211128 - IC1396 "Elephant Trunk" nebula
|
click image to enlarge
|
ASTRO:
type=HII emission nebula const=Cepheus mag=8.8 dist=2400 ly size=130 ly IMAGE: location=EB Driveway BrtlCls=4 moon=34% WnCr exposure=DSLR OSC: 26x420s (3.0h), ISO3200 palette=HOO EQUIPMENT: camera=Nikon D90 (mod) optics=ES102 w0.65x rdcr. eff. F=464mm, f/4.55 filter=Radian Triad Quad NB mount=Celestron AVX guiding= Orion 60x240mm, ZWO ASi244MC SOFTWARE: acquisition=Stellarium, APT, PHD2, processing=DSS, PhotoshopCC, GradXT, StarNet++, TopazDeNoiseAI, LrC |
|
Like an illustration in a galactic just-so story, the Elephant Trunk Nebula winds through the emission region and young star cluster complex IC 1396, in the high and far off constellation Cepheus. Just the cosmic Elephant Trunk itself is over 20 light-years long. This detailed telescopic view features the bright swept-back ridges and pockets of hot interstellar gas and dust that abound in the region. But the darker, tendril-shaped clouds contain the raw material where star formation occurs. The earliest stage of such formation is protostars; which scientists have found strong evidence these embryonic precursors to stars are nestled inside the darkest, most dense clouds.
Appx 2,400 light-years distant, the IC 1396 complex covers a large region on the sky, spanning over 5 arc-degrees. Following the math at that distance, it spans a whopping 130 light-years, roughly 130,000 times the diameter of our solar system. The apparent view within the bounds of this image spans a 2 arc-degree wide field of view; about the size of 4 full Moons. Amusingly, the dark shapes below and to the right of the outstretched Elephant's Trunk, are known as "The Caravan".
The Elephant Trunk is a concentration of interstellar gas and dust within the much larger ionized gas region. The prominent part of the nebula located at the end of the elephant's trunk is the dark, dense globule IC 1396A. It is commonly called the Elephant Trunk because of its appearance at visible light wavelengths of a dark patch with a bright, sinuous rim. The bright rim is the surface of the dense cloud which is being illuminated and ionized from behind by a very bright, massive star, HD 206267 (shown here above the rim with a simulated starburst). The entire IC 1396 region is ionized by that massive star, except for The Caravan, which because of its thick density remains dark as it protects itself from the star's harsh ultraviolet rays.
The Elephant Trunk is known to be a site of star formation, containing several very young stars (less than 100,000 yrs old) discovered in 2003 through infrared astrometry. Two older stars (a couple million years - still young by astronomical standards) are present in a small, circular cavity in the head of the globule. Current theory outlines that stellar-winds from these stars have pushed open the cavity. The combined action of the intense light and strong interstellar winds from the massive star HD 206267 ionizing and compressing inward on the outside of the cloud is pushing against winds from the younger stars pushing from the center outward; and the struggle between those opposing forces is creating a very high compression of the gas and dust inside the nebula. The resulting pressure inside the cloud is believed to be triggering the current generation of protostars.
HD 206267 is an apparent triple star system. Two of the members of that trio form a binary pair that are caught in each others' gravitational fields, rapidly orbiting around each other every 3.7 days. A third member lies further away. It is unclear whether this third member is gravitationally bound to the binary pair. It may simply be spatially located within our line of sight behind the binary. Regardless, the trio is emitting a stellar wind that reaches an exceptional velocity of over 3,000 km/s, ...among the strongest of any measured for stars of this type. All three of these stars are massive, and the intense ultraviolet radiation they give off ionizes the gas of the entire visible boundary of IC 1396. They are causing dense compression globules to form, eventually leading to further star formation. Scientists have found evidence the stellar wind produced by these stars is strong enough to strip smaller, nearby stars of their protoplanetary disks.
