Archives mensuelles : mars 2023

Are your eyes good enough to see the Crab Nebula expand? The Crab Nebula is cataloged as M1, the first on Charles Messier’s famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Over the past decade, its expansion has been documented in this stunning time-lapse movie. In each year from 2008 to 2022, an image was produced with the same telescope and camera from a remote observatory in Austria. The sharp, processed frames even reveal the dynamic energetic emission surrounding the rapidly spinning pulsar at the center. The Crab Nebula lies about 6,500 light-years away toward the constellation of the Bull (Taurus). via NASA https://ift.tt/B4qNAXl

To see the feathered serpent descend the Mayan pyramid requires exquisite timing. You must visit El Castillo — in Mexico’s Yucatán Peninsula — near an equinox. Then, during the late afternoon if the sky is clear, the pyramid’s own shadows create triangles that merge into the famous illusion of a slithering viper. Also known as the Temple of Kukulkan, the impressive step-pyramid stands 30 meters tall and 55 meters wide at the base. Built up as a series of square terraces by the pre-Columbian civilization between the 9th and 12th century, the structure can be used as a calendar and is noted for astronomical alignments. The featured composite image was captured in 2019 with Jupiter and Saturn straddling the diagonal central band of our Milky Way galaxy. Tomorrow marks another equinox — not only at Temple of Kukulcán, but all over planet Earth. via NASA https://ift.tt/r1Jlahj

Wolf Rayet 124

Driven by powerful stellar winds, expanding shrouds of gas and dust frame hot, luminous star Wolf-Rayet 124 in this sharp infrared view. The eye-catching 6-spike star pattern is characteristic of stellar images made with the 18 hexagonal mirrors of the James Webb Space Telescope. About 15,000 light-years distant toward the pointed northern constellation Sagitta, WR 124 has over 30 times the mass of the Sun. Produced in a brief and rarely spotted phase of massive star evolution in the Milky Way, this star’s turbulent nebula is nearly 6 light-years across. It heralds WR 124’s impending stellar death in a supernova explosion. Formed in the expanding nebula, dusty interstellar debris that survives the supernova will influence the formation of future generations of stars. via NASA https://ift.tt/VwA2Rcu

Le journal « Midi libre » annonce un plan de départs contraints qui touchera principalement « les plus jeunes salariés »

Le plan « impactera prioritairement les plus jeunes salariés de l’entreprise », déclare son directeur, évoquant « une situation extrêmement grave, qui oblige le quotidien à s’orienter vers le scénario du pire ».

Source : Le journal « Midi libre » annonce un plan de départs contraints qui touchera principalement « les plus jeunes salariés »

The Medusa Nebula

Braided and serpentine filaments of glowing gas suggest this nebula’s popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away in the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. The Medusa’s transforming star is the faint one near the center of the overall bright crescent shape. In this deep telescopic view, fainter filaments clearly extend below and right of the bright crescent region. The Medusa Nebula is estimated to be over 4 light-years across. via NASA https://ift.tt/T89NK1b

Millions of Stars in Omega Centauri

Globular star cluster Omega Centauri, also known as NGC 5139, is 15,000 light-years away. The cluster is packed with about 10 million stars much older than the Sun within a volume about 150 light-years in diameter. It’s the largest and brightest of 200 or so known globular clusters that roam the halo of our Milky Way galaxy. Though most star clusters consist of stars with the same age and composition, the enigmatic Omega Cen exhibits the presence of different stellar populations with a spread of ages and chemical abundances. In fact, Omega Cen may be the remnant core of a small galaxy merging with the Milky Way. Omega Centauri’s red giant stars (with a yellowish hue) are easy to pick out in this sharp, color telescopic view. via NASA https://ift.tt/z7rJYaf

This was a sky to show the kids. Early this month the two brightest planets in the night sky, Jupiter and Venus, appeared to converge. At their closest, the two planets were separated by only about the angular width of the full moon. The spectacle occurred just after sunset and was seen and photographed all across planet Earth. The displayed image was taken near to the time of closest approach from Wiltingen, Germany, and features the astrophotographer, spouse, and their two children. Of course, Venus remains much closer to both the Sun and the Earth than Jupiter — the apparent closeness between the planets in the sky of Earth was only angular. Jupiter and Venus have passed and now appear increasingly far apart. Similar planetary convergence opportunities will eventually arise. In a few months, for example, Mars and Venus will appear to congregate just as the Sun sets. via NASA https://ift.tt/gpTZJaU

Stars are forming in the Soul of the Queen of Aethopia. More specifically, a large star forming region called the Soul Nebula can be found in the direction of the constellation Cassiopeia, whom Greek mythology credits as the vain wife of a King who long ago ruled lands surrounding the upper Nile river. Also known as Westerhout 5 (W5), the Soul Nebula houses several open clusters of stars, ridges and pillars darkened by cosmic dust, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). The featured image is a composite of exposures made in different colors: red as emitted by hydrogen gas, yellow as emitted by sulfur, and blue as emitted by oxygen. via NASA https://ift.tt/dqhO4Bc

What lies at the end of a rainbow? Something different for everyone. For the photographer taking this picture, for example, one end of the rainbow ended at a tree. Others nearby, though, would likely see the rainbow end somewhere else. The reason is because a rainbow’s position depends on the observer. The center of a rainbow always appears in the direction opposite the Sun, but that direction lines up differently on the horizon from different locations. This rainbow’s arc indicates that its center is about 40 degrees to the left and slightly below the horizon, while the Sun is well behind the camera and just above the horizon. Reflections and refractions of sunlight from raindrops in a distant storm in the direction of the rainbow are what causes the colorful bands of light. This single exposure image was captured in early January near Knight’s Ferry, California, USA. via NASA https://ift.tt/YCd9hLB

What lies at the bottom of Hyperion’s strange craters? To help find out, the robot Cassini spacecraft that once orbited Saturn swooped past the sponge-textured moon and took images of unprecedented detail. A six-image mosaic from the 2005 pass, featured here in scientifically assigned colors, shows a remarkable world strewn with strange craters and an odd, sponge-like surface. At the bottom of most craters lies some type of unknown dark reddish material. This material appears similar to that covering part of another of Saturn’s moons, Iapetus, and might sink into the ice moon as it better absorbs warming sunlight. Hyperion is about 250 kilometers across, rotates chaotically, and has a density so low that it likely houses a vast system of caverns inside. via NASA https://ift.tt/qSzBdno