Journal ArticleDOI
The NASA Ames PAH IR Spectroscopic Database Version 2.00: Updated Content, Web Site, and On(Off)line Tools
C. Boersma,Charles W. Bauschlicher,Alessandra Ricca,Alessandra Ricca,A. L. Mattioda,A. L. Mattioda,Jan Cami,Jan Cami,Els Peeters,Els Peeters,F. Sánchez de Armas,G. Puerta Saborido,D. M. Hudgins,Louis J. Allamandola +13 more
Reads0
Chats0
TLDR
A significantly updated version of the NASA Ames PAH IR Spectroscopic Database, the first major revision since its release in 2010, is presented in this paper, which contains 700 computational and 75 experimental spectra compared with 583 and 60 in the initial version.Abstract:
A significantly updated version of the NASA Ames PAH IR Spectroscopic Database, the first major revision since its release in 2010, is presented. The current version, version 2.00, contains 700 computational and 75 experimental spectra compared, respectively, with 583 and 60 in the initial release. The spectra span the 2.5-4000 μm (4000-2.5 cm-1) range. New tools are available on the site that allow one to analyze spectra in the database and compare them with imported astronomical spectra as well as a suite of IDL object classes (a collection of programs utilizing IDL's object-oriented programming capabilities) that permit offline analysis called the AmesPAHdbIDLSuite. Most noteworthy among the additions are the extension of the computational spectroscopic database to include a number of significantly larger polycyclic aromatic hydrocarbons (PAHs), the ability to visualize the molecular atomic motions corresponding to each vibrational mode, and a new tool that allows one to perform a non-negative least-squares fit of an imported astronomical spectrum with PAH spectra in the computational database. Finally, a methodology is described in the Appendix, and implemented using the AmesPAHdbIDLSuite, that allows the user to enforce charge balance during the fitting procedure.read more
Citations
More filters
Journal ArticleDOI
Detection of the aromatic molecule benzonitrile (c-C6H5CN) in the interstellar medium.
Brett A. McGuire,Brett A. McGuire,Andrew M. Burkhardt,Sergei Kalenskii,Christopher N. Shingledecker,Anthony J. Remijan,Eric Herbst,Michael C. McCarthy +7 more
TL;DR: The discovery of benzonitrile (c-C6H5CN), one of the simplest nitrogen-bearing aromatic molecules, in the interstellar medium is presented, providing a chemical link to the carriers of the unidentified infrared bands.
Journal ArticleDOI
Astrochemistry of dust, ice and gas: introduction and overview
van Dishoeck,F Ewine +1 more
TL;DR: A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented in this paper, where the importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples.
Journal ArticleDOI
The NASA Ames PAH IR Spectroscopic Database: Computational Version 3.00 with Updated Content and the Introduction of Multiple Scaling Factors
TL;DR: In this paper, the authors describe the use of multiple scale factors, instead of the single scaling factor used previously, to align the theoretical harmonic frequencies with the experimental fundamentals, and the impact of these changes on the analysis of an astronomical spectrum through database-fitting is considered.
Journal ArticleDOI
Prebiotic Astrochemistry and the Formation of Molecules of Astrobiological Interest in Interstellar Clouds and Protostellar Disks
TL;DR: Because these chemical processes are universal and should occur in these environments wherever they are found, this implies that some of the starting materials for life are likely to be widely distributed throughout the universe.
Journal ArticleDOI
PAH EMISSION AT THE BRIGHT LOCATIONS OF PDRs: THE grandPAH HYPOTHESIS
H. Andrews,C. Boersma,Michael W. Werner,John H. Livingston,Louis J. Allamandola,Alexander G. G. M. Tielens +5 more
TL;DR: In this paper, the authors used the NASA Ames PAH IR Spectroscopic Database to fit the observations and analyze the derived PAH populations, and found that PAH emission in the 5-15 μm range appears to be rather insensitive to variations of the radiation field.
References
More filters
Journal ArticleDOI
A simplex method for function minimization
John A. Nelder,R. Mead +1 more
TL;DR: A method is described for the minimization of a function of n variables, which depends on the comparison of function values at the (n 41) vertices of a general simplex, followed by the replacement of the vertex with the highest value by another point.
Book
Solving least squares problems
TL;DR: Since the lm function provides a lot of features it is rather complicated so it is going to instead use the function lsfit as a model, which computes only the coefficient estimates and the residuals.
Journal ArticleDOI
Solving Least Squares Problems
Journal ArticleDOI
Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
Bruce T. Draine,Aigen Li +1 more
TL;DR: In this paper, the authors calculated IR emission spectra for dust heated by starlight, for mixtures of amorphous silicate and graphitic grains, including varying amounts of PAH particles.
Journal ArticleDOI
Interstellar Polycyclic Aromatic Hydrocarbon Molecules
TL;DR: In this paper, a review of the observed mid-IR spectral properties of polycyclic aromatic hydrocarbons (PAHs) is presented, emphasizing the contribution of these species to photoelectric heating and the ionization balance of the interstellar gas and to the formation of small hydrocarbon radicals and carbon chains.