Introducing PyCross: PyCloudy Rendering Of Shape Software for pseudo 3D ionisation modelling of nebulae

Abstract

Research into the processes of photoionised nebulae plays a significant part in our understanding of stellar evolution. It is extremely difficult to visually represent or model ionised nebula, requiring astronomers to employ sophisticated modelling code to derive temperature, density and chemical composition. Existing codes are available that often require steep learning curves and produce models derived from mathematical functions. In this article we will introduce PyCross: PyCloudy Rendering Of Shape Software. This is a pseudo 3D modelling application that generates photoionisation models of optically thin nebulae, created using the Shape software. Currently PyCross has been used for novae and planetary nebulae, and it can be extended to Active Galactic Nuclei or any other type of photoionised axisymmetric nebulae. Functionality, an operational overview, and a scientific pipeline will be described with scenarios where PyCross has been adopted for novae (V5668 Sagittarii (2015) & V4362 Sagittarii (1994) and a planetary nebula (LoTr1). Unlike the aforementioned photoionised codes this application neither requires any coding experience, nor the need to derive complex mathematical models, instead utilising the select features from Cloudy / PyCloudy and Shape. The software was developed using a formal software development lifecycle, written in Python and will work without the need to install any development environments or additional python packages. This application, Shape models and PyCross archive examples are freely available to students, academics and research community on GitHub for download.

Two new nova shells associated with V4362 Sagittarii and DO Aquilae

“…To manage condensations and more complex structures associated with nova shells there are several available 3D or pseudo 3D codes available, notably RAINY3D (Moraes & Diaz 2011, 2009, pyCloudy (Morisset 2013), pyCROSS (Fitzgerald et al 2020) and MOCASSIN (Ercolano et al 2003).…”

Shock shaping? Nebular Spectroscopy of Nova V906 Carinae

“…In order to refine the parameter space for deriving solutions to shell temperatures and densities we used the photoionisation code C version 17.00 (Ferland et al 2017), as well as several python wrappers available for it, namely C Morisset (2013), N Luridiana et al (2015) for diagnostics and, finally, CROSS (Fitzgerald et al 2020) that pairs SHAPE and C…”

“…Despite the difficulties in constraining the system, we wanted to simulate the ionisation structure of a purely photoionised look at the V906 Car shell at about a year post maximum. We used the above diagnostic information, including morphology, kinematics, temperature and densities, and with C (Fitzgerald et al 2020) at hand we model the ionisation structure of the nova shell, see Figure 11. Here, in this model neutral H is seen to occupy the entire shell, with neutral C and Fe brightest in the equatorial region.…”

The Formation of Very Massive Stars in Early Galaxies and Implications for Intermediate Mass Black Holes

“…ionic emission data from the CHIANTI database (Dere et al 1997;Landi et al 2012). Its chief limitation is that it is largely constrained to modelling environments in 1-D and/or assuming spherical symmetry (though see, e.g., Morisset 2013;Fitzgerald et al 2020, for recent efforts to extend its implementation to pseudo-3D problems). For this reason, and because we do not follow the stellar evolution of each formed star in detail, we must make a number of simplifying approximations in using cloudy to estimate the impact of ionising feedback.…”