ASTRONOMY - Regulus and the Dwarf Galaxy

 2024 April 26

Regulus and the Dwarf Galaxy
Image Credit & Copyright: Markus Horn

Explanation: In northern hemisphere spring, bright star Regulus is easy to spot above the eastern horizon. The alpha star of the constellation Leo, Regulus is the spiky star centered in this telescopic field of view. A mere 79 light-years distant, Regulus is a hot, rapidly spinning star that is known to be part of a multiple star system. Not quite lost in the glare, the fuzzy patch just below Regulus is diffuse starlight from small galaxy Leo I. Leo I is a dwarf spheroidal galaxy, a member of the Local Group of galaxies dominated by our Milky Way Galaxy and the Andromeda Galaxy (M31). About 800 thousand light-years away, Leo I is thought to be the most distant of the known small satellite galaxies orbiting the Milky Way. But dwarf galaxy Leo I has shown evidence of a supermassive black hole at its center, comparable in mass to the black hole at the center of the Milky Way.

ASTRONOMY - NGC 604: Giant Stellar Nursery

 2024 April 25

NGC 604: Giant Stellar Nursery
Image Credit: NASA, ESA, CSA, STScI

Explanation: Located some 3 million light-years away in the arms of nearby spiral galaxy M33, giant stellar nursery NGC 604 is about 1,300 light-years across. That's nearly 100 times the size of the Milky Way's Orion Nebula, the closest large star forming region to planet Earth. In fact, among the star forming regions within the Local Group of galaxies, NGC 604 is second in size only to 30 Doradus, also known as the Tarantula Nebula in the Large Magellanic Cloud. Cavernous bubbles and cavities in NGC 604 fill this stunning infrared image from the James Webb Space Telescope's NIRCam. They are carved out by energetic stellar winds from the region's more than 200 hot, massive, young stars, all still in early stages of their lives.

ASTRONOMY - Dragon's Egg Bipolar Emission Nebula

 2024 April 24

Dragon's Egg Bipolar Emission Nebula
Image Credit & Copyright: Rowan Prangley

Explanation: How did a star form this beautiful nebula? In the middle of emission nebula NGC 6164 is an unusually massive star. The central star has been compared to an oyster's pearl and an egg protected by the mythical sky dragons of Ara. The star, visible in the center of the featured image and catalogued as HD 148937, is so hot that the ultraviolet light it emits heats up gas that surrounds it. That gas was likely thrown off from the star previously, possibly the result of a gravitational interaction with a looping stellar companion. Expelled material might have been channeled by the magnetic field of the massive star, in all creating the symmetric shape of the bipolar nebula. NGC 6164 spans about four light years and is located about 3,600 light years away toward the southern constellation Norma.

ASTRONOMIE - Survolez un magnifique lac de lave de 200 km de diamètre sur la lune volcanique Io !

La sonde Juno de la Nasa en orbite autour de Jupiter fait depuis quelque temps des survols rapprochés de Io, la lune volcanique de la géante gazeuse. Les données collectées permettent de reconstituer à l'ordinateur le film d'un survol de synthèse encore plus rapproché montrant l'extraordinaire lac de lave géant de Loki Patera.

FuturaSciences

SANTé/MEDECINE - HISTOIRE - 1980 : invention de l'IRM

Inventée par Paul Lauterbur et Peter Mansfield en 1980, l'imagerie par résonance magnétique (IRM) est une technique non invasive d'imagerie médicale permettant d'obtenir des vues 2D ou 3D du corps vivant.

© KasugaHuang, CC by-sa 3.0

SANTé/MEDECINE - Les avancées contre le cancer

Intelligence artificielle, nouvelles chimiothérapies... La recherche avance sur tous les fronts en ce qui concerne le cancer. De vraies bonnes nouvelles qui embellissent notre avenir.

Le Pr Philippe Casassus, hématologue et auteur des 'États d’âme d’un professeur de médecine' (éd. Glyphe, 2019) en est convaincu: la médecine est à un tournant. "Je suis frappé par l’accélération exponentielle des progrès. C’est flagrant notamment contre le cancer: dans dix ans, nous le soignerons bien différemment d’aujourd’hui, les traitements progressent si vite."

NotreTemps

ASTRONOMY - Contrail Shadow X

 2024 April 23

Contrail Shadow X
Image Credit & Copyright: Fatih Ekmen

Explanation: What created this giant X in the clouds? It was the shadow of contrails illuminated from below. When airplanes fly, humid engine exhaust may form water droplets that might freeze in Earth's cold upper atmosphere. These persistent streams of water and ice scatter light from the Sun above and so appear bright from below. On rare occasions, though, when the Sun is near the horizon, contrails can be lit from below. These contrails cast long shadows upwards, shadows that usually go unseen unless there is a high cloud deck. But that was just the case over Istanbul, Türkiye, earlier this month. Contrails occur all over planet Earth and, generally, warm the Earth when the trap infrared light but cool the Earth when they efficiently reflect sunlight. The image was taken by a surprised photographer in the morning on the way to work.

SANTé/MEDECINE - Homme ou animal : qui est le plus fort ? - Vitesse

Le guépard peut se moquer en regardant courir Usain Bolt, recordman du monde du 100 m (9 secondes 58 centièmes) et du 200 m (19 secondes 19 centièmes). Certes, le Jamaïcain reste l'Homme le plus rapide de l'histoire. Lorsqu'il a réalisé ces exploits, il a parcouru la ligne droite à la vitesse moyenne de 37,58 km/h départ arrêté, avoisinant les 45 km/h après environ 80 m de course.

Un résultat pourtant bien lent pour un guépard (Acinonyx jubatus) qui franchirait la ligne du 100 mètres en un peu plus de 3 secondes lancé à sa vitesse maximale : 110 km/h. Il mettrait juste un peu plus de temps départ arrêté.

© Aktiv I Oslo.no, CC by-nc 2.0, JonathanC Photography, Shutterstock et Aki Sasaki, CC by-nc 2.0

SANTé/MEDECINE - La compléxité de la tête humaine - Tête vue de côté avec les nerfs trijumeaux

Sur cette représentation de la tête vue de côté apparaissent les nerfs trijumeaux en jaune. Ces nerfs crâniens se séparent en trois branches, comme leur nom l'indique, et ils amènent des fibres sensitives au niveau du visage, ainsi que des fibres motrices servant à activer les muscles de la mastication.

© Patrick J. Lynch, medical illustrator, CC by 2.5

ASTRONOMY - Moon and Smoke Rings from Mt. Etna

2024 April 22

Moon and Smoke Rings from Mt. Etna
Image Credit & Copyright: Dario Giannobile

Explanation: Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster. A circle of low pressure develops so that the emitted puff of volcanic gas and ash loops around in a ring, a familiar geometric structure that can be surprisingly stable as it rises. Smoke rings are quite rare and need a coincidence of the right geometry of the vent, the right speed of ejected smoke, and the relative calmness of the outside atmosphere. In the featured image taken about two weeks ago from Gangi, Sicily, Italy, multiple volcanic smoke rings are visible. The scene is shaded by the red light of a dawn Sun, while a crescent Moon is visible in the background.