Periodic Reporting for period 4 - BEBOP (Binaries Escorted By Orbiting Planets)
Período documentado: 2023-05-01 hasta 2024-10-31
In the past two decades, thousands of planets have been detected in orbit around nearby stars. Their many properties, architectures and configurations is allowing to compare our solar system to all other planetary systems and find out how typical, or atypical the formation of planets within the solar system was. While we have improved our understand of the physical processes behind planet formation there are still many questions than answered. The main reason for this is that exoplanetary research is still quite recent, but also because we have identified systems very different from what was anticipated, and it is difficult to explain how varied planetary systems are, including our own.
One approach to enhance our understand of planet formation is to gain somewhat control on the many properties that affect planet formation. One way to do this is to look at circumbinary planets. Those are planets that have two suns in orbit of another, at the centre of the system, rather than just one. This strange and unusual configuration was not thought to be possible until 10 years ago. Having two stars at the centre of the system affects how the dust and the gas that eventually create to planets moves, which in turn affects how planets are created from it. It was thought that the presence of two stars would disturb the dust too much, preventing it from accumulating into a planet. Yet circumbinary exist, and therefore there is something we do not fully understand behind planet formation, but particularly on how dust accumulates to make planets.
Understanding how those strange planets managed to be created will tell us which physical processes are the most important behind the formation of planets. Our hope that once we know that, we will also get to know better how planet form around single stars like the Sun, and therefore complete the story about our Earth came to be, and the story of the origin of life.
The goal of the project is to increase how well we know circumbinary planets, and therefore investigate planetary formation. The only forward to detect new circumbinary planets (only two handfuls are known at this stage), which we have been doing in the past two and half years and which is set to continue.
By the end of the project novel methods of data analysis have been released which demonstrated how circumbinary exoplanets can be detected using ground-based telescopes. We also detected three planets with these methods and currently have eight serious other candidates that are being prepared for publication. Our results suggest that circumbinary planets are less massive than planets orbiting single stars, a fact that was unknown before starting this project. This made our work harder, but also showed that the initial hypothesis, that a binary star affects the outcome of planet formation is actually valid. We now need to quantify by how much and in which setting is planet formation affect so it can be compared to models and thus gain some physical understanding about planet formation at large. Some methods also improve how well we know stars which will have implications for many other parts of astrophysics.
One approach to enhance our understand of planet formation is to gain somewhat control on the many properties that affect planet formation. One way to do this is to look at circumbinary planets. Those are planets that have two suns in orbit of another, at the centre of the system, rather than just one. This strange and unusual configuration was not thought to be possible until 10 years ago. Having two stars at the centre of the system affects how the dust and the gas that eventually create to planets moves, which in turn affects how planets are created from it. It was thought that the presence of two stars would disturb the dust too much, preventing it from accumulating into a planet. Yet circumbinary exist, and therefore there is something we do not fully understand behind planet formation, but particularly on how dust accumulates to make planets.
Understanding how those strange planets managed to be created will tell us which physical processes are the most important behind the formation of planets. Our hope that once we know that, we will also get to know better how planet form around single stars like the Sun, and therefore complete the story about our Earth came to be, and the story of the origin of life.
The goal of the project is to increase how well we know circumbinary planets, and therefore investigate planetary formation. The only forward to detect new circumbinary planets (only two handfuls are known at this stage), which we have been doing in the past two and half years and which is set to continue.
By the end of the project novel methods of data analysis have been released which demonstrated how circumbinary exoplanets can be detected using ground-based telescopes. We also detected three planets with these methods and currently have eight serious other candidates that are being prepared for publication. Our results suggest that circumbinary planets are less massive than planets orbiting single stars, a fact that was unknown before starting this project. This made our work harder, but also showed that the initial hypothesis, that a binary star affects the outcome of planet formation is actually valid. We now need to quantify by how much and in which setting is planet formation affect so it can be compared to models and thus gain some physical understanding about planet formation at large. Some methods also improve how well we know stars which will have implications for many other parts of astrophysics.
The main objective was to collect data on nearby binary stars and start the search for planets orbiting them. Data access was the most important objective fulfilled by the project thus far. We had to apply to various observatories and we won competitions that award time to the most interesting astronomical projects. The second, also very important achievement was to identify our first candidate exoplanets, and well as show that indeed, circumbinary planets can be detected using regular telescopes (all have so far been identified using space telescopes). While this work is not public yet, we have detected for the first circumbinary planets using ground-based telescopes. We did this in northern hemisphere using the most recognised detection method: radial velocities. We have also done that in the Southern Hemisphere. In addition, we made the first detection of a transit, when the planet passes in front of one of the two stars, using a telescope in Antarctica.
