240116 - Sh2-298 "Thor's Helmet" nebula
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click image to enlarge
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ASTRO:
type=Pre-supernova planetary nebula const=Canis Major mag=11.5 dist=12,000 ly size=52 ly IMAGE: location=EB Driveway BrtlCls=4; moon=37% WxCr exposure=CMOS OSC: 43x360s (4.3h), bin2x2 EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=ES102 w 24mm EP 1.73x afocal prj., FL=1238mm, f/12.1 (eff.) filter=Optolong L-eXtreme Duo NB mount=Celestron AVX EQ guiding= Orion 60x240mm, ZWO ASI244MC SOFTWARE: acquisition=Stellarium, APT, PHD2 processing=PixInsight (RCAstro), Photoshop (APF-R) (Lumenzia), LrC |
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Thor not only has his own day (Thursday), but also his helmet in the heavens. Popularly called Thor's Helmet, NGC 2359 is a hat-shaped emission planetary nebula; ...a cosmic cloud with wing-like appendages, and including with some amount of imagination, a resemblance of the head and face of the Norse God himself. Heroically sized, Thor's Helmet is about 52 light-years across. In fact, the cosmic head-covering is actually an interstellar bubble, blown by a fast stellar wind from the bright, massive star near the bubble's center. Known as a Wolf-Rayet star, the central star WR7 is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution.
NGC 2359 is located about 12,000 light-years away toward the constellation of Canis Major. This image is a mixed cocktail of data from a dual narrow band filter, capturing not only natural looking stars but details of the nebula's filamentary structures. WR7 is expected to explode in a spectacular supernova sometime within the next few thousand years. It is similar in nature to Sh2-162, the Bubble Nebula, but interactions with a nearby large molecular cloud are thought to have contributed to its more complex shape and curved bow-shock structure.
Thor's Helmet is also catalogued as Sharpless 2-298 (Sh2-298) and Gum 4. It contains the equivalent of several hundred solar masses of ionized material, plus several thousand more of un-ionized gas. It is comprised largely of interstellar material swept up by winds from the central star, although some material appears to be enriched with the products of fusion likely coming directly from the star. The age estimate of the nebula is appx 157,000 years old. It has been studied at radio and x-ray wavelengths, but it is still unclear whether it was produced at the central; star's main sequence stage of development as a red supergiant, or as a luminous blue variable, or mainly as a Wolf-Rayet star.
The nebula is actually fairly large, spanning appx 52 ly across; but due to its distance from Earth, it only occupies appx 1/4 of an arc-degree (or ~15 arc-seconds) in our sky. With such a small apparent footprint, amateur astrophotographers can sometimes be challenged "reaching" it with wide-field equipment having shorter focal lengths. Medium-sized to larger telescopes (5" in diameter and above) can resolve it nicely. The predominant blue color stems from the dual narrow band filter which emphasizes the concentration of ionized oxygen in the nebula by allowing emitted light in the OIII emission line wavelength to reach the camera sensor, while simultaneously blocking most other frequencies of light.
NGC 2359 is located about 12,000 light-years away toward the constellation of Canis Major. This image is a mixed cocktail of data from a dual narrow band filter, capturing not only natural looking stars but details of the nebula's filamentary structures. WR7 is expected to explode in a spectacular supernova sometime within the next few thousand years. It is similar in nature to Sh2-162, the Bubble Nebula, but interactions with a nearby large molecular cloud are thought to have contributed to its more complex shape and curved bow-shock structure.
Thor's Helmet is also catalogued as Sharpless 2-298 (Sh2-298) and Gum 4. It contains the equivalent of several hundred solar masses of ionized material, plus several thousand more of un-ionized gas. It is comprised largely of interstellar material swept up by winds from the central star, although some material appears to be enriched with the products of fusion likely coming directly from the star. The age estimate of the nebula is appx 157,000 years old. It has been studied at radio and x-ray wavelengths, but it is still unclear whether it was produced at the central; star's main sequence stage of development as a red supergiant, or as a luminous blue variable, or mainly as a Wolf-Rayet star.
The nebula is actually fairly large, spanning appx 52 ly across; but due to its distance from Earth, it only occupies appx 1/4 of an arc-degree (or ~15 arc-seconds) in our sky. With such a small apparent footprint, amateur astrophotographers can sometimes be challenged "reaching" it with wide-field equipment having shorter focal lengths. Medium-sized to larger telescopes (5" in diameter and above) can resolve it nicely. The predominant blue color stems from the dual narrow band filter which emphasizes the concentration of ionized oxygen in the nebula by allowing emitted light in the OIII emission line wavelength to reach the camera sensor, while simultaneously blocking most other frequencies of light.