Herbig stars' near-infrared excess: An origin in the protostellar disk's magnetically supported atmosphere

Journal Article · Wed Jan 01 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/780/1/42· OSTI ID:22348336

Turner, N. J. ^[1]; Benisty, M.; Dullemond, C. P. ^[2]

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1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

Young stars with masses 2-8 times solar, the Herbig Ae and Be stars, often show a near-infrared excess too large to explain with a hydrostatically supported circumstellar disk of gas and dust. At the same time, the accretion flow carrying the circumstellar gas to the star is thought to be driven by magnetorotational turbulence, which, according to numerical MHD modeling, yields an extended low-density atmosphere supported by the magnetic fields. We demonstrate that the base of the atmosphere can be optically thick to the starlight and that the parts lying near 1 AU are tall enough to double the fraction of the stellar luminosity reprocessed into the near-infrared. We generate synthetic spectral energy distributions (SEDs) using Monte Carlo radiative transfer calculations with opacities for submicron silicate and carbonaceous grains. The synthetic SEDs closely follow the median Herbig SED constructed recently by Mulders and Dominik and, in particular, match the large near-infrared flux, provided the grains have a mass fraction close to interstellar near the disk's inner rim.

• OSTI ID: 22348336
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 780; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ATMOSPHERES
DENSITY
DUSTS
ENERGY SPECTRA
LUMINOSITY
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS
MONTE CARLO METHOD
OPACITY
PROTOPLANETS
RADIANT HEAT TRANSFER
RESONANCE IONIZATION MASS SPECTROSCOPY
SIMULATION
STARS
TURBULENCE