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The asteroseismic analysis of stellar power density spectra is often computationally expensive. The models used in the analysis may use several dozen parameters to accurately describe features in the spectra caused by oscillation modes and…

Solar and Stellar Astrophysics · Physics 2023-08-23 M. B. Nielsen , G. R. Davies , W. J. Chaplin , W. H Ball , J. M. J. Ong , E. Hatt , B. P. Jones , M. Logue

Molecular oxygen has been the subject of many observational searches as chemical models predicted it to be a reservoir of oxygen. Although it has been detected in two regions of the interstellar medium, its rarity is a challenge for…

Astrophysics of Galaxies · Physics 2019-06-04 V. Wakelam , M. Ruaud , P. Gratier , I. A. Bonnell

Modern observations of the interstellar medium (ISM) in galaxies detect a variety of atomic and molecular species. The goal is to connect these observations to the astrochemical properties of the ISM. 3D hydro-chemical simulations attempt…

Astrophysics of Galaxies · Physics 2019-02-20 Thomas G. Bisbas , Andreas Schruba , Ewine F. van Dishoeck

Ten protostellar outflows in the Orion molecular clouds were mapped in the $^{12}$CO/$^{13}$CO ${J=6\rightarrow5}$ and $^{12}$CO ${J=7\rightarrow6}$ lines. The maps of these mid-$J$ CO lines have an angular resolution of about 10$''$ and a…

The structure and properties of the diffuse interstellar medium (ISM) on small scales, sub-au to 1 pc, are poorly understood. We compare interstellar absorption-lines, observed towards a selection of O- and B-type stars at two or more…

The development of our understanding of the gaseous component of the interstellar medium is reviewed. During the 20th century our picture of diffuse material in space has grown from a simple model of isolated clouds in thermal equilibrium…

Astrophysics · Physics 2009-09-25 Priscilla C. Frisch

The nature of turbulence in the warm ionized component of the interstellar medium (WIM) can be investigated using Fabry-Perot spectroscopy of optical emission lines. The H-alpha intensity provides the emission measure (EM) along a line of…

Astrophysics · Physics 2007-05-23 S. L. Tufte , R. J. Reynolds , L. M. Haffner

We performed an intensive photometric monitoring of the PMS stars falling in a field of about 10x10 arc-minutes in the vicinity of the Orion Nebula Cluster (ONC). Photometric data were collected between November 2006 and January 2007 with…

Solar and Stellar Astrophysics · Physics 2009-11-05 A. Frasca , E. Covino , L. Spezzi , J. M. Alcala' , E. Marilli , G. Furesz , D. Gandolfi

We have obtained high resolution (FWHM = 4.4 km/s) Keck spectra of images A and C of the gravitationally lensed QSO Q1422+231. The images are separated by 1.3" on the sky. In an absorption system at z = 3.538 gas column density variations…

Astrophysics · Physics 2007-05-23 Michael Rauch , Wallace L. W. Sargent , Thomas A. Barlow

Oxygen is the third most abundant element in the universe, but its chemistry in the interstellar medium is still not well understood. In order to critically examine the entire oxygen budget, we attempt here initially to estimate the…

Solar and Stellar Astrophysics · Physics 2015-05-13 René Liseau , Kay Justtanont

The paper analyzes the absorption line profile at 21 cm for the hydrogen atom in the interstellar medium. The hydrogen atom is treated as a three-level system illuminated by a powerful light source at neighboring resonances corresponding to…

Atomic Physics · Physics 2018-11-05 D. Solovyev

Context. In order to understand the evolution of molecular clouds it is important to identify the departures from self-similarity associated with the scales of self-gravity and the driving of turbulence. Aims. A method is described based on…

Astrophysics · Physics 2009-11-11 M. Gustafsson , J. L. Lemaire , D. Field

We present an initial overview of the filamentary structure in the Orion A molecular cloud utilizing a high angular and velocity resolution C$^{18}$O(1-0) emission map that was recently produced as part of the CARMA-NRO Orion Survey. The…

Determining the atomic and molecular content of the interstellar medium (ISM) as a function of environmental parameters is of fundamental importance to understand the star-formation process across the epochs. Although there exist various…

Astrophysics of Galaxies · Physics 2022-12-07 Thomas G. Bisbas , Ewine F. van Dishoeck , Chia-Yu Hu , Andreas Schruba

A principal component analysis of cosmic microwave background (CMB) anisotropy measurements is used to investigate degeneracies among cosmological parameters. The results show that a degeneracy with tensor modes -- the `tensor degeneracy'…

Astrophysics · Physics 2009-11-07 George Efstathiou

We present the analysis of NOEMA interferometric observations of the high-mass star-forming region W75N(B) with a focus on molecular composition and distribution of prebiotic molecules in the source's multiple cores. Over twenty molecules…

Astrophysics of Galaxies · Physics 2025-02-13 Morgan M. Giese , Will E. Thompson , Dariusz C. Lis , Susanna L. Widicus Weaver

We present a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments onboard Spitzer. In total, five distinct fields were mapped covering 9 sq. degrees in five mid-IR bands spanning 3-24 microns. The…

Intensity interferometry permits very long optical baselines and the observation of sub-milliarcsecond structures. Using planned kilometric arrays of air Cherenkov telescopes at short wavelengths, intensity interferometry may increase the…

Instrumentation and Methods for Astrophysics · Physics 2015-03-17 Dainis Dravins , Hannes Jensen , Stephan LeBohec , Paul D. Nuñez

Understanding the initial properties of star-forming material and how they affect the star formation process is key. From an observational point of view, the feedback from young high-mass stars on future star formation properties is still…