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Glimpse of glittering stars and gas

GLIMPSE360 and 2MASS image

Two bright stars illuminate clouds of gas in this false-colour image made from Spitzer Space Telescope GLIMPSE360 and Two Micron All Sky Survey data. The gas is composed of polycyclic aromatic hydrocarbons (PAHs), molecules that on Earth are found in car exhausts and grilled food on BBQs!

  • Spitzer space telescope making Milky Way map
  • Focusing on our galaxy’s outer reaches

NASA’s Spitzer space telescope—which is similar to the Hubble Space Telescope but is optimised to pick up infrared radiation (heat)—is partway through producing a huge map of the outskirts of our Milky Way galaxy.

Our galaxy is made up of a central bulge surrounded by octopus-like spiral arms. The overall shape is that of a disc…round, with a thicker middle and thinner edges.

Our Solar System is located on one of the spiral arms, about two-thirds of the way out from the central bulge.

The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 360, or GLIMPSE360, is a follow-up to the GLIMPSE and GLIMPSE3D surveys, which focused on the inner parts of our galaxy.

GLIMPSE360 will look outwards to where the Milky Way’s star fields begin to fade out and intergalactic space begins.

“GLIMPSE360 will see to the edge of the Milky Way galaxy better than any telescope has before,” says Barbara Whitney, principal investigator for the survey, Senior Scientist at the University of Wisconsin and a Senior Research Scientist at the Space Science Institute in Boulder, Colorado.

Astronomers don’t know much about the outer limits of the Milky Way, and a number of puzzles remain to be solved.

GLIMPSE360 and 2MASS image

The bubble in the centre of this gas cloud is being "inflated" by strong winds blown from young, hot stars. (False-colour image.)

One of them is how and why stars are born in regions where there is little star-making material—interstellar clouds of gas and dust.

“It’s like looking into the wilderness of our galaxy,” says Whitney. “While mapping the stars and dust out there, we hope to answer some major questions about an environment that is very different from the inner Milky Way.”

Studies of other galaxies have shown that there can be a surprising amount of star formation going on in the outer reaches.

Being an infrared telescope, Spitzer was launched with a cooling system to keep it’s own equipment very cold in order to prevent stray heat from interfering with its observations. But the coolant fluid ran out in early 2009, and the telescope has been operating in “warm mode” ever since. It can’t do quite the same observations as before, but it is still an incredibly capable facility that is in very good technical health.

“We look forward to what GLIMPSE360 will show us,” Whitney says. “The adventure is just getting started.”

Story by Jonathan Nally, Editor,

Images courtesy NASA / JPL-Caltech / 2MASS / B. Whitney (SSI/University of Wisconsin).

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Buckyballs in space!

Artist's conception of buckyballs in space

NASA's Spitzer Space Telescope has at last found buckyballs in space, as illustrated by this artist's conception showing the carbon balls coming out from the type of object where they were discovered—a dying star and the material it sheds, known as a planetary nebula. (The nebula Tc 1 does not show up well in images, so a picture of the NGC 2440 nebula, taken by the Hubble Space Telescope, was used in this artist's conception.)

  • Soccer ball-shaped molecules detected in a nebula
  • Buckyballs are collections of 60 carbon atoms
  • Spitzer Space Telescope in “right place at the right time”

How’s this for a kick-off? Astronomers using NASA’s Spitzer Space Telescope have discovered carbon molecules, known as “buckyballs,” in space for the first time. Buckyballs are soccer-ball-shaped molecules that were first seen in a laboratory 25 years ago.

They are named for their resemblance to architect Buckminster Fuller’s geodