The Spitzer Space Telescope - Images Continued
Messier 104 - The "Sombrero" Galaxy
NASA's Spitzer and Hubble Space Telescopes joined
forces to create this striking composite image of one of the most popular sights
in the universe. Messier 104 is commonly known as the Sombrero galaxy because in
visible light, it resembles the broad-brimmed Mexican hat. However, in Spitzer's
striking infrared view, the galaxy looks more like a "bull's eye."
In Hubble's visible light image (lower left
panel), only the near rim of dust can be clearly seen in silhouette. Recent
observations using Spitzer's infrared array camera (lower right panel) uncovered
the bright, smooth ring of dust circling the galaxy, seen in red. Spitzer's
infrared view of the starlight, piercing through the obscuring dust, is easily
seen, along with the bulge of stars and an otherwise hidden disk of stars within
the dust ring.
Spitzer's full view shows the disk is warped, which is often the result of a gravitational encounter with another galaxy, and clumpy areas spotted in the far edges of the ring indicate young star-forming regions. The Sombrero galaxy is located some 28 million light-years away. Viewed from Earth, it is just six degrees south of its equatorial plane. Spitzer detected infrared emission not only from the ring, but from the centre of the galaxy too, where there is a huge black hole, believed to be a billion times more massive than our Sun. There is a full resolution image (4.5Mb) here.
Star Forming Region DR-6
This dust cloud, looking a bit like a Face in Space,
is a nebula called "DR 6" residing in the plane of our Milky Way
galaxy. It is home to a cluster of about 10 massive newborn stars, ranging
in size from 10 to 20 times the mass of our Sun. The nebular "eyes"
and "mouth" were carved out by intense heat and winds, which shoot
outward from the stars (located in the central bar or "nose"). The
green material remaining in the eyes and mouth is comprised of gas, while the
red regions and tendrils beyond make up the dusty cloud that originally gave
birth to the young stars.
Within the nebula's nose, a second generation of stars is in the process of forming. These stars, in turn, will sculpt their stellar nursery, and ultimately affect the birth of yet another generation of stars. DR 6 is located 3,900 light-years away in the constellation Cygnus. The distance from one end of its central bar to the other is the about 3.5 light-years, or about the same distance from our Sun to its nearest neighbour, Alpha Centauri. Click here for a FULL RESOLUTION IMAGE (1.0Mb)
The magnificent spiral arms of this nearby galaxy
are highlighted here. Located in the northern constellation of Ursa Major this
galaxy is easily visible through binoculars or a small telescope. M81 is located
at a distance of 12 million light-years. Because of its proximity, M81
provides astronomers with an enticing opportunity to study the anatomy of a
spiral galaxy in detail. The spatial resolution at infrared wavelengths show a
clear separation between the several key constituents of the galaxy: the old
stars, the interstellar dust heated by star formation activity, and the embedded
sites of massive star formation. The infrared images also permit quantitative
measurements of the galaxy's overall dust content, as well as the rate at which
new stars are being formed.
The infrared image was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). Winding outward from the bluish-white central bulge of the galaxy, where old stars predominate and there is little dust, the grand spiral arms are dominated by infrared emission from dust. Dust in the galaxy is bathed by ultraviolet and visible light from the surrounding stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles, composed of silicates (which are chemically similar to beach sand) and polycyclic aromatic hydrocarbons, trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation. Click here for a FULL RESOLUTION IMAGE (1.1Mb)
These images compare the well-known visible-light
picture of the glowing Trifid Nebula (left panel) with infrared views from
Spitzer (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
The false-colour Spitzer images show a very different side of the Trifid Nebula. The dark lanes of dust which trisect the nebula in the visible-light picture, become bright regions of star-forming activity in the Spitzer pictures. All together, Spitzer uncovered 30 massive embryonic stars and 120 smaller newborn stars throughout the 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 Radio-astronomy millimetre 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.
We 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 multi-band 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 centre of the nebula in all four images. Type O stars are the most massive stars, ending their brief lives in explosive supernovae. The small newborn stars probably arose at the same time as the O star, and from the same original cloud of gas and dust. Click here for a FULL RESOLUTION IMAGE (0.9Mb)
Located about 2,000 light years from Earth in the
constellation Lyra, the Ring Nebula is also known as Messier 57. It is a
planetary nebula, which is a shell of material ejected from a dying star. The
outer shell of this planetary nebula looks surprisingly similar to the delicate
petals of a camellia blossom. The
"ring" is a thick cylinder of glowing gas and dust around the doomed
star. As the star begins to run out of fuel, its core becomes smaller and
hotter, boiling off its outer layers.
