Image ©Pearson Education
Galactic halos – comprising of the theorized dark matter halo– show an interesting characteristic in the constant nature of their volume density.
Galaxies come in all shapes and sizes with the most common and well-studied being similar to our Milky way galaxy and known as disc or spiral galaxies. A well-known problem in physics is the observed rotation velocities of stars with respect to the distance from their galactic centre. These rotation curves, as they are known, intriguingly do not appear as expected – that is they appear flat instead of falling off and decreasing with distance. Read more here.
In the cold dark matter model of the universe these flat rotation curves are attributed to dark matter, hence the name ‘dark matter’ haloes.
In an effort to better understand this, scientists have been comparing the...
A star that formed at the time of the early universe has just been identified, and its unique characteristics may reveal new insights to star formation.
Stars are theorized to have formed in the collapsing dust of a nebulae, with the star forming in the centre of rotation and the planets forming in the corresponding protostellar disk. It has also been hypothesized that low-mass stars and brown dwarfs could also be formed from gravitational instabilities in the extended protostellar disc. Computer simulations to explore this idea suggest such a possibility. However, as yet they have been unable to run the simulations long enough to verify that the fragments would survive disk migration. Now the discovery of a very old star may just be able to prove that they would survive.
In a paper recently published in the Astrophysical Journal, a team led by Kevin Schlaufman report the discovery of a...
Of all the science-fiction-sounding names that have come to fruition in recent years, perhaps none is as mysterious or seemingly fictitious as time crystals. The name evokes something between Back to the Future and Donnie Darko, and the reality is perhaps crazier than either.
Two separate groups of scientists recently reported that they observed time crystals, which lends credence to the idea that this theoretical state of matter is something humans can actually create and observe. And indeed, time crystals can be grown in a child’s bedroom.
However, it requires nuclear sensors and lasers to help time crystals reach their full potential and then measure and observe them. This combination of dramatic scientific terms and shockingly simple objects is a great analogy for time crystals as a whole.
Read on to understand what they are and how they might affect our lives.
Planet formation is not yet understood and to complicate matters Mercury is an anomaly – now a new ambitious mission hopes to resolve the mysteries and shed light on planet formation.
Planets and stars are theorized to have formed in the collapsing dust of a nebulae, with the star forming in the centre of rotation and the planets forming in the corresponding disk. The planetary characteristics are thus thought to be dependent on their size and distance from the central star. For example, gaseous planets – such as Jupiter, Saturn, Uranus and Neptune – are believed to have first formed as rocky planets and it was their greater size and position that allowed them to accrete and maintain a gaseous envelope.
However, although not completely understood (read more here), this understanding is based on the observed and inferred characteristics of the planets. However,...
The universe as we currently understand it may not be allowed to exist – at least according to the cosmological model of string theorists.
To understand the behavior and evolution of the universe, cosmological models provide a mathematical description capable of making validated predictions. Current models are based on Einstein’s general relativity and assume a ‘flat’ universe – that is a universe that appears flat on large scales. Within this framework the geometry of the universe can then be described as a closed ‘de Sitter’ universe or open ‘anti-de Sitter’ universe.
Observations show that the universe is expanding at an ever so-slightly increasing rate and that as it expands the vacuum energy remains constant. The best cosmological model to describe such a universe is an inflation model which occurs in a quasi-de Sitter universe...
Relativistic jets synonymous with black holes have been observed in a highly magnetized neutron star for the first time – putting current theories into question!
We see jets of ionized matter in all types of astrophysical objects from the plasma jets seen emanating from the surface of stars like our Sun (read more here) to the relativistic jets emanating from black holes. The energy of these jets and relativistic nature depends on the nature of the object and the location of the jet formation – with the most prominent generally emanating from the polar regions as extended beams along the axis of rotation.
However, although these jets are observed in some neutron stars, they have never been observed in highly magnetized neutron stars. This phenomenon has previously led theorists to conclude that magnetic fields inhibit their formation. Subsequent theories suggested that...
General relativity tells us that light will be affected by gravity. This so-called bending of spacetime has now just been observed in the warped light of a star orbiting the Milky Way’s very own super massive black hole (SMBH) - Sagittarius A*.
The bending of light due to the presence of a massive object - where the massive object is blocking its path and refocusing it, like a lens – is known as gravitational lensing. The light will be traveling at a constant speed along curved space – the medium or path has therefore not changed, and so no energy is lost. However, if the photon of electromagnetic radiation moves away from the curved path then energy will be lost, and the wavelength will be increased – this is known as gravitational redshift.
Utilizing infrared observations made at the Very Large Telescope in Chile, astronomers were able to follow a group of high...