Hunting for accreting young gas giant planets

Tuesday 3 July, 14:40

During the last years (sub-)mm and high contrast imaging observations have targeted dozens of circumstellar disks, revealing a breathtaking diversity in substructures like gaps, spirals, etc. It is thought that at least some of the observed structures are related to the formation of protoplanets, involving material accretion from the circumstellar disk onto the young planet. To test this hypothesis, the detection of accreting planetary mass companions is crucial and would bring unprecedented constraints for the planet formation mechanism, possibly allowing the distinction between different models. One way to identify accreting young planets is the detection of H-alpha emission from a point source embedded in the circumstellar disk. In this talk, we present the analysis of the largest and deepest SPHERE/ZIMPOL sample of available H-alpha data, which includes 7 young objects specifically selected for the presence of particularly interesting disk structures and protoplanetary candidates. The observations confirmed the detection of the stellar companion HD142527B with the highest S/N to date and allowed its astrometric and photometric characterization as well as the calculation of its mass accretion rate. Also, the unique case of HD142527B helped us to define the best instrument setup and analysis technique for SPHERE/ZIMPOL H-alpha future observations. We used optimized PSF subtraction tools to reach the highest possible contrast and to put unprecedented constraints on the H-alpha line flux emitted in the surrounding of the other objects. Our analysis has large implications for accretion processes occurring in disks of young objects.

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