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Título de Acceso Abierto
The Astrophysical Journal (ApJ)
Resumen/Descripción – provisto por la editorial en inglés
The Astrophysical Journal is an open access journal devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Publications in ApJ constitute significant new research that is directly relevant to astrophysical applications, whether based on observational results or on theoretical insights or modeling.Palabras clave – provistas por la editorial
astronomy; astrophysics
Disponibilidad
| Institución detectada | Período | Navegá | Descargá | Solicitá |
|---|---|---|---|---|
| No detectada | desde jul. 1995 / hasta dic. 2023 | IOPScience |
Información
Tipo de recurso:
revistas
ISSN impreso
0004-637X
ISSN electrónico
1538-4357
Editor responsable
American Astronomical Society (AAS)
Idiomas de la publicación
- inglés
País de edición
Reino Unido
Información sobre licencias CC
Cobertura temática
Tabla de contenidos
Three-dimensional Instability of Flame Fronts in Type I X-Ray Bursts
Yuri Cavecchi
; Anatoly Spitkovsky
<jats:title>Abstract</jats:title> <jats:p>We present the first realistic 3D simulations of flame front instabilities during type I X-ray bursts. The unperturbed front is characterized by the balance between the pressure gradient and the Coriolis force of a spinning neutron star (<jats:italic>ν</jats:italic> = 450 Hz in our case). This balance leads to a fast horizontal velocity field parallel to the flame front. This flow is strongly sheared in the vertical direction. When we perturb the front an instability quickly corrugates the front. We identify this instability as the baroclinic instability. Most importantly, the flame is not disrupted by the instability and there are two major consequences: the overall flame propagation speed is ∼10 times faster than in the unperturbed case and distinct flame vortices appear. The speedup is due to the corrugation of the front and the dynamics of the vortices. These vortices may also be linked to the oscillations observed in the light curves of the bursts.</jats:p>
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 142
The Thermal Force in Astrophysical Plasmas: Current Free Coulomb Friction
J. D. Scudder
<jats:title>Abstract</jats:title> <jats:p>The<jats:italic> t</jats:italic> <jats:italic>hermal force</jats:italic> (TF) is an exchange force mediated by Coulomb collisions between electrons and ions in a heat-conducting astrophysical plasma, is one of three, non-inertial, balancing terms in the parallel component of the generalized Ohm’s law, and is magnetic field aligned with a size that scales with and is parallel to the dimensionless heat flux. The TF (i) increases the size of <jats:italic>E</jats:italic> <jats:sub>∥</jats:sub> above that implied by the electron pressure divergence; (ii) deepens the electrostatic trap for electrons about the Sun; (iii) strengthens the electron kurtosis and skewness, further levitating ions out of their gravitational well, (iv) constrains the heat flow in a plasma where parallel currents are preempted; and (v) is shown to be directly measurable using the full electron velocity distribution function above and below thermal energies. (vi) The usually ignored TF modifies all species internal energy equations; it enhances the rate of conduction cooling by the electrons, increases the ion entropy, and forestalls adiabatic behavior. Using estimates at 1 au this effect is especially strong in the higher speed wind <jats:italic>U</jats:italic> > 400 km s<jats:sup>−1</jats:sup> regime. (vii) On rather general grounds any physical heat transport is accompanied by an underlying TF; in almost all known cases of modeling astrophysical plasmas this dependence is ignored or demonstrably incorrect. It follows that attempts to predict species specific pressures without inclusion of the TF is <jats:italic>futile</jats:italic>.</jats:p>
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 146
Determining the Transport of Magnetic Helicity and Free Energy in the Sun’s Atmosphere
Peter W. Schuck; Spiro K. Antiochos
<jats:title>Abstract</jats:title> <jats:p>The most important factors determining solar coronal activity are believed to be the availability of magnetic free energy and the constraint of magnetic helicity conservation. Direct measurements of the helicity and magnetic free energy in the coronal volume are difficult, but their values may be estimated from measurements of the helicity and free energy transport rates through the photosphere. We examine these transport rates for a topologically open system such as the corona, in which the magnetic fields have a nonzero normal component at the boundaries, and derive a new formula for the helicity transport rate at the boundaries. In addition, we derive new expressions for helicity transport due to flux emergence/submergence versus photospheric horizontal motions. The key feature of our formulas is that they are manifestly gauge invariant. Our results are somewhat counterintuitive in that only the lamellar electric field produced by the surface potential transports helicity across boundaries, and the solenoidal electric field produced by a surface stream function does not contribute to the helicity transport. We discuss the physical interpretation of this result. Furthermore, we derive an expression for the free energy transport rate and show that a necessary condition for free energy transport across a boundary is the presence of a closed magnetic field at the surface, indicating that there are current systems within the volume. We discuss the implications of these results for using photospheric vector magnetic and velocity field measurements to derive the solar coronal helicity and magnetic free energy, which can then be used to constrain and drive models for coronal activity.</jats:p>
