230916- CTB-1 "Medulla" nebula
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click image to enlarge
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ASTRO:
type=Super Nova Remnant const=Cassiopeia mag=(not published; very faint) dist=10 k ly size=100 ly IMAGE: location=EB Driveway BrtlCls=4 exposure=CMOS OSC: 94x360s (9.4h) EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=Explore Scientific ED102 CF corrector=Stellarview 1.0x flattener, FL=714mm (prime), f/7.0 filter=Optolong L-eXtreme DuoNB; Radian Triad Ultra QuadNB mount=Celestron AVX EQ guiding=Orion 60x240mm, ZWO ASI224MC SOFTWARE: acquisition=Stellarium, APT, PHD2 processing=PixInsight, RCAstro, PhotoshopCC, Lumenzia, APF-R, LrC |
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What powers this unusual nebula? CTB-1 (also identified as Abell 85, and SNR G116.9+00.1) is the expanding gas shell left behind when a massive star toward the constellation of Cassiopeia exploded about 10,000 years ago. As it ran out of nuclear fuel elements at its core, and without the process of nuclear fusion creating stabilizing outward pressures within, the star likely imploded inward on itself. Then as it reached critical mass, a resulting supernova (or explosion) occurred.
Nicknamed the "Medulla Nebula" for its brain-like shape, the remnant of this expanding gas bubble still glows in visible light by the heat generated through its collision with surrounding interstellar gas and dust. Why the nebula also glows in X-ray light, though, remains a mystery. One hypothesis holds that an energetic pulsar was created by the exploding star, which powers the nebula with a fast outwardly moving wind. Following this lead, professional astronomers have recently found a pulsar that appears to have been expelled from the supernova explosion. That pulsar has been found to be traveling through space at over 1000 km/s in a direction directly away from the nebula.
HISTORY -
1955 - American astronomer George Ogden Abell discovers during the Palomar Observatory Sky Survey (or POSS) a large arc-like nebula with low surface brightness that he first thinks is an old planetary nebula. He lists it in his 1955 publication as object #72.
1959 - R. W. Wilson and J. G Bolten of the California Institute of Technology Radio Observatory team perform a survey of galactic radiation in this same area of the sky, and find 110 discrete radio sources. Cross-referencing these sources to the POSS plates, they find a correlation, and list it as as "number 1" (or, CTB-1, for Caltech Observation, List B, object #1), and reports that it has a diameter of about 1° (arc-degree), which is appx 2x the size of our full moon in the sky.
1965 - American astronomer Beverly T. Lynds publishes her catalog of bright nebulae. She lists the Medulla as an H-II region, and gives it the designation LBN 576 (for "Lynds' Bright Nebula" - object #576).
1966 - George Abell publishes his second survey of old planetary nebulae, and lists the CTB-1 object with the number Abell 85, having a diameter of 2077" (arc-seconds). He describes it as an asymmetrical ring with bright spots or regions. He also notes, "The center of the extended radio source CTB-1 is 0.4° east of the nebula; ...this may be a supernova remnant."
1968 - A. Poveda and L. Woltjer confirm CTB-1 to be a supernova remnant. They publish their findings in the International Astronomical Journal, Vol. 73, p. 65 where they explain that on the basis of the mathematical relationship between radio surface brightness and the physical radius of the nebula, distances can be determined with sufficient accuracy to show that CTB-1 demonstrates a local spiral structure. Such a structure delineates the nebula is a supernova remnant, as opposed to a planetary nebula.
The radio pulsar PSR J0002+6216 has been identified to be born from the same supernova explosion that created CTB-1. Using the technique of radio photometry, scientists have found evidence of the pulsar made visible in this image from NASA's Fermi Lab. The pulsar lies at the apex of a long tail, narrowly collimated and cometary-like; being appx 7 arc-minutes long (21 ly at the nebula's measured distance). The tail has been classified as a bow-shock pulsar wind nebula. It points back toward the geometric center of the supernova remnant CTB-1. The pulsar's motion through space has been measured at a very high velocity of more than 1100 km/s in a traverse direction (away from the nebula, but across our line of sight as seen from here on Earth). An asymmetrical supernova explosion would explain the cause of a significant natal kick velocity (much like a fire-cracker "kicking" its paper wrapper away from itself as it explodes), as well as the pulsar's currently measured high velocity.
