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Affichage des articles dont le libellé est Dust. Afficher tous les articles
Affichage des articles dont le libellé est Dust. Afficher tous les articles

07/08/2023

ASTRONOMY - The Pelican Nebula in Gas, Dust, and Stars

 2023 August 7

Mulitple filaments of dark brown run from top to bottom while
a bright orange dome with small pillars occurs on the bottom right. 
In the background is a blue-glowing gas. Stars dot the frame.
Please see the explanation for more detailed information.

The Pelican Nebula in Gas, Dust, and Stars
Credit & Copyright: Abe Jones

Explanation: The Pelican Nebula is slowly being transformed. IC 5070 (the official designation) is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds. The featured picture was produced in three specific colors -- light emitted by sulfurhydrogen, and oxygen -- that can help us to better understand these interactions. The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright orange on the right. Particularly dense tentacles of cold gas remain. Millions of years from now, the Pelican nebula, bounded by dark nebula LDN 935, might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.

19/10/2022

ASTRONOMY - A Galaxy Beyond Stars, Gas, Dust

 2022 October 19

The featured image shows distant spiral galaxy NGC 7497
in a field of foreground stars, gas, and dust. The foreground
gas and dust is in our own Milky Way galaxy and so well in 
front of the galaxy -- but appears to go right through it. 
Please see the explanation for more detailed information.

A Galaxy Beyond Stars, Gas, Dust
Image Credit & Copyright: Howard Trottier; Text: Emily Rice

Explanation: Do we dare believe our eyes? When we look at images of space, we often wonder whether they are "real", and just as often the best answer varies. In this case, the scene appears much as our eyes would see it, because it was obtained using RGB (Red, Green, Blue) filters like the cone cells in our eyes, except collecting light for 19 hours, not a fraction of a second. The featured image was captured over six nights, using a 24-inch diameter telescope in the Sierra Nevada Mountains, in CaliforniaUSA. The bright spiral galaxy at the center (NGC 7497) looks like it is being grasped by an eerie tendril of a space ghost, and therein lies the trick. The galaxy is actually 59 million light years away, while the nebulosity is MBM 54, less than one thousand light years away, making it one of the nearest cool clouds of gas and dust -- galactic cirrus -- within our own Milky Way Galaxy. Both are in the constellation of Pegasus, which can be seen high overhead from northern latitudes in the autumn.

11/10/2022

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

 2022 October 11

The featured image shows a close up of the Pelican Nebula
highlighted by several dark pillars, one of which spouts jets
on either side.
Please see the explanation for more detailed information.

Stars, Dust, Pillars, and Jets in the Pelican Nebula
Image Credit & Copyright: Adriano Almeida

Explanation: 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.

25/09/2019

Science & Technology - Astronomy picture of the day : The Pelican Nebula in Gas, Dust, and Stars

2019 September 25
See Explanation.  Clicking on the picture will download
the highest resolution version available.
The Pelican Nebula in Gas, Dust, and Stars 
Image Credit & Copyright: Yannick Akar
Explanation: The Pelican Nebula is slowly being transformed. IC 5070, the official designation, is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds. The featured picture was produced in three specific colors -- light emitted by sulfurhydrogen, and oxygen -- that can help us to better understand these interactions. The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright orange on the right. Particularly dense tentaclesof cold gas remain. Millions of years from now this nebula might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.

SANTé/MEDECINE - A la découverte de l'oreille - L'oreille externe

L' oreille externe comprend le pavillon qui entoure le canal qui mène au tympan . Dans l' oreille moyenne se trouvent les osselets...