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We report the detection and investigate the properties of high-excitation lambda-doubling line emission of hydroxyl (OH) detected towards three asymptotic giant branch (AGB) stars (W Hya, R Dor, and IK Tau) using ALMA. The OH lines are…

太阳与恒星天体物理 · 物理学 2019-03-06 T. Khouri , L. Velilla-Prieto , E. De Beck , W. H. T. Vlemmings , H. Olofsson , B. Lankhaar , J. H. Black , A. Baudry

Chandra gratings spectra of a sample of 15 massive OB stars were analyzed under the basic assumption that the X-ray emission is produced in an ensemble of shocks formed in the winds driven by these objects. Shocks develop either as a result…

天体物理学 · 物理学 2009-11-13 Svetozar A. Zhekov , Francesco Palla

We investigate the chemical evolution of a forming molecular cloud behind an interstellar shock wave. We conduct three-dimensional magnetohydrodynamics simulations of the converging flow of atomic gas, including a simple chemical network…

星系天体物理 · 物理学 2026-01-08 Yuto Komichi , Yuri Aikawa , Kazunari Iwasaki , Kenji Furuya

Motivated by recent observations with Herschel/PACS, and the availability of new rate coefficients for the collisional excitation of CO (Yang et al. 2010), the excitation of warm astrophysical CO is revisited with the use of numerical and…

星系天体物理 · 物理学 2015-06-04 David A. Neufeld

Water is an important molecule in interstellar and circumstellar environments. Previous observations of mid-infrared rotational lines of OH suggest that these lines may be used to probe the photodissociation of water. In this work, cross…

星系天体物理 · 物理学 2021-06-30 Benoît Tabone , Marc C. van Hemert , Ewine F. van Dishoeck , John H. Black

Supernova remnants (SNRs) exert strong influence on the physics and chemistry of the nearby molecular clouds (MCs) through shock waves and the cosmic rays (CRs) they accelerate. To investigate the SNR-cloud interaction in the prototype…

星系天体物理 · 物理学 2024-03-21 Tian-Yu Tu , Yang Chen , Ping Zhou , Samar Safi-Harb

We model the temperature and chemical structure of molecular clouds as a function of depth into the cloud, assuming a cloud of constant density n illuminated by an external FUV (6 eV < E < 13.6 eV) flux G_0 (scaling factor in multiples of…

天体物理学 · 物理学 2011-02-11 David Hollenbach , Michael J. Kaufman , Edwin A. Bergin , Gary J. Melnick

The supernova explosion increases cosmic ray and x-ray fluxes in the surrounding interstellar medium. Cosmic ray particles and x-ray radiation penetrate nearby molecular clouds and affect the chemical and thermal evolution of the gas. Here…

星系天体物理 · 物理学 2019-12-25 A. V. Nesterenok

The hydroxyl radical (OH) is found in various environments within the interstellar medium (ISM) of the Milky Way and external galaxies, mostly either in diffuse interstellar clouds or in the warm, dense environments of newly formed low-mass…

Supernovae (SNe) inject $\sim 10^{51}$ erg in the interstellar medium, thereby shocking and heating the gas. A substantial fraction of this energy is later lost via radiative cooling. We present a post-processing module for the FLASH code…

Aims: Our aim is to identify the dominant molecular cooling lines and characteristic emission features in the 1.3 mm window of distinct regions in the northern part of the Orion A molecular cloud. By defining and analysing template regions,…

星系天体物理 · 物理学 2020-04-15 N. Brinkmann , F. Wyrowski , J. Kauffmann , D. Colombo , K. M. Menten , X. D. Tang , R. Güsten

A collisionless shock may be strongly modified by the presence of neutral atoms through the processes of charge exchange between ions and neutrals and ionization of the latter. These two processes lead to exchange of energy and momentum…

高能天体物理现象 · 物理学 2015-06-04 P. Blasi , G. Morlino , R. Bandiera , E. Amato , D. Caprioli

Deep optical CCD images of the supernova remnant G 15.1-1.6 were obtained and filamentary and diffuse emission has been discovered. The images, taken in the emission lines of Halpha+[N II], [S II] and [O III], reveal filamentary and diffuse…

天体物理学 · 物理学 2009-11-13 P. Boumis , J. Alikakos , P. E. Christopoulou , F. Mavromatakis , E. M. Xilouris , C. D. Goudis

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

天体物理学 · 物理学 2009-11-13 P. Hennebelle , R. Banerjee , E. Vazquez-Semadeni , R. Klessen , E. Audit

We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 microns (1.9 THz) towards Galactic longitudes near 340deg (5 LOSs) and 20deg (11 LOSs) as part of the GOT C+ survey. Out of the total 146…

星系天体物理 · 物理学 2015-05-19 T. Velusamy , W. D. Langer , J. L. Pineda , P. F. Goldsmith , D. Li. , H. W. Yorke

Supernovae and their remnants provide energetic feedback to the ambient interstellar medium (ISM), which is often distributed in multiple gas phases. Among them, warm molecular hydrogen (H$_2$) often dominates the cooling of the shocked…

星系天体物理 · 物理学 2022-11-29 Yunwei Deng , Zhi-Yu Zhang , Ping Zhou , Junzhi Wang , Min Fang , Lingrui Lin , Fuyan Bian , Zhiwei Chen , Yong Shi , Guoyin Chen , Hui Li

The atomic-to-molecular hydrogen (H/H2) transition has been extensively studied as it controls the fraction of gas in a molecular state in an interstellar cloud. This fraction is linked to star-formation by the Schmidt-Kennicutt law. While…

星系天体物理 · 物理学 2021-12-08 Vincent Maillard , Emeric Bron , Franck Le Petit

Expansion of wind-blown bubbles or HII regions lead to formation of shocks in the interstellar medium, which compress surrounding gas into dense layers. We made spatially and velocity-resolved observations of the RCW~120 PDR and nearby…

星系天体物理 · 物理学 2023-01-18 M. S. Kirsanova , Ya. N. Pavlyuchenkov , A. O. H. Olofsson , D. A. Semenov , A. F. Punanova

We present the results of GBT observations of all four ground-state hydroxyl (OH) transitions toward 15 supernova remnants (SNRs) which show OH(1720 MHz) maser emission. This species of maser is well established as an excellent tracer of an…

天体物理学 · 物理学 2009-11-13 J. W. Hewitt , F. Yusef-Zadeh , M. Wardle

The oxygen-bearing molecular ions OH+, H2O+, and H3O+ are key species that probe the ionization rate of (partially) molecular gas that is ionized by X-rays and cosmic rays permeating the interstellar medium. We report Herschel far-infrared…