THE PROPAGATION OF Ly{alpha} IN EVOLVING PROTOPLANETARY DISKS

Journal Article · Sat Oct 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/739/2/78; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587477

Bethell, Thomas J

We study the role resonant scattering plays in the transport of Ly{alpha} photons in accreting protoplanetary disk systems subject to varying degrees of dust settling. While the intrinsic stellar far-UV (FUV) spectrum of accreting T Tauri systems may already be dominated by a strong, broad Ly{alpha} line ({approx}80% of the FUV luminosity), we find that resonant scattering further enhances the Ly{alpha} density in the deep molecular layers of the disk. Ly{alpha} is scattered downward efficiently by the photodissociated atomic hydrogen layer that exists above the molecular disk. In contrast, FUV-continuum photons pass unimpeded through the photodissociation layer and (forward-)scatter inefficiently off dust grains. Using detailed, adaptive grid Monte Carlo radiative transfer simulations we show that the resulting Ly{alpha}/FUV-continuum photon density ratio is strongly stratified; FUV-continuum-dominated in the photodissociation layer and Ly{alpha}-dominated field in the molecular disk. The enhancement is greatest in the interior of the disk (r {approx} 1 AU) but is also observed in the outer disk (r {approx} 100 AU). The majority of the total disk mass is shown to be increasingly Ly{alpha} dominated as dust settles toward the midplane.

• OSTI ID: 21587477
• Journal Information: Astrophysical Journal, Vol. 739, Issue 2; Other Information: DOI: 10.1088/0004-637X/739/2/78; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DENSITY
DISSOCIATION
DUSTS
FAR ULTRAVIOLET RADIATION
LYMAN LINES
MONTE CARLO METHOD
PHOTONS
PROTOPLANETS
RADIANT HEAT TRANSFER
RESONANCE SCATTERING
SIMULATION
T TAURI STARS
BINARY STARS
BOSONS
CALCULATION METHODS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY TRANSFER
ERUPTIVE VARIABLE STARS
HEAT TRANSFER
INELASTIC SCATTERING
MASSLESS PARTICLES
PHYSICAL PROPERTIES
RADIATIONS
SCATTERING
STARS
ULTRAVIOLET RADIATION
VARIABLE STARS