Space News & Blog Articles

Look through the names and origins of the constellations and you will soon realise that many cultures had a hand in their conceptualisation. Among them are the Egyptians who were fantastic astronomers. The movement of the sky played a vital role in ancient Egypt including the development of the 365 day year and the 24 hour day. Like many other cultures they say the Sun, Moon and planets as gods. Surprisingly though, the bright Milky Way seems not to have played a vital role. Some new research suggests that this may not be the case and it may have been a manifestation of the sky goddess Nut! 

It’s a fairly well accepted theory that the pyramids of Egypt were constructed in some way as a representation of or tribute to the sky. The Sun god Ra was often depicted sailing the Sun across the sky in a boat but the Milky Way was never seemed to be a big part, other than perhaps some consideration that the river Nile could represent it. 

Back in the days of ancient Egypt, light pollution really wasn’t a thing. The Milky Way would have been far more prominent than for many stargazers today. A recent study by astrophysicists at the University of Portsmouth suggest that a lesser heard god by the name of Nut had something to do with it. 

Hunt through Egyptian artwork and you will often see a star-filled woman arched over another person. The woman is Nut, the goddess of the sky and the other figure represents her brother, the god of Earth, Geb. Nut has a very specific job though, she protects the Earth from being flooded from waters of the void! Presumably this would be the void of space but of course back then we didn’t have such a great understanding of the cosmos. She also swallowed the Sun as it sets, giving birth to it again in the morning. 

Thankfully the Egyptians were fabulous at recording things and so there have been plenty of Egyptian texts to refer to. Running simulations from the evidence in the documents, the team (led by Dr Or Graur Associate Professor in Astrophysics) suggest that the Milky Way represented Nut’s outstretched arms in the winter and her backbone in the summer. This suggestion aligns with the broad patterns in the Milky Way. 

In 2011, astronomers with the Wide Angle Search for Planets (WASP) consortium detected a gas giant orbiting very close to a Sun-like (G-type) star about 700 light-years away. This planet is known as WASP-39b (aka. “Bocaprins”), one of many “hot Jupiters” discovered in recent decades that orbits its star at a distance of less than 5% the distance between the Earth and the Sun (0.05 AU). In 2022, shortly after the James Webb Space Telescope (JWST) it became the first exoplanet to have carbon dioxide and sulfur dioxide detected in its atmosphere.

Alas, researchers have not constrained all of WASP-39b’s crucial details (particularly its size) based on the planet’s light curves, as observed by Webb. which is holding up more precise data analyses. In a new study led by the Max Planck Institute for Solar System Research (MPS), an international team has shown a way to overcome this obstacle. They argue that considering a parent star’s magnetic field, the true size of an exoplanet in orbit can be determined. These findings are likely to significantly impact the rapidly expanding field of exoplanet study and characterization.

The study was led by Dr. Nadiia M. Kostogryz and her fellow researchers from the MPS. They were joined by astronomers and astrophysicists from the Center for Astronomy (Heidelberg University), the Astrophysics Group at Keele University, the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT), and the Space Telescope Science Institute (STScI). The paper describing their research, “Magnetic origin of the discrepancy between stellar limb-darkening models and observations,” was recently published in Nature Astronomy.

The “hot Jupiter” exoplanet WASP-69b orbits its star so closely that its atmosphere is being blown into space. Credit: Adam Makarenko/W. M. Keck Observatory

A light curve is the measurement of a star’s brightness over longer periods. Using the Transit Method (Transit Photometry), astronomers monitor stars for periodic dips in brightness, which can result from an exoplanet passing (transiting) in front of their face relative to the observer. In addition to being the most widely used method for detecting exoplanets, precise observations of light curves allow astronomers to estimate the size and orbital period of the exoplanets.