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 151
Vortex Formations and Its Associated Surges in a Sunspot Light Bridge
Heesu Yang; Eun-Kyung Lim; Haruhisa Iijima; Vasyl Yurchyshyn; Kyung-Suk Cho; Jeongwoo Lee; Brigitte Schmieder; Yeon-Han Kim; Sujin Kim; Su-Chan Bong
<jats:title>Abstract</jats:title> <jats:p>We report on the successive occurrence of 0.″5 wide photospheric vortices with strong transverse shear flows at the edge of a sunspot light bridge (LB), and the subsequent ejection of chromospheric surges observed using a Visible Inteferometry Spectrograph, a broadband TiO filter, and a Near InfRared Imaging Spectrograph of the Goode Solar Telescope operating at Big Bear Solar Observatory. The H<jats:italic>α</jats:italic> surges ejected at the location of the vortices often appeared in a hollow cylindrical structure. We also observed quasi-periodic vortex-associated bright H<jats:italic>α</jats:italic> plasma blobs moving upward with a speed of up to 4 km s<jats:sup>−1</jats:sup>. In view of the strong shear flow at the edge of the LB, it is likely that the vortices form under the Kelvin–Helmholtz instability. The surges may result from either the magnetic tension generated after magnetic reconnection or an acoustic impulse of a fast photospheric transverse flow. Otherwise, the surges could also be associated with Alfvénic waves, in which case their origin could be torsional magnetic fields generated in the process of the vortex formation.</jats:p>
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 175
The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Evolution of the Molecular Gas in CO-selected Galaxies
Manuel Aravena; Roberto Decarli; Jorge Gónzalez-López; Leindert Boogaard; Fabian Walter; Chris Carilli; Gergö Popping; Axel Weiss; Roberto J. Assef; Roland Bacon; Franz Erik Bauer; Frank Bertoldi; Richard Bouwens; Thierry Contini; Paulo C. Cortes; Pierre Cox; Elisabete da Cunha; Emanuele Daddi; Tanio Díaz-Santos; David Elbaz; Jacqueline Hodge; Hanae Inami; Rob Ivison; Olivier Le Fèvre; Benjamin Magnelli; Pascal Oesch; Dominik Riechers; Ian Smail; Rachel S. Somerville; A. M. Swinbank; Bade Uzgil; Paul van der Werf; Jeff Wagg; Lutz Wisotzki
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 136
The ALMA Spectroscopic Survey in the HUDF: the Molecular Gas Content of Galaxies and Tensions with IllustrisTNG and the Santa Cruz SAM
Gergö Popping; Annalisa Pillepich; Rachel S. Somerville; Roberto Decarli; Fabian Walter; Manuel Aravena; Chris Carilli; Pierre Cox; Dylan Nelson; Dominik Riechers; Axel Weiss; Leindert Boogaard; Richard Bouwens; Thierry Contini; Paulo C. Cortes; Elisabete da Cunha; Emanuele Daddi; Tanio Díaz-Santos; Benedikt Diemer; Jorge González-López; Lars Hernquist; Rob Ivison; Olivier Le Fèvre; Federico Marinacci; Hans-Walter Rix; Mark Swinbank; Mark Vogelsberger; Paul van der Werf; Jeff Wagg; L. Y. Aaron Yung
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 137
The ALMA Spectroscopic Survey in the HUDF: CO Luminosity Functions and the Molecular Gas Content of Galaxies through Cosmic History
Roberto Decarli; Fabian Walter; Jorge Gónzalez-López; Manuel Aravena; Leindert Boogaard; Chris Carilli; Pierre Cox; Emanuele Daddi; Gergö Popping; Dominik Riechers; Bade Uzgil; Axel Weiss; Roberto J. Assef; Roland Bacon; Franz Erik Bauer; Frank Bertoldi; Rychard Bouwens; Thierry Contini; Paulo C. Cortes; Elisabete da Cunha; Tanio Díaz-Santos; David Elbaz; Hanae Inami; Jacqueline Hodge; Rob Ivison; Olivier Le Fèvre; Benjamin Magnelli; Mladen Novak; Pascal Oesch; Hans-Walter Rix; Mark T. Sargent; Ian Smail; A. Mark Swinbank; Rachel S. Somerville; Paul van der Werf; Jeff Wagg; Lutz Wisotzki
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 138
The Atacama Large Millimeter/submillimeter Array Spectroscopic Survey in theHubbleUltra Deep Field: CO Emission Lines and 3 mm Continuum Sources
Jorge González-López; Roberto Decarli; Riccardo Pavesi; Fabian Walter; Manuel Aravena; Chris Carilli; Leindert Boogaard; Gergö Popping; Axel Weiss; Roberto J. Assef; Franz Erik Bauer; Frank Bertoldi; Richard Bouwens; Thierry Contini; Paulo C. Cortes; Pierre Cox; Elisabete da Cunha; Emanuele Daddi; Tanio Díaz-Santos; Hanae Inami; Jacqueline Hodge; Rob Ivison; Olivier Le Fèvre; Benjamin Magnelli; Pascal Oesch; Dominik Riechers; Hans-Walter Rix; Ian Smail; A. M. Swinbank; Rachel S. Somerville; Bade Uzgil; Paul van der Werf
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 139
The ALMA Spectroscopic Survey in the HUDF: Nature and Physical Properties of Gas-mass Selected Galaxies Using MUSE Spectroscopy
Leindert A. Boogaard; Roberto Decarli; Jorge González-López; Paul van der Werf; Fabian Walter; Rychard Bouwens; Manuel Aravena; Chris Carilli; Franz Erik Bauer; Jarle Brinchmann; Thierry Contini; Pierre Cox; Elisabete da Cunha; Emanuele Daddi; Tanio Díaz-Santos; Jacqueline Hodge; Hanae Inami; Rob Ivison; Michael Maseda; Jorryt Matthee; Pascal Oesch; Gergö Popping; Dominik Riechers; Joop Schaye; Sander Schouws; Ian Smail; Axel Weiss; Lutz Wisotzki; Roland Bacon; Paulo C. Cortes; Hans-Walter Rix; Rachel S. Somerville; Mark Swinbank; Jeff Wagg
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 140
Major Mergers Are Not the Dominant Trigger for High-accretion AGNs at z ∼ 2
Victor Marian; Knud Jahnke; Mira Mechtley; Seth Cohen; Bernd Husemann; Victoria Jones; Anton Koekemoer; Andreas Schulze; Arjen van der Wel; Carolin Villforth; Rogier A. Windhorst
Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.
Pp. 141