ASTRONOMY - Barred Spiral Galaxy NGC 6217

 2022 February 21

Barred Spiral Galaxy NGC 6217
Image Credit: NASA, ESA, and the Hubble SM4 ERO Team

Explanation: Many spiral galaxies have bars across their centers. Even our own Milky Way Galaxy is thought to have a modest central bar. Prominently barred spiral galaxy NGC 6217, featured here, was captured in spectacular detail in this image taken by the Advanced Camera for Surveys on the orbiting Hubble Space Telescope in 2009. Visible are dark filamentary dust lanes, young clusters of bright blue stars, red emission nebulas of glowing hydrogen gas, a long bar of stars across the center, and a bright active nucleus that likely houses a supermassive black hole. Light takes about 60 million years to reach us from NGC 6217, which spans about 30,000 light years across and can be found toward the constellation of the Little Bear (Ursa Minor).

ASTRONOMY - Peculiar Galaxies of Arp 273

 2022 February 19

Peculiar Galaxies of Arp 273
Image Credit & Copyright: Jason Guenzel

Explanation: The spiky stars in the foreground of this backyard telescopic frame are well within our own Milky Way Galaxy. But the two eye-catching galaxies lie far beyond the Milky Way, at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters. Cataloged as Arp 273 (also as UGC 1810), the galaxies do look peculiar, but interacting galaxies are now understood to be common in the universe. Nearby, the large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. The peculiar galaxies of Arp 273 may offer an analog of their far future encounter. Repeated galaxy encounters on a cosmic timescale can ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years.

AERONAUTIQUE - AirFish 8

L'AirFish 8 de Wigetworks arrive en fin d'expérimentation. Il ne s'agit pas vraiment d'un avion, ni même d'un bateau, mais d'une espèce d'aérodyne hybride exploitant le phénomène d'effet de sol pour voler à quelques mètres de hauteur d'une surface plane.

Il ne s'agit pas d'un hydravion, ni d'un hydroglisseur... Conçu et testé depuis dix ans par la firme singapourienne Wigetworks, l'AirFish 8 est ce que l'on appelle un ekranoplan. Ce terme est la transcription russe d'un aérodyne à effet de sol. Russe, car cette invention date de la guerre froide et c'est l'armée soviétique qui a développé ce type d'engin. L'effet de sol permet d'augmenter la portance d'un aérodyne et de diminuer sa traînée. Avec moins de traînée, la finesse de l'appareil est augmentée et il peut parcourir plus de distance avec beaucoup moins d'énergie.

FuturaSciences

ASTRONOMY - Chamaeleon I Molecular Cloud

 2022 February 18

Chamaeleon I Molecular Cloud
Image Credit & Copyright: Acquisition: Stas Volskiy (Chilescope.com), Processing: Robert Eder

Explanation: Dark markings and bright nebulae in this telescopic southern sky view are telltale signs of young stars and active star formation. They lie a mere 650 light-years away, at the boundary of the local bubble and the Chamaeleon molecular cloud complex. Regions with young stars identified as dusty reflection nebulae from the 1946 Cederblad catalog include the C-shaped Ced 110 just above and left of center, and bluish Ced 111 below it. Also a standout in the frame, the orange tinted V-shape of the Chamaeleon Infrared Nebula (Cha IRN) was carved by material streaming from a newly formed low-mass star. The well-composed image spans 1.5 degrees. That's about 17 light-years at the estimated distance of the nearby Chamaeleon I molecular cloud.

The Romanian Foundation for Excellence in Music - Wolfgang Amadeus Mozart

"Ave Verum Corpus"

POURQUOI - SANTé/MéDECINE - Pourquoi a-t-on soif quand on mange un aliment salé ?

Le sel est essentiel à la vie, mais l'organisme n'en a besoin que d'une petite quantité. Quand le corps reçoit trop de sel, que la concentration de sel devient trop élevée dans son sang, il doit faire en sorte de s'en débarrasser. Le corps élimine le surplus de sel dans l'urine, via les reins.Mais en éliminant le sel, ils éliminent aussi de l'eau, parce que le sel entraîne naturellement l'eau avec lui. Il y a alors un déséquilibre dans le sang. Le sang manque d'eau. Quand la quantité d'eau diminue dans le sang, le sang en informe le cerveau.

Afin de rétablir l'équilibre en eau dans le sang, le cerveau nous donne la sensation de soif, en ordonnant entre autres aux glandes salivaires de réduire leurs sécrétions.

Notre bouche et notre gorge sont sèches, on a soif, on boit un grand verre d'eau.

Tout ce liquide fournit à l'organisme l'eau qui lui manque pour rétablir l'équilibre du sang en eau.

Pourquoi

ASTRONOMY - Eiffel Tower Prominence on the Sun

 2022 February 16

Eiffel Tower Prominence on the Sun
Video Credit & Copyright: Hawk Wolinski

Explanation: What's that on the Sun? Although it may look like a flowing version of the Eiffel Tower, it is a solar prominence that is actually much bigger -- about the height of Jupiter. The huge prominence emerged about ten days ago, hovered over the Sun's surface for about two days, and then erupted -- throwing a coronal mass ejection (CME) into the Solar System. The featured video, captured from the astrophotographer's backyard in Hendersonville, Tennessee, USA, shows an hour time-lapse played both forwards and backwards. That CME did not impact the Earth, but our Sun had unleashed other recent CMEs that not only triggered Earthly auroras, but puffed out the Earth's atmosphere enough to cause just-launched Starlink satellites to fall back. Activity on the Sun, including sunspots, prominences, CMEs and flares, continues to increase as the Sun evolves away from a deep minimum in its 11-year magnetic cycle.

AERONAUTIQUE - Le SpaceLiner : un avion suborbital

SpaceLiner est un projet d'avion suborbital réutilisable sur lequel le Centre allemand pour l'aéronautique et l'astronautique a commencé à travailler en 2005. Cet avion pouvant transporter 50 passagers décollerait à la verticale comme les navettes spatiales.

Une fois propulsé par son lanceur muni de 9 moteurs cryogéniques, l'engin pourra planer à très haute vitesse en parcourant de grandes distances. Théoriquement, un SpaceLiner pourrait relier l'Australie et le continent européen en 90 minutes. Cependant, ce projet très ambitieux n'aboutira pas, au mieux, avant 2040-2050.

© ToSch1983, Deutsches Zentrum für Luft und Raumfahrt, GFDL

ASTRONOMY - The Galactic Center in Radio from MeerKAT

 2022 February 15

The Galactic Center in Radio from MeerKAT
Image Credit: Ian Heywood (Oxford U.), SARAO; Color Processing: Juan Carlos Munoz-Mateos (ESO)

Explanation: 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. Goals for MeerKAT include searching for radio emission from neutral hydrogen emitted in a much younger universe and brief but distant radio flashes.

ASTRONOMY - In the Heart of the Heart Nebula

 2022 February 14

In the Heart of the Heart Nebula
Image Credit & Copyright: Adam Jensen

Explanation: What excites the Heart Nebula? First, the large emission nebula dubbed IC 1805 looks, in whole, like a human heart. Its shape perhaps fitting of the Valentine's Day, this heart glows brightly in red light emitted by its most prominent element: excited hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center. In the heart of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their energetic light and winds. The open cluster of stars contains a few bright stars nearly 50 times the mass of our Sun, many dim stars only a fraction of the mass of our Sun, and an absent microquasar that was expelled millions of years ago. The Heart Nebula is located about 7,500 light years away toward the constellation of the mythological Queen of Aethiopia (Cassiopeia).