domingo, 17 de febrero de 2013

Ghostly Bok Globules --Possible Habitats for Sentient ET Machines?


Ghostly NGC 1999, a reflection nebula in the constellation Orion, shows a remarkable jet-black cloud near its center, located just to the right and lower right of the bright star. This dark cloud is an example of a "Bok globule," named after the late University of Arizona astronomer Bart Bok.  SETI's chief scientist suggests they should be prime targets in the search for extraterrestrial life. The globule is a cold cloud of gas, molecules and cosmic dust, which is so dense it blocks all of the light behind it. The globule is seen silhouetted against the reflection nebula illuminated by V380 Orionis. Astronomers believe that new stars may be forming inside Bok globules, through the contraction of the dust and molecular gas under their own gravity. 

Bok globules are a prime search target for sentient ET machines. These dense regions of dust and gas are notorious for producing multiple-star systems. At around negative 441 degrees Fahrenheit, they are about 160 degrees F colder than most of interstellar space. Data centers generate a lot of heat, and keeping them cool is a major challenge for modern computing. Intelligent computers would likely seek out a low-temperature habitat, according to SETI chief astronomer, Seth Shostak.
"I think we could spend at least a few percent of our time... looking in the directions that are maybe not the most attractive in terms of biological intelligence but maybe where sentient machines are hanging out." Shostak thinks SETI ought to consider expanding its search to the energy- and matter-rich neighborhoods of Bok globules, black holes and neutron stars.

Like fog around a street lamp, a reflection nebula shines only because the light from an embedded source illuminates its dust; the nebula does not emit any visible light of its own. The nebula is famous in astronomical history because the first Herbig-Haro object was discovered immediately adjacent to it (it lies just outside the new Hubble image). Herbig-Haro objects are now known to be jets of gas ejected from very young stars.

The nebula is illuminated by a bright, recently formed star, visible just to the left of center. This star is cataloged as V380 Orionis, and its white color is due to its high surface temperature of about 10,000 degrees Celsius, nearly twice that of our own sun. Its mass is estimated to be 3.5 times that of the sun. The star is so young that it is still surrounded by a cloud of material left over from its formation, here seen as the NGC 1999 reflection nebula.

Source: The Daily Galaxy via NASA and The Hubble Heritage Team (STScI)

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