Context. Protoplanetary disks are the birth environments of planetary systems. Therefore, the study of young, circumstellar environments is essential in understanding the processes taking place in planet formation and the evolution of planetary systems.
Aims: We detect and characterize circumstellar disks and potential companions around solar-type, pre-main sequence stars in the Scorpius-Centaurus association (Sco-Cen).
Methods: As part of our ongoing survey we carried out high-contrast imaging with VLT/SPHERE/IRDIS to obtain polarized and total intensity images of the young (11-7+16 Myr old) K3IV star Wray 15-788 within the Lower Centaurus Crux subgroup of Sco-Cen. For the total intensity images, we remove the stellar halo via an approach based on reference star differential imaging in combination with principal component analysis.
Results: Both total intensity and polarimetric data resolve a disk around the young, solar-like Sco-Cen member Wray 15-788. Modeling of the stellar spectral energy distribution suggests that this is a protoplanetary disk at a transition stage. We detect a bright outer ring at a projected separation of 370 mas (≈56 au), hints of inner substructures at 170 mas (≈28 au), and a gap in between. Within a position angle range of only 60° < ϕ < 240°, we are confident at the 5σ level that we detect actual scattered light flux from the outer ring of the disk; the remaining part is indistinguishable from background noise. For the detected part of the outer ring we determine a disk inclination of i = 21° ± 6° and a position angle of φ = 76° ± 16°. Furthermore, we find that Wray 15-788 is part of a binary system with the A2V star HD 98363 at a separation of 50'' (≈6900 au).
Conclusions: The detection of only half of the outer ring might be due to shadowing by a misaligned inner disk. A potential substellar companion can cause the misalignment of the inner structures and can be responsible for clearing the detected gap from scattering material. However, we cannot rule out the possibility of a non-detection due to our limited signal-to-noise ratio (S/N), combined with brightness azimuthal asymmetry. From our data we can exclude companions more massive than 10 Mjup within the gap at a separation of 230 mas (≈35 au). Additional data are required to characterize the disk's peculiar morphology and to set tighter constraints on the potential perturber's orbital parameters and mass.
Astronomy and Astrophysics
- Pub Date:
- April 2019
- protoplanetary disks;
- planets and satellites: formation;
- planet-disk interactions;
- techniques: image processing;
- stars: individual: Wray 15-788;
- stars: individual: HD 98363;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- Accepted for publication in A&