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How astronomers observe the distant reaches of the universe

2019 Fleming Medal recipient Dan Falk leads panel discussion on dark matter, exoplanets, extraterrestrial life
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Modern astronomy methods are used to study phenomena from planet formation to spiral galaxies. PHOTO COURTESY OF HANSEN JIANG/ASTRONOMY AND SPACE EXPLORATION SOCIETY
Modern astronomy methods are used to study phenomena from planet formation to spiral galaxies. PHOTO COURTESY OF HANSEN JIANG/ASTRONOMY AND SPACE EXPLORATION SOCIETY

How do astronomers study celestial objects millions of miles away? The Astronomy and Space Exploration Society explored this question during a panel hosted on November 27 looking at the current observational methods of astronomy.

Audience members of all ages filed into Cody Hall that evening as a panel of four graduate students faced them, eager to share their knowledge. Award-winning science journalist Dan Falk moderated the event and guided the discussion as the night progressed.

The four panellists each come from diverse areas of research. Taylor Kutra, a second-year graduate student, studies the processes and environments in which planet formation occurs. Alysa Obertas, a fifth-year graduate student, studies the orbital dynamics of compact solar systems.

Third-year graduate student Emily Deibert focuses on ground-based observational methods of studying exoplanet atmospheres. Finally, Colleen Gilhuly, a fourth-year graduate student, studies spiral galaxies and their formation with Dragonfly, a telescope array, which is being operated on in New Mexico by researchers from U of T and Yale University.

Exoplanets: what do we know and how?

Falk began the discussion by asking what astronomers currently know about exoplanets and what still remains a mystery. 

Deibert acknowledged the bias in current exoplanet discovery methods, claiming that most discovered exoplanets are ‘Hot Jupiters’ ⁠— massive Jupiter-sized planets that orbit relatively close to their host stars. This does not occur as a result of them being the most common, but rather because they are the easiest type of exoplanet to detect. 

Instead, Kutra estimates that the most common exoplanets are ‘Super Earths’ — planets between the size of Earth and Neptune.

However, Kutra explained that exoplanet formation is still a mystery due to the problem of dust coagulation. She explained that it’s difficult for dust to coagulate due to the metre barrier problem, which is when a metre-sized proto-planet faces a headwind, slowing the coagulated rocky matter, causing it to fall into the star. 

Similarly, Falk raised another mystery: how is it possible to study planets that are not in our solar system at all? The panel remarked that this involves techniques like looking at the spectrum of exoplanets in order to determine what types of gases and features are present. In fact, Deibert observes the “fingerprints” of molecules that can only be resolved by large ground-based telescopes with high resolutions. 

Kutra also noted that we do not have the most common types of exoplanets in our solar system, which exacerbates the difficulty of understanding them.

Among such difficulties, it has become an interdisciplinary objective for both planetary and exoplanetary scientists to unravel the mysteries of planet formation.

Dark matter and extraterrestrial life

As the discussion turned to dark matter, Gilhuly described the U of T-led Dragonfly telephoto array, which aims to find the true nature of dark matter and its upshot for galaxy formation.

Large telescopes usually cannot sustain lenses because they tend to deform under their own weight. However, Dragonfly has sustained a massive lens with nano-structured coating that changes the material’s refractive index and reduces light scatter. This is favourable to observe bodies that are large and faint, like ultra-diffuse galaxies. 

After the guided portion of the discussion, Falk opened up the floor to questions. Immediately, a young boy shot his hand up and asked, “Are black holes dark matter?” inciting laughter amongst the audience. Surprisingly, the answer was somewhat complicated, as black holes are in some ways dark matter, but may only account for 10 per cent of the dark matter in the Milky Way. Thus, there must be something else accounting for the other 90 per cent.

Several other questions centred on the topic of extraterrestrial life, particularly whether exoplanets could possibly support life. Kutra acknowledged that hospitable atmospheres are essential for complicated molecules to form — it is a necessary but insufficient condition. Obertas further elaborated that there is an evolutionary element to extraterrestrial life.

It may be that the evolution of life follows a completely different course, with different foundational elements. Furthermore, we may not even be able to recognize extraterrestrial life because of how different their make-up is to our own.

Disclosure: Haya Sardar is the Secretary of the Astronomy and Space Exploration Society and Emily Deibert has previously written with The Varsity.