{'fraction_non_alphanumeric': 0.023894862604540025, 'fraction_numerical': 0.023894862604540025, 'mean_word_length': 5.207407407407407, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Spectropolarimetry of Magnetospheric Accretion on the Classical T Tauri Star BP Tauri

High-resolution (R ≈ 60,000) circular spectropolarimetry of the classical T Tauri star BP Tauri is presented. No net polarization is detected in photospheric absorption lines, placing strong limits (3 σ) on the mean longitudinal magnetic field (±200 G) that is present over the surface of the star. On the other hand, strong circular polarization is measured in the He I λ5876 emission line of BP Tau, indicating a mean longitudinal magnetic field of 2460±120 G in the line formation region. This implies that accretion occurs preferentially along large-scale magnetic loops that occupy a small fraction of the stellar surface. These observations represent the first direct evidence for magnetically controlled accretion onto classical T Tauri stars.