IC5146_Cocoon Nebula and Barnard 168
After two months of clouds, I finally saw some clear skies...
IC 5146 (the Cocoon Nebula) is a reflection /emission nebula (lower left) located about 2,500 light-years away in the constellation Cygnus.
Barnard 168 is a dark nebula that surrounds IC 5146 and forms the dark lane extending up and to the right in this image.
Reflection nebulae are clouds of interstellar dust which reflect the light of a nearby star or stars.
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.
A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae.
Dark nebulae appear so because of sub-micrometer-sized dust particles, coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths. Also present are molecular hydrogen, atomic helium, C18O (CO with oxygen as the 18O isotope), CS, NH3 (ammonia), H2CO (formaldehyde), c-C3H2 (cyclopropenylidene) and a molecular ion N2H+ (diazenylium), all of which are relatively transparent. These clouds are the spawning grounds of stars and planets, and understanding their development is essential to understanding star formation.
The history pertaining to the discovery of molecular clouds is closely related to the development of radio astronomy and astrochemistry. During World War II, at a small gathering of scientists, Henk van de Hulst first reported he had calculated the neutral hydrogen atom should transmit a detectable radio signal. This discovery was an important step towards the research that would lead to detecting molecular clouds.
The neutral hydrogen atom consists of a proton with an electron in its orbit. Both the proton and the electron have a spin property. When the spin state flips from a parallel condition to antiparallel, which contains less energy, the atom gets rid of the excess energy by radiating a spectral line at a frequency of 1420.405 MHz.
This frequency is generally known as the 21-cm line, referring to its wavelength in the radio band. The 21-cm line is the signature of HI and makes the gas detectable to astronomers back on earth. The discovery of the 21-cm line was the first step towards the technology that would allow astronomers to detect compounds and molecules in interstellar space.
Hydrogen is the most abundant species of atom in molecular clouds, and under the right conditions it will form the H2 molecule. Despite its abundance, the detection of H2 proved difficult. Due to its symmetrical molecule, H2 molecules have a weak rotational and vibrational modes, making it virtually invisible to direct observation.
The solution to this problem came when Arno Penzias, Keith Jefferts, and Robert Wilson identified CO in the star-forming region in the Omega Nebula. Carbon monoxide is a lot easier to detect than H2 because of its rotational energy and asymmetrical structure. CO soon became the primary tracer of the clouds where star-formation occurs. (WIKI)
Rio Rancho NM Bortle 5 zone, July 9 to forever, 2024
William Optics Redcat 51
ZWO 183mm pro
ZWO 30mm f/4 mini guide scope and ZWO 120 Mini
Optolong Ha G B filters
ZWO ASI Air Pro
Sky-Watcher HEQ5 (misbehaved, disassembled, changed nothing, cursed, reassembled...works again)
Darks GraXpert dithering
Gain 111 at -10C
Processed in DSS GraXpert and PS
IC5146_Cocoon Nebula and Barnard 168
After two months of clouds, I finally saw some clear skies...
IC 5146 (the Cocoon Nebula) is a reflection /emission nebula (lower left) located about 2,500 light-years away in the constellation Cygnus.
Barnard 168 is a dark nebula that surrounds IC 5146 and forms the dark lane extending up and to the right in this image.
Reflection nebulae are clouds of interstellar dust which reflect the light of a nearby star or stars.
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.
A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae.
Dark nebulae appear so because of sub-micrometer-sized dust particles, coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths. Also present are molecular hydrogen, atomic helium, C18O (CO with oxygen as the 18O isotope), CS, NH3 (ammonia), H2CO (formaldehyde), c-C3H2 (cyclopropenylidene) and a molecular ion N2H+ (diazenylium), all of which are relatively transparent. These clouds are the spawning grounds of stars and planets, and understanding their development is essential to understanding star formation.
The history pertaining to the discovery of molecular clouds is closely related to the development of radio astronomy and astrochemistry. During World War II, at a small gathering of scientists, Henk van de Hulst first reported he had calculated the neutral hydrogen atom should transmit a detectable radio signal. This discovery was an important step towards the research that would lead to detecting molecular clouds.
The neutral hydrogen atom consists of a proton with an electron in its orbit. Both the proton and the electron have a spin property. When the spin state flips from a parallel condition to antiparallel, which contains less energy, the atom gets rid of the excess energy by radiating a spectral line at a frequency of 1420.405 MHz.
This frequency is generally known as the 21-cm line, referring to its wavelength in the radio band. The 21-cm line is the signature of HI and makes the gas detectable to astronomers back on earth. The discovery of the 21-cm line was the first step towards the technology that would allow astronomers to detect compounds and molecules in interstellar space.
Hydrogen is the most abundant species of atom in molecular clouds, and under the right conditions it will form the H2 molecule. Despite its abundance, the detection of H2 proved difficult. Due to its symmetrical molecule, H2 molecules have a weak rotational and vibrational modes, making it virtually invisible to direct observation.
The solution to this problem came when Arno Penzias, Keith Jefferts, and Robert Wilson identified CO in the star-forming region in the Omega Nebula. Carbon monoxide is a lot easier to detect than H2 because of its rotational energy and asymmetrical structure. CO soon became the primary tracer of the clouds where star-formation occurs. (WIKI)
Rio Rancho NM Bortle 5 zone, July 9 to forever, 2024
William Optics Redcat 51
ZWO 183mm pro
ZWO 30mm f/4 mini guide scope and ZWO 120 Mini
Optolong Ha G B filters
ZWO ASI Air Pro
Sky-Watcher HEQ5 (misbehaved, disassembled, changed nothing, cursed, reassembled...works again)
Darks GraXpert dithering
Gain 111 at -10C
Processed in DSS GraXpert and PS