3D Astrophysics Newsletter

2017_8_1_yan8.1 Today´s new entry:

Towards a three-dimensional distribution of the molecular clouds in the Galactic Centre

Qing-Zeng Yan, A. J. Walsh, J. R. Dawson, J. P. Macquart, R. Blackwell, M. G. Burton, G. Rowell, Bo Zhang, Ye Xu, Zheng-Hong Tang, P. J. Hancock

Abstract: We present a study of the three-dimensional structure of the molecular clouds in the Galactic Centre (GC) using CO emission and OH absorption lines. Two CO isotopologue lines, 12CO (J=1-0) and 13CO (J=1-0), and four OH ground-state transitions, surveyed by the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH), contribute to this study. We develop a novel method to calculate the OH column density, excitation temperature, and optical depth precisely using all four OH lines, and we employ it to derive a three-dimensional model for the distribution of molecular clouds in the GC for six slices in Galactic latitude. The angular resolution of the data is 15.5 arcmin, which at the distance of the GC (8.34 kpc) is equivalent to 38 pc. We find that the total mass of OH in the GC is in the range 2400-5100 Solar mass. The face-on view at a Galactic latitude of b=0° displays a bar-like structure with an inclination angle of 67.5±2.1° with respect to the line of sight. No ring-like structure in the GC is evident in our data, likely due to the low spatial resolution of the CO and OH maps.

Journal: Monthly Notices of the Royal Astronomical Society (MNRAS), accepted
 Accepted (07 July 2017), 15 pages, 12 figures
URL of preprint: https://arxiv.org/pdf/1707.02378.pdf
Submitted by: Qing-Zeng Yan


3D Astrophysics Newsletter

Summary of the first half of 2017:

7.1 Catching a Grown-Up Starfish Planetary Nebula: I. Morpho-Kinematical study of PC 22
Sabin L., Gómez-Muñoz M. A., Guerrero M. A., Zavala S., Ramos-Larios G., Vázquez R., Corral L., Blanco Cárdenas M.W., Guillén P.F., Olguín L., Morisset C., Navarro S.

7.2 Cosmography and Data Visualization
Daniel Pomarede, Helene M. Courtois, Yehuda Hoffman, R. Brent Tully

7.3 The Fabric of the Universe: Exploring the cosmic web in 3D prints and woven textiles
Benedikt Diemer & Isaac Facio

7.4 Modelling the 3D physical structure of astrophysical sources with GASS
David Quénard, Sandrine Bottinelli, Emmanuel Caux

7.5 Hybrid polygon and hydrodynamic nebula modeling with multi-waveband radiation transfer in astrophysics
Wolfgang Steffen & Nico Koning

7.6 Reconstruction of a helical prominence in 3D from IRIS spectra and images
B. Schmieder, M. Zapiór, A. López Ariste, P. Levens, N. Labrosse, R. Gravet

3D Astrophysics Newsletter

2017_7_7_vohl7.7 Today´s new entry:

Real-time colouring and filtering with graphics shaders

Dany Vohl, Christopher J. Fluke, David G. Barnes, Amr H. Hassan

Abstract: Despite the popularity of the Graphics Processing Unit (GPU) for general purpose computing, one should not forget about the practicality of the GPU for fast scientific visualisation. As astronomers have increasing access to three dimensional (3D) data from instruments and facilities like integral field units and radio interferometers, visualisation techniques such as volume rendering offer means to quickly explore spectral cubes as a whole. As most 3D visualisation techniques have been developed in fields of research like medical imaging and fluid dynamics, many transfer functions are not optimal for astronomical data. We demonstrate how transfer functions and graphics shaders can be exploited to provide new astronomy-specific explorative colouring methods. We present 12 shaders, including four novel transfer functions specifically designed to produce intuitive and informative 3D visualisations of spectral cube data. We compare their utility to classic colour mapping. The remaining shaders highlight how common computation like filtering, smoothing and line ratio algorithms can be integrated as part of the graphics pipeline. We discuss how this can be achieved by utilising the parallelism of modern GPUs along with a shading language, letting astronomers apply these new techniques at interactive frame rates. All shaders investigated in this work are included in the open source software
shwirl (Vohl 2017).

Journal: Monthly Notices of the Royal Astronomical Society (MNRAS),  accepted for publication
Comments: Accepted on 30 June 2017, 24 pages, 19 figures, 14 algorithms, 1 table
URL: Download preprint
Submitted by: Dany Vohl