Self-sustained Ionization and Vanishing Dead Zones in Protoplanetary Disks

Inutsuka, Shu‐ichiro; Sano, Takayoshi

doi:10.1086/432796

Cited by 91 publications

(96 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The general properties of AXP/SGRs can be explained with T p ∼ 100 -200 K (Ertan et al 2009). This is consistent with the results of the analysis indicating that the disk should be active even at 300 K (Inutsuka & Sano 2005). In our long-term evolution model T p and C are degenerate parameters.…”

Section: Long-term Evolution Of Swift J18223-1606supporting

confidence: 92%

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

Benli

Çalışkan

Ertan

et al. 2013

ApJ

View full text Add to dashboard Cite

We investigate the X-ray enhancement and the long-term evolution of the recently discovered, second "low-B magnetar" Swift J1822.3-1606 in the frame of the fallback disk model. During a soft gamma burst episode, the inner disk matter is pushed back to larger radii forming a density gradient at the inner disk. Subsequent relaxation of the inner disk could account for the observed Xray enhancement light curve of Swift J1822.3-1606. We obtain model fits to the X-ray data with basic disk parameters similar to those employed to explain the X-ray outburst light curves of other anomalous X-ray pulsars and soft gamma repeaters. The long period (8.4 s) of the neutron star can be reached by the effect of the disk torques in the long-term accretion phase (1 − 3 × 10 5 yr). The currently ongoing X-ray enhancement could be due to a transient accretion epoch or the source could still be in the accretion phase in quiescence. Considering these different possibilities, we determine the model curves that could represent the long-term rotational and the X-ray luminosity evolution of Swift J1822.3-1606, which constrain the strength of the magnetic dipole field to the range of 1 − 2 × 10 12 G on the surface of the neutron star.

show abstract

Section: Long-term Evolution Of Swift J18223-1606supporting

confidence: 92%

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

Benli

Çalışkan

Ertan

et al. 2013

ApJ

View full text Add to dashboard Cite

show abstract

“…Ionization Rate There are various primary ionization sources, for example, Galactic cosmic rays, UV and X-rays from central stars, decay of radionuclide, and thermal ionization, etc. Here, just simplicity, we neglect the possible contribution of energetic electrons (Inutsuka & Sano 2005), and only consider cosmic rays, X-rays, and radionuclide. With orbital radius r and perpendicular oriented length z, ionization rate is written as follows:…”

Section: Disk Property Of Protoplanetary Disksmentioning

confidence: 99%

A Fast and Accurate Calculation Scheme for Ionization Degrees in Protoplanetary and Circumplanetary Disks With Charged Dust Grains

Fujii

Okuzumi

Inutsuka

2011

ApJ

Self Cite

View full text Add to dashboard Cite

We develop a fast and accurate calculation method for ionization degrees in protoplanetary and circumplanetary disks including dust grains. We apply our method to calculate the ionization degree of circumplanetary disks. It is important to understand the structure and evolution of protoplanetary/circumplanetary disks since they are thought to be the sites of planet/satellite formation. The turbulence that causes gas accretion is supposed to be driven by magnetorotational instability (MRI) that occurs only when the ionization degree is high enough for magnetic field to be coupled to gas. We calculate the ionization degrees in circumplanetary disks to estimate the sizes of MRI-inactive regions. We properly include the effect of dust grains because they efficiently capture charged particles and make ionization degree lower. Inclusion of dust grains complicates the reaction equations and requires expensive computation. In order to accelerate the calculation of ionization reactions, we develop a semianalytic method based on the charge distribution model proposed previously. This method enables us to study the ionization state of disks for a wide range of model parameters. For a previous model of circum-Jovian disk, we find that an MRI-inactive region covers almost all regions even without dust grains. This suggests that the gas accretion rates in circumplanetary disks are much smaller than previously thought.

show abstract

“…The resistivity at all heights in the disk is typically unchanged as gas mixes between the surface layers and interior, because the recombination on the grains is fast enough to keep the ionization near its local equilibrium value. However, with the grains removed, recombination is slow enough for ionized gas to reach the midplane (Inutsuka & Sano 2005). In our calculation with no grains, the undead zone shrinks after 150 yr as ionized gas is carried down from the surface layers.…”

Section: No 2 2008 Dead Zone Accretion Flows In Protostellar Disks mentioning

confidence: 99%

Dead Zone Accretion Flows in Protostellar Disks

Turner

Sano

2008

ApJ

156

169

View full text Add to dashboard Cite

Planets form inside protostellar disks in a dead zone where the electrical resistivity of the gas is too high for magnetic forces to drive turbulence. We show that much of the dead zone nevertheless is active and flows toward the star while smooth, large-scale magnetic fields transfer the orbital angular momentum radially outward. Stellar X-ray and radionuclide ionization sustain a weak coupling of the dead zone gas to the magnetic fields, despite the rapid recombination of free charges on dust grains. Net radial magnetic fields are generated in the magnetorotational turbulence in the electrically conducting top and bottom surface layers of the disk, and reach the midplane by ohmic diffusion. A toroidal component to the fields is produced near the midplane by the orbital shear. The process is similar to the magnetization of the solar tachocline. The result is a laminar, magnetically driven accretion flow in the region where the planets form.

show abstract

Self-sustained Ionization and Vanishing Dead Zones in Protoplanetary Disks

Cited by 91 publications

References 24 publications

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

A Fast and Accurate Calculation Scheme for Ionization Degrees in Protoplanetary and Circumplanetary Disks With Charged Dust Grains

Dead Zone Accretion Flows in Protostellar Disks

Contact Info

Product

Resources

About