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dcyphr | Two Directly Imaged, Wide-orbit Giant Planets around the Young, Solar Analog TYC 8998-760-1

Abstract

There are a small number of multiplanet systems known today. This study detected a second planet around the star TYC 8998-760-1. This is the first multiplanet system to be directly imaged around a young star, and is ideal to continue imaging because the two planets are far apart. There is also reason to believe that a third, unseen planet is also in orbit around TYC 8998-760-1.

Aims

This study aims to report the findings of a newly identified gas giant planet that orbits the star TYC 8998-760-1. This finding, along with the previously identified planet orbiting the star, makes for a new multiplanet system discovery.

Introduction

Different imaging techniques have been used recently to visualize planets. Out of all of the planets that have been identified, only two stars have solid evidence of truly having multiplanet systems orbit around them. The stars are HR 8799, which is 30 million years old and has 4 giant planets orbiting it, and PDS 70, which is 5.4 million years old and has two planets orbiting it. Finding these systems has encouraged researchers to look for more, and learn about how the different planets in the system interact with each other to help the systems form. Through this search, the research team identified a planet orbiting TYC 8998-760-1, which is about 16.7 million years old. This study reports the findings of a new, second gas giant planet that orbits around TYC 8998-760-1.

Results and Analysis

The new planet orbiting TYC 8998-760-1 is named TYC 8998-760-1 c, and the previously discovered planet was named TYC 8998-760-1 b. Because the two planets orbiting TYC 8998-760-1 are well separated, the research team was able to obtain a lot of data on the planet. They looked at data in the H band and K1 band, which can tell us the position angle and the separations of the system. The data shows that TYC 8998-760-1 c is not what is expected from a stationary background object, meaning there is likely movement of the planet. This data matches the expected data if the star TYC 8998-760-1 were to have another planet in addition to TYC 8998-760-1 b. The researchers also looked at the energy distribution, temperature, surface gravity, radius, and luminosity to determine more properties of the planet. The mass and color were determined using this data and data from other studied planets. TYC 8998-760-1 c was the most red planet in color compared to the planets used as a reference. The research team also found that the planets either formed in the location they were found in, or were pushed out of another system by a third unknown planet.


Observational Methods

The research team used the Spectro-Polarimetric Highcontrast Exoplanet REsearch (SPHERE) instrument in the Infra-Red Dual Imaging and Spectrograph Mode (IRDIS) and the Very Large Telescope (VLT) to image TYC 8998-760-1.

Conclusion

The calculated estimate values are as follows: temperature was 1240 Kelvin (1772 F), the gravity log was 3.5 dex, the radius was 1.1 Rjup (Rjup is the radius of Jupiter), the luminosity log was -4.65, and the spectral type was L7.5. The mass was about 6 times the mass of Jupiter, which is in agreement with the red color of the planet. The system seems stable in near-circular orbits, but is chaotic in higher timescales.

The study of this multiplanet system should continue because we could learn about the effect that two gas giant planets have on each other in such a system. With more data, we could predict how this multiplanet system formed, and understand more about multiplanet gas giant systems in general.