyes trained on this area of the sky. If a magnetar really is lighting it up, then, within a few years, the ejected material from the burst will begin appearing in radio wavelengths.
To learn more, go here: https://arxiv.org/pdf/2008.08593.pdf
Is radioactivity the key to habitability?
As it turns out, organic material, liquid water, sunlight and possibly, a large moon might not be enough to ensure an exoplanet’s habitability. It also may depend in part on whether enough long-lived radioactive elements are present in the planet’s deep interior.
That’s because the radioactive decay of uranium and thorium produce the heat needed to power plate tectonics and volcanism, driving convection in a planet’s molten metallic core. That convection, in turn, creates an internal dynamo in Earth’s interior that produces a protective magnetic field, shielding the surface from the harmful effects of solar radiation.
Astronomers found radiogenic heating is too high, a dynamo cannot be sustained indefinitely because most of the thorium and uranium will end up in the mantle, producing enough heat to make the mantle act as an insulator. That, in turn, would prevent a molten core from losing heat fast enough to generate the convection required for a magnetic field. It also could trigger rampant volcanism and frequent mass extinction events. Conversely, too little radiogenic heating in the core results in a geologically dead planet.
By checking for radioactivity, astronomers will be able to more accurately assess if a planet is habitable or not. To learn more, go here: Radiogenic Heating and Its Influence on Rocky Planet Dynamos and Habitability
Do you have any cool astronomy research news from this week? Share it in the comments below!