Stars, Dust, Pillars, and Jets in the Pelican Nebula

What dark structures arise within the Pelican Nebula? On the whole, the nebula appears like a bird (a pelican) and is seen toward the constellation of a different bird: Cygnus, a Swan. But inside, the Pelican Nebula is a place lit up by new stars and befouled by dark dust. Smoke-sized dust grains start as simple carbon compounds formed in the cool atmospheres of young stars but are dispersed by stellar winds and explosions. Two impressive Herbig-Haro jets are seen emitted by the star HH 555 on the right, and these jets are helping to destroy the light year-long dust pillar that contains it. Other pillars and jets are also visible. The featured image was scientifically-colored to emphasize light emitted by small amounts of heavy elements in a nebula made predominantly of the light elements hydrogen and helium. The Pelican Nebula (IC 5067 and IC 5070) is about 2,000 light-years away and can be found with a small telescope to the northeast of the bright star Deneb.

from NASA https://ift.tt/8Z1XKwc

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The Galactic Center in Radio from MeerKAT

What's happening at the center of our galaxy? It's hard to tell with optical telescopes since visible light is blocked by intervening interstellar dust. In other bands of light, though, such as radio , the galactic center can be imaged and shows itself to be quite an interesting and active place . The featured picture shows the latest image of our Milky Way's center by the MeerKAT array of 64 radio dishes in South Africa . Spanning four times the angular size of the Moon (2 degrees ), the image is impressively vast, deep, and detailed. Many known sources are shown in clear detail, including many with a prefix of Sgr, since the galactic center is in the direction of the constellation Sagittarius . In our Galaxy's Center lies Sgr A , found here in the image center, which houses the Milky Way's central supermassive black hole. Other sources in the image are not as well understood, including the Arc , just to the left of Sgr A , and numerous filamentary threads....

Why is the sky near Antares and Rho Ophiuchi so colorful, yet dusty? The colors result from a mixture of objects and processes. Fine dust -- illuminated by starlight -- produces blue reflection nebulae . Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae . Backlit dust clouds block starlight and so appear dark . Antares , a red supergiant and one of the brighter stars in the night sky , lights up the yellow-red clouds on the upper right of the featured image. The Rho Ophiuchi star system lies at the center of the blue reflection nebula on the left, while a different reflection nebula, IC 4605 , lies just below and right of the image center. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum . from NASA https://ift.tt/fdIYn7J

The Observable Universe

How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you -- is the observable universe . In light, the farthest we can see comes from the cosmic microwave background , a time 13.8 billion years ago when the universe was opaque like thick fog. Some neutrinos and gravitational waves that surround us come from even farther out, but humanity does not yet have the technology to detect them. The featured image illustrates the observable universe on an increasingly compact scale , with the Earth and Sun at the center surrounded by our Solar System , nearby stars , nearby galaxies , distant galaxies , filaments of early matter , and the cosmic microwave background . Cosmologists typically assume that our observable universe is just the nearby part of a greater entity known as "the universe" where the same physics applies. However, there are several lines of popular but spe...

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