LIDA – The Leiden Ice Database For Astrochemistry

By Keith Cowing
Press Release
August 26, 2022
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LIDA – The Leiden Ice Database For Astrochemistry
Screenshot of the three-dimensional (3D) molecule viewer embedded in LIDA using the JSmol package. The viewer is connected to external public databases of molecule structures and can be viewed using the searching bar below the molecules. A few dedicated controls can be used to move and animate the molecule. The calculated vibrational modes can be listed and animated using the green button. As proof of concept, the yellow arrows indicate the vibrational motion of the water bending mode seen at 1643 cm−1 in Figure 3. Buttons for making a movie and download the image file as PNG are also provided.

High quality vibrational spectra of solid-phase molecules in ice mixtures and for temperatures of astrophysical relevance are needed to interpret infrared observations toward protostars and background stars.

Over the last 25 years, the Laboratory for Astrophysics at Leiden Observatory has provided more than 1100 spectra of diverse ice samples. Timely with the recent launch of the James Webb Space Telescope, we have fully upgraded the Leiden Ice Database for Astrochemistry (LIDA) adding recently measured spectra.

The goal of this manuscript is to describe what options exist to get access to and work with a large collection of IR spectra, and the UV/vis to mid-infrared refractive index of H2O ice and astronomy-oriented online tools to support the interpretation of IR ice observations. LIDA uses Flask and Bokeh for generating the web pages and graph visualization, respectively, SQL for searching ice analogues within the database and Jmol for 3D molecule visualization.

The infrared data in the database are recorded via transmission spectroscopy of ice films condensed on cryogenic substrates. The real UV/vis refractive indices of H2O ice are derived from interference fringes created from the simultaneous use of a monochromatic HeNe laser beam and a broadband Xe-arc lamp, whereas the real and imaginary mid-IR values are theoretically calculated. LIDA also offers online tools.

The first tool, SPECFY, used to create a synthetic spectrum of ices towards protostars.

The second tool aims at the calculation of mid-infrared refractive index values. LIDA allows to search, download and visualize experimental data of astrophysically relevant molecules in the solid phase, as well as to provide the means to support astronomical observations.

As an example, we analyse the spectrum of the protostar AFGL 989 using the resources available in LIDA and derive the column densities of H2O, CO and CO2 ices.

W. R. M. Rocha, M. G. Rachid, B. Olsthoorn, E. F. van Dishoeck, M. K. McClure, H. Linnartz

Comments: Accepted for publication in A&A. 29 pages, 9 figures. Online database at this https URL
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2208.12211 [astro-ph.IM] (or arXiv:2208.12211v1 [astro-ph.IM] for this version)
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Submission history
From: Will Robson Monteiro Rocha
[v1] Thu, 25 Aug 2022 17:01:42 UTC (8,927 KB)
Full paper:
Astrobiology, Astrochemistry

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