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Graduate student Carla Anderson successfully completed her Masters research project under the guidance of Prof. Matt Redman of the Centre for Astronomy. Carla investigated the end phases of stellar evolution, specifically the somewhat confusingly named "planetary nebulae". These objects are vast expanding shells of ionized gas that are shed by red giant stars towards the end of their life. They are called "planetary nebulae" because in observations with the earliest telescopes in the 18th century they appeared as small round disks and so astronomers thought that they could be related to planets.  In her research work Carla tackled the difficult question why there are many different morphologies of such nebulae, in particular some of these objects are very asymmetric. For this purpose she investigated the hypothesis that planetary nebulae might actually be shaped not just by the central star but also by planets that exist around these dying suns. As the planets get engulfed they interact with the ionized gas in a complex way, breaking spherical symmetry. A schematic sketch to illustrate the full evolution of an exoplanet orbiting a starfrom the Main Sequence to the Planetary Nebula phase. During the RGB phase, the tidal force and stellar wind change the orbit of the planet. This exoplanet is engulfed on the AGB and imparts its angular momentum into the star’s envelope, changing the morphology of the PN.   Carla used the latest statistics of detected exoplanet systems and the state of the art code SIMSPLASH developed at the Centre for Astronomy by former members Laura Boyle and Nicola Keaveney. The simulation code takes into account many of the star-planet system’s parameters and calculates whether or not and at what point in time the exoplanet is engulfed based on their tidal evolution and the star’s mass-loss. Carla did not just update the simulation code and the exoplanet statistics, but also included many new scenarios, especially exoplanet systems in binary stars. A major result of her thesis is the diagram below that shows how many exoplanet systems get engulfed by the central star during the final phases of its evolution. Carla's results suggest that too few of the existing exoplanet systems will eventually be engulfed on the AGB by their dying star to explain the many asymmetric planetary nebulae discovered to date. Future updates to the simulations, including more complex 3 body problems, as well as observations with the James Webb Space Telescope might allow to investigate this hypothesis further.We congratulate Carla to finishing this amazing piece of research work and wish her all the best for her future career.

This information will enhance our ability to detect and characterise the cosmic gravitational wave background, a key prediction of Einstein’s Theory of General Relativity. University of Galway astronomers along with collaborators in the European Pulsar Timing Array consortium have just published in the journal Astronomy & Astrophysics the most in-depth study yet of how the solar wind affects the perfect clock-like beat of radio pulses detected from distant pulsars. Understanding how the space weather associated with the Sun distorts these time signals is critical in being able to detect the subtle underlying variations in space-time associated with the cosmic gravitational wave background. These waves permeate the cosmos and are believed to originate from innumerable supermassive black hole binary systems in the centres of distant galaxies, stirring up ripples in space-time as they orbit one another, which spread away like waves on a pond, flexing and bending space and time as they wash over us day and night. These distortions are so unimaginably small they don’t affect us or our daily lives. The only way to detect and study them is to use the Galaxy as a laboratory bench and the collapsed remnants of exploding stars called pulsars scattered nearby us. These pulsars – collapsed stars the size of Galway Bay – spin tens to hundreds of times a second with a precision better than the best atomic clocks, yielding lighthouse beams of radio emission whose beats are easily detected with radio telescopes. By combining the observations of radio telescopes across the world, astronomers can analyse individual pulsar pulse streams to identify the subtle signatures of underlying gravitational wave ripples. To do that requires understanding and removing the effects of ‘static’ in the form of the tenuous plasma that is present in deep space, but also the plasma constantly radiated away from the Sun, also known as the solar wind. The latter has always been a particular problem given the variability of ‘space weather’ around our nearest star. However, new work by Sai Chaitanya Susarla, an astronomy PhD researcher in University of Galway’s School of Natural Sciences Physics Unit, has yielded a methodology that can limit the distortions to these pulsar signals caused by the Sun’s ambient plasma, significantly improving our ability to detect and characterise the cosmic gravitational wave background, by studying the clock patterns of several radio pulsars that pass by the Sun on its annual journey on the ecliptic plane along the Zodiac.  Sai Chaitanya Susarla said: “I am very happy to see this work finally published, it formed the basis of my doctoral studies here at the University of Galway and will be incredibly valuable for the scientific community in being able detect and characterise gravitational waves using pulsar timing arrays. It is also demonstrating a way to use radio observations of pulsars to remotely study the Sun’s environment, which may be very useful for other scientists in trying to understand the basis of space weather and its impact on our home planet” Dr Aaron Golden, School of Natural Sciences, College of Science and Engineering, University of Galway and Sai Chaitanya Susarla’s co-PhD supervisor, said: “This is a tremendous result for Sai and for the School of Natural Sciences, highlighting the huge impact our young researchers are making in the fundamental sciences, as well as in rethinking what we mean by our ‘planetary health’ from a solar system perspective. Sai’s work provides a new means of monitoring our Sun and to identify how solar storms form and evolve - this will add to our understanding on how the most powerful of such storms affect our planet.”  University of Galway alumnus Professor Evan Keane, Associate Professor of Radio Astronomy in Trinity College Dublin’s School of Physics, Head of the Irish LOFAR Telescope and co-PhD supervisor, added: “This is an excellent example of how low frequency radio astronomy using facilities such as the I-LOFAR telescope in Birr can contribute to basic and applied scientific research - not only do we have a more precise means of understanding the cosmos at the most fundamental level, but also a new technique that could ultimately contribute towards an ‘early warning’ system for space weather. Auroras are pretty to look at, but really powerful displays are associated with colossal ground induced currents that can shred power infrastructure. Hopefully Sai’s work can help build a better picture of what the warning signs of such events might be.”    Read the full paper here; published in the professional research journal Astronomy & Astrophysics.

The INAM 2024 took place in Galway on August 29th and 30th. The meeting showcased the wide range of scientific topics that astronomers all across Ireland are working on. We saw an exciting program with 35 invited and contributed talks as well as more than 20 posters with a total number of 80 participants. With the recent 6 year anniversary of the Republic of Ireland joining the European Southern Observatory we heard talks in a special ESO session. ESOs current and future facilities were highlighted by Bruno Leibundgut the current program scientist for the Very Large Telescope in the Chilean Atacama desert. Great craic was had during the public talk of Leo Enright, highlighting astronomical science in Ireland from Newgrange to the Moon and the following night out in the pub in town. With an unusually collaborative sunny weather streak, Galway presented itself from its best side for a successful INAM. The INAM was organized and run with the help of the amazing undergrad students from the Astronomy Student Society in Galway.

While astronomers have discovered many thousand planets around distant stars, they have yet to find a system that closely resembles our own solar system, with rocky planets in the habitable zone and large gas giants in the outer system. The systems that were found instead show an enormous diversity, with rocky planets on orbits that takes them all the way around their star in only a few days, or super-Jupiters that are so far away from the system center that one orbit takes them hundreds of years. One major field in modern astronomy is to try and figure out why so many different planetary systems form around stars. The answer to that tells us how common systems like our own solar system are in the Galaxy, a key question toward our understanding how much life might be out there. Using the largest ground based telescopes from the European Southern Observatory in Chile astronomers at the Centre for Astronomy in Galway are imaging the birth places of planets around young stars. These are huge dust and gas rich disks. Recently a large survey of such planet-forming disks was completed and published in a series of three scientific papers in the journal Astronomy & Astrophysics. This survey program was lead by Dr. Christian Ginski from the Centre for Astronomy. Hear Dr. Ginski talk about the survey results here. These exciting new results were also featured by a press release of the European Southern Observatory as well as in the Irish national news at 6. By studying the birth places of planets we can find out how planets begin to form and what influences the formation of planetary systems. These are images of dusty disks around young stars that are hundreds of light years away from Earth. These disks are seen in near-infrared light. Beautiful ring and spiral structures indicate that planets have already started forming. These disks are 10s to 100s of astronomical units in diameter, but so far away from us that they are only as large as a pint glass in Galway as seen from the nearby town of Tuam some 40 km away (image credit: ESO/C. Ginski).  

Join Dr. Ray Butler on the News at 6 to learn more about the upcoming solar eclipse.