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TOPIC: W3 Star Forming Complex
Blobrana


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W3 star-forming region
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W3_Herschel_display.jpg

One of the current big problems in astrophysics is explaining how high mass stars form. By looking at star-forming regions in great detail with Herschel, astronomers are starting to piece together a picture. The region shown above is known as "W3", and is a Giant Molecular Cloud which lies around 6200 light years away in one of the spiral arms of our Galaxy.
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Blobrana


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RE: W3 Star Forming Complex
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Title: Age spread in Galactic star forming region W3 Main
Authors: A. Bik (1), Th. Henning (1), A. Stolte (2), W. Brandner (1), D. A. Gouliermis (1), M. Gennaro (1), A. Pasquali (3), B. Rochau (1), H. Beuther (1), N. Ageorges (4), W. Seifert (5), Y. Wang (6), N. Kudryavtseva (1), ((1) MPIA, Heidelberg, Germany, (2) AIfA, Bonn, Germany, (3) ARI, Heidelberg, Germany, (4) MPE, Garching, Germany, (5) LSW, Heidelberg, Germany, (6) Purple Mountain Observatory, Nanjing, China)

We present near-infrared JHKs imaging as well as K-band multi-object spectroscopy of the massive stellar content of W3 Main using LUCI at the LBT. We confirm 13 OB stars by their absorption line spectra in W3 Main and spectral types between O5V and B4V have been found. Three massive Young Stellar Objects are identified by their emission line spectra and near-infrared excess. From our spectrophotometric analysis of the massive stars and the nature of their surrounding HII regions we derive the evolutionary sequence of W3 Main and we find an age spread of 2-3 Myr.

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 W3 Main

Credit: X-ray: NASA/CXC/Penn State/L.Townsley et al.; Optical: Pal Obs. DSS

Position (J2000): RA 02h 25m 40.60s | Dec +62º 05' 52.40"



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Blobrana


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Posts: 131433
Date:
HII region W3A
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Title: First science results from SOFIA/FORCAST: The mid-infrared view of the compact HII region W3A
Authors: F. Salgado, O. Berne, J. D. Adams, T. L. Herter, G. Gull, J. Schoenwald, L. D. Keller, J. M. De Buizer, W. D. Vacca, E. E. Becklin, R. Y. Shuping, A. G. G. M., Tielens, H. Zinnecker

The massive star forming region W3 was observed with the faint object infrared camera for the SOFIA telescope (FORCAST) as part of the Short Science program. The 6.4, 6.6, 7.7, 19.7, 24.2, 31.5 and 37.1 \um bandpasses were used to observe the emission of Polycyclic Aromatic Hydrocarbon (PAH) molecules, Very Small Grains and Big Grains. Optical depth and colour temperature maps of W3A show that IRS2 has blown a bubble devoid of gas and dust of ~0.05 pc radius. It is embedded in a dusty shell of ionised gas that contributes 40% of the total 24 \um emission of W3A. This dust component is mostly heated by far ultraviolet, rather than trapped Ly \alpha photons. This shell is itself surrounded by a thin (~0.01 pc) photodissociation region where PAHs show intense emission. The infrared spectral energy distribution (SED) of three different zones located at 8, 20 and 25\arcsec from IRS2, show that the peak of the SED shifts towards longer wavelengths, when moving away from the star. Adopting the stellar radiation field for these three positions, DUSTEM model fits to these SEDs yield a dust-to-gas mass ratio in the ionised gas similar to that in the diffuse ISM. However, the ratio of the IR-to-UV opacity of the dust in the ionised shell is increased by a factor \simeq 3 compared to the diffuse ISM.

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Blobrana


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Posts: 131433
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RE: W3 Star Forming Complex
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New Star Cluster W3A Images Captured by SOFIA Observatory

NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) researchers have captured new images of a recently born cluster of massive stars named W3A.
The cluster is seen lurking in the depths of the large gas and dust cloud from which it formed. The larger image shows the overall structure of the W3 region, lying 6,400 light years away in the direction of the constellation Perseus, as seen at near-infrared wavelengths by the Spitzer Space Telescope. The inset image composed of data obtained by SOFIA at mid-infrared wavelengths zooms in on the violent interaction zone around the massive star cluster.
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Blobrana


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Posts: 131433
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W3(OH)TW
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Title: Disks and outflows in the massive protobinary system W3(OH)TW
Authors: Luis A. Zapata (CRyA-UNAM), Carolina Rodríguez-Garza (CRyA-UNAM), Luis F. Rodríguez (CRyA-UNAM), Josep M. Girart (CSIC-IEEC), Huei-Ru Chen (NTHU)

Sensitive and high angular resolution (~ 0.7") (sub)millimetre line and continuum observations of the massive star forming region W3(OH) made with the Submillimeter Array are presented. We report the first detection of two bipolar outflows emanating from the young and massive "Turner-Welch" [TW] protobinary system detected by the emission of the carbon monoxide. The outflows are massive (10 solar masses), highly-collimated (10°), and seem to be the extended molecular component of the strong radio jets and a 22 GHz maser water outflow energised also by the stars in the W3(OH)TW system. Observations of the 890 \mu m continuum emission and the thermal emission of the CH_3 OH might suggest the presence of two rotating circumstellar disk-like structures associated with the binary system. The disks-like structures have sizes of about 1500 AU, masses of a few solar masses and appear to energise the molecular outflows and radio jets. We estimate that the young stars feeding the outflows and that are surrounded by the massive disk-like structures maybe are B-type.

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Blobrana


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Posts: 131433
Date:
RE: W3 Star Forming Complex
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A "stellar cradle," an area of space where stars one tenth the mass of the Sun are forming, has been photographed by the National Astronomical Observatory of Japan.
The existence of the cluster of brown dwarf stars was discovered in 1995, but photographing them has been a challenge due to the very low amounts of light they emit.

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Blobrana


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Title: The Diverse Stellar Populations of the W3 Star Forming Complex
Authors: Eric D. Feigelson, Leisa K. Townsley (Dept of Astronomy & Astrophysics, Penn State University)

An 800 sq-arcmin mosaic image of the W3 star forming complex obtained with the Chandra X-ray Observatory gives a valuable new view of the spatial structure of its young stellar populations. The Chandra image reveals about 1300 faint X-ray sources, most of which are PMS stars in the cloud. Some, but not all, of the high-mass stars producing hypercompact and ultracompact H II (UCHII) regions are also seen, as reported in a previous study.
The Chandra images reveal three dramatically different embedded stellar populations. The W3 Main cluster extends over 7 pc with about 900 X-ray stars in a nearly-spherical distribution centred on the well-studied UCHII regions and high-mass protostars. The cluster surrounding the prototypical UCHII region W3(OH) shows a much smaller (<0.6 pc), asymmetrical, and clumpy distribution of about 50 PMS stars. The massive star ionising the W3 North H II region is completely isolated without any accompanying PMS stars. In W3 Main, the inferred ages of the widely distributed PMS stars are significantly older than the inferred ages of the central OB stars illuminating the UCHIIs. We suggest that different formation mechanisms are necessary to explain the diversity of the W3 stellar populations: cluster-wide gravitational collapse with delayed OB star formation in W3 Main, collect-and-collapse triggering by shock fronts in W3(OH), and a runaway O star or isolated massive star formation in W3 North.

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