Starship Asterisk*

http://en.wikipedia.org/wiki/Karl_Ludwig_Harding wrote:

<<Karl Ludwig Harding (September 29, 1765 – August 31, 1834) was a German astronomer notable for having discovered the asteroid 3 Juno (1804), the Helix Nebula (c. 1824) and three comets.

Harding was born in Lauenburg. He was educated at the University of Göttingen, where he studied theology. In 1796 Johann Hieronymus Schröter hired Harding as a tutor for his son. Schröter was an enthusiastic astronomer, and Harding was soon appointed observer and inspector in his observatory.

In 1804, Harding discovered Juno at Schröter's observatory. He then went to Göttingen to assist Carl Friedrich Gauss. There he was professor of astronomy.

The crater Harding on the Moon is named after him, and so is the asteroid 2003 Harding.>>

biddie67 wrote:Only 700 LY away ... so close yet so far away ... I wonder if I could spot this nebula with just my binoculars ...

http://en.wikipedia.org/wiki/Planetary_nebula wrote:
Current issues in planetary nebula studies

<<A long standing problem in the study of planetary nebulae is that in most cases, their distances are very poorly determined. For the nearest planetary nebulae, it is possible to determine distances by measuring their expansion parallax. High resolution observations taken several years apart will show the expansion of the nebula perpendicular to the line of sight, while spectroscopic observations of the Doppler shift will reveal the velocity of expansion in the line of sight. Comparing the angular expansion with the derived velocity of expansion will reveal the distance to the nebula.

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic. It is believed that interactions between material moving away from the star at different speeds gives rise to most observed shapes. However, some astronomers believe that double central stars must be responsible for the more complex and extreme planetary nebulae. Several planetary nebulae have been shown to contain strong magnetic fields, something which has been hypothesized by Grigor Gurzadyan in the 1960s. Magnetic interactions with ionized gas could be responsible for shaping some planetary nebulae.

There are two methods of determining metal abundances in nebulae. These rely on different types of spectral lines—recombination lines and collisionally excited lines. Large discrepancies are sometimes seen between the results derived from the two methods. Some astronomers explain this by presence of small temperature fluctuations within planetary nebulae; others claim that the discrepancies are too large to be explained by temperature effects, and hypothesize the existence of cold knots containing very little hydrogen to explain the observations. However, no such knots have yet been observed.>>

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic.

Pentaxian wrote:

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic.

What I refer to in this beautiful image of the Helix Nebula as "blobs" that inhabit the inner ring (approx), and appear as globular entities with a trailing "robe" in their shadows, what are they called, and what do they consist of? >o I've of course seen them in many images that are similar, or not, such as in the "horsehead nebula".

Dacio wrote:I painted The Helix on 2009, check it out here

Céline Richard wrote:Thank you Dacio for posting the video the "Hubble Minute"
From above, the Helix Nebula looks like a little to the interior of the Yellowstone's volcano, so beautiful!

Dacio wrote:You are right, the Helix nebula does look like something out of Yellowstone, and I know what you are referring to:The Grand Prismatic Spring.
If I believed in psychics (and I don't), I would think you are one because I was working last week on a draft for a painting of "The Grand Prismatic Spring".