scholarly journals Vertical Shearing Instabilities in Radially Shearing Disks: The Dustiest Layers of the Protoplanetary Nebula

2008 ◽  
Vol 675 (2) ◽  
pp. 1549-1558 ◽  
Author(s):  
E. Chiang
Keyword(s):  
Protoplanetary Nebula ◽  
Vertical Shearing

Particle-Gas Dynamics in the Midplane of a Protoplanetary Nebula

Icarus ◽  
1993 ◽  
Vol 106 (1) ◽  
pp. 102-134 ◽  
Author(s):  
Jeffrey N. Cuzzi ◽  
Anthony R. Dobrovolskis ◽  
Joelle M. Champney
Keyword(s):  
Gas Dynamics ◽  
Protoplanetary Nebula

How Unique is the Protoplanetary Nebula Star HR 4049?

1987 ◽  
pp. 509-510
Author(s):  
C. L. Waelkens ◽  
L. B. F. M. Waters
Keyword(s):  
Protoplanetary Nebula

scholarly journals UV Monochromatic Imaging of the Protoplanetary Nebula Hen 3-1475 Using HST STIS

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 141
Author(s):  
Xuan Fang ◽  
Martín Guerrero ◽  
Ana Castro ◽  
Jesús Toalá ◽  
Bruce Balick ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Critical Role ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Comparison Analysis ◽  
Space Telescope ◽  
Monochromatic Imaging ◽  
Protoplanetary Nebula ◽  
Low Dispersion ◽  
Negative Gradient

Collimated outflows and jets play a critical role in shaping planetary nebulae (PNe), especially in the brief transition from a spherical AGB envelope to an aspherical PN, which is called the protoplanetary nebula (pPN) phase. We present UV observations of Hen 3-1475, a bipolar pPN with fast, highly collimated jets, obtained with STIS on board the Hubble Space Telescope (HST). The deep, low-dispersion spectroscopy enabled monochromatic imaging of Hen 3-1475 in different UV nebular emission lines; this is the first of such attempt ever conducted for a pPN. The northwest inner knot (NW1) is resolved into four components in Mg ii λ 2800. Through comparison analysis with the HST optical narrowband images obtained 6 yr earlier, we found that these components of NW1 hardly move, despite of a negative gradient of high radial velocities, from −1550 km s - 1 on the innermost component to ∼−300 km s - 1 on the outermost. These NW1 knot components might thus be quasi-stationary shocks near the tip of the conical outflow of Hen 3-1475.

scholarly journals GJ 1214b and the prospects for liquid water on super Earths

2010 ◽  
Vol 6 (S276) ◽  
pp. 189-192
Author(s):  
Leslie A. Rogers ◽  
Sara Seager
Keyword(s):  
Liquid Water ◽  
Equilibrium Temperature ◽  
Average Density ◽  
Outer Envelope ◽  
Water Ice ◽  
Transiting Planets ◽  
Protoplanetary Nebula ◽  
Pass Through ◽  
Gas Layer ◽  
Gas Component

AbstractGJ 1214b is one of the first discovered transiting planets having mass (6.55 M⊕) and radius (2.678 R⊕) smaller than Neptune. To account for its low average density (1870 kg m−3), GJ 1214b must have a significant gas component. We use interior structure models to constrain GJ 1214b's gas envelope mass, and to explore the conditions needed to achieve within the planet pressures and temperatures conducive to liquid water. We consider three possible origins for the gas layer: direct accretion of gas from the protoplanetary nebula, sublimation of ices, and outgassing from rocky material. Despite having an equilibrium temperature below 647 K (the critical temperature of water) GJ 1214b does not have liquid water under most conditions we consider. Even if the outer envelope is predominantly sublimated water ice, in our model a low intrinsic planet luminosity (less than 2 TW) is needed for the water envelope to pass through the liquid phase; at higher interior luminosities the outer envelope transitions from a vapor to a super-fluid then to a plasma at successively greater depths.

scholarly journals 10- m imaging of the bipolar protoplanetary nebula Mz-3

1996 ◽  
Vol 283 (4) ◽  
pp. 1379-1382 ◽  
Author(s):  
D. E. Quinn ◽  
T. J. T. Moore ◽  
R. G. Smith ◽  
C. H. Smith ◽  
T. Fujiyoshi
Keyword(s):  
Protoplanetary Nebula

A Simplified Model for an Evolving Protoplanetary Nebula

2003 ◽  
Vol 592 (2) ◽  
pp. 1193-1200 ◽  
Author(s):  
Sanford S. Davis
Keyword(s):  
Simplified Model ◽  
Protoplanetary Nebula

scholarly journals Wind–MRI interactions in local models of protoplanetary discs – I. Ohmic resistivity

2020 ◽  
Vol 498 (1) ◽  
pp. 750-770
Author(s):  
Philip K C Leung ◽  
Gordon I Ogilvie
Keyword(s):  
Large Scale ◽  
Transport Processes ◽  
Toroidal Field ◽  
Strong Wind ◽  
Flux Transport ◽  
Wind Structure ◽  
Three Stages ◽  
Magnetic Disc ◽  
Vertical Shearing ◽  
Protoplanetary Discs

ABSTRACT A magnetic disc wind is an important mechanism that may be responsible for driving accretion and structure formation in protoplanetary discs. Recent numerical simulations have shown that these winds can take either the traditional ‘hourglass’ symmetry about the mid-plane, or a ‘slanted’ symmetry dominated by a mid-plane toroidal field of a single sign. The formation of this slanted symmetry state has not previously been explained. We use radially local 1D vertical shearing box simulations to assess the importance of large-scale MRI channel modes in influencing the formation and morphologies of these wind solutions. We consider only Ohmic resistivity and explore the effect of different magnetizations, with the mid-plane β parameter ranging from 105 to 102. We find that our magnetic winds go through three stages of development: cyclic, transitive, and steady, with the steady wind taking a slanted symmetry profile similar to those observed in local and global simulations. We show that the cycles are driven by periodic excitation of the n = 2 or 3 MRI channel mode coupled with advective eviction, and that the transition to the steady wind is caused by a much more slowly growing n = 1 mode altering the wind structure. Saturation is achieved through a combination of advective damping from the strong wind, and suppression of the instability due to a strong toroidal field. A higher disc magnetization leads to a greater tendency towards, and more rapid settling into the slanted symmetry steady wind, which may have important implications for mass and flux transport processes in protoplanetary discs.

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