Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70

Abstract

Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. Aims. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes. Methods. We analyse new and archival near-infrared (NIR) images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo and Gemini/NICI instruments in polarimetric differential imaging (PDI) and angular differential imaging (ADI) modes. Results. We detect a point source within the gap of the disk at about 195 mas (∼22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance.The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of ∼54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than ∼17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains. Conclusions. The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres and evolutionary models.Based on observations performed with ESO Telescopes at the Paranal Observatory under programmes 095.C-0298, 095.C-0404, 096.C-0333, 097.C-0206, 097.C-1001, 099.C-0891. are imprinted by the initial conditions of the disks and which develop through a variety of dynamical interactions is crucial for understanding the planet population. It is therefore of high importance to study planets and their environments at the stage during which these objects are formed. Transition disks (TDs) are of key interest in this context, as many of them are believed to bear direct ...

Accretion Properties of PDS 70b with MUSE*

“…The planetary mass is commonly estimated by comparing photometric and spectroscopic observations with planetary evolution and atmospheric models (e.g., Müller et al 2018;Keppler et al 2018;Christiaens et al 2019a;Haffert et al 2019;Mesa et al 2019). On the other hand, our method based on the accretion shock model can estimate a dynamic planetary mass (Aoyama & Ikoma 2019).…”

“…A good example of robustly detected accreting planets at tens of au from a central star is the PDS 70 planetary system. This system includes a weakly accreting young star (spectral type of K7, mass of 0.8 M ⊙ , accretion rate of 6 × 10 −11 M ⊙ yr −1 , age of 5 Myr, distance of 113 pc; Pecaut & Mamajek 2016;Keppler et al 2019;Haffert et al 2019;Müller et al 2018;Gaia Collaboration et al 2018) associated with two planetary-mass companions (Haffert et al 2019;Isella et al 2019;Christiaens et al 2019a,b;Keppler et al 2018;Müller et al 2018;Wagner et al 2018). Aoyama & Ikoma (2019) estimated that PDS 70b's mass and mass accretion rate are ∼12 M Jup and ∼4 × 10 −8 M Jup yr −1 , respectively, while the values for PDS 70c are ∼10 M Jup and ∼1 × 10 −8 M Jup yr −1 .…”

Atmospheric Characterization and Further Orbital Modeling of κ Andromeda b

“…With the development of Adaptive Optics (AO), direct imaging has uniquely been probing exoplanet populations of young and wide-orbit gas giants (e.g., Marois et al 2010;Lagrange et al 2010;Kuzuhara et al 2013;Currie et al 2015;Macintosh et al 2015;Keppler et al 2018). Young gas giants are amenable to direct detection at infrared wavelength as they are still radiating away their heat of formation, which means that these planets still have vestiges of planet formation, and are bright enough to be resolved with high-contrast imaging instruments around nearby, bright stars.…”

A Swift view of X-ray and UV radiation in the planet-forming T Tauri system PDS 70

“…PDS 70 is a nearby (113 pc) example of a young T-Tauri star with a disc inclined at 45-50 degrees (Hashimoto et al 2012), making it possible to resolve and image the disc with optical and IR observations (e.g. Riaud et al 2006;Christiaens et al 2019b;Keppler et al 2018). Understanding conditions in this, and other similar systems, provides a direct window on the process of planet formation.…”

“…It now appears that this is a gap rather than the entire central region being clear. Coronographic observations were unable to detect the inner region of the disc, but NIR imaging has since identified an inner edge to the gap at 17 AU (Keppler et al 2018).…”