Space News & Blog Articles

Gravitational wave astronomy has been one of the hottest new types of astronomy ever since the LIGO consortium officially detected the first gravitational wave (GW) back in 2016. Astronomers were excited about the number of new questions that could be answered using this sensing technique that had never been considered before. But a lot of the nuance of the GWs that LIGO and other detectors have found in the 90 gravitational wave candidates they have found since 2016 is lost. 

Researchers have a hard time determining which galaxy a gravitational wave comes from. But now, a new paper from researchers in the Netherlands has a strategy and developed some simulations that could help narrow down the search for the birthplace of GWs. To do so, they use another darling of astronomers everywhere—gravitational lensing.

Importantly, GWs are thought to be caused by merging black holes. These catastrophic events literally distort space-time to the point where their merger causes ripples in gravity itself. However, those signals are extraordinarily faint when they reach us—and they are often coming from billions of light-years away. 

Detectors like LIGO are explicitly designed to search for those signals, but it’s still tough to get a strong signal-to-noise ratio. Therefore, they’re also not particularly good at detailing where a particular GW signal comes from. They can generally say, “It came from that patch of sky over there,” but since “that patch of sky” could contain billions of galaxies, that doesn’t do much to narrow it down.

But astronomers lose a lot of context regarding what a GW can tell them about its originating galaxy if they don’t know what galaxy it came from. That’s where gravitational lensing comes in.

The TRAPPIST-1 solar system generated a swell of interest when it was observed several years ago. In 2016, astronomers using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) at La Silla Observatory in Chile detected two rocky planets orbiting the red dwarf star, which took the name TRAPPIST-1. Then, in 2017, a deeper analysis found another five rocky planets.

It was a remarkable discovery, especially because up to four of them could be the right distance from the star to have liquid water.

The TRAPPIST-1 system still gets a lot of scientific attention. Potential Earth-like planets in a star’s habitable zone are like magnets for planetary scientists.

Finding seven of them in one system is a unique scientific opportunity to examine all kinds of interlinked questions about exoplanet habitability. TRAPPIST-1 is a red dwarf, and one of the most prominent questions about exoplanet habitability concerns red dwarfs (M dwarfs.) Do these stars and their powerful flares drive the atmospheres away from their planets?

New research in the Planetary Science Journal examines atmospheric escape on the TRAPPIST-1 planets. Its title is “The Implications of Thermal Hydrodynamic Atmospheric Escape on the TRAPPIST-1 Planets.” Megan Gialluca, a graduate student in the Department of Astronomy and Astrobiology Program at the University of Washington, is the lead author.

I can remember when Perseverance was launched, travelled out into the Solar System and landed on Mars in February 2021.  In all the time since it arrived, having clocked up 1000 days of exploration, it has collected 23 samples from different geological areas within the Jezero Crater. The area was once home to an ancient lake and if there is anywhere on Mars to find evidence of ancient (fossilised) life, it is here. 

The date was 30 July 2020 when a gigantic Atlas V-541 rocket roared off the launchpad from Cape Canaveral in Florida. On board was the Perseverance rover, on its way to Mars. It arrived around 7 months later, entered the Martian atmosphere and successfully landed using a complex sequence of parachutes, retrorockets and for the first time, a sky crane to lower it from a hovering platform. Its chief purpose on Mars was to explore the geology, climate and atmospheric conditions as a precursor to human exploration. 

The landing site, the Jezero Crater, was chosen because previous orbital studies revealed clear evidence of an ancient lake that once filled the crater. It is thought that water is a key ingredient to the evolution of life so if there had been a body of water, then there is a greater chance of life evolving. Studying the rocks here is like taking a flick through the history books as it preserves signs of ancient life and also ancient environmental conditions. 

The crater had been formed, like the majority of other craters in the Solar System from some form of impact event. In the case of Jezero it was an asteroid impact around 4 billion years ago. On its arrival at the crater the floor was soon discovered to be made of igneous rock, formed from a huge underground chamber of magma and bought to the surface through volcanic activity. Since then, other types of rock from sand and mud were found providing evidence of the presence of water in Mars’ distant past. 

By the time Perseverance had hit the 1000 day anniversary of its exploration of the red planet it had collected the rock samples, safely packaged them up ready for collection and by and large, completed its exploration of the ancient lake bed. One sample in particular which has been called ‘Lefroy Bay’ has been found to contain fine grained silica. This material is commonly found on Earth and known to preserve fossils. Another of the samples contains phosphate which, on Earth is most definitely associated with biological processes. Both of these contain carbon which can be used to study the environmental conditions from when the rock formed. 

Back in the year 2000, Epsilon Eridani b was discovered. It is a Jupiter-like exoplanet 10.5 light years away but it has taken decades of observations to learn more about the planet. One thing that remains a mystery is it’s orbit which, until recently has been unknown. There has never been a direct image of the planet either, so now, it’s the turn of JWST to see what it can do. 

The concept of exoplanets has been around for a few decades now but the first confirmed discovery occurred in 1992. Astronomers at the Arecibo Observatory discovered a number of Earth-mass planets orbiting around the pulsar PSR B1257+12. Since then, over 5,000 planets have been discovered around other star systems. Astronomers use a number of Studying them once they have been confirmed requires more direct study.

One such exoplanet is known as Epsilon Eridani b which also goes by the name AEgir. Exoplanets are named after their host star (in this case Epsilon Eridani) and the letter ‘b’ designates that it was the first exoplanet discovered around that star. The next to be discovered would be ‘c’ and so on although in the case of Epsilon Eridani it is the only planet. It is thought to orbit around the star at a distance of 3.5 astronomical units (where 1 AU is the average distance between the Sun and Earth) and takes about 7.6 years to complete one orbit.  

One area of exoplanet study that has been lacking over recent years is the study of the surface and atmospheric conditions, in particular a study into their potential habitability. Cold exoplanets seem to have received the least study due to their faint appearance in the mid-infrared wavelength. Due to the properties of these cold planets, direct imaging techniques are required and must employ high contrast processes.  To date, no instrument has been capable of delivering. 

The crux of the challenge is that the cold exoplanets have no intrinsic energy source and only re-use the radiation from the host star. Their luminosity is based upon their size and distance from host star but usually the radiation is at the same wavelength as the emission from the star. To address this challenge, a paper has been published in ‘Astronomy & Astrophysics’ journal by a team led by C. Tschudi from the Institute for Particle Physics and Astrophysics in Switzerland.