The Astrophysical Journal (ASTROPHYS J)
The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Many of the classic discoveries of the twentieth century have first been reported in the Journal, which has also presented much of the important recent work on quasars, pulsars, neutron stars, black holes, solar and stellar magnetic fields, X-rays, and interstellar matter. The Astrophysical Journal Letters (http://www.journals.uchicago.edu/toc/apjl/current) is Part 2 of The Astrophysical Journal. Letters articles are published first as unpaginated papers on University of Chicago Press's Rapid Release website, then moved to a complete electronic issue, and finally are published in print with Part 1 on the 1st, 10th, and 20th of every month.
RG Journal Impact: 3.80*
RG Journal impact history
|2017 RG Journal impact||Available summer 2018|
|2015 / 2016 RG Journal impact||3.80|
|2014 RG Journal impact||5.86|
|2013 RG Journal impact||6.11|
|2012 RG Journal impact||6.45|
|2011 RG Journal impact||5.30|
|2010 RG Journal impact||4.99|
|2009 RG Journal impact||5.64|
|2008 RG Journal impact||6.38|
|2007 RG Journal impact||5.55|
|2006 RG Journal impact||5.41|
|2005 RG Journal impact||5.17|
|2004 RG Journal impact||5.28|
|2003 RG Journal impact||5.33|
|2002 RG Journal impact||4.73|
|2001 RG Journal impact||4.92|
|2000 RG Journal impact||4.77|
RG Journal impact over time
|Website||Astrophysical Journal, The website|
|Other titles||The Astrophysical journal, ApJ|
|Material type||Periodical, Internet resource|
|Document type||Journal / Magazine / Newspaper, Internet Resource|
Publications in this journal
- [Show abstract] [Hide abstract] ABSTRACT: Understanding the dynamic behavior of spicules, e.g., in terms of magnetohydrodynamic (MHD) wave mode(s), is key to unveiling their role in energy and mass transfer from the photosphere to corona. The transverse, torsional, and field-aligned motions of spicules have previously been observed in imaging spectroscopy and analyzed separately for embedded wave-mode identification. Similarities in the Doppler signatures of spicular structures for both kink and torsional Alfvén wave modes have led to the misinterpretation of the dominant wave mode in these structures and is a subject of debate. Here, we aim to combine line- of-sight (LOS) and plane-of-sky (POS) velocity components using the high spatial/temporal resolution Hα imaging-spectroscopy data from the CRisp Imaging SpectroPolarimeter based at the Swedish Solar Telescope to achieve better insight into the underlying nature of these motions as a whole. The resultant three-dimensional velocity vectors and the other derived quantities (e.g., magnetic pressure perturbations) are used to identify the MHD wave mode(s) responsible for the observed spicule motion. We find a number of independent examples where the bulk transverse motion of the spicule is dominant either in the POS or along the LOS. It is shown that the counterstreaming action of the displaced external plasma due to spicular bulk transverse motion has a similar Doppler profile to that of the m = 0 torsional Alfvén wave when this motion is predominantly perpendicular to the LOS. Furthermore, the inferred magnetic pressure perturbations support the kink wave interpretation of observed spicular bulk transverse motion rather than any purely incompressible MHD wave mode, e.g., the m = 0 torsional Alfvén wave.
- [Show abstract] [Hide abstract] ABSTRACT: The aim of the present work is to unravel the radiolytic decomposition of adenine (C5H5N5) under conditions relevant to the Martian surface. Being the fundamental building block of (deoxy)ribonucleic acids, the possibility of survival of this biomolecule on the Martian surface is of primary importance to the astrobiology community. Here, neat adenine and adenine–magnesium perchlorate mixtures were prepared and irradiated with energetic electrons that simulate the secondary electrons originating from the interaction of the galactic cosmic rays with the Martian surface. Perchlorates were added to the samples since they are abundant—and therefore relevant oxidizers on the surface of Mars—and they have been previously shown to facilitate the radiolysis of organics such as glycine. The degradation of the samples were monitored in situ via Fourier transformation infrared spectroscopy and the electron ionization quadruple mass spectrometric method; temperature-programmed desorption profiles were then collected by means of the state-of-the-art single photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), allowing for the detection of the species subliming from the sample. The results showed that perchlorates do increase the destruction rate of adenine by opening alternative reaction channels, including the concurrent radiolysis/oxidation of the sample. This new pathway provides a plethora of different radiolysis products that were identified for the first time. These are carbon dioxide (CO2), isocyanic acid (HNCO), isocyanate (OCN−), carbon monoxide (CO), and nitrogen monoxide (NO); an oxidation product containing carbonyl groups (R1R2–C=O) with a constrained five-membered cyclic structure could also be observed. Cyanamide (H2N–C≡N) was detected in both irradiated samples as well.
- [Show abstract] [Hide abstract] ABSTRACT: Protons and electrons observed in the solar wind possess temperature anisotropies for which upper and lower bounds appear to be partially regulated by marginal conditions associated with various kinetic plasma instabilities. Such features are most clearly seen when a collection of measurements is plotted as a two-dimensional histogram in phase space. While the partial outer boundaries of such data distribution may well be explained by various instability threshold conditions, an outstanding issue is that the majority of data points are actually located sufficiently away from the boundaries and reside in near isotropic conditions. This implies that certain processes are operative that counteract the adiabatic effect in the radially expanding solar wind, without which solar wind plasma will inexorably be forced to proceed toward the marginal firehose condition. A number of physical processes have been proposed in the literature to explain such a feature. The present paper suggests yet another mechanism. It considers dynamic electrons and protons in the quasilinear evolution of anisotropy-driven instabilities, which is in contrast to previous studies where either protons or electrons are assumed to be stationary when considering the dynamics of the other particle species. It is shown that the dynamical interplay between the two species during the quasilinear development of parallel electron firehose and proton-cyclotron instabilities leads to a counter-balancing effect, which prevents the uniform progression of the solar wind protons toward the marginal firehose state. © 2017. The American Astronomical Society. All rights reserved..
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