Two wide-orbit, gas-giant companions around TYC 8998-760-1

We were able to take the first direct image of a multi-planet system around a young, Sun-like star. We found the planets around a young, solar analogue that is about 17 Million year old - a baby amongst other stars and especially when compariong it to our own Sun with an age of more than 4.5 Billion years. By taking several images of the star over a couple of years, we could identify two giant companions around it. The technique used to distinguish these gravitationally bound companions from unassociated background stars is visualized in the figure to the right. When blinking two epochs of observations that are centered on the host star - which resides at the origin of the coordinate system - background stars are markedly jittering around, whilst the two companions stay more or less at the same place relative to TYC 8998-760-1. This confirms the two objects as bound companions around this 'Young Sun'. The inner planet 'b' is detected at a separation of more than 160 Astronomical Units - one Astronomical Unit is defined by the Earth-Sun distance in our Solar System - and the outer planet 'c' is at least twice as far away from its Sun. This is much farther away than the separation of any Solar System planet to our Sun. Neptune, for instance, has an average distance to the Sun of approximately 30 Astronomical Units.

To characterize these two gas-giant planets, we took data using several filters in near infrared wavelengths (from 1 to 5 microns). As visualized in the figure to the right, both companions are significantly redder than the previously identified background stars. These multi-wavelength measurements allowed us to estimate the temperature of both planets. We found that planet 'b' is as hot as 1700 K (≈ 1400°C) and planet 'c' has a temperature of approximately 1200 K (≈ 900°C). These temperatures are rather high compared to the palnets of our Solar System. Due to their youth both planets are still hot from their formation process and they will cool down continuously. Furthermore, we derived masses for both planets. We found that the inner planet weights 14 times the mass of Jupiter and the outer planet is as heavy as six times the mass of Jupiter. Even though the planets around TYC 8998-760-1 seem to be markedly different from everything we know in our own Solar System, the discovery is an important milestone, nevertheless. Future studies of this system will allow to understand the dynamics and formation processes that were shaping this Sun-like environment, which might come along with fundamental new insights into the history of our own Solar System.