NGC 7293 (C63) - Helix Nebula
NGC 7293 (also designated Caldwell 63) is a planetary nebula in the constellation Aquarius. It has an apparent visual magnitude of 7.6 and its angular diameter is 25 arc-minutes. NGC 7293 lies at an estimated distance of 650 light years, spanning about 0.8 parsecs (2.5 light-years) in diameter. The Equinox 2000 coordinates are RA= 22h 29.6m, Dec= -20° 50´ which makes NGC 7293 best seen during the autumn. The Caldwell Autumn Star Chart shows the position of all Caldwell objects visible during that season. As one of the more famous objects in the Caldwell Catalog, it is commonly known as the Helix Nebula.
The image above shows the uncropped view of NGC 7293 through the Astro-Physics 130EDF APO Refractor (130mm, f/6, fl=780mm).
NGC 7293 is thought to be shaped like a prolate spheroid with strong density concentrations toward the filled disk along the equatorial plane. The diameter of the inner disk is 8×19 arcmin (0.52 pc); the outer torus is 12×22 arcmin (0.77 pc); and the outer-most ring is about 25 arcmin (1.76 pc). We see the outer-most ring as flattened on one side due to its colliding with the ambient interstellar medium. Expansion of the whole planetary nebula structure is estimated to have occurred in the last 6,560 years, and 12,100 years for the inner disk. (this description from Wikipedia)
Planetary nebulae are formed towards the end of life of an intermediate mass star that has thrown off its outer atmosphere (the nebula) exposing it to a very hot and luminous core. The ultraviolet light from the core energizes the shell of gas causing the nebula to glow. The period when a planetary nebula is visible around its core star is relatively short lived - estimated to be about 10,000 years. For more on planetary nebulae see: Wikipedia.
For additional information on NGC 7293, see the Caldwell Catalog as well as specific entries for NGC 7293 in Wikipedia and SEDS.
Technical Details
- Object: NGC 7293
- Other Names: Caldwell 63, Helix Nebula
- Object Type: planetary nebula
- Object Data: Apparent Magnitude = 7.6, Angular Size = 25 arc-minutes
- Object Position (Equinox 2000): RA= 22h 29.6m, Dec= -20° 50´, Constellation = Aquarius
- Date: 2019 Sep 28
- Location: Bifrost Astronomical Observatory, Portal, AZ
- Telescope: Astro-Physics 130EDF APO Refractor (130mm, f/6, fl=780mm)
- Mount: Astro-Physics 1200GTO
- Camera: ZWO ASI183MC Pro
- Field of View: 58.2' x 38.8' at 0.63 arc-sec/pixel
- Exposure: 22 x 300 sec (= 1 hr 20 min), f/6, Unit Gain, Temp.=-20° C
- File Name: NGC7293-2019Sep28-1a.jpg
- Processing (Deep Sky Stacker): using Lights, Darks and Flats
- Processing (Photoshop CC): Curves, Levels, Layer Masks, Vibrance, Noise Reduction
- Original Image Size: 5496 × 3672 pixels (20.2 MP); 18.3" x 12.3" @ 300 dpi
- Rights: Copyright 2019 by Fred Espenak. All Rights Reserved. See: Image Licensing.