230217 - Sh2-311 Skull & Crossbones" nebula
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click image to enlarge
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ASTRO:
type=Emission Nebula mag=7.1 const=Puppis dist=21,000 ly size=172 ly (as measured diagonally across only the "face") IMAGE: location=EB Driveway BrtlCls=4 exposure=CMOS OSC; 39x420s (4.6h), Gain120 EQUIPMENT: camera=ZWO ASi2600MC-Pro optics=ES102 w1.0x flattener, FL=714mm, f/7.0 filter=Optolong L-eXtreme Duo NB mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, APT, PHD2, processing=DSS, PhotoshopCC, RCAstro, LrC |
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Conjuring images of a popular Hollywood nemesis, "The Terminator", Sh2-311 shows a strong resemblance to the caricature made famous by actor and politician Arnold Schwarzenegger. Officially nicknamed the "Skull and Crossbones" nebula, this stellar nursery has an appearance that has also been likened to that of a colorful mandrill primate of central Africa. It includes areas where large clouds of hydrogen gas incubate new stars. This region is also featured in the book, "Hubble's Universe: Greatest Discoveries and Latest Images" by Canadian astronomer and accomplished astrophotographer, Terence Dickinson.
The starry components of the region are catalogued as NGC 2467, and have long been considered to be the nucleus of the star association called, Puppis I, being named after its home constellation of Puppis. However, recent studies have shown NGC 2467 does not represent a distinct and single open star cluster; rather, it represents a superimposition of several stellar groups along the same approximate line of sight, as seen from our perspective here on Earth, that have distinctly different distances and radial velocities. One of these is a young and very distant group beyond the star, Puppis OB2, while another nearer group with older stars lies at a similar distance as star Puppis OB1.
The region is dominated by a massive young star, HD 64315 (located in the "chin" of the caricature), of spectral type O6. Two stellar clusters also exist in the area, Haffner 19 (H19) and Haffner 18 (H18). H19 (seen as the right, glaring "eye" of the caricature) is a compact cluster containing a Strömgren sphere which is ionized by a hot B0 V-type star. H18 (encompassing almost the whole "nose" region of the caricature) contains a very young star, FM3060a (located at the left side of the "nose", appx where one might imaging a "nostril" to be), that has just come into existence and still surrounded by its birth cocoon of gas. The age of H19 is estimated to be appx 2 M yr, while the age H18 is considering by some to be as young as only 1 M yr (very young by astronomical standards). The field contains other early-stage stars like HD 64568 (above the "scalp - hairline" of the caricature) whose relationship with the clusters is unclear.
The H II region of Sh2-311 has been the target of various investigations to learn more about the process of star formation. Unresolved questions include understanding the degree to which stars already formed, especially the massive O or B stars, can affect the future formation of more stars in the region: Do these pre-existing stars trigger the formation of others? One such investigation was conducted using the Spitzer Space Telescope, which discovered 45 young stellar objects (YSOs), or protostars, in the region during its "cold" mission (i.e. before its supply of liquid helium ran out.) The YSOs are mostly found along the edge of the H II region. The concentrated distribution of these objects' and their spatial correlations with the ionization fronts provides evidence for triggered star formation. The newly forming protostars are concentrated in areas where the shock front driven in advance of the ionization front compresses the molecular gas.
It has been estimated that H19, H18, and the Sh2-311 nebula (in which lies HD 64315) are about 21,000 light-years, 19,000 ly, and 21,000 ly away respectively, placing them in the Perseus Arm of our home Milky Way galaxy. A significant discrepancy exists between the distances to these features when estimated kinematically, versus their distances estimated photometrically. Regardless of these discrepancies, H19 and H18 may be considered to be a binary pair of clusters (i.e. their motion through space appears to be gravitationally coherent, or linked).
The starry components of the region are catalogued as NGC 2467, and have long been considered to be the nucleus of the star association called, Puppis I, being named after its home constellation of Puppis. However, recent studies have shown NGC 2467 does not represent a distinct and single open star cluster; rather, it represents a superimposition of several stellar groups along the same approximate line of sight, as seen from our perspective here on Earth, that have distinctly different distances and radial velocities. One of these is a young and very distant group beyond the star, Puppis OB2, while another nearer group with older stars lies at a similar distance as star Puppis OB1.
The region is dominated by a massive young star, HD 64315 (located in the "chin" of the caricature), of spectral type O6. Two stellar clusters also exist in the area, Haffner 19 (H19) and Haffner 18 (H18). H19 (seen as the right, glaring "eye" of the caricature) is a compact cluster containing a Strömgren sphere which is ionized by a hot B0 V-type star. H18 (encompassing almost the whole "nose" region of the caricature) contains a very young star, FM3060a (located at the left side of the "nose", appx where one might imaging a "nostril" to be), that has just come into existence and still surrounded by its birth cocoon of gas. The age of H19 is estimated to be appx 2 M yr, while the age H18 is considering by some to be as young as only 1 M yr (very young by astronomical standards). The field contains other early-stage stars like HD 64568 (above the "scalp - hairline" of the caricature) whose relationship with the clusters is unclear.
The H II region of Sh2-311 has been the target of various investigations to learn more about the process of star formation. Unresolved questions include understanding the degree to which stars already formed, especially the massive O or B stars, can affect the future formation of more stars in the region: Do these pre-existing stars trigger the formation of others? One such investigation was conducted using the Spitzer Space Telescope, which discovered 45 young stellar objects (YSOs), or protostars, in the region during its "cold" mission (i.e. before its supply of liquid helium ran out.) The YSOs are mostly found along the edge of the H II region. The concentrated distribution of these objects' and their spatial correlations with the ionization fronts provides evidence for triggered star formation. The newly forming protostars are concentrated in areas where the shock front driven in advance of the ionization front compresses the molecular gas.
It has been estimated that H19, H18, and the Sh2-311 nebula (in which lies HD 64315) are about 21,000 light-years, 19,000 ly, and 21,000 ly away respectively, placing them in the Perseus Arm of our home Milky Way galaxy. A significant discrepancy exists between the distances to these features when estimated kinematically, versus their distances estimated photometrically. Regardless of these discrepancies, H19 and H18 may be considered to be a binary pair of clusters (i.e. their motion through space appears to be gravitationally coherent, or linked).