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Project Progress

To support efforts to understand the nature and detectability of terrestrial planet characteristics for planets around stars of different spectral type, this task focuses on collecting and preparing full wavelength, continuous stellar spectra for use by the planetary climate and chemistry models (c. f. Task 6). Last year, we collected F and K spectra, and this year we worked towards providing spectra of quiescent and active M stars. We sought and recalibrated International Ultraviolet Explorer UV spectra for between 15 and 20 M-dwarfs. Analysis of the UV spectra for AD Leo, a well-known flare star with abundant UV data revealed five guises: flare, post-flare, non-flaring, “typical,” and no emission lines. The averaged “typical” UV spectra for both AD Leo, and GJ643, were appended to absolutely calibrated optical+infrared (IR) energy distributions to generate complete FUV-FIR “quiescent” spectra. Future work will include producing early-M to mid-M dwarf spectra, which are much less active cool stars, prior to tackling the full time-dependent situation for the more active M-stars. These collated, full-wavelength-range stellar spectra are being publicly archived.

We also continued development of the molecular spectra database, http://vpl.ipac.caltech.edu/spectra/ , which is a collection of line lists and absorption cross-sections for molecules of interest to the Virtual Planetary Laboratory (VPL). There are currently 61 molecules with entries in the database, with more being added as information becomes available. Data can be absorption cross sections and/or actual line lists, and may come from multiple sources. The most common sources are infrared absorption cross-sections from Pacific Northwest National Lab (PNNL), infrared line lists from the High Resolution Transmission Molecular Absorption (HITRAN) database, and UV cross-sections from personal collections of VPL personnel. Images of the data are provided on the website, although the actual data is not yet linked, but is available on request. Work is underway to make the source data available for download from the VPL server.

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