2020A&A...643A..99B

Context. Young stars interact with their accretion disk through their strong magnetosphere.
Aims. We aim to investigate the magnetospheric accretion/ejection process in the young stellar system DoAr 44 (V2062 Oph).
Methods. We monitored the system over several rotational cycles, combining high-resolution spectropolarimetry at both optical and near-IR wavelengths with long-baseline near-IR inteferometry and multicolor photometry.
Results. We derive a rotational period of 2.96 d from the system's light curve, which is dominated by stellar spots. We fully characterize the central star's properties from the high signal-to-noise, high-resolution optical spectra we obtained during the campaign. DoAr 44 is a young 1.2M_☉ star, moderately accreting from its disk (M_acc=6.5x10^–9M_☉/yr), and seen at a low inclination (i≃30°). Several optical and near-IR line profiles probing the accretion funnel flows (Hα, Hβ, HeI 1083nm, Paβ) and the accretion shock (HeI 587.6nm) are modulated at the stellar rotation period. The most variable line profile is HeI 1083nm, which exhibits modulated redshifted wings that are a signature of accretion funnel flows, as well as deep blueshifted absorptions indicative of transient outflows. The Zeeman-Doppler analysis suggests the star hosts a mainly dipolar magnetic field, inclined by about 20° onto the spin axis, with an intensity reaching about 800G at the photosphere, and up to 2±0.8kG close to the accretion shock. The magnetic field appears strong enough to disrupt the inner disk close to the corotation radius, at a distance of about 4.6R* (0.043au), which is consistent with the 5R* (0.047au) upper limit we derived for the size of the magnetosphere in our Paper I from long baseline interferometry.
Conclusions. DoAr 44 is a pre-transitional disk system, exhibiting a 25-30au gap in its circumstellar disk, with the inner and outer disks being misaligned. On a scale of 0.1au or less, our results indicate that the system is steadily accreting from its inner disk through its tilted dipolar magnetosphere. We conclude that in spite of a highly structured disk on the large scale, perhaps the signature of ongoing planetary formation, the magnetospheric accretion process proceeds unimpeded at the star-disk interaction level.