DIAGNOSING MASS FLOWS AROUND HERBIG Ae/Be STARS USING THE HE I λ10830 LINE

Journal Article · Sat Dec 20 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/797/2/112· OSTI ID:22364830

Cauley, P. Wilson ^[1]

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1. Department of Astronomy, Wesleyan University, 45 Wyllys Avenue, Middletown, CT 06459 (United States)

We examine He I λ10830 profile morphologies for a sample of 56 Herbig Ae/Be stars (HAEBES). We find significant differences between HAEBES and classical T-Tauri stars (CTTS) in the statistics of both blueshifted absorption (i.e., mass outflows) and redshifted absorption features (i.e., mass infall or accretion). Our results suggest that, in general, Herbig Be (HBe) stars do not accrete material from their inner disks in the same manner as CTTS, which are believed to accrete material via magnetospheric accretion, whereas Herbig Ae (HAe) stars generally show evidence for magnetospheric accretion. We find no evidence in our sample of narrow blueshifted absorption features, which are typical indicators of inner disk winds and are common in He I λ10830 profiles of CTTS. The lack of inner-disk-wind signatures in HAEBES, combined with the paucity of detected magnetic fields on these objects, suggests that accretion through large magnetospheres that truncate the disk several stellar radii above the surface is not as common for HAe and late-type HBe stars as it is for CTTS. Instead, evidence is found for smaller magnetospheres in the maximum redshifted absorption velocities in our HAEBE sample. These velocities are, on average, a smaller fraction of the system escape velocity than is found for CTTS, suggesting accretion is taking place closer to the star. Smaller magnetospheres, and evidence for boundary layer accretion in HBe stars, may explain the less common occurrence of redshifted absorption in HAEBES. Evidence is found that smaller magnetospheres may be less efficient at driving outflows compared to CTTS magnetospheres.

• OSTI ID: 22364830
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 797; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ACCRETION DISKS
BOUNDARY LAYERS
COMPARATIVE EVALUATIONS
HELIUM
MAGNETIC FIELDS
MASS
MORPHOLOGY
RED SHIFT
STAR ACCRETION
STELLAR MAGNETOSPHERES
STELLAR WINDS
T TAURI STARS
VELOCITY