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The Sun is responsible for the eruption of billions of tons of plasma andthe generation of near light-speed particles that propagate throughout the solarsystem and beyond. If directed towards Earth, these events can be damaging toour tecnological infrastructure. Hence there is an effort to understand the causeof the eruptive events and how they propagate from Sun to Earth. However, thephysics governing their propagation is not well understood, so there is a need todevelop a theoretical description of their propagation, known as a PropagationModel, in order to predict when they may impact Earth. It is often difficultto define a single propagation model that correctly describes the physics ofsolar eruptive events, and even more difficult to implement models capable ofcatering for all these complexities and to validate them using real observational data.In this paper, we envisage that workflows offer both a theoretical andpractical framerwork for a novel approach to propagation models. We definea mathematical framework that aims at encompassing the different modalitieswith which workflows can be used, and provide a set of generic building blockswritten in the TAVERNA workflow language that users can use to build theirown propagation models. Finally we test both the theoretical model and thecomposite building blocks of the workflow with a real Science Use Case that wasdiscussed during the 4th CDAW (Coordinated Data Analysis Workshop) eventheld by the HELIO project. We show that generic workflow building blocks canbe used to construct a propagation model that succesfully describes the transitof solar eruptive events toward Earth and predict a correct Earth-impact time

Heliophysics is the branch of physics that investigates the interactions and cor-relation of different events across the Solar System. The mathematical modelsthat describe and predict how physical events move across the solar system (ie.Propagation Models) are of great relevance. These models depend on parame-ters that users must set, hence the ability to correctly set the values is key toreliable simulations. Traditionally, parameter values can be inferred from dataeither at the source (the Sun) or arrival point (the target) or can be extrapo-lated from common knowledge of the event under investigation. Another way ofsetting parameters for Propagation Models is proposed here: instead of guess-ing a priori parameters from scientific data or common knowledge, the model isexecuted as a parameter-sweep job and selects a posteriori the parameters thatyield results most compatible with the event data. In either case (a priori anda posteriori), the correct use of Propagation Models requires information toeither select the parameters, validate the results, or both. In order to do so, itis necessary to access sources of information. For this task, the HELIO projectproves very effective as it offers the most comprehensive integrated informationsystem in this domain and provides access and coordination to services to mineand analyze data. HELIO also provides a Propagation Model called SHEBA,the extension of which is currently being developed within the SCI-BUS project(a coordinated effort for the development of a framework capable of offering toscience gateways seamless access to major computing and data infrastructures).

The goal of the SunPy project is to facilitate and promote the use and development of community-led, free, and open source data analysis software for solar physics based on the scientific Python environment. The project achieves this goal by developing and maintaining the sunpy core package and supporting an ecosystem of affiliated packages. This paper describes the first official stable release (version 1.0) of the core package, as well as the project organization and infrastructure. This paper concludes with a discussion of the future of the SunPy project. [ABSTRACT FROM AUTHOR]