This light-year-long knot of interstellar gas and dust resembles a
caterpillar on its way to a feast. But the meat of the story is not only
what this cosmic caterpillar eats for lunch, but also what's eating it.
Harsh winds from extremely bright stars are blasting ultraviolet
radiation at this "wanna-be" star and sculpting the gas and dust into
its long shape.
The culprits are 65 of the hottest, brightest known stars, classified
as O-type stars, located 15 light-years away from the knot, towards the
right edge of the image. These stars, along with 500 less bright, but
still highly luminous B-type stars make up what is called the Cygnus OB2
association. Collectively, the association is thought to have a mass
more than 30,000 times that of our Sun.
The caterpillar-shaped knot, called IRAS 20324+4057, is a protostar
in a very early evolutionary stage. It is still in the process of
collecting material from an envelope of gas surrounding it. However,
that envelope is being eroded by the radiation from Cygnus OB2.
Protostars in this region should eventually become young stars with
final masses about one to ten times that of our Sun, but if the eroding
radiation from the nearby bright stars destroys the gas envelope before
the protostars finish collecting mass, their final masses may be
reduced.
Spectroscopic observations of the central star within IRAS 20324+4057
show that it is still collecting material quite heavily from its outer
envelope, hoping to bulk up in mass. Only time will tell if the formed
star will be a "heavy-weight" or a "light-weight" with respect to its
mass.
This image of IRAS 20324+4057 is a composite of Hubble Advanced
Camera for Surveys data taken in green and infrared light in 2006, and
ground-based hydrogen data from the Isaac Newton Telescope in 2003, as
part of the IPHAS H-alpha survey. The object lies 4,500 light-years away
in the constellation Cygnus.
For more information, contact:
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
Zolt Levay
Space Telescope Science Institute, Baltimore, Md.
410-338-4907
Space Telescope Science Institute, Baltimore, Md.
410-338-4907
