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.
Journal Impact: 3.80*
Journal impact history
|2016 Journal impact||Available summer 2017|
|2015 Journal impact||3.80|
|2014 Journal impact||5.86|
|2013 Journal impact||6.11|
|2012 Journal impact||6.45|
|2011 Journal impact||5.30|
|2010 Journal impact||4.99|
|2009 Journal impact||5.64|
|2008 Journal impact||6.38|
|2007 Journal impact||5.55|
|2006 Journal impact||5.41|
|2005 Journal impact||5.17|
|2004 Journal impact||5.28|
|2003 Journal impact||5.33|
|2002 Journal impact||4.73|
|2001 Journal impact||4.92|
|2000 Journal impact||4.77|
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: In recent years, the analysis of absorption lines in quasi-stellar object (QSO) spectra, using the many-multiplet (MM) method, has provided evidence for space–time variations in the fine-structure constant, α. Future studies aim to reduce systematic errors in these measurements by considering a greater number of transitions, but this is only possible for lines where high-precision laboratory standards exist. Two transitions of high importance for future MM analyses, but which currently lack accurately measured wavelengths, are the Ti ii transitions observed at 1910 Å. We report accurate measurements of these transitions by high-resolution Fourier transform spectroscopy, giving line wavenumbers of (52,329.889 ± 0.001) cm −1 and (52,339.240 ± 0.001) cm −1 . Lines from other important Ti ii, Mg i, Mg ii, and Zn ii transitions were measured simultaneously, minimizing their relative wavenumber uncertainties, and permitting the newly measured 1910 Å Ti ii line wavenumbers to be linked directly to lines from other studies.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, we develop a new technique for driving global non-potential simulations of the Sun's coronal magnetic field solely from sequences of radial magnetic maps of the solar photosphere. A primary challenge to driving such global simulations is that the required horizontal electric field cannot be uniquely determined from such maps. We show that an "inductive" electric field solution similar to that used by previous authors successfully reproduces specific features of the coronal field evolution in both single and multiple bipole simulations. For these cases, the true solution is known because the electric field was generated from a surface flux-transport model. The match for these cases is further improved by including the non-inductive electric field contribution from surface differential rotation. Then, using this reconstruction method for the electric field, we show that a coronal non-potential simulation can be successfully driven from a sequence of ADAPT maps of the photospheric radial field, without including additional physical observations which are not routinely available.
- [Show abstract] [Hide abstract] ABSTRACT: We consider interactions between protons and Alfvén/ion-cyclotron (A/IC) waves in collisionless low-β plasmas in which the proton distribution function f is strongly modified by wave pitch-angle scattering. If the angle θ between the wave vector and background magnetic field is zero for all the waves, then strong scattering causes f to become approximately constant on surfaces of constant η, where η v 2⊥ + 1.5 v 2/3A|v ∥|4/3. Here, v ⊥ and v ∥ are the velocity components perpendicular and parallel to the background magnetic field, and v A is the Alfvén speed. If f = f(η), then A/IC waves with θ = 0 are neither damped nor amplified by resonant interactions with protons. In this paper, we argue that if some mechanism generates high-frequency A/IC waves with a range of θ values, then wave-particle interactions initially cause the proton distribution function to become so anisotropic that the plasma becomes unstable to the growth of waves with θ = 0. The resulting amplification of θ = 0 waves leads to an angular distribution of A/IC waves that is sharply peaked around θ = 0 at the large wavenumbers at which A/IC waves resonate with protons. Scattering by this angular distribution of A/IC waves subsequently causes f to become approximately constant along surfaces of constant η, which in turn causes oblique A/IC waves to be damped by protons. We calculate the proton and electron contributions to the damping rate analytically, assuming Maxwellian electrons and f = f(η). Because the plasma does not relax to a state in which proton damping of oblique A/IC waves ceases, oblique A/IC waves can be significantly more effective at heating protons than A/IC waves with θ = 0.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.