M51: 潮汐流与氢α峭壁
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玫瑰不必是红色的
2024年2月9日 When Roses Aren’t Red Image Credit & Copyright: Tommy Lease (Denver Astronomical Society) Explanation: Not all roses are red of course, but they can still be very pretty. Likewise, the beautiful Rosette Nebula and other star forming regions are often shown in astronomical images with a predominately red hue, in part because the dominant emission in the nebula is from hydrogen atoms. Hydrogen’s strongest optical emission line, known as H-alpha, is in the red region of the spectrum. But the beauty of an emission nebula need not be appreciated in red light alone. Other atoms in the nebula are also excited by energetic starlight and produce narrow emission lines as well. In this close-up view of the Rosette Nebula, narrowband images are mapped into…
M33的氢气云
2023年10月13日 Hydrogen Clouds of M33 Image Credit & Copyright: Reinhold Wittich Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. The galaxy’s central 30,000 light-years or so are shown in this sharp galaxy portrait. The portrait features M33’s reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33’s giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and…
2023年近日点的太阳
2023年1月14日 Perihelion Sun 2023 Image Credit & Copyright: Peter Ward (Barden Ridge Observatory) Explanation: Perihelion for 2023, Earth’s closest approach to the Sun, was on January 4 at 16:17 UTC. That was less than 24 hours after this sharp image of the Sun’s disk was recorded with telescope and H-alpha filter from Sydney, Australia, planet Earth. An H-alpha filter transmits a characteristic red light from hydrogen atoms. In views of the Sun it emphasizes the Sun’s chromosphere, a region just above the solar photosphere or normally visible solar surface. In this H-alpha image of the increasingly active Sun planet-sized sunspot regions are dominated by bright splotches called plages. Dark filaments of plasma snaking across the solar disk transition to bright prominences when seen above the…
M33的氢气云
2021年9月30日 The Hydrogen Clouds of M33 Image Credit & Copyright: Luca Fornaciari Explanation: Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. Sprawling along loose spiral arms that wind toward the core, M33’s giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To highlight the HII regions in this telescopic image, broadband data used to produce a color view of the…
红蓝相间的鹈鹕星云
2021年03月01日 The Pelican Nebula in Red and Blue Image Credit & Copyright: M. Petrasko, M. Evenden, U. Mishra (Insight Obs.) Explanation: The Pelican Nebula is changing. The entire nebula, officially designated IC 5070, is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, is particularly interesting because it is an unusually active mix of star formation and evolving gas clouds. The featured picture was processed to bring out two main colors, red and blue, with the red dominated by light emitted by interstellar hydrogen. Ultraviolet light emitted by young energetic stars is slowly transforming cold gas in the nebula to hot gas, with the advancing boundary between the two, known as an ionization front, visible in…