Annotated image of the W3 giant
molecular cloud combining Herschel
bands at 70 μm (blue), 160 μm (green) and 250 μm (red). The image spans 2
x 2 degrees. North is up and east is to the left. Copyright: ESA/PACS
& SPIRE consortia, A. Rivera-Ingraham & P.G. Martin,
Univ. Toronto, HOBYS Key Programme (F. Motte). More Images
In this new view of a vast star-forming cloud called W3, ESA’s Herschel space observatory tells the story of how massive stars are born.
W3 is a giant molecular cloud containing an enormous stellar nursery,
some 6200 light-years away in the Perseus Arm, one of our Milky Way
Galaxy’s main spiral arms.
Spanning almost 200 light-years, W3 is one of the largest star-formation
complexes in the outer Milky Way, hosting the formation of both low-
and high-mass stars. The distinction is drawn at eight times the mass of
our own Sun: above this limit, stars end their lives as supernovas.
Dense, bright blue knots of hot dust marking massive star formation
dominate the upper left of the image in the two youngest regions in the
scene: W3 Main and W3 (OH). Intense radiation streaming away from the
stellar infants heats up the surrounding dust and gas, making it shine
brightly in Herschel’s infrared-sensitive eyes.
Older high-mass stars are also seen to be heating up dust in their
environments, appearing as the blue regions labelled AFGL 333 in the
lower left of the annotated version of the image, and the loop of KR
140, at bottom right.
Extensive networks of much colder gas and dust weave through the scene
in the form of red filaments and pillar-like structures. Several of
these cold cores conceal low-mass star formation, hinted at by tiny
yellow knots of emission.
By studying the two regions of massive star formation – W3 Main and W3
(OH) – scientists have made progress in solving one of the major
conundrums in the birth of massive stars. That is, even during their
formation, the radiation blasting away from these stars is so powerful
that they should push away the very material they are feeding from. If
this is the case, how can massive stars form at all?
Observations of W3 point toward a possible solution: in these very dense
regions, there appears to be a continuous process by which the raw
material is moved around, compressed and confined, under the influence
of clusters of young, massive protostars.
Through their strong radiation and powerful winds, populations of young
high-mass stars may well be able to build and maintain localised clumps
of material from which they can continue to feed during their earliest
and most chaotic years, despite their incredible energy output.
Notes for Editors
“Herschel observations of the W3 GMC: Clues to the formation of clusters
of high-mass stars,” by A. Rivera-Ingraham et al., is published in The Astrophysical Journal, 766, 85; doi:10.1088/0004-637X/766/2/85.
The study was part of the Guaranteed Time Key Programme HOBYS, the Herschel imaging survey of OB Young Stellar objects.
The image presented here was taken in three colour bands centred on 70 μm (blue), 160 μm (green) and 250 μm (red).
Herschel is an ESA space observatory with science instruments provided
by European-led Principal Investigator consortia and with important
participation from NASA.
For further information, please contact:
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer@esa.int
Alana Rivera-Ingraham
University of Toronto
Email: rivera@cita.utoronto.ca
Göran Pilbratt
ESA Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt@rssd.esa.int