An international research team led by the University of Vienna has made a major breakthrough. In a study recently published in Nature Astronomy, they describe how they conducted the first direct measurements of stellar wind in three Sun-like star systems. Using X-ray emission data obtained by the ESA’s X-ray Multi-Mirror-Newton (XMM-Newton) of these stars’ “astrospheres,” they measured the mass loss rate of these stars via stellar winds. The study of how stars and planets co-evolve could assist in the search for life while also helping astronomers predict the future evolution of our Solar System.

The research was led by Kristina G. Kislyakova, a Senior Scientist with the Department of Astrophysics at the University of Vienna, the deputy head of the Star and Planet Formation group, and the lead coordinator of the ERASMUS+ program. She was joined by other astrophysicists from the University of Vienna, the Laboratoire Atmosphères, Milieux, Observations Spatiales (LAMOS) at the Sorbonne University, the University of Leicester, and the Johns Hopkins University Applied Physics Laboratory (JHUAPL).

Astrospheres are the analogs of our Solar System’s heliosphere, the outermost atmospheric layer of our Sun, composed of hot plasma pushed by solar winds into the interstellar medium (ISM). These winds drive many processes that cause planetary atmospheres to be lost to space (aka. atmospheric mass loss). Assuming a planet’s atmosphere is regularly replenished and/or has a protective magnetosphere, these winds can be the deciding factor between a planet becoming habitable or a lifeless ball of rock.

Logarithmic scale of the Solar System, Heliosphere, and Interstellar Medium (ISM). Credit: NASA-JPL

While stellar winds mainly comprise protons, electrons, and alpha particles, they also contain trace amounts of heavy ions and atomic nuclei, such as carbon, nitrogen, oxygen, silicon, and even iron. Despite their importance to stellar and planetary evolution, the winds of Sun-like stars are notoriously difficult to constrain. However, these heavier ions are known to capture electrons from neutral hydrogen that permeates the ISM, resulting in X-ray emissions. Using data from the XXM-Newton mission, Kislyakova and her team detected these emissions from other stars.

One of the big mysteries about dark matter particles is whether they interact with each other. We still don’t know the exact nature of what dark matter is. Some models argue that dark matter only interacts gravitationally, but many more posit that dark matter particles can collide with each other, clump together, and even decay into particles we can see. If that’s the case, then objects with particularly strong gravitational fields such as black holes, neutron stars, and white dwarfs might capture and concentrate dark matter. This could in turn affect how these objects appear. As a case in point, a recent study looks at the interplay between dark matter and neutron stars.

Neutron stars are made of the most dense matter in the cosmos. Their powerful gravitational fields could trap dark matter and unlike black holes, any radiation from dark matter won’t be trapped behind an event horizon. So neutron stars are a perfect candidate for studying dark matter models. For this study, the team looked at how much dark matter a neutron star could capture, and how the decay of interacting dark matter particles would affect its temperature.

The details depend on which specific dark matter model you use. Rather than addressing variant models, the team looked at broad properties. Specifically, they focused on how dark matter and baryons (protons and neutrons) might interact, and whether that would cause dark matter to be trapped. Sure enough, for the range of possible baryon-dark matter interactions, neutron stars can capture dark matter.

The team then went on to look at how dark matter thermalization could occur. In other words, as dark matter is captured it should release heat energy into the neutron star through collisions and dark matter annihilation. Over time the dark matter and neutron star should reach a thermal equilibrium. The rate at which this occurs depends on how strongly particles interact, the so-called scattering cross-section. The team found that thermal equilibrium is reached fairly quickly. For simple scalar models of dark matter, equilibrium can be reached within 10,000 years. For vector models of dark matter, equilibrium can happen in just a year. Regardless of the model, neutron stars can reach thermal equilibrium in a cosmic blink of an eye.

If this model is correct, then dark matter could play a measurable role in the evolution of neutron stars. We could, for example, identify the presence of dark matter by observing neutron stars that are warmer than expected. Or perhaps even distinguish different dark matter models by the overall spectrum of neutron stars.