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Five x 30 sec image stack of NGC 2024 and Zeta Orion captured with a 100mm f5 Helios refractor and Canon EOS350D.

Picture 938



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Study finds surprising new clues about the formation of sun-like star clusters

An important advance in understanding how clusters of stars like our sun are formed has been made by a team that includes seven astronomers at Penn State and two at other universities. Using data from NASA's Chandra X-ray Observatory and infrared telescopes, the astronomers have shown that earlier theories about the process that creates star clusters in giant clouds of gas and dust cannot be correct.
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Flame Nebula
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Flame Nebula: NASA's Chandra Delivers New Insight into Formation of Star Clusters

flame_rollover_525.jpg

This composite image shows one of the clusters, NGC 2024, which is found in the center of the so-called Flame Nebula about 1,400 light years from Earth. In this image, X-rays from Chandra are seen as purple, while infrared data from NASA's Spitzer Space Telescope are colored red, green, and blue.
A study of NGC 2024 and the Orion Nebula Cluster, another region where many stars are forming, suggest that the stars on the outskirts of these clusters are older than those in the central regions. This is different from what the simplest idea of star formation predicts, where stars are born first in the center of a collapsing cloud of gas and dust when the density is large enough.

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NASA's Chandra Observatory Delivers New Insight into Formation of Star Clusters

chandra_star_cluster_insight_0.png?itok=swjoykke

Using data from NASA's Chandra X-ray Observatory and infrared telescopes, astronomers have made an important advance in the understanding of how clusters of stars come into being.
The data show early notions of how star clusters are formed cannot be correct. The simplest idea is stars form into clusters when a giant cloud of gas and dust condenses. The center of the cloud pulls in material from its surroundings until it becomes dense enough to trigger star formation. This process occurs in the center of the cloud first, implying that the stars in the middle of the cluster form first and, therefore, are the oldest.

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Orion B9/SMM 3
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Title: 13CO and C18O J=2-1 mapping of the environment of the Class 0 protostellar core SMM 3 in Orion B9
Authors: Oskari Miettinen

We attempt to achieve a better understanding of the gas distribution and velocity field around the deeply embedded Class 0 protostar SMM 3 in the Orion B9 star-forming region. Using the APEX 12-m telescope, we mapped the line emission from the J=2-1 rotational transition of two CO isotopologues, 13CO and C18O, over a 4' x 4' region around Orion B9/SMM 3. Both the 13CO and C18O lines exhibit two well separated velocity components at about 1.3 and 8.7 km/s. The emission of both CO isotopologues is more widely distributed than the submillimetre dust continuum emission as probed by LABOCA. The LABOCA 870-micron peak position of SMM 3 is devoid of strong CO isotopologue emission, which is consistent with our earlier detection of strong CO depletion in the source. No signatures of a large-scale outflow were found towards SMM 3. The 13CO and C18O emission seen at ~1.3 km/s is concentrated into a single clump-like feature at the eastern part of the map. The peak H2 column density towards a C18O maximum of the low-velocity component is estimated to be ~10^22 cm-2. A velocity gradient was found across both the 13CO and C18O maps. Interestingly, SMM 3 lies on the border of this velocity gradient. The 13CO and C18O emission at ~1.3 km/s is likely to originate from the "low-velocity part" of Orion B. Our analysis suggests that it contains high density gas, which conforms to our earlier detection of deuterated species at similarly low radial velocities. The sharp velocity gradient in the region might represent a shock front resulting from the feedback from the nearby expanding HII region NGC 2024. The formation of SMM 3, and possibly of the other members of Orion B9, might have been triggered by this feedback.

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Flame nebula
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The 'Flame' Burns Bright in New WISE Image

pia15635-640.jpg

A new image from NASA's Wide-field Infrared Survey Explorer, or WISE, shows the candle-like Flame nebula lighting up a cavern of dust. The Flame nebula is part of the Orion complex, a turbulent star-forming area located near the constellation's star-studded belt.
The image is being released today along with a new batch of data from the mission. Last March, WISE released its all-sky catalogue and atlas containing infrared images and data on more than a half billion objects, including everything from asteroids to stars and galaxies. Now, the mission is offering up additional data from its second scan of the sky.

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RE: NGC 2024
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Title: [12CII] and [13CII] 158 mum emission from NGC 2024: Large column densities of ionised carbon
Authors: U. U. Graf, R. Simon, J. Stutzki, S. W. J. Colgan, X. Guan, R. Güsten, R. Hartogh, C. E. Honingh, H.-W. Hübers

Context: We analyse the NGC 2024 HII region and molecular cloud interface using [12CII] and [13CII] observations.
Aims: We attempt to gain insight into the physical structure of the interface layer between the molecular cloud and the HII region.
Methods. Observations of [12CII] and [13CII] emission at 158 {\mu}m with high spatial and spectral resolution allow us to study the detailed structure of the ionisation front and estimate the column densities and temperatures of the ionised carbon layer in the PDR.
Results: The [12CII] emission closely follows the distribution of the 8 mum continuum. Across most of the source, the spectral lines have two velocity peaks similar to lines of rare CO isotopes. The [13CII] emission is detected near the edge-on ionisation front. It has only a single velocity component, which implies that the [12CII] line shape is caused by self-absorption. An anomalous hyperfine line-intensity ratio observed in [13CII] cannot yet be explained.
Conclusions: Our analysis of the two isotopes results in a total column density of N(H)~1.6 x 10^23 cm^-2 in the gas emitting the [CII] line. A large fraction of this gas has to be at a temperature of several hundred K. The self-absorption is caused by a cooler (T<=100 K) foreground component containing a column density of N(H)~10^22 cm^-2.

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The Flame Nebula, designated as NGC 2024 (and Sh2-277) is an emission nebula in the Constellation Orion. It is about 900 to 1,500 light-years away.
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