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Contains:  Helix nebula, NGC 7293
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NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko
NGC7293 Helix nebula HaO3 bicolor
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NGC7293 Helix nebula HaO3 bicolor

Technical card


Dates:Sept. 30, 2018

Frames:
Baader Ha 7nm 36mm: 45x300" bin 1x1
Baader OIII 8.5nm 36mm: 54x300" bin 1x1

Integration: 8.2 hours

Avg. Moon age: 20.13 days

Avg. Moon phase: 70.83%


Basic astrometry details

Astrometry.net job: 3006621

RA center: 22h 29' 38"

DEC center: -20° 50' 13"

Pixel scale: 2.141 arcsec/pixel

Orientation: 175.257 degrees

Field radius: 0.841 degrees


Resolution: 2000x2000

Locations: Remote observatory, Kiev, Ukraine

Data source: Own remote observatory

Remote source: Non-commercial independent facility

Description

The Helix Nebula, also known as NGC 7293, is a planetary nebula located in the constellation Aquarius. This object is one of the closest to the Earth of all the bright planetary nebulae. The distance, measured by the Gaia mission, is 655±13 light-years. It is similar in appearance to the Cat's Eye Nebula and the Ring Nebula, whose size, age, and physical characteristics are similar to the Dumbbell Nebula, varying only in its relative proximity and the appearance from the equatorial viewing angle. The Helix Nebula has sometimes been referred to as the "Eye of God" in pop culture, as well as the "Eye of Sauron".

The Helix Nebula is an example of a planetary nebula, formed by an intermediate to low-mass star, which sheds its outer layers near the end of its evolution. Gases from the star in the surrounding space appear, from our vantage point, as if we are looking down a helix structure. The remnant central stellar core, known as the central star of the planetary nebula, is destined to become a white dwarf star. The observed glow of the central star is so energetic that it causes the previously expelled gases to brightly fluoresce.

The nebula is in the constellation of Aquarius, and lies about 650 light-years away, spanning about 0.8 parsecs (2.5 light-years). Its age is estimated to be 10600+2300
−1200 years, based on its measured expansion rate of 31 km·s−1.

The Helix Nebula is thought to be shaped like a prolate spheroid with strong density concentrations toward the filled disk along the equatorial plane, whose major axis is inclined about 21° to 37° from our vantage point. The size of the inner disk is 8×19 arcmin in diameter (0.52 pc); the outer torus is 12×22 arcmin in diameter (0.77 pc); and the outer-most ring is about 25 arcmin in diameter (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. Spectroscopically, the outer ring's expansion rate is 40 km/s, and about 32 km/s for the inner disk.

A closer view of knots in the nebula
The Helix Nebula was the first planetary nebula discovered to contain cometary knots. Its main ring contains knots of nebulosity, which have now been detected in several nearby planetary nebulae, especially those with a molecular envelope like the Ring nebula and the Dumbbell Nebula. These knots are radially symmetric (from the CS) and are described as "cometary", each centered on a core of neutral molecular gas and containing bright local photoionization fronts or cusps towards the central star and tails away from it. All tails extend away from the PNN in a radial direction. Excluding the tails, each knot is approximately the size of the Solar system. There are about 40,000 cometary knots in the Helix Nebula.

The excitation temperature varies across the Helix nebula.[17] The rotational-vibrational temperature ranges from 1800 K in a cometary knot located in the inner region of the nebula are about 2.5'(arcmin) from the CS, and is calculated at about 900 K in the outer region at the distance of 5.6'.
(c) Wikipedia

Comments

Author

Sergiy_Vakulenko
Sergiy_Vakulenko
License: Attribution Creative Commons
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Revisions

  • NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko
    Original
  • Final
    NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko
    B
  • NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko
    C
  • NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko
    D

B

Description: Another bicolor cmbination

C

Description: Ha channel

D

Description: O3 channel

Sky plot

Sky plot

Histogram

NGC7293 Helix nebula HaO3 bicolor, 



    
        

            Sergiy_Vakulenko