2017/10/05 by Alicia N. Aarnio, Alicia Aarnio, John D. Monnier +7
Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Balmer series #Herbig Ae/Be star #Outflow #Radiative transfer #Spectral line #Stars #T Tauri star #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aa8997
published as ApJ 848, 2017, 18 · 34 pages, 52 figures, published in the ApJ
openalex created_date 2017/09/25 · openalex publication_date 2017/10/05 · arxiv created 2017/12/12 · arxiv updated 2017/12/13 · openalex updated_date 2026/08/06
Abstract Recent observational work has indicated that mechanisms for accretion and outflow in Herbig Ae/Be star–disk systems may differ from magnetospheric accretion (MA) as it is thought to occur in T Tauri star–disk systems. In this work, we assess the temporal evolution of spectral lines probing accretion and mass loss in Herbig Ae/Be systems and test for consistency with the MA paradigm. For two Herbig Ae/Be stars, HD 98922 (B9e) and V1295 Aql (A2e), we have gathered multi-epoch (∼years) and high-cadence (∼minutes) high-resolution optical spectra to probe a wide range of kinematic processes. Employing a line equivalent width evolution correlation metric introduced here, we identify species co-evolving (indicative of common line origin) via novel visualization. We interferometrically constrain often problematically degenerate parameters, inclination and inner-disk radius, allowing us to focus on the structure of the wind, magnetosphere, and inner gaseous disk in radiative transfer models. Over all timescales sampled, the strongest variability occurs within the blueshifted absorption components of the Balmer series lines; the strength of variability increases with the cadence of the observations. Finally, high-resolution spectra allow us to probe substructure within the Balmer series’ blueshifted absorption components: we observe static, low-velocity features and time-evolving features at higher velocities. Overall, we find the observed line morphologies and variability are inconsistent with a scaled-up T Tauri MA scenario. We suggest that as magnetic field structure and strength change dramatically with increasing stellar mass from T Tauri to Herbig Ae/Be stars, so too may accretion and outflow processes.