The telescope's infrared array camera detected this material expelled from the withering star. Previous images of the Ring Nebula taken by visible-light telescopes usually showed just the inner glowing loop of gas around the star. The outer regions are especially prominent in this new image because Spitzer sees the infrared light from hydrogen molecules. The molecules emit infrared light because they have absorbed ultraviolet radiation from the star or have been heated by the wind from the star. Note the tiny galaxy IC 1296 at top right. Click here for a FULL RESOLUTION IMAGE (3.5Mb)
Nebulous Area RCW79 in Centaurus
RCW 79 is seen in the southern Milky Way, 17,200
light-years from Earth in the constellation of Centaurus. The bubble is 70-light
years in diameter, and probably took about one million years to form from the
radiation and winds of hot young stars. The
balloon of gas and dust is an example of stimulated star formation. Such stars
are born when the hot bubble expands into the interstellar gas and dust around
it. RCW 79 has spawned at least two groups of new stars along the edge of
the large bubble. Some are visible inside the small bubble in the lower left
corner. Another group of baby stars appears near the opening at the top.
NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features. FULL RESOLUTION IMAGE (2MB)
Messier 1 - The "Crab" Nebula
The Crab Nebula is the shattered remnant of a
massive star that ended its life in a massive supernova explosion. Nearly a
thousand years old, the supernova was noted in the constellation of Taurus by
Chinese astronomers in the year 1054 AD when they suddenly saw a brilliant new
star in the daytime sky. This view of the supernova remnant shows the
infrared view of this complex object. The blue region traces the cloud of
energetic electrons trapped within the star's magnetic field, emitting so-called
"synchrotron" radiation. The yellow-red features follow the well-known
filamentary structures that permeate this nebula. Though they are known to
contain hot gases, their exact nature is still a mystery that astronomers are
The energetic cloud of electrons are driven by a rapidly rotating neutron star, or pulsar, at its core. The nebula is about 6,500 light-years away from the Earth, and is 5 light-years across. This false-colour image presents images from Spitzer's Infrared Array Camera (IRAC) and Multiband Imaging Photometer (MIPS) at 3.6 (blue), 8.0 (green), 24 (red) microns. FULL RESOLUTION IMAGE (1MB)
The Star Forming Region of Eta Carinae
This false-colour image taken by NASA's Spitzer
Space Telescope shows the "South Pillar" region of the star-forming
region called the Carina Nebula. Like cracking open a watermelon and finding its
seeds, the infrared telescope "busted open" this murky cloud to reveal
star embryos (yellow or white) tucked inside finger-like pillars of thick dust
(pink). Hot gases are green and foreground stars are blue. Not all of the
newfound star embryos can be easily spotted. Though the nebula's most
famous and massive star, Eta Carinae, is too bright to be observed by infrared
telescopes, the downward-streaming rays hint at its presence above the picture
frame. Ultraviolet radiation and stellar winds from Eta Carinae and its siblings
have shredded the cloud to pieces, leaving a mess of tendrils and pillars. This
shredding process triggered the birth of the new stars uncovered by Spitzer.
The inset visible-light picture of the Carina Nebula shows quite a different view. Dust pillars are fewer and appear dark because the dust is soaking up visible light. Spitzer's infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. Eta Carinae is a huge star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime.
Eta Carinae's home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star's slightly less massive siblings, in addition to the younger generations of stars. FULL RESOLUTION IMAGE (7MB)
NGC 4725 in Coma Berenices
This peculiar galaxy is thought to have only one
spiral arm. Most spiral galaxies have two or more arms. Astronomers refer to NGC
4725 as a ringed barred spiral galaxy because a prominent ring of stars
encircles a bar of stars at its centre (the bar is seen here as a horizontal
ridge with faint red features). Our own Milky Way galaxy has multiple arms and a
proportionally smaller bar and ring. In this false-colour image, the
galaxy's arm is highlighted in red, while its centre and outlying halo are
blue. Red represents warm dust clouds illuminated by newborn stars, while
blue indicates older, cooler stellar populations. The red spokes seen projecting
outward from the arm are clumps of stellar matter that may have been pushed
together by unstable magnetic fields.
NGC 4725 is located 41 million light-years away in the constellation of Coma Berenices. FULL RESOLUTION IMAGE (0.5Mb)