A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H2), and the formation of H II regions. This is in contrast to other areas of the interstellar medium that contain predominantly ionized gas.
Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H2 is carbon monoxide (CO). The ratio between CO luminosity and H2 mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies.[1]
Within molecular clouds are regions with higher density, where much dust and many gas cores reside, called clumps. These clumps are the beginning of star formation if gravitational forces are sufficient to cause the dust and gas to collapse.[2]
^Craig Kulesa. "Overview: Molecular Astrophysics and Star Formation". Research Projects. Retrieved September 7, 2005.
^Astronomy(PDF). Rice University. 2016. p. 761. ISBN 978-1938168284 – via Open Stax.
A molecularcloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of...
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simply as molecularclouds, or sometime dense clouds. Neutral and ionized clouds are sometimes also called diffuse clouds. An interstellar cloud is formed...
Star formation is the process by which dense regions within molecularclouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming...
The Perseus molecularcloud (Per MCld) is a nearby (~1000 ly) giant molecularcloud in the constellation of Perseus and contains over 10,000 solar masses...
gravitational instability within a molecularcloud, caused by regions of higher density—often triggered by compression of clouds by radiation from massive stars...
the Solar System—a dusty dark nebula known as the Corona Australis MolecularCloud, lying about 430 light years away. Within it are stars at the earliest...
orbit it. It was formed 4.6 billion years ago when a dense region of a molecularcloud collapsed, forming the Sun and a protoplanetary disc. The Sun is an...
dark nebula or absorption nebula is a type of interstellar cloud, particularly molecularclouds, that is so dense that it obscures the visible wavelengths...
from the gravitational collapse of matter within a region of a large molecularcloud. Most of this matter gathered in the center, whereas the rest flattened...
abundance of 10−7 typical of molecularclouds, the formation will proceed at a rate of 1.6×10−9 cm−3s−1 in a molecularcloud of total density 105 cm−3....
within the densest regions of the ISM, which ultimately contributes to molecularclouds and replenishes the ISM with matter and energy through planetary nebulae...
diffuse clouds have been established for some works (Hartquist 1990). The •HO radical is linked with the production of H2O in molecularclouds. Studies...
the Swedish-built Odin satellite had made the first detection of clouds of molecular oxygen in space, following observations in the constellation Ophiuchus...
Barnard 68 is a molecularcloud, dark absorption nebula or Bok globule, towards the southern constellation Ophiuchus and well within the Milky Way galaxy...
others are produced by stars. Examples of the former case are giant molecularclouds, the coldest, densest phase of interstellar gas, which can form by...
as Caldwell 49) is an H II region located near one end of a giant molecularcloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC...
tens to a few thousand stars that were formed from the same giant molecularcloud and have roughly the same age. More than 1,100 open clusters have been...
years. The Orion Nebula is in turn surrounded by the much larger Orion molecularcloud complex which is hundreds of light years across, spanning the whole...
The Oort cloud (/ɔːrt, ʊərt/), sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances...
28 °F). Hydronium is an abundant molecular ion in the interstellar medium and is found in diffuse and dense molecularclouds as well as the plasma tails of...
produces strong molecular maser emission and was one of the first radio masers discovered. VY CMa is embedded in the large molecularcloud Sh2-310, a large...
is part of the much larger Orion molecularcloud complex. It appears within the southern region of the dense dust cloud known as Lynds 1630, along the edge...
the cloud will collapse, is called Jeans collapse criterion. The Jeans instability likely determines when star formation occurs in molecularclouds. In...
an H II region, which has an hour-glass morphology. Dust from the molecularcloud in which W40 formed obscures the nebula, rendering W40 difficult to...
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