Optical spectroscopy of WISPIT 2

The Halpha residual filling was measured relative to synthetic photospheric profiles and compared with the chromospheric-noise level of Manara et al. (2013A&A...551A.107M, Cat. J/A+A/551/A107). Halpha remains in net absorption but is partially filled in by emission.

The weak residual filling, at 1.5-2.0 sigma, lies about 1dex below the chromospheric-noise level, consistent with chromospheric emission and no detectable accretion. We place a 95 percent upper limit of dM_acc_/dt<3.6x10^-11^M_{sun}_/yr, below even the lowest epoch of PDS 70 monitoring and implying a host-to-planet ratio (dM_star/dt)/(dM_2b_/dt)<18. We also measure Teff= 4551+/-150K and a first, low-resolution, model-dependent global metallicity [M/H]=-0.17+/- 0.16; the surface gravity and Li I equivalent width support the pre-main-sequence nature of the host.

Both known double-protoplanet hosts, PDS 70 and WISPIT 2, therefore appear to show strongly suppressed or undetectable stellar accretion. Larger spectroscopic samples are needed to test whether this is common in multi-protoplanet transition disks.