Ices with JWST

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

Largest Comet Ever Discovered

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.

DART Success

Welcome back to the first Lite bulletin since the half-term break. As I have discussed previously, I am going to attempt to link the previous week’s bulletin to this. Last week I discussed Near Earth Objects (NEO) around our planet and one such object that will cross the orbit of Earth (as we are on the other side!). This week I will be, again, discussing DART (Double Asteroid Redirection Test) collision with the asteroid moon Dimorphos which is orbiting the asteroid Didymos.

The two articles I will be discussing are:

https://www.bbc.co.uk/news/science-environment-63221577

https://www.theguardian.com/science/2022/oct/11/nasa-dart-spacecraft-asteroid-successful

I have talked about DART in bulletin #24, along with the second Lite topic. The outline of the mission is to test Planetary Defence systems. The Planetary Defence process is designed to protect Earth from a collision with a NEO, as a result, DART was collided with an asteroid moon (Dimorphos) with the goal of deflecting its orbit.

The collision was successful, and the next step was to make follow-up observations to determine whether the orbit was altered, hence if the mission was a success. Any alterations would be determined by timing the orbital period of Dimorphos, which was originally 11 hours 55 minutes. The new timings were found to be 11 hours 23 minutes, a change of 32 minutes. This is considered a success since the predictions were for a change of 10 minutes. Since this was a test of Earth defences, this has been demonstrated to be a viable method for deflecting an Earth-bound object.

Scientists are also interested in these results for research purposes since the amount of deflection that has occurred to Dimorphos will say something about its internal composition, and they can now test the models they have produced to work this out.

Curriculum topics to be considered
Orbital physics, such as circular motion and Kepler’s Laws
Conservation of momentum

How often is Mars hit?

As mentioned in the Lite bulletin released two weeks ago, I will endeavour to make a link between this and the previous Astronomy in the News bulletin. This week I will be discussing a result from a study on the planet Mars. In the AITN news bulletin last week (#44), I discussed the potential for life on the planet. Here I will be discussing the following article:

https://www.theguardian.com/science/2022/sep/19/meteoroid-shock-waves-help-scientists-locate-new-craters-on-mars

(If you follow the link through, there is a free version of the research paper although I don’t know how long that will last!)

This article discusses some results from the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission. I discussed this mission in Astronomy in the News #14. The goal of InSight is to use the onboard seismometer to measure marsquakes (seismic events) on the planet to determine the 3D structure of the interior. By doing so, astronomers can determine the early geological activity on Mars, and constrain formation models of the terrestrial planets within the Solar System.

One of the other results from the mission is to determine how many times Mars is hit by meteoroids. The impact from the space rock would cause the seismometer to measure a marsquake. However, such is the sensitivity of the instruments on board, it was able to detect 3 events. The first was when the meteoroid entered the atmosphere, producing a shock wave that “tipped” the instrument. The second occurred when it exploded into multiple objects, and the third was the impact on the surface. The measurements from InSight pinpointed a rough location for the impact crater, and this was confirmed by comparing before and after images of the surface.

This is valuable data for the InSight mission since all seismic events are not marsquakes, and by highlighting which are and are not seismic events helps their models. Another potential consequence of these data are that they can work towards determining the impact rate on the surface of Mars. The number of impact craters on a surface, such as the Moon, are used as a geological clock.

Curriculum topics to be considered
Propagation of sound waves

DART makes a direct hit

Every week in Astronomy in the News Lite, I will attempt to make a link between this and the previous full bulletin by choosing an article that from a similar scientific topic. This week, I will be looking at the DART (Double Asteroid Redirection Test) collision with the asteroid moon Dimorphos which is orbiting the asteroid Didymos.

There are a number of articles I will be discussing today which are linked below:

https://www.theguardian.com/science/2022/sep/25/nasas-dart-probe-to-smash-into-asteroid-in-first-earth-defence-test

https://www.bbc.co.uk/news/science-environment-63039191

https://www.theguardian.com/science/2022/sep/26/nasa-spacecraft-asteroid-crash-planetary-defense-test

https://www.theguardian.com/science/2022/sep/29/nasa-planetary-defense-test-images

I previously discussed this mission in the AITN bulletin #24. The outline of the mission is to test Planetary Defence systems. The Planetary Defence process is designed to protect Earth from a collision with a Near Earth Object (NEO). After detecting and characterising any potentially hazardous NEOs, if one is on a collision course with Earth, a deflection mission would be launched. This is where DART comes into it. DART, as mentioned above, was collided with an asteroid moon (Dimorphos) with the goal of deflecting its orbit. The collision aspect of the mission was successful with a “direct hit” reported, as evidenced by the images released by NASA!

HST and JWST images of the collision of DART and Dimorphos. Credit: ESA/JWST

The next step to this project is to make some follow-up observations over the next few weeks to determine if and by how much the orbit of Dimorphos has changed. The smaller body is about 160km across and, prior to the collision, had a orbital period of 11.92 hours. If the mission went as expected, the new orbital period should be 11.75 hours.

Curriculum topics to be considered
Orbital physics, such as circular motion and Kepler’s Laws
Conservation of momentum

Furthest galaxy ever discovered?

The first AITN Lite will be a follow-up to last week’s bulletin about the first images coming from the James Webb Space Telescope (JWST). Last week, we discussed the spectacular images from the new facility, but this week we will discuss some of the possible science results that come from these initial images.

The article that I will be discussing is:

https://www.bbc.co.uk/news/science-environment-62311562

and a free, permanent research link to the paper that it refers to can be found here:

https://arxiv.org/abs/2207.12356

I have discussed in the Astronomy in the News bulletins #06 and #26 that the JWST will be detecting the earliest galaxies in the Universe by identifying the light from the first stars that were formed after the Big Bang. Simulations of galaxy formation show that star formation should begin 150-250 million years after the Big Bang, which would correspond to redshifts of z = 15-20.

To identify redshifts of galaxies, two different techniques are used, photometric and spectroscopic. The detections in this article correspond to photometric observations, which I will discuss here. Multiple observations are made of the galaxy at different wavelengths, and a model spectral energy distribution is fit to these measured points. This fit would then reveal the wavelengths at which the Lyman and Balmer breaks occur at (the links should give you more information!).

Using this method, the team here have identified a galaxy at a redshift of 16.7, or just 235 million years after the Big Bang. This detection will be followed up spectroscopically, also using JWST, to determine a more accurate redshift for this galaxy and confirm whether this is a good estimate. The JWST is, however, the perfect facility to make these extremely high redshift detections of galaxies as it operates in the infrared wavelength regime. At the redshifts in question, the Lyman and Balmer breaks would be in the infrared, as the higher the redshift, the redder an optical line will appear!

Curriculum topics to be considered
Electron orbits (Lyman and Balmer series come from this!)
Red shift

Welcome to AITN Lite

Welcome to Astronomy in the News Lite. This will be a complementary service to the regular Astronomy in the News bulletins. The two services will both be fortnightly, alternating between them but there is also the scope for special releases at any time! AITN Lite will give a brief description of a news story from the world of Astronomy, with some key facts, and some of the topics from the curriculums that you can look at in conjunction with it. It may highlight older stories that didn’t feature in an Astronomy in the News bulletin due to time pressures, and my research when I, or one of my colleagues publishes a paper!

I hope you enjoy this new service, and continue to subscribe to Astronomy in the News, and I cannot wait to share the exciting results from the world of astronomy with you.