2015 in review

The WordPress.com stats helper monkeys prepared a 2015 annual report for this blog.

Here’s an excerpt:

A San Francisco cable car holds 60 people. This blog was viewed about 2,700 times in 2015. If it were a cable car, it would take about 45 trips to carry that many people.

Click here to see the complete report.

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3D Structure of Planetary Nebulae

pacificRimThis week, December 14-17, the 11th Pacific Rim Conference on Stellar Astrophysics has been held in Hong Kong. A substantial section of the conference was dedicated to planetary nebulae. Here is a link to the video of my talk on “The 3D Structure of Planetary Nebulae” which might be of interest to the 3D Astrophysics community.

3D Astrophysics Newsletter

2015_danehkar_2.png4.7 Today´s new entry:

Discovery of Collimated Bipolar Outflows in the Planetary Nebula TH 2-A

Ashkbiz Danehkar

Abstract: We present a comprehensive set of spatially resolved, integral field spectroscopic mapping of the Wolf–Rayet planetary nebula Th 2-A, obtained using the Wide Field Spectrograph on the Australian National University 2.3-m telescope. Velocity-resolved Hα channel maps with a resolution of 20 km s−1 allow us to identify different kinematic components within the nebula. This information is used to develop a three-dimensional morpho-kinematic model of the nebula using the interactive kinematic modeling tool shape. These results suggest that Th 2-A has a thick toroidal shell with an expansion velocity of 40±10 km s−1 , and a thin prolate ellipsoid with collimated bipolar outflows toward its axis reaching velocities in the range of 70–110 km s−1 , with respect to the central star. The relationship between its morpho-kinematic structure and peculiar [WO]-type stellar characteristics deserves further investigation.

Journal: The Astrophysical Journal, 815, 1, article 35
URL to paper: http://iopscience.iop.org/article/10.1088/0004-637X/815/1/35
Submitted by: Ashkbiz Danehkar

The bounty is in the detail

pottery

Part of an inscription on ancient pottery is on a missing piece.

To what level of detail should one try to take the 3D reconstruction of an observed nebula? Is it worth the effort to reproduce every little brightness variation or the shape and position of each cloudlet? It may be argued that this is like painting the details of the clouds in the sky and more of an aesthetic value than for scientific insight. Or is it more like registering the location and shape of every piece of shattered pottery in an archaeologic dig that provides valuable information on the ancient society once the object is restored?

Recent experience shows that adding small-scale details to an astronomical reconstruction is more like putting together an ancient vase that was broken into many pieces. Even in astronomy the bounty, not only the devil, sometimes is in the detail. Here are a two examples of how the attention to detail in 3D reconstructions can reveal unexpected scientific insight. Continue reading

3D Astrophysics Newsletter

2015_durech4.6 Today´s new entry:

Asteroids@home – A BOINC distributed computing project for asteroid shape reconstruction

Josef Durech, Josef Hanus, Radim Vanco

Abstract: We present the project Asteroids@home that uses distributed computing to solve the time-consuming inverse problem of shape reconstruction of asteroids. The project uses the Berkeley Open Infrastructure for Network Computing (BOINC) framework to distribute, collect, and validate small computational units that are solved independently at individual computers of volunteers connected to the project. Shapes, rotational periods, and orientations of the spin axes of asteroids are reconstructed from their disk-integrated photometry by the lightcurve inversion method.

Journal: Astronomy and Computing 13 (2015) 80-84
URL of preprint: http://arxiv.org/abs/1511.08640
Submitted by: Josef Durech