230712 - IC1318 Gamma Cygni (Sadr region) cloud complex - "Butterfly" nebula
|
click image to enlarge.
|
ASTRO:
type=Emission Nebula (HII Region) mag=2.2 const=Cygnus dist=4900 ly size=58 ly IMAGE: location=EB Driveway BrtlCls=4 moon=25%, WnCr exposure=CMOS OSC; 42x300s (3.5h), Gain110 EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=ES102 w0.8x rdcr, F=571mm, f/5.6 filter=Optolong L-eXtreme Duo NB mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, APT, PHD2, processing=PixInsight, PhotoshopCC, RCAstro, LrC |
|
The Sadr Region (also known as IC 1318, or the Gamma Cygni Nebula) is a diffuse emission nebula surrounding the star known by the proper name Sadr, or "Gamma" (γ) Cygni. (γ is the 3rd letter of the Greek alphabet; indicating this is the 3rd brightest star inside the IAU constellation boundaries.) Sadr is located at the center of the asterism called, The Northern Cross, or called by its accepted IAU constellation name, Cygnus (the Swan). In this image, Sadr is high-lighted with an artificially added starburst. Filling the left part of the frame and shaped like two glowing cosmic wings divided by a long dark dust lane, IC 1318's popular name is understandably The Butterfly Nebula. The bright and diffuse "wings" of the butterfly are emission nebulae, receiving their energy to emit light from the energetic radiation and stellar winds of Sadr. The field of view in this image spans about 3 degrees (six Full Moons) of the sky. The distance to star Gamma Cygni is around 1800 light-years, but the nebula resides further away at appx 4900 ly.
With an apparent visual magnitude of 2.2, Gamma Cygni is among the brighter stars visible in the night sky. The stellar classification of this star is F8 Iab, indicating that it has reached the supergiant stage of its stellar evolution. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It shows some unusual dynamic features, including variations in radial velocity (expansion and contraction of the outer limits of its corona) of up to 2 km/s, occurring on a time scale of 100 days or more. Indeed, on the Hertzsprung–Russell scale diagram, Gamma Cygni lies close to the instability strip and its spectrum is markedly like that of a Cepheid variable.
Compared to the Sun this is an enormous star, with 12 times the Sun's mass and about 150 times the Sun's radius. It is emitting over 33,000 times as much energy as the Sun, at an effective temperature of 6,100 K in its outer envelope. This temperature is what gives the star the characteristic yellow-white hue of an F-type star. Massive stars like this one consume their nuclear fuel much more rapidly than the Sun, so the estimated age of this star is only about 12 million years old; fairly young as stars go.
While generally not visible with the naked unaided eye, the nebulous regions around Sadr are still considered to be bright (for nebulae). It is for this reason the Butterfly is a favorite of amateur astrophotographers.
With an apparent visual magnitude of 2.2, Gamma Cygni is among the brighter stars visible in the night sky. The stellar classification of this star is F8 Iab, indicating that it has reached the supergiant stage of its stellar evolution. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It shows some unusual dynamic features, including variations in radial velocity (expansion and contraction of the outer limits of its corona) of up to 2 km/s, occurring on a time scale of 100 days or more. Indeed, on the Hertzsprung–Russell scale diagram, Gamma Cygni lies close to the instability strip and its spectrum is markedly like that of a Cepheid variable.
Compared to the Sun this is an enormous star, with 12 times the Sun's mass and about 150 times the Sun's radius. It is emitting over 33,000 times as much energy as the Sun, at an effective temperature of 6,100 K in its outer envelope. This temperature is what gives the star the characteristic yellow-white hue of an F-type star. Massive stars like this one consume their nuclear fuel much more rapidly than the Sun, so the estimated age of this star is only about 12 million years old; fairly young as stars go.
While generally not visible with the naked unaided eye, the nebulous regions around Sadr are still considered to be bright (for nebulae). It is for this reason the Butterfly is a favorite of amateur astrophotographers.