Hubble anniversary !

May 2023 marked the 33rd anniversary of the launch of the iconic Hubble Space Telescope. When the telescope launched, its life expectancy was only ~15 years, so it has definitely gone "beyond plus ultra". To celebrate, ESA/NASA released a new Hubble image of the close star-forming region NGC 1333, 960 light-years away. 

JWST: protoclusters

One of the main goals of the James Webb Space Telescope is to observe the early universe, allowing us to understand how the first ever stars and galaxies formed and evolved. The term protocluster is used for galaxy clusters at very high redshifts, such as galaxies grouped together in an era in which contains few known galaxies (i.e., shortly after the big bang).

I spoke a little bit about the JWST image of Pandora's Cluster in my February recap. Pandora's Cluster is a huge cluster of galaxies 4 billion light-years away from us. Morishita et al used JWST data to analyse the spectra of some galaxies in Pandora's Cluster. They found that there is a group of galaxies at approximately the same redshift, suggesting that they were part of a protocluster, making it the most distant protocluster we've ever seen! 

JWST: exoplanet GJ1214B

Exoplanet GJ1214B is one of the most studied and well documented exoplanets in astronomy. It was only the second "super Earth" to ever have its radius and mass measured. It's smaller than the gas giants (i.e., Jupiter), but not as dense as the rocky planets (i.e., Earth), putting it somewhere in between Earth and Neptune. Such a planet does not exist in our Solar System, which is why it's so interesting!

GJ1214B orbits a red dwarf (much smaller and cooler than our Sun) 47 light-years away. It passes in front of its host star every ~1.5 days, allowing us to snatch details about the planet (from its transit curves) fairly often. Astronomers have wondered about GJ1214B's atmosphere for some time now – is it similar to ours, or totally different? An instrument onboard JWST known as MIRI (Mid-Infrared Instrument) has the ability to (finally) probe into the planet's atmosphere. Kempton et al used MIRI to do exactly that by taking what is known as a "phase curve" of GJ1214B. They found that GJ1214B is extremely metal-rich – the planets harbours lots of elements heavier than hydrogen such as oxygen, carbon, and methane. There were spectra dips at particular wavelengths (5 - 9 microns) of electromagnetic radiation – wavelengths which indicate that there is (probably) water on its surface :O. The paper thus suggests that GJ1214B is a water world surrounded by a hydrogen-helium atmosphere, which is again nothing like we have in our Solar System. The albedo (reflectivity) of GJ1214B is also the highest ever observed in an exoplanet; this means that the clouds on the planet are comprised of particles which reflect light super efficiently.

JWST: exoplanet GJ 486b

Another JWST exoplanet observation! GJ 486b is actually super similar to GJ1214B – it's orbiting a red dwarf star with a period of ~1.5 days, but the radius of the planet is a lot closer to Earth's (~1.3 x Earth radii). However, the planet weighs in at ~ 3 x Earth mass, making it an incredibly dense planet.

If this planet has an atmosphere, it could potentially support life. This is the question astrophysicists are trying to answer with the JWST data from this exoplanet (and many other exoplanets). Moran et al concluded that a water-based atmosphere fits the data best, but there is some confusion within the exoplanet community as GJ 486b is super close to its host star. The planet is therefore very hot (~700K / 426 celsius) and so technically shouldn't be able to harbour a watery atmosphere. JWST is currently collecting more data from the region, which will hopefully help in building a more complete story down the line.

published: 07/06/23 by kaan evcimen