## Project Gallery 2023

Secondary students from across Europe became exoplanet detectives with ESA and used Cheops satellite data to uncover the mysteries of two exoplanet targets: KELT-3b and TOI-560c.

Explore the projects below.

**C/2022 E3 ZTF**

Best Project Prize Winner

Gymnázium Na Vítězné pláni Prague – Prague Czech Republic 18 years old, 17 years old 2 / 2

**TOI-560c**

**TOI-560c**

TOI-560c project description:

We are two teenagers in High school and we decided to join the Prague Hackathon because we both are interested in astronomy and space, and this looked like a really nice project and a good opportunity.

The Hackathon took place in the Prague Planetarium and lasted 24 hours during which we were analyzing data about exoplanet TOI-560 c. We made hypotheses, searched for more data about the exoplanet and counted and verified our hypotheses. There were twelve teams from the whole Czech Republic and organizers who were prepared to help us.

TOI-560c Results and Analysis

We were investigating basic facts about exoplanet TOI-560 c such as radius, density, distance from its star, etc.

After we knew more about the exoplanet we focused on the question of whether or not there could be life on it. We were investigating if TOI-560 c could maintain an atmosphere if it had one. And we also focused on characteristics of its star, for example, its luminosity and spectral flux to find out more about the conditions on the planet.

It was an exciting experience and we would like to present our journey and conclusions in the paragraphs below.

The first five calculations were obligatory tasks, others we made up ourselves.

Transit depth

In the beginning, we received data with percentage values of light coming from the star TOI-560 during the exoplanet’s transit recorded by the Cheops satellite. Using the parameters of the planet’s radius and mid-transit time (we already knew the star radius) we created an approximate luminosity decay curve in the Allesfitter program. This also gave us the approximate radius of the exoplanet. The program evaluated our curve and determined how accurate we were and we got a real value to compare. As a result we saw that our estimate of the transit depth had 2,6% deflection from Allesfitter. The program also gave us some more information such as the orbital period. (The Light curve and histograms are attached in the file #1 and #2.)

Radius

We used transit depth to count the planet’s radius. The result of this calculation gave us a radius of 15,679.25137 kilometers. (The entire calculation is attached in file #3.)

Orbital period

The next task was to answer the question of when the next transit of the planet around its star will occur. For this calculation, we assumed that 23 January at 13:12 when Cheops observed TOI-560 was the start of the transit. Since the orbital period lasts 18.8797 days we calculated that the next transit will happen on Friday 23 June at 14:06 which is exactly 12.0376 days from the date we made the calculations (Sunday 11 June).

Orbital distance

To calculate the orbital distance of TOI-560 c from its star we used a formula that was based on Kepler’s third law. You can find this formula and the whole calculation process attached in the fourth file. The result of the calculation gave us a distance of 3,586,728,628 km.

Liquid water

After this, we focused on the questions of temperature, liquid water and habitability of the exoplanet. We had information that the temperature was 225 ± 15°C. Water is liquid between 0°C and 100°C, depending on the atmospheric pressure. We searched on Google for a graph of the state of water as a function of pressure and temperature and we found out that the pressure had to be at least 1 MPa for the water to be liquid. On Earth, we have 1MPa pressure at a depth of 91.89 meters (including atmospheric pressure) and at 102.24 meters (without atmospheric pressure). Also, our atmospheric pressure is 101,300 Pa with a gravitation constant of 9.81. If TOI-560 c had the same atmosphere as the Earth, atmospheric pressure would be 163,464 Pa due to its 1.62 times stronger gravitation. This we calculated using the radius and the mass of the planet (the mass was specified in the instructions). From the calculation (file #5), we concluded that the atmosphere of TOI-560 c would have to be 6.12 times larger or denser than the Earth’s atmosphere in order to have water in liquid form.

Volume and density

The last obligatory task was to calculate the density of TOI-560 c. We used the formula ρ=M/V. We already knew that the mass of the planet was approximately 9.70 * the mass of the Earth. But we didn’t know the volume. We used a simple formula which assumes that the planet is perfectly round – 4/3*π*R3. So we knew the volume is 1.6146 * 1023 km3. Then we calculated that the density was 3.587786, which is 1.5 times smaller than the density of Earth (5.51). But it is more than two times bigger than the density of Neptune. From that, we can conclude that TOI-560 c isn’t a gas planet, but also isn’t from heavy material. Its density is similar to the density of Mars (3.93) so it’s possible that it has a similar structure as Mars. (Calculations are attached in file #3)

Life

When we finished obligatory tasks we decided to return to the question of life. We determined four categories of conditions for the presence of life:

magnetosphere

liquid water

atmosphere (with oxygen and ozone)

heat (temperature) and light

With the information currently available the scientists cannot be sure if TOI-560 c has a magnetosphere. It would have to have a metal core. Since it has a similar structure to Mars we can assume that this is not likely. If it had the metal core, the rest of the planet would have had to be made of gas – to be extremely light in order to fit the average density of the planet. However, we cannot make any conclusions for certain about this matter.

We wrote about liquid water in the previous paragraph.

First thing we have to know related to the atmosphere is if TOI-560 c has strong enough gravity to be able to maintain an atmosphere. We supposed that yes but we made some calculations to be sure (they are attached in file #6). Escape velocity which has to have every object that wants to leave the surface of TOI-560 c is 22.25 km*s-1 and molecule H2 has a root-mean-square speed of 2,491.51 m*s-1 (file 7). Escape velocity is much bigger than root-mean-square speed so TOI-560 c can maintain even the fastest molecules H2. Another thing is ozone O3 and oxygen O2. Based on available data we can’t find out anything about the structure of the hypothetical atmosphere. But the telescope HARPS with its spectrograph is able to confirm the existence of the atmosphere and even detect its structure.

Light and heat on TOI-560 c are provided from its star TOI-560. In fact, TOI-560 is two times bigger than the sun. The luminosity of the sun is 3.827*1026 W and the luminosity of TOI-560 is 6.04429*1029 W. The spectral flux also depends on the distance of the object from the star. And because the orbital distance of TOI-560 c from its star is about 0.1249 AU, the spectral flux is 13.681.47386 W*m-2 which is 10 times bigger than the spectral flux of the sun on Earth. (Calculations are attached in file #8)

Habitability depends on the orbital distance from the star. If Earth was too close or too far from the Sun there couldn’t be liquid water and life at all. But we don’t know how much the planet’s temperature is affected by the hypothetical atmosphere and how much by the distance. However, we can calculate habitable zones and neglect the atmosphere.

TOI-560c Conclusions

Now we know more about the planet and its conditions, we can compare it to the planets of the Solar system (graphs in file #9). In some aspects, the planet is similar to rock planets but in others to the gas giants. It’s really unlikely to have life here because of the high temperature and small distance from the star (there’s radiation from the star). It would be useful to have more information about the exoplanet’s structure and its atmosphere if it has one. The telescope HARPS could provide valuable information regarding the different aspects of the atmosphere.

Supporting files: