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A new class of exoplanets is beginning to emerge: planets whose dayside atmospheres more closely resemble stellar atmospheres as most of their molecular constituents dissociate. The effects of the dissociation of these species will be…

Earth and Planetary Astrophysics · Physics 2018-05-02 Taylor J. Bell , Nicolas B. Cowan

[Abridged] Photoionization, whether by starlight or other sources, has difficulty in accounting for the observed spectra of the optical filaments that often surround central galaxies in large clusters. Our first paper examined whether…

A numerically solvable two-dimensional (2D) model, employed by the authors to study the dissociative recombination of H$_2^+$ in the ungerade symmetry [Phys. Rev. A $\mathbf{98}$, 062706 (2018)], is extended to describe the collision…

Chemical Physics · Physics 2025-11-26 Dávid Hvizdoš , Roman Čurík , Chris H. Greene

Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…

Solar and Stellar Astrophysics · Physics 2020-06-24 Boy Lankhaar , Wouter Vlemmings

We present IFU observations of six emission-line nebulae that surround the central galaxy of cool core clusters. Qualitatively similar nebulae are observed in cool core clusters even when the dynamics and possibly formation and excitation…

Astrophysics · Physics 2009-11-13 N. A. Hatch , C. S. Crawford , A. C. Fabian

The analysis and interpretation of the H2 line emission from planetary nebulae have been done in the literature assuming that the molecule survives only in regions where the hydrogen is neutral, as in photodissociation, neutral clumps or…

Astrophysics of Galaxies · Physics 2015-03-17 Isabel Aleman , Ruth Gruenwald

In the present work, we use a photoionisation code to study the H2 emission of the Helix nebula (NGC 7293) cometary knots, particularly that produced in the interface H+/H0 of the knot, where a significant fraction of the H2 1-0 S(1)…

Astrophysics of Galaxies · Physics 2010-10-21 Isabel Aleman , Albert A. Zijlstra , Mikako Matsuura , Ruth Gruenwald , Rafael Kimura

Galactic cosmic rays (CRs) play a crucial role in ionisation, dissociation, and excitation processes within dense cloud regions where UV radiation is absorbed by dust grains and gas species. CRs regulate the abundance of ions and radicals,…

We revisit the question of the ionization of the diffuse medium in late type galaxies, by studying NGC 891, the prototype of edge-on spiral galaxies. The most important challenge for the models considered so far was the observed increase of…

Astrophysics of Galaxies · Physics 2015-03-19 Nahiely Flores-Fajardo , Christophe Morisset , Grazyna Stasinska , Luc Binette

The origin of rovibrational H_2 emission in the central galaxies of cooling flow clusters is poorly understood. Here we address this issue using data from our near-infrared spectroscopic survey of 32 of the most line luminous such systems,…

Astrophysics · Physics 2009-09-17 R. J. Wilman , A. C. Edge , R. M. Johnstone , A. C. Fabian , S. W. Allen , C. S. Crawford

Radiative cooling by metals in shocked gas mediates the formation of ionization front instabilities in the galaxy today that are responsible for a variety of phenomena in the interstellar medium, from the morphologies of nebulae to…

Astrophysics · Physics 2009-11-13 Daniel Whalen , Michael L. Norman

Recent observations and theoretical investigations of neutron stars indicate that their atmospheres consist not of hydrogen or iron but possibly other elements such as helium. We calculate the ionization and dissociation equilibrium of…

Astrophysics · Physics 2008-11-26 Kaya Mori , Jeremy S. Heyl

We present LVG and non-local radiative transfer calculations involving the rotational and hyperfine structure of the spectrum of N$_2$H$^+$ with collisional rate coefficients recently derived by us. The goal of this study is to check the…

Astrophysics · Physics 2008-11-26 F. Daniel , J. Cernicharo , M. -L. Dubernet

We present N2D+ 3-2 (IRAM) and H2D+ 1_11 - 1_10 and N2H+ 4-3 (JCMT) maps of the small cluster-forming Ophiuchus B2 core in the nearby Ophiuchus molecular cloud. In conjunction with previously published N2H+ 1-0 observations, the N2D+ data…

Astrophysics of Galaxies · Physics 2015-05-19 R. K. Friesen , J. Di Francesco , P. C. Myers , A. Belloche , Y. L. Shirley , T. L. Bourke , P. André

In this paper we explore the dynamics of ionization bounded planetary nebulae after the termination of the fast stellar wind. When the stellar wind becomes negligible, the hot, shocked bubble depressurizes and the thermal pressure of the…

Astrophysics · Physics 2009-11-11 G. Garcia-Segura , J. A. Lopez , W. Steffen , J. Meaburn , A. Manchado

The photodissociation of the HD+ molecular ion in intense short- pulsed linearly polarized laser fields is studied using a time- dependent wave-packet approach where molecular rotation is fully included. We show that applying a coherent…

chem-ph · Physics 2019-04-04 Eric Charron , Annick Giusti-Suzor , Frederick Mies

The interaction of a strong flux of photons with matter through an ionizing-front (I-front) is an ubiquitous phenomenon in the context of astrophysics and inertial confinement fusion (ICF) where intense sources of radiation put matter into…

Plasma Physics · Physics 2015-11-18 Olivier Poujade , Max Bonnefille , Marc Vandenboomgaerde

This paper presents an analysis of the concentration of the hydrogen molecule inside the ionized region of planetary nebulae. The equations corresponding to the ionization and chemical equilibria of H, H+, H-, H2, H2+, and H3+ are coupled…

Astrophysics · Physics 2009-11-10 I. Aleman , R. Gruenwald

The laser-induced fragmentation dynamics of this most fundamental polar molecule HeH$^+$ are measured using an ion beam of helium hydride and an isotopologue at various wavelengths and intensities. In contrast to the prevailing…

Chemical Physics · Physics 2018-08-21 P. Wustelt , F. Oppermann , Lun Yue , M. Möller , T. Stöhlker , S. Gräfe , M. Lein , G. G. Paulus , A. M. Sayler

Gas in galactic disks is collected by gravitational instabilities into giant atomic-molecular complexes, but only the inner, molecular parts of these structures are able to collapse to form stars. Determining what controls the ratio of…

Astrophysics · Physics 2009-11-13 Mark R. Krumholz , Christopher F. McKee , Jason Tumlinson