Orion’s Rainbow of Infrared Light – NASA

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Orion’s Rainbow of Infrared Light

www.nasa.gov Orion’s Rainbow of Infrared Light

Astronomers have spotted young stars in the Orion Nebula
changing right before their eyes, thanks to the European Space
Agency’s Herschel Space Observatory and NASA’s Spitzer
Space Telescope. The colorful specks—developing stars strung
across the image—are rapidly heating up and cooling down,
speaking to the turbulent, rough-and-tumble process of reach-
ing full stellar adulthood.

The rainbow of colors represents different wavelengths of infra-
red light captured by both Spitzer and Herschel. Infrared data at
wavelengths of 8.0 and 24 microns from Spitzer are rendered in
blue. Herschel data with wavelengths of 70 and 160 microns are
represented in green and red, respectively. Spitzer is designed
to see shorter infrared wavelengths than Herschel. By combin-
ing their observations, astronomers get a more complete picture
of star formation.

In the portion of the Orion Nebula pictured here, the telescopes’
infrared vision reveals a host of embryonic stars hidden in gas
and dust clouds. These stars are at the very earliest stages of
evolution.

A star forms when a clump of this gas and dust collapses,
creating a warm glob of material fed by an encircling disk. In
several hundred thousand years, some of the forming stars will
accrete enough material to trigger nuclear fusion at their cores
and then blaze into stardom.

Herschel mapped this region of the sky once a week for six
weeks in the late winter and spring of 2011. To monitor for

activity in protostars, Herschel’s Photodetector Array Camera
and Spectrometer probed long infrared wavelengths of light
that trace cold dust particles, while Spitzer gauged the warmer
dust emitting shorter infrared wavelengths. In these data, as-
tronomers noticed that several of the young stars varied in their
brightness by more than 20 percent over just a few weeks. As
this twinkling comes from cool material emitting infrared light,
the material must be far from the hot center of the young star,
likely in the outer disk or surrounding gas envelope. At that
distance, it should take years or centuries for material to spiral
closer in to the growing starlet, rather than mere weeks.

A couple of scenarios under investigation could account for this
short span. One possibility is that lumpy filaments of gas funnel
from the outer to the central regions of the star, temporarily
warming the object as the clumps hit its inner disk. Or, it could
be that material occasionally piles up at the inner edge of the
disk and casts a shadow on the outer disk.

Herschel’s exquisite sensitivity opens up new possibilities for
astronomers to study star formation and observe short-term
variability in Orion protostars. Follow-up observations with
Herschel will help astronomers identify the physical processes
responsible for the variability.

Herschel is a European Space Agency cornerstone mission,
with science instruments provided by consortia of European
institutes and with important participation by NASA. NASA’s
Herschel Project Office is based at JPL. JPL contributed
mission-enabling technology for two of Herschel’s three science
instruments. The NASA Herschel Science Center, part of the
Infrared Processing and Analysis Center at the California
Institute of Technology in Pasadena, supports the United States
astronomical community. Caltech manages JPL for NASA.

http://www.herschel.caltech.edu

http://sci.esa.int/herschel

JPL manages the Spitzer Space Telescope mission for NASA’s
Science Mission Directorate, Washington. Science operations
are conducted at the Spitzer Science Center at Caltech. Caltech
manages JPL for NASA.

See more Spitzer images at

http://www.spitzer.caltech.edu

LG-2013-01-013-JPL — JPL 400-1524 01/13

National Aeronautics and Space AdministrationJet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California