Aeolian scours as putative signatures of wind erosion and sediment transport direction on Mars     

Mark A. Bishop   《Geomorphology》2011,125(4):317

  相似文献   

Torsional oscillations of relativistic stars with dipole magnetic fields     

H. Sotani  K. D. Kokkotas  N. Stergioulas 《Monthly notices of the Royal Astronomical Society》2007,375(1):261-277

  相似文献   

On the force-free magnetosphere of an aligned rotator     

A. N. Timokhin 《Monthly notices of the Royal Astronomical Society》2006,368(3):1055-1072

  相似文献   

Mass accretion on to T Tauri stars     

S. G. Gregory  M. Jardine  I. Simpson  J.-F. Donati 《Monthly notices of the Royal Astronomical Society》2006,371(2):999-1013

  相似文献   

Chemical Telemetry of OH Observed to Measure Interstellar Magnetic Fields     

Dr Serena Viti PhD  Thomas W. Hartquist  Philip C. Myers 《Astrophysics and Space Science》2006,302(1-4):109-115

We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the ionization front, ices are destroyed and species formed on the grain surfaces are injected into the gas phase. Photodissociation removes gas phase molecular species as the gas flows towards the ionization front. We identify models for which the OH column densities are comparable to those measured in observations undertaken to study the magnetic fields in star forming regions and give results for the column densities of other species that should be abundant if the observed OH arises through a combination of the liberation of H₂O from surfaces and photodissociation. They include CH₃OH, H₂CO, and H₂S. Observations of these other species may help establish the nature of the OH spatial distribution in the clouds, which is important for the interpretation of the magnetic field results.  相似文献   

Anharmonic and standing dynamo waves: theory and observation of stellar magnetic activity     

S. Baliunas  P. Frick  D. Moss  E. Popova  D. Sokoloff  W. Soon 《Monthly notices of the Royal Astronomical Society》2006,365(1):181-190

  相似文献   

On the first generation of stars     

Joseph Silk  Mathieu Langer 《Monthly notices of the Royal Astronomical Society》2006,371(1):444-450

We argue that the first stars may have spanned the conventional mass range rather than be identified with the very massive objects  (∼100–10³ M_⊙)  favoured by numerical simulations. Specifically, we find that magnetic field generation processes acting in the first protostellar systems suffice to produce fields that exceed the threshold for magneto-rotational instability (MRI) to operate, and thereby allow the MRI dynamo to generate equipartition-amplitude magnetic fields on protostellar mass scales below  ∼50 M_⊙  . Such fields allow primordial star formation to occur at essentially any metallicity by regulating angular momentum transfer, fragmentation, accretion and feedback in much the same way as occurs in conventional molecular clouds.  相似文献   

Kelvin–Helmholtz driven propeller in AE Aquarii: A unified model for thermal and non-thermal flares     

L. A. Venter  P. J. Meintjes 《Monthly notices of the Royal Astronomical Society》2006,366(2):557-565

In this paper, an attempt is made to integrate the propeller ejection of material by the fast rotating white dwarf in AE Aquarii with the highly transient thermal and non-thermal emission in a single unifying model. It has been shown that the violent interaction between the fast rotating magnetosphere and a clumpy fragmented stream, in AE Aquarii specifically, may result in the growth of unstable modes of the Kelvin–Helmholtz instability and associated turbulence over length scales comparable to the stream radius on time-scales  τ_K-H ∼  t _dyn (∼ 600 s  ). For all conversion efficiencies of magnetohydrodynamic (MHD) power to mechanical energy ε≥ 0.1, these instabilities result in the effective azimuthal acceleration of the gas parcels to the escape velocity over time-scales   t _acc≤ 1000 s (∼ t _dyn)  . Further, it has been shown that the turbulence in the flow will cascade down to the dissipative level over time-scales  τ_cas∼ 3 h  . If released through dissipative shocks, this reservoir can drive a luminosity of   L ∼ 10³³ erg s⁻¹  , which can significantly contribute to the total emission when blobs collide in the exit stream, resulting in shock heating and associated flares. During the propeller process, particles can also be accelerated to high energies, which may be the driving mechanism behind the non-thermal radio to mid-infrared emission. The confluence of these ejected magnetized clouds may result in radio remnant surrounding AE Aquarii, which is optically thin between frequencies ν≥ 100 MHz–1 GHz.  相似文献   

Genetic magnetohelioseismology with Hankel analysis data     

A. D. Crouch  P. S. Cally  P. Charbonneau  D. C. Braun  M. Desjardins 《Monthly notices of the Royal Astronomical Society》2005,363(4):1188-1204

  相似文献   

Probing primordial magnetic fields with the 21-cm fluctuations     

Hiroyuki Tashiro  Naoshi Sugiyama 《Monthly notices of the Royal Astronomical Society》2006,372(3):1060-1068

  相似文献