The Medulla appears so faint that it takes many hours of exposure with a telescopic camera to create an image; ...precisely what makes it so interesting and challenging for amateur astro-imagers who are working on perfecting their craft. The nebula appears as a large gas bubble, which resembles a cross section through a human brain at the point where the spinal cord extends (the medulla oblongata), which is why CTB-1 got the nickname "Medulla" nebula among early astronomers. Today, amateur astronomers also attach the common imagery of a "Popped Balloon" and "Garlic" to the nebula. As of the time of this writing, none of these common names have yet to be officially recognized by the IAU (International Astronomical Union), who is the world-wide "keeper" of such names.
Nicknamed the "Medulla Nebula" for its brain-like shape, the remnant of this expanding gas bubble still glows in visible light by the heat generated through its collision with surrounding interstellar gas and dust. Why the nebula also glows in X-ray light, though, remains a mystery. One hypothesis holds that an energetic pulsar was created by the exploding star, which powers the nebula with a fast outwardly moving wind. Following this lead, professional astronomers have recently found a pulsar that appears to have been expelled from the supernova explosion. That pulsar has been found to be traveling through space at over 1000 km/s in a direction directly away from the nebula.
HISTORY -
1955 - American astronomer George Ogden Abell discovers during the Palomar Observatory Sky Survey (or POSS) a large arc-like nebula with low surface brightness that he first thinks is an old planetary nebula. He lists it in his 1955 publication as object #72.
1959 - R. W. Wilson and J. G Bolten of the California Institute of Technology Radio Observatory team perform a survey of galactic radiation in this same area of the sky, and find 110 discrete radio sources. Cross-referencing these sources to the POSS plates, they find a correlation, and list it as as "number 1" (or, CTB-1, for Caltech Observation, List B, object #1), and reports that it has a diameter of about 1° (arc-degree), which is appx 2x the size of our full moon in the sky.
1965 - American astronomer Beverly T. Lynds publishes her catalog of bright nebulae. She lists the Medulla as an H-II region, and gives it the designation LBN 576 (for "Lynds' Bright Nebula" - object #576).
1966 - George Abell publishes his second survey of old planetary nebulae, and lists the CTB-1 object with the number Abell 85, having a diameter of 2077" (arc-seconds). He describes it as an asymmetrical ring with bright spots or regions. He also notes, "The center of the extended radio source CTB-1 is 0.4° east of the nebula; ...this may be a supernova remnant."
1968 - A. Poveda and L. Woltjer confirm CTB-1 to be a supernova remnant. They publish their findings in the International Astronomical Journal, Vol. 73, p. 65 where they explain that on the basis of the mathematical relationship between radio surface brightness and the physical radius of the nebula, distances can be determined with sufficient accuracy to show that CTB-1 demonstrates a local spiral structure. Such a structure delineates the nebula is a supernova remnant, as opposed to a planetary nebula.
The radio pulsar PSR J0002+6216 has been identified to be born from the same supernova explosion that created CTB-1. Using the technique of radio photometry, scientists have found evidence of the pulsar made visible in this image from NASA's Fermi Lab. The pulsar lies at the apex of a long tail, narrowly collimated and cometary-like; being appx 7 arc-minutes long (21 ly at the nebula's measured distance). The tail has been classified as a bow-shock pulsar wind nebula. It points back toward the geometric center of the supernova remnant CTB-1. The pulsar's motion through space has been measured at a very high velocity of more than 1100 km/s in a traverse direction (away from the nebula, but across our line of sight as seen from here on Earth). An asymmetrical supernova explosion would explain the cause of a significant natal kick velocity (much like a fire-cracker "kicking" its paper wrapper away from itself as it explodes), as well as the pulsar's currently measured high velocity.
The Medulla appears so faint that it takes many hours of exposure with a telescopic camera to create an image; ...precisely what makes it so interesting and challenging for amateur astro-imagers who are working on perfecting their craft. The nebula appears as a large gas bubble, which resembles a cross section through a human brain at the point where the spinal cord extends (the medulla oblongata), which is why CTB-1 got the nickname "Medulla" nebula among early astronomers. Today, amateur astronomers also attach the common imagery of a "Popped Balloon" and "Garlic" to the nebula. As of the time of this writing, none of these common names have yet to be officially recognized by the IAU (International Astronomical Union), who is the world-wide "keeper" of such names.