JWST's image of Uranus

James Webb Space Telescope has taken yet another stunning image of a planet in our Solar System (above). Uranus is a gassy planet and is the seventh planet from the Sun, taking 84 years to complete a single orbit. It's quite a unique planet as it rotates on its side at roughly a 90-degree angle from the plane of its orbit. This causes extreme seasons as the planet's poles experiences many years of constant sunlight followed by an equal number of years of complete darkness.

On the right side of the image, there’s an area of brightening at the pole facing the Sun known as a polar cap. This "polar cap" is unique to Uranus – it seems to appear when the pole enters direct sunlight in the summer and vanishes in the fall. It's hoped that JWST data will help scientists understand the mysteries behind this mechanism. At the edge of the polar cap lies a bright cloud as well as a second very bright cloud at the planet’s left limb. Such clouds are typical for Uranus in infrared wavelengths, and likely are linked to stormy activity. The planet has 13 known rings and 11 of them are visible in this released Webb image. Scientists expect that future Webb images of Uranus will reveal the two faint outer rings that were discovered with the Hubble Space Telescope during the 2007 ring-plane crossing.

An ejected supermassive black hole?!

A paper published in April claims to have spotted a supermassive black hole (SMBH) which has escaped from the centre of its galaxy! This was a completely serendipitous discovery that was found in an image taken by the Hubble Space Telescope for a project focussed on dwarf galaxies which seemingly contain no dark matter. In the images collected for the project, van Dokkum et al spotted a strange long, thin feature (as seen in Figure 1 of the paper). 

There are a couple of questions to ask when faced with an unidentified object such as the one spotted. 1) is it actually a real object (i.e., is it just an artefact of some sorts)? and 2) how far away is this weird thing you've found? We can eliminate the possibility of the first option by taking a look at other images of the object taken in different wavelength bands. The second point is important as if we're capturing a distant background object, effects such as gravitational lensing could explain any oddities.

After comprehensively studying the image, van Dokkum et al determined the object to be at the same distance as a galaxy nearby by comparing redshifts, associating the object with the galaxy itself. From the images, they determined that the most likely explanation to be something ejecting from the galaxy, leaving a trail in its wake. The question now is – what is this mysterious object?

A way to go about answering this question would be to look at the object's emission spectra. Van Dokkum et al noticed that, from the emission spectra, a super high energy process must be taking place nearby the object – one such as accretion from a black hole. They suggest a scenario where two galaxies in the past merged together, causing their black holes to orbit one another. X amount of years later, a third galaxy comes along with its own black hole, causing all of the black holes to be ejected from the system. This hypotheses is also backed up by the fact that we cannot actually see a black hole at the centre of the galaxy, although this could just be down to dust obstruction and/or resolution deficiencies. 

The brightest gamma ray burst, ever!

Gamma ray bursts are incredibly energetic bursts of radiation observed in distant galaxies, lasting anywhere between a few milliseconds to hours. Just to put things into context – these bursts can give out more energy in the space of a few milliseconds than the Sun does in its entire life!

We think that these gamma ray bursts occur from supernovae (explosions which take place when massive stars die). Williams et al discovered a gamma ray burst, dubbed GRB221009A, which was more than 10 times (!) brighter than any other gamma ray burst previously detected by the instrument used to measure it (the Swift Observatory). It was so bright that it completely saturated/blinded the instruments on the telescope! Studying the afterglow of GRB221009A led to some confusion, as none of the theories/models we currently have fit the observations of the afterglow. Proof that GRB221009A is the BOAT (brightest of all time): here, courtesy of Burns et al.

Scientists have also used JWST to study the afterglow of GRB221009A, making it the first gamma ray burst to be observed by the fancy new telescope.

Protoplanetary discs in Orion

Protoplanetary discs are discs formed around very young stars (protostars) where planetary formation takes place – my undergraduate research project at Cambridge heavily involved analysis of these discs :) Using the Very Large Array (VLA) and the Atacama Large Millimetre/sub-millimetre Array (ALMA), astronomers have been able to capture images of 328 new protoplanetary disks around protostars in the Orion Molecular Clouds, a giant star-forming region approximately 1,400 light-years from Earth in the constellation Orion.

Partial penumbral lunar eclipse and more shooting stars

On the 8th of May, in the eastern hemisphere, there'll be a "partial penumbral lunar eclipse"! I touched on solar eclipses in my March 23' article – this happens when the Moon passes in between the Sun and the Earth. A lunar eclipse occurs when the Earth passes in between the Sun and the Moon, causing the Earth to cast a shadow on the Moon's surface. It is "partial" as the Moon doesn't fully pass into the Earth's shadow; it passes through the outer part of Earth's shadow – known as the "penumbra".

The southern hemisphere is where you'll be able to best observe the peak of the Eta Aquariid meteor shower, taking place on the 5th/6th of May. This particular meteor shower is happening due to the Earth passing through the leftover debris of Halley's Comet, which is next expected to approach Earth on the 27th of July 2061.

Happy May, everyone! :) This year is flying by!

I think that May is my favourite month of the year. It's the heart of spring - my favourite season. Flowers and trees bloom and all look so beautiful, the weather gets warmer, the skies clear, and it's also my birth month!

I've never actually done anything special for my birthday, at least in recent memory. My last 6 or so birthdays have fallen during exam season, so I've just studied during them while promising myself that I'll celebrate my birthday later in the year to make up for it. Naturally, I always ended up breaking those promises I made to myself. I'm not too sure why, but I've kinda always associated my birthday with sadness. Maybe I was just using my studies as an excuse to avoid the reality of it all. Anyways, I hope that I'll be able to break that cycle and finally make less sad memories on my (22nd) birthday this year :)

published: 01/05/23 by kaan evcimen