But recent observations have shown this is an illusion, as the NGC cluster is actually not a star cluster but an extended stellar group of four cluster components within the Gemini OB1 association. The cluster complex formed within NGC during a lingering starburst event some 5 million years ago. The bright emission nebula NGC appears like a miniature Orion Nebula and offers something for observers with any size telescope. The ghostly glow is most comfortably viewed through binoculars under a dark sky.
Sharpless 2— This peculiar kidney bean-shaped star-forming region lies some 6, light-years away in the Perseus spiral arm of our Milky Way. It lies in the direction of the galactic anticenter, just north of open cluster M36 in Auriga. In optical images, the nebula appears as a small and nearly structureless glowing cloud whose northern half shines more brightly than its southern half.
A dark lane of dust separates the two hemispheres, making it look as if the brighter section is being mirrored in a pool of water. Sh 2— is a fine target for those using inch and larger telescopes, which at x will show the bifurcated nebula as a pale 10' oval glow with a dark band separating its two disparate halves. But skilled observers have spied the nebula using a 5-inch telescope, so try your luck.
NGC Born from a very dense and dusty environment some 7, light-years away, the nebula sports a central hollow cleared by radiation from a young, hot trapezium of stars and outer looping bands of dust and gas that glow with molecules of polycyclic aromatic hydrocarbons; these ubiquitous molecules are known to astronomers as the prebiotic roots of life. Actually, data from the Two Micron All Sky Survey have shown the nebula does not harbor a single cluster but a double cluster: the NGC cluster and a much fainter stellar gathering to the south near the edge of the hollow.
Through a 5-inch telescope at powers ranging from x to x, the nebula has a smooth, milky sheen that gradually, then rapidly, fades away from the bright cluster core. In this case, on the lip of a dense molecular cloud. High magnifications will show two bright horns of gas northwest of the exciting star against a wider and less-condensed skirt of light. This tiny 2' mote of emission nebulosity all but pleads to be noticed among the rich stellar sands of the Vulpecula Milky Way. Little is known about its true physical nature.
Amateur astronomers have done admirably in imaging it, and those who have spied it visually have been astounded by its tiny intensity. Its bright center shines around 11th magnitude and has a flattened appearance, oriented east-west. An expansive emission and reflection nebula near 5th-magnitude 12 Vulpeculae, NGC surrounds the 7th-magnitude open cluster NGC , whose Trapezium-like core of hot central stars excites the nebula while clearing away a central cavity. With imagination, the scene looks like a wilted rose melting in the heat.
Others using twice that aperture have reported seeing finer details. This small 7' and dim emission and reflection nebula lies some 3, light-years away in northwestern Sagitta. In terms of color, the scene is most peculiar. The pink emission nebula appears to lie in a nest of blue reflection nebulosity, through which threads of dark nebulae streaming off the dark river weave in and out, as if trying to sew the two glows together. IC I call it the Black Waterfall because in images, multiple rivulets of dark matter cascade across its face like feathery water.
IC is but a ridge of gaseous emission with dark clouds of cool gas invading its borders. A dark absorption cloud LDN sweeps through this entire area like a Death Eater from the Harry Potter series, sucking light from distant stars and rendering them invisible.
Through a 5-inch at 22x, IC is a pale wash of rectangular light sweeping past a 7th-magnitude central illuminating star. Through an inch at x, it appears as three irregular parallel strips of pale light stretching roughly east-west and separated by dark nebulosity.
NGC is a simple sight — essentially three fragmented patches of dim light forming a triangle of uniform glows. The brightest patch surrounds a roughly 9th-magnitude star. As an example, in M42 a single one of the young stars in the Trapezium is sufficiently hot to cause the entire nebula to glow. This turnaround takes less than. Neutral hydrogen areas are called HI regions and areas of positively charged hydrogen ions are called HII regions.
You probably recall that emission nebulae are commonly referred to as "HII regions". Electrons that have been stripped from the hydrogen atoms can rejoin atoms and resume the process of Balmer decays all over again. This ongoing process is what gives us the reddish-colored nebulae. So that's the technical explanation. You were warned! Jack Kramer Most of us know that radiation from a hot star causes hydrogen gas in a nebula to glow with a pinkish-red color, plus there are often other colors due to different elements.
LCAS is a c 3 not-for profit organization chartered to promote the interest and participation in astronomy. The light source for a planetary nebula is the dying star has exposed its core and has lit up the surrounding clouds of dust and gas. Evant Horizon.
An Emission Nebula is a nebula that shines brightly naturally as compared to that of a Reflection Nebula that is lit up by light from an external source. An emission nebula is lit up by an internal source. Diffuse Nebula can also refer to Reflection Nebulae as well. A nebula can be classified as more than one type, take the Trifid Nebula , it has elements of both Emission and Reflection Nebula.
Some parts emit their own light and the other parts reflect the light. The main difference between an Emission Nebula and a Reflection Nebula is that Emissions create their own light whereas a Reflection is lit up by reflecting light that hits it. It reflects light from Rigel in the neighbouring Orion constellation.
The opposite of an Emissions Nebula is a dark nebula. The difference between an Emissions Nebula and a Dark Nebula is that the latter is not lit up either internally or externally. It is dark hence its name. The Great Orion Nebula is one of the closest star forming region to Earth. It was speculated that the Sun was born in this nebula some five billion years ago.
Earth would have been born in a similar sort of nebula if this one wasn't it. The nebula is visible with the naked eye on a clear night.
You'd only be able to see a blur with a good pair of visual aids.
0コメント