What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. NASA's Hubble Space Telescope has photographed dense knots of dust and gas in our Milky Way Galaxy. This cosmic dust is a concentration of elements that are responsible for the formation of stars in our galaxy and throughout the universe. These dark, opaque knots of gas and dust are called "Bok globules," and they are absorbing light in the center of the nearby emission nebula and star-forming region, NGC 281. These images were taken with Hubble's Advanced Camera for Surveys in October 2005. NGC 281 is located nearly 9,500 light-years away in the direction of the constellation Cassiopeia.
Technical facts about this news release: About the Object Object Description: Bok Globules in NGC 281 Position (J2000): R.A. 00h 53m 04s.59 Dec. +56° 38' 18".01 Constellation: Cassiopeia Distance: 9,500 light-years (2.9 kiloparsecs) Dimensions: This image is roughly 2.4 arcminutes (6.5 light-years or 2 parsecs) wide. About the Data Data Description: This image was created from HST data from proposal 10713 K. Noll, H. Bond, C. Christian, L. Frattare, F. Hamilton, Z. Levay, M. Mutchler, W. Januszewski, and T. Royle (Hubble Heritage Team/STScI/AURA) and P. McCullough (STScI). Instrument: ACS/WFC Exposure Date(s): October 31, 2005 Exposure Time: 2.1 hours Filters: F435W("B"), F555W("V"), F658N (H alpha), F814W("I") About the Image Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Release Date: April 4, 2006 Color: This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using several different filters. Three filters sample broad wavelength ranges; one isolates the light of hydrogen. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: F658N (Hydrogen-alpha) red/orange F814W ("I") red F555W ("V") green F435W ("B") blue Orientation/Scale: Nearby Dust Clouds in the Milky Way [ http://imgsrc.hubbl…]
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*Image Type:*: Astronomical
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*Release Date*:April 4, 2006 09:00 AM (EDT)
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*News Release Number:*: STScI-2006-13a
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*Title*:Nearby Dust Clouds in the Milky Way
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*Description*: The yearly ritual of spring cleaning clears a house of dust as well as dust "bunnies," those pesky dust balls that frolic under beds and behind furniture. NASA's Hubble Space Telescope has photographed similar dense knots of dust and gas in our Milky Way Galaxy. This cosmic dust, however, is not a nuisance. It is a concentration of elements that are responsible for the formation of stars in our galaxy and throughout the universe. These opaque, dark knots of gas and dust are called "Bok globules," and they are absorbing light in the center of the nearby emission nebula and star-forming region, NGC 281. The globules are named after astronomer Bart Bok, who proposed their existence in the 1940's. Bok hypothesized that giant molecular clouds, on the order of hundreds of light-years in size, can become perturbed and form small pockets where the dust and gas are highly concentrated. These small pockets become gravitationally bound and accumulate dust and gas from the surrounding area. If they can capture enough mass, they have the potential of creating stars in their cores; however, not all Bok globules will form stars. Some will dissipate before they can collapse to form stars. That may be what's happening to the globules seen here in NGC 281. Near the globules are bright blue stars, members of the young open cluster IC 1590. The cluster is made up of a few hundred stars. The cluster's core, off the image towards the top, is a tight grouping of extremely hot, massive stars with an immense stellar wind. The stars emit visible and ultraviolet light that energizes the surrounding hydrogen gas in NGC 281. This gas then becomes super heated in a process called ionization, and it glows pink in the image. The Bok globules in NGC 281 are located very close to the center of the IC 1590 cluster. The exquisite resolution of these Hubble observations shows the jagged structure of the dust clouds as if they are being stripped apart from the outside. The heavy fracturing of the globules may appear beautifully serene but is in fact evident of the harsh, violent environment created by the nearby massive stars. The Bok globules in NGC 281 are visually striking nonetheless. They are silhouetted against the luminous pink hydrogen gas of the emission nebula, creating a stark visual contrast. The dust knots are opaque in visual light. Conversely, the nebulous gas surrounding the globules is transparent and allows light from background stars and even background galaxies to shine through. These images were taken with Hubble's Advanced Camera for Surveys in October 2005. The hydrogen-emission image that clearly shows the outline of the dark globules was combined with images taken in red, blue, and green light in order to help establish the true color of the stars in the field. NGC 281 is located nearly 9,500 light-years away in the direction of the constellation Cassiopeia. For more information, please contact: Keith Noll, Space Telescope Science
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Institute, Baltimore, Md., (phone) 410-338-1828, (e-mail) noll@stsci.edu or Peter McCullough, Space Telescope Science Institute, Baltimore, Md., (phone) 410-338-5068, (e-mail) pmcc@stsci.edu
