21st Century Telescopes
The sky is huge we can observe it in many ways, optical, x-rays and gamma rays for example. To have greater observation, you need big telescopes.
The world’s largest is in the Canaries, for example, and it has produced some amazing images – for example, one galaxy ‘eating’ into another. Or you can see small galaxies cartwheeling through a bigger one.
Visible light is not enough to look at in modern telescopes. Need to ‘see’ much more. Infrared, for example, can see through stellar clouds that can block our view. She mentions the James Webb Telescope, which produces so many superb images in optical and infrared. It was able to see things that it was not possible to see before.
These telescopes have helped us with Exo Solar planets. We also have powerful radio telescopes on the ground, like the green bank telescope in the USA. China has the FAST telescope, which is huge, and producing amazing images.
Today, telescope arrays are used to increase resolution. There is the VLA, the very large array. We see a lot more detail when we observe with arrays. There is ALMA, which has taken images of newborn starts. When we send telescopes to space, we can view at even greater resolution. In space you cannot use a normal telescope.
Also, x-rays can be observed from space-based telescopes, but not from the ground. She talked about the Fermi Large Area Telescope, which measures high energy photons. Blue optical light from particles travelling at light speed through the atmosphere can be observed.
The Milky Way can, thus, be observed in very high energy gamma rays. Dr Masha Chernyakova talks about new collaborations where telescopes in the northern and southern hemisphere will be linked.
How Stars and Planets form
Prof Turlough Downes said he is a theoretical scientist. He said we can start by saying that stars and planets exist, as we can see them in the sky. Pretty much everywhere we look up, we see planets orbiting stars. Stars form in molecular clouds, which are cold and dense.
At the start they form a disk-shaped object in these clouds. We have no idea how planets form, he said, but we do know how stars form. We can use telescopes to look more closely now at disks. They are beautiful.
A protostar needs material to fall in there to drive nuclear fusion, which is at the heart of any star. Gas and dust can orbit around a protostar forever. In order to get onto the star, the material has to orbit more quickly. That happens when material density in the disk around the star is unevenly distributed. This can explain how a star forms, but not a planet.
We don’t know how planet formation works. This is exciting. We need to remove the angular momentum to allow material to fall into a star. We don’t know how that happens. We need more data and better observations about how these disks behave to understand all of this.
Journey to a Black Hole
The talk began with a scientific explanation of what a Black Hole is, and what kind of things can be expected to happen near one of them.
Prof Abraham Harte talked about the ‘escape velocity’ necessary to escape the gravitational pull from a Black Hole. He talked about compression of the Sun. He said that our Sun would have to be compressed to the size of about half of north Dublin city to turn it into a Black Hole.
He talked about how a star dies and collapses in on itself to produce a Black Hole. Gravity is driving this process. A Black Hole then is an object whose gravitational field allows nothing, not even light, to escape, he said. There is a Black Hole at the centre of our galaxy, and scientists believe, at the centre of all galaxies.
He talked about what would happen to a spacecraft if it got near to a Black Hole. In one scenario, at a certain distance, it orbits irregularly but doesn’t fall in. In other case, when the craft gets too close, it will fall in.
Black holes bend light, and the trajectories of big objects, like planets. He talked about the movie Interstellar, which depicts a realistic Black Hole. Black holes can rotate and that also influences what is around them, he said. He showed the recent images taken of the Black Hole at the Centre of the Milky way, and another galaxy.
The Search for Alien Worlds
Citizen Scientists can take part in the search for alien worlds, Dr Oisin Creaner said. He talked about a project called Star Guide, where everyone, even those with a small telescope, can join in the search.
He talked about the history of the search for alien worlds, and the discovery of the first exoplanet outside our Solar System. He talked about how the technology and techniques that scientists use to enable alien worlds to be found. How the transit of a planet in front of a Star can reveal its presence to observers.
Most of the exoplanets that have been discovered, to date, have been discovered by the ‘transit method’. It’s possible to determine how heavy a planet is from observations too.
Then scientists can guess what a planet is made from, Dr Creaner said, whether that is a solid or a gas, for example. Some exoplanets are easier to see than others, for example, big planets that orbit small stars more rapidly.
That causes a lot of dimming of the star when the planet transits in front of it, which can be more easily picked up by astronomers. On Earth oxygen is produced by living things, and we can search for its presence on exoplanets via telescopes.
It is cheaper to use a lot of private telescopes together scattered around the world, than to take up the time of expensive telescopes, when looking for exoplanet transits.
There is, he said, always a distortion effect of the atmosphere when using ground-based telescopes. There are scientific tools that can correct this distortion. The idea is that anti-distortion calculations will be done for the amateur astronomers to make it easier for them.