New Views of a Familiar Beauty
This image composite compares the well-known visible-light
picture of the glowing Trifid Nebula (left panel)
with infrared views from NASA's Spitzer Space Telescope
(remaining three panels). The Trifid Nebula is a giant
star-forming cloud of gas and dust located 5,400 light-years
away in the constellation Sagittarius.
The
false-color Spitzer images reveal a different side
of the Trifid Nebula. Where dark lanes of dust are
visible trisecting the nebula in the visible-light
picture, bright regions of star-forming activity are
seen in the Spitzer pictures. All together, Spitzer
uncovered 30 massive embryonic stars and 120 smaller
newborn stars throughout the Trifid Nebula, in both
its dark lanes and luminous clouds. These stars are
visible in all the Spitzer images, mainly as yellow
or red spots. Embryonic stars are developing stars
about to burst into existence. Ten of the 30 massive
embryos discovered by Spitzer were found in four dark
cores, or stellar "incubators," where stars
are born. Astronomers using data from the Institute
of Radioastronomy millimeter telescope in Spain had
previously identified these cores but thought they
were not quite ripe for stars. Spitzer's highly sensitive
infrared eyes were able to penetrate all four cores
to reveal rapidly growing embryos.
Astronomers
can actually count the individual embryos tucked inside
the cores by looking closely at the Spitzer image
taken by its infrared array camera (top right). This
instrument has the highest spatial resolution of Spitzer's
imaging cameras. The Spitzer image from the multiband
imaging photometer (bottom right), on the other hand,
specializes in detecting cooler materials. Its view
highlights the relatively cool core material falling
onto the Trifid's growing embryos. The middle panel
is a combination of Spitzer data from both of these
instruments.
The
embryos are thought to have been triggered by a massive
"type O" star, which can be seen as a white
spot at the center of the nebula in all four images.
Type O stars are the most massive stars, ending their
brief lives in explosive supernovas. The small newborn
stars probably arose at the same time as the O star,
and from the same original cloud of gas and dust.
The
Spitzer infrared array camera image is a three-color
composite of invisible light, showing emissions from
wavelengths of 3.6 microns (blue), 4.5 microns (green),
5.8 and 8.0 microns (red). The Spitzer multiband imaging
photometer image shows 24-micron emissions. The Spitzer
mosaic image combines data from these pictures, showing
light of 4.5 microns (blue), 8.0 microns (green) and
24 microns (red). The visible-light image is from
the National Optical Astronomy Observatory, Tucson,
Ariz.
About
the Object
Object Name: Messier 20 - Trifid Nebula
Object Type: Nebula
Position (J2000): RA: 18h02m23.4s Dec: -23d01m50.1s
Distance: 5,500 light-years or 1.67 kpc
Constellation: Sagittarius
About the Data
Image Credit:
NASA/JPL-Caltech/J.Rho(SSC/Caltech)
Instrument: IRAC, MIPS
Wavelength:
IRAC: 3.6, 4.5, 5.8, and 8.0 microns
MIPS: 24 microns
Exposure Date:
IRAC: 2004-03-31
MIPS: 2004-04-11
Exposure Time:
IRAC: 8 sec per sky position
MIPS: 48sec per sky position
Image Scale: about 20 x 25 arcmin
Orientation:
Release Date: 12 January 2005
Observers
J. Rho - Principal Investigator (Spitzer Science Center/Caltech)
W. T. Reach (Spitzer Science Center/Caltech)
B. Lefloch (Laboratoire d'Astrophysique, Observatoire
de Grenoble)
G. Fazio (Harvard-Smithsonian Center for Astrophysics)