At magnitude 8.8, the Elephant Trunk nebula is relatively bright. As such, it is a favorite for amateur astronomers to capture photographically. In this example, a quadruple-narrowband filter was used to 'narrow-down' and separate the dominant frequencies of light. Then colors were "mapped" (assigned) that represent different atomic elements prevalent within the nebula cloud. Ionized hydrogen atoms are mapped to red as they emit their characteristic wavelength by attracting electrons, releasing photons of light, and settling down into their less energetic, un-ionized state. Similarly, ionized oxygen is mapped to blue as it emits its characteristic wavelength in the same way. The color scheme, often referred to as the "HOO" (hydrogen-oxygen-oxygen) palette of colors, is a derivative of the very popular and widely used "SHO" (sulfur-hydrogen-oxygen) palette which was developed by NASA to improve visual contrast between different atomic elements for study by professional scientific astronomers. Because the HOO palette is also quite beautiful, it has become a favorite image processing style among amateur astrophotographers.
Appx 2,400 light-years distant, the IC 1396 complex covers a large region on the sky, spanning over 5 arc-degrees. Following the math at that distance, it spans a whopping 130 light-years, roughly 130,000 times the diameter of our solar system. The apparent view within the bounds of this image spans a 2 arc-degree wide field of view; about the size of 4 full Moons. Amusingly, the dark shapes below and to the right of the outstretched Elephant's Trunk, are known as "The Caravan".
The Elephant Trunk is a concentration of interstellar gas and dust within the much larger ionized gas region. The prominent part of the nebula located at the end of the elephant's trunk is the dark, dense globule IC 1396A. It is commonly called the Elephant Trunk because of its appearance at visible light wavelengths of a dark patch with a bright, sinuous rim. The bright rim is the surface of the dense cloud which is being illuminated and ionized from behind by a very bright, massive star, HD 206267 (shown here above the rim with a simulated starburst). The entire IC 1396 region is ionized by that massive star, except for The Caravan, which because of its thick density remains dark as it protects itself from the star's harsh ultraviolet rays.
The Elephant Trunk is known to be a site of star formation, containing several very young stars (less than 100,000 yrs old) discovered in 2003 through infrared astrometry. Two older stars (a couple million years - still young by astronomical standards) are present in a small, circular cavity in the head of the globule. Current theory outlines that stellar-winds from these stars have pushed open the cavity. The combined action of the intense light and strong interstellar winds from the massive star HD 206267 ionizing and compressing inward on the outside of the cloud is pushing against winds from the younger stars pushing from the center outward; and the struggle between those opposing forces is creating a very high compression of the gas and dust inside the nebula. The resulting pressure inside the cloud is believed to be triggering the current generation of protostars.
HD 206267 is an apparent triple star system. Two of the members of that trio form a binary pair that are caught in each others' gravitational fields, rapidly orbiting around each other every 3.7 days. A third member lies further away. It is unclear whether this third member is gravitationally bound to the binary pair. It may simply be spatially located within our line of sight behind the binary. Regardless, the trio is emitting a stellar wind that reaches an exceptional velocity of over 3,000 km/s, ...among the strongest of any measured for stars of this type. All three of these stars are massive, and the intense ultraviolet radiation they give off ionizes the gas of the entire visible boundary of IC 1396. They are causing dense compression globules to form, eventually leading to further star formation. Scientists have found evidence the stellar wind produced by these stars is strong enough to strip smaller, nearby stars of their protoplanetary disks.
At magnitude 8.8, the Elephant Trunk nebula is relatively bright. As such, it is a favorite for amateur astronomers to capture photographically. In this example, a quadruple-narrowband filter was used to 'narrow-down' and separate the dominant frequencies of light. Then colors were "mapped" (assigned) that represent different atomic elements prevalent within the nebula cloud. Ionized hydrogen atoms are mapped to red as they emit their characteristic wavelength by attracting electrons, releasing photons of light, and settling down into their less energetic, un-ionized state. Similarly, ionized oxygen is mapped to blue as it emits its characteristic wavelength in the same way. The color scheme, often referred to as the "HOO" (hydrogen-oxygen-oxygen) palette of colors, is a derivative of the very popular and widely used "SHO" (sulfur-hydrogen-oxygen) palette which was developed by NASA to improve visual contrast between different atomic elements for study by professional scientific astronomers. Because the HOO palette is also quite beautiful, it has become a favorite image processing style among amateur astrophotographers.