Welcome to this week’s AITN Lite is concerning exoplanets, as did last week’s AITN bulletin. This Lite bulletin will discuss a “perfect” Solar System. The article in question can be found here:

https://www.bbc.co.uk/news/science-environment-67488931

Last week we discussed how the formation of a planet too large for its host star was a challenge to our understanding of planet formation. This week is at the other end of the scale. Our Solar System was a violent, chaotic place when it was forming. There were multiple planet-sized objects that slammed into other planets (such as how the moon was formed). As a result, we ended up with a vast range in size and mass of planets in our Solar System. The formation mechanism of Jupiter-sized planets is much different to that of Earth-sized planets.

The planetary system in this article is very uniform in comparison. There are 6 planets, all with a size that can be considered as sub-Neptune. These are theorised to be the most abundant planets in our Galaxy, with the 6 here about 2-3 times larger than Earth. In comparison, Neptune is 4 times larger than Earth. As the planets are all uniform in size, planet formation theories can be compared to this system. Along with this, the central star is very bright and as such, the atmospheres of these planets can be investigated to see if there is any sign of life!

Welcome to this week’s AITN Lite and, as usual, I’ve attempted to make a link between the full bulletin and this. week’s AITN discussed multiple JWST results one of which was Jupiter-sized objects in the Orion molecular cloud, whereas this will discuss ongoing star formation in that cloud. The article in question can be found here:

https://www.bbc.co.uk/news/science-environment-67243772

Star formation starts with a molecular cloud. The molecular cloud, consisting of gas and dust, is disrupted, causing a turbulent environment. This turbulence causes regions within the cloud to become denser, and gravity takes over causing them to collapse. These regions become even denser and hotter, and begin to spin, forming a disc. Eventually, the protostar (the forming star) begins to burn hydrogen in the form of nuclear fusion. The stellar wind of the star will then, eventually, blow away the molecular gas from which it formed, leaving the star to burn.

These images of HH212 display the part of the sequence around when the collapsing region begins to spin and form a disc and starts to burn hydrogen. When this happens, the forming star needs to conserve angular momentum, and the only way it can do this is by producing an outflow. This outflow will stop the forming star from ripping apart. The magnetic fields, that could be an important part of the formation process (this is still a very active area of research), form and force the material into these bi-polar outflows. This is what is seen in the image from the article. The outflows hit the ambient gas and causes these amazing bow shocks! Monitoring of this object over years has shown how it has changed over the decades, and since it’s a very young star (less than 50,000 years) there is noticeable change!

Welcome to this week’s AITN Lite and apologies for the lack of full bulletin last week. This AITN Lite will be linked to the last bulleting and Lite from a month or so and is discussing NASA sending a probe to an asteroid, which observations have suggested is made up of 60% iron and nickel. The article can be found here:

https://www.bbc.co.uk/news/science-environment-67099605

The destination asteroid is called 16 Psyche. It is a large asteroid at 175 miles across, and is located in the asteroid belt between Mars and Jupiter. As an M-type asteroid, it contains higher concentrations of iron and nickel than other asteroids and they are considered very rare, with less than 10 known to exist in the Solar System. The interest in these objects is that they are thought to have formed from the remnant cores of early protoplanets. Their outer layers, crust and mantles, were removed by collisions in the early Solar System when it was much more chaotic than it is now.

The Psyche mission, named obviously due to its destination, was launched in October of this year and is expected to reach 16 Psyche after a journey of 70 months. After this journey, it will spend 21 months in orbit. The most major of its science goals are to understand the building blocks of planetary formation, iron cores, and to explore these new metal worlds. Along with these scientific goals, of which you can find more information at this link , there are some technological goals. It is aiming to test ion propulsion as a method for traversing the Solar System, along with laser communications that could be up to 100 times more efficient by the current means.

Welcome to this week’s AITN Lite and we are talking about an article from quite a while ago. Last week’s AITN bulletin discussed the returning of a sample from an asteroid. This week is about an asteroid that is potentially hazardous to Earth. The article can be found here:

https://www.theguardian.com/science/2023/jan/24/space-dust-from-42bn-year-old-asteroid-could-hold-key-to-preventing-cataclysmic-collisions-with-earth

A sample was returned from the asteroid Itokawa and those particles were analysed. This asteroid is considered a rubble pile asteroid. They consist of reassembled fragments from larger asteroids that have collided and shattered. The gravitational pull of the constituent parts, made up of fragments of all sizes, keeps them. The analysis found that the Argon isotope ratio, which can be used as a dating technique, gave an age of 4.2 billion years.

This age is comparable with that of the Solar System itself, aged at 4.57 billion years. As such, over that time, it would have been subject to many collisions, and yet it has survived. Compared to a more solid, monolithic asteroid, this is a much longer timescale. These solid asteroids have a lifespan of hundreds of millions of years, a factor of 10 shorter. The conclusion that can be made from this is that these rubble pile asteroids are harder to destroy and, as such, are much more abundant in the Solar System than previously thought, and this may influence the way we would deflect one that was on a direct path towards Earth.

Welcome to this week’s AITN Lite and the first of the new academic year. As always, I try to link these to the previous week’s bulletin, and having picked three science stories last week, I had lots of choice. One of the JWST images highlighted last week was a planetary nebula from the death of a star. This week is about a planet that has survived the beginning of the death of its host star. The article can be found here:

https://www.bbc.co.uk/news/science-environment-66042269

The planet, 8 Ursae Minoris b, is orbiting a helium-burning red giant. A helium-burning red giant is formed when a main sequence star runs out of burning hydrogen, and the core contracts. This contraction leads to the expansion of the star, but gravitational collapse in the core will cause a hydrogen burning shell. This causes further stellar expansion, and once the hydrogen is exhausted, collapse occurs in the core and expansion of the star continues. This core contraction causes helium burning to begin. This expansion, in the case of the Sun, would expand to nearly Earth and, at the very least, engulf Mercury and Venus.

This is the fact that makes 8 Ursae Minoris b such an interesting planet. It has a relatively close orbit of 0.5 astronomical units (the distance between the Earth and the Sun; AU), but the expansion of the star should have taken this star out to 0.7 AU. The fact that the planet is still orbiting means that it can’t have been engulfed. An explanation that scientists have come up with is that this star was once a binary system. When the star has expanded, it has engulfed its companion star first. This companion star, a white dwarf that was burning helium, has allowed the helium burning to start in the red giant, and has stopped its expansion, given 8 Ursae Minoris b a reprieve!

Curriculum topics to be considered
Stellar life cycle

Welcome to this week’s AITN Lite! I know it’s a while since the last AITN bulletin, but that discussed the largest cosmic explosion. Here today we are going to discuss the brightest cosmic explosion, GRB221009A. The previously discussed accretion event has given off more energy, but this gamma-ray burst (GRB) has the brightest peak ever seen! The article can be found here:

https://www.theguardian.com/science/2023/mar/28/cosmic-explosion-last-year-may-be-brightest-ever-seen

GRBs are some of the most energetic events in the Universe, and there are two broad categories separated by the time that the burst exists for. Short GRBs are explosions that last for less than 2 seconds, with long GRBs lasting longer than that. Short GRBs are thought to occur from the merger of two small, dense objects such as neutron stars and black holes. However, longer GRBs, such as GRB221009A are unambiguously associated with the end of a high-mass star’s life since they are associated with regions of star formation. High-mass stars don’t live for very long, thus star-formation regions are usually still present when they die.

GRB221009A was first detected by the Fermi and Swift space-based gamma-ray telescopes. However, the flux was so bright that it saturated the detector! The follow-up of GRB221009A across multiple wavelengths, from the x-ray to the radio, along with looking at the emission spectra of previous gamma-ray bursts allowed them to determine it was the brightest ever observed! Since it was a long-duration gamma-ray burst, it is expected that this was the result of a massive star exploding and going supernova. However, the follow-up observations have yet to find evidence of the afterglow of a supernova. It is, therefore, possible that the star collapsed directly to a black hole, such as that discussed in AITN #27. Further follow-up observations are planned to truly determine what occurred in this exceptional object.

Curriculum topics to be considered
Stellar life cycle
Electromagnetic spectrum

Welcome to this week’s AITN Lite! As usual, I have tried to find a link between the full bulletin last week. The bulletin was about the jets launched from the central black hole in galaxies, and this week’s is about black holes, just not those in the centre of galaxies. To be specific, it is about the first dormant black hole unambiguously discovered in an extragalactic system. The article can be found here:

https://www.theguardian.com/science/2022/jul/18/first-dormant-black-hole-found-outside-the-milky-way

Massive stars preferentially form in binary or multiple systems. Stars with an initial mass between 8 and 16 solar masses have a multiplicity fraction of greater than 60%, which rises to 80% for masses more than 16. These massive stars end their lives in core-collapse supernovae. Stars that are initially more massive than 40 solar masses leave behind a black hole, and some even collapse straight into a black hole. However, when two massive stars are in a binary system, and one has exploded via supernova, you end up with a black hole orbiting a massive star.

In this system, VFTS 243, a 9 solar mass black hole is found orbiting a 25 solar mass star. VFTS243’s black hole was difficult to discover though since it is considered dormant. It is dormant as it does not have significant levels of x-ray emission, the usual method for detecting a black hole, which is emitted due to material accreting into it. A long observing program of the kinematics of the star left the authors with no other plausible scenario that there was a companion black hole.

Curriculum topics to be considered
Stellar life cycle

Welcome back to AITN Lite! It was hard to find a link to the last Astronomy in the News bulletin, so I have chosen the following story instead. This story is about a dwarf planet within our Solar System, Quaoar. The article can be found here:

https://www.theguardian.com/science/2023/feb/08/ring-discovered-around-dwarf-planet-quaoar-confounds-theories

Quaoar is a dwarf planet in the Kuiper Belt that is about half the size of Pluto. It has a moon, Weywot, which is thought to be a fragment of Quaoar that was ejected into orbit due to a collision event. However, the most striking feature of Quaoar is the recently discovered ring that surrounds the system. It is not unusual for planets or dwarf planets to have a ring, but this ring lies at a distance that is twice that should be capable of maintaining a stable ring.

The distance where the boundary between stable and unstable rings is called the Roche limit. Within this limit, the tidal forces from the central body will tear apart any object that attempts to form, causing a ring. Outside of this limit, the self-gravity of the objects in the ring will eventually allow coalescence and cause a moonlet.

As mentioned above, Quaoar shouldn’t have this ring as it should be coming together to form a moonlet, a process that is relatively quick on astronomical timescales, a matter of decades. The fact a ring exists, the authors of this study have postulated that the particles could be icy, which would cause elastic collisions, thus stopping the particles coming together to form the moonlet.

For further reading, a free version of the research article can be found here.

Welcome back to AITN Lite, and this week’s bulletin is about discovering ices and chemical species in interstellar clouds with the James Webb Space Telescope (JWST). This is linked to last week’s full bulletin by the new observations ongoing with the JWST. It is an article from this week, with the article discussed linked here:

https://www.bbc.co.uk/news/science-environment-64380397

Star formation occurs in the densest areas of molecular clouds, and one of the by-products of star formation is planet formation. When a planet forms, its molecular and elemental makeup are set by the species present in the molecular cloud from which it formed. Therefore, studying the formation of Earth is akin to palaeontology in that we are trying to discover what happened from what is left behind.

However, the advantage we have over “dinosaur detectives” is that we can look at the formation of other stellar and planetary systems and this is where JWST is very important. The presence of a spectrometer on the telescope allows the composition of the interstellar dust to be determined. By observing the molecular cloud Chameleon I, the ice grains within the dust can be detected by analysing the absorption features in the spectrum from the background stars. The ices detected included ¹³CO₂, OCN^–, ¹³CO, OCS and other complex organic molecules such as acetone, ethanol, and acetaldehyde. The existence of these species allows scientists to understand where the chemistry for life came from along with understanding how interstellar chemistry proceeds.

For further reading, a free version of the research paper can be found here:

https://arxiv.org/abs/2301.09140

Curriculum topics to be considered
Organic chemistry
Star formation

This week’s Lite bulletin is (admittedly tentatively) to the previous AITN bulletin in that it discusses other objects in the Solar System, beyond planets and moons, but that’s the end of the link! It is an article from April about the largest comet ever discovered, with the article discussed linked here:

https://www.bbc.co.uk/news/science-environment-61097826

This comet, thankfully, won’t cause any concern for Earth (since it won’t get within a billion miles of us at its closest approach, however, it is a behemoth. This comet is 85 miles across and is 50 times larger than usual, weighing in at a mass of 500 trillion tonnes (5 x10¹⁴ kg). Now this mass doesn’t compare to that of Earth or the Moon (6 x10²⁴ kg and 7 x10²² kg, respectively) but it is still very large.

The discovery of this object, and its size, was confirmed using the Hubble Space Telescope, but it was initially observed by the Dark Energy Survey, a survey that is trying to observe galaxies to determine the nature of dark energy in the Universe. This survey would also pick up near-by objects, and this comet would have left a trail on the images, indicating something close and fast moving, relative to the Earth!

As alluded to above, comets are different to asteroids, mainly due to the presence of an atmosphere surrounding the central body (nucleus). This nucleus, made of rock, dust, ice and other frozen molecules, is surrounded by a very thin atmosphere. When the comet makes its way towards the Sun, this atmosphere is heated by the radiation pressure of the star, causing a “coma” or tail (which points away from the Sun) and this is what makes comets look so spectacular in the sky. This tail is made up of water and dust.