Meanwhile, we have also participated in multiple investigations that discovered planets orbiting single stars. The reason we are engaged in such activities, is because we wish to compare the properties of circumbinary planets to the properties of planets orbiting single stars. For instance we wish to know whether they have the same typical masses, the same orbital periods etc, or whether they are distinct. Each similarity and difference will be used to refine the theory of planet formation.
In addition, we have worked in refining what we know about the binary stars we target themselves. Doing so, our most important discovery thus far is that of a rare pair of stars called brown dwarfs, that orbiting one another and eclipse one another. This configuration allowed to measure their mass and radius. In addition, we could know their luminosity and age and as such were able to refine theoretical developments made in the 1990s and that had remained mostly unvalidated by data since then.
We communicate these results regularly at scientific conferences, but also communicate our results to the public in various events, some to schools, some of groups of adults.
Our main results were:
1 - the first detection of a circumbinary planet using the radial-velocity method
2 - the first discovery of a circumbinary planet using a ground based telescope
3 - the first detections of transits of circumbinary planets using ground based telescope
4 - the first detection of a circumbinary planet orbiting a double-lined binary
5 - still under review, the first detection of a polar circumbinary planet
6 - circumbinary planets close to their binary tend to be low mass and have large radii
7 - there is a large previously unknown population of long period, Saturn-mass circumbinary planets. Very few circumbinary planets have masses greater than twice that of Jupiter.
8 - the first detection of the phase curve of a low mass ratio binary, with applications to exoplanet atmospheres
9 - a new method to measure the absolute mass of stars
10 - the discovery of a rare pair of eclipsing brown dwarfs (still one of only two known)
11 - a new protocol to identify whether a planet is likely to host liquid water at its surface
Meanwhile, we have also participated in multiple investigations that discovered planets orbiting single stars. The reason we are engaged in such activities, is because we wish to compare the properties of circumbinary planets to the properties of planets orbiting single stars. For instance we wish to know whether they have the same typical masses, the same orbital periods etc, or whether they are distinct. Each similarity and difference will be used to refine the theory of planet formation.
In addition, we have worked in refining what we know about the binary stars we target themselves. Doing so, our most important discovery thus far is that of a rare pair of stars called brown dwarfs, that orbiting one another and eclipse one another. This configuration allowed to measure their mass and radius. In addition, we could know their luminosity and age and as such were able to refine theoretical developments made in the 1990s and that had remained mostly unvalidated by data since then.
We communicate these results regularly at scientific conferences, but also communicate our results to the public in various events, some to schools, some of groups of adults.
Our main results were:
1 - the first detection of a circumbinary planet using the radial-velocity method
2 - the first discovery of a circumbinary planet using a ground based telescope
3 - the first detections of transits of circumbinary planets using ground based telescope
4 - the first detection of a circumbinary planet orbiting a double-lined binary
5 - still under review, the first detection of a polar circumbinary planet
6 - circumbinary planets close to their binary tend to be low mass and have large radii
7 - there is a large previously unknown population of long period, Saturn-mass circumbinary planets. Very few circumbinary planets have masses greater than twice that of Jupiter.
8 - the first detection of the phase curve of a low mass ratio binary, with applications to exoplanet atmospheres
9 - a new method to measure the absolute mass of stars
10 - the discovery of a rare pair of eclipsing brown dwarfs (still one of only two known)
11 - a new protocol to identify whether a planet is likely to host liquid water at its surface
The project advanced the state of the art by demonstrating how to detect circumbinary planets in single and double lined binary systems. The project also successfully conducted an all sky radial-velocity monitoring of over 100 binaries identifying 9 new planets (one published, eight remaining to be published). These results inform our interpreation that close-in circumbinary planets are low mass and large radius and that planets more massive than twice Jupiter's mass are particularly rare, while they are fairly frequent in single star settings.
Results from this project will continue to be published for the next year or two as there is enough data to do so. Their interpretation also needs to be formalised.
The project created a legacy and an excitement about circumbinary planets, which is represented in regular talks and high impact publications.
Results from this project will continue to be published for the next year or two as there is enough data to do so. Their interpretation also needs to be formalised.
The project created a legacy and an excitement about circumbinary planets, which is represented in regular talks and high impact publications.