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.