星系NGC 5775的垂直磁场

星系NGC 5775的垂直磁场

ByNASA中文

2021年01月27日 The Vertical Magnetic Field of NGC 5775 Image Credit: NRAO, NASA, ESA, Hubble; Processing & Text: Jayanne English (U. Manitoba) Explanation: How far do magnetic fields extend up and out of spiral galaxies? For decades astronomers knew only that some spiral galaxies had magnetic fields. However, after NRAO’s Very Large Array (VLA) radio telescope (popularized in the movie Contact) was upgraded in 2011, it was unexpectedly discovered that these fields could extend vertically away from the disk by several thousand light-years. The featured image of edge-on spiral galaxy NGC 5775, observed in the CHANG-ES (Continuum Halos in Nearby Galaxies) survey, also reveals spurs of magnetic field lines that may be common in spirals. Analogous to iron filings around a bar magnet, radiation from electrons…

NGC 1316的中心: 星系碰撞之后

NGC 1316的中心: 星系碰撞之后

ByNASA中文

2021年01月26日 Central NGC 1316: After Galaxies Collide Image Credit: NASA, ESA, Hubble; Processing & Copyright: Daniel Nobre Explanation: How did this strange-looking galaxy form? Astronomers turn detectives when trying to figure out the cause of unusual jumbles of stars, gas, and dust like NGC 1316. Inspection indicates that NGC 1316 is an enormous elliptical galaxy that somehow includes dark dust lanes usually found in a spiral galaxy. Detailed images taken by the Hubble Space Telescope shows details, however, that help in reconstructing the history of this gigantic tangle. Deep and wide images show huge collisional shells, while deep central images reveal fewer globular clusters of stars toward NGC 1316’s interior. Such effects are expected in galaxies that have undergone collisions or merging with other galaxies…

智利火山上空的南十字

智利火山上空的南十字

ByNASA中文

2021年01月25日 Southern Cross over Chilean Volcano Image Credit & Copyright: Tomáš Slovinský Explanation: Have you ever seen the Southern Cross? This famous four-star icon is best seen from Earth’s Southern Hemisphere. The featured image was taken last month in Chile and captures the Southern Cross just to the left of erupting Villarrica, one of the most active volcanos in our Solar System. Connecting the reddest Southern Cross star Gacrux through the brightest star Acrux points near the most southern location in the sky: the South Celestial Pole (SCP), around which all southern stars appear to spin as the Earth turns. In modern times, no bright star resides near the SCP, unlike in the north where bright Polaris now appears near the NCP. Extending the Gacrux…

邻近的大质量螺旋星系NGC 2841

邻近的大质量螺旋星系NGC 2841

ByNASA中文

2021年01月24日 Massive Nearby Spiral Galaxy NGC 2841 Image Credit: NASA, ESA, Hubble, Subaru; Composition & Copyright: Roberto Colombari Explanation: It is one of the more massive galaxies known. A mere 46 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major. This sharp view of the gorgeous island universe shows off a striking yellow nucleus and galactic disk. Dust lanes, small, pink star-forming regions, and young blue star clusters are embedded in the patchy, tightly wound spiral arms. In contrast, many other spirals exhibit grand, sweeping arms with large star-forming regions. NGC 2841 has a diameter of over 150,000 light-years, even larger than our own Milky Way. The featured composite image merges exposures from the orbiting 2.4-meter Hubble…

仙后座A

仙后座A

ByNASA中文

2021年01月23日 Recycling Cassiopeia A Image Credit: X-ray – NASA, CXC, SAO; Optical – NASA,STScI Explanation: Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After a few million years, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the explosion which created this supernova remnant would have been first seen in planet Earth’s sky about 350 years ago, although it took that light about 11,000 years to reach us. This false-color image, composed of X-ray and optical image data from…

银河环

银河环

ByNASA中文

2021年01月22日 The Milky Ring Image Credit & Copyright: Alvin Wu Explanation: An expanse of cosmic dust, stars and nebulae along the plane of our Milky Way galaxy form a beautiful ring in this projected all-sky view. The creative panorama covers the entire galaxy visible from planet Earth, an ambitious 360 degree mosaic that took two years to complete. Northern hemisphere sites in western China and southern hemisphere sites in New Zealand were used to collect the image data. Like a glowing jewel set in the milky ring, the bulge of the galactic center, is at the very top. Bright planet Jupiter is the beacon just above the central bulge and left of red giant star Antares. Along the plane and almost 180 degrees from the…

M78的大视野影像

M78的大视野影像

ByNASA中文

2021年01月21日 M78 Wide Field Image Credit & Copyright: Wes Higgins Explanation: Interstellar dust clouds and glowing nebulae abound in the fertile constellation of Orion. One of the brightest, M78, is centered in this colorful, wide field view, covering an area north of Orion’s belt. At a distance of about 1,500 light-years, the bluish reflection nebula is around 5 light-years across. Its tint is due to dust preferentially reflecting the blue light of hot, young stars. Reflection nebula NGC 2071 is just to the left of M78. Flecks of emission from Herbig-Haro objects, energetic jets from stars in the process of formation, stand out against the dark dust lanes. The exposure also brings out the region’s fainter, pervasive reddish glow of atomic hydrogen gas. Tomorrow’s picture:…

涡状星系的磁场

涡状星系的磁场

ByNASA中文

2021年01月20日 The Magnetic Field of the Whirlpool Galaxy Image Credit: NASA, SOFIA, HAWC+, Alejandro S. Borlaff; JPL-Caltech, ESA, Hubble; Text: Jayanne English (U. Manitoba) Explanation: Do magnetic fields always flow along spiral arms? Our face-on view of the Whirlpool Galaxy (M51) allows a spectacularly clear view of the spiral wave pattern in a disk-shaped galaxy. When observed with a radio telescope, the magnetic field appears to trace the arms’ curvature. However, with NASA’s flying Stratospheric Observatory for Infrared Astronomy (SOFIA) observatory, the magnetic field at the outer edge of M51’s disk appears to weave across the arms instead. Magnetic fields are inferred by grains of dust aligning in one direction and acting like polaroid glasses on infrared light. In the featured image, the field orientations…

月华、木星与土星

月华、木星与土星

ByNASA中文

2021年01月19日 A Lunar Corona with Jupiter and Saturn Image Credit & Copyright: Alessandra Masi Explanation: Why does a cloudy moon sometimes appear colorful? The effect, called a lunar corona, is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently. Lunar Coronae are one of the few quantum mechanical color effects that can be easily seen with the unaided eye. Solar coronae are also sometimes evident. The featured composite image was captured a few days before the close Great Conjunction between Saturn and Jupiter last month. In the foreground, the Italian village of Pieve di Cadore is visible in front of the Sfornioi Mountains….

超新星遗迹─延髓星云

超新星遗迹─延髓星云

ByNASA中文

2021年01月18日 The Medulla Nebula Supernova Remnant Image Credit & Copyright: Russell Croman Explanation: What powers this unusual nebula? CTB-1 is the expanding gas shell that was left when a massive star toward the constellation of Cassiopeia exploded about 10,000 years ago. The star likely detonated when it ran out of elements, near its core, that could create stabilizing pressure with nuclear fusion. The resulting supernova remnant, nicknamed the Medulla Nebula for its brain-like shape, still glows in visible light by the heat generated by its collision with confining interstellar gas. Why the nebula also glows in X-ray light, though, remains a mystery. One hypothesis holds that an energetic pulsar was co-created that powers the nebula with a fast outwardly moving wind. Following this lead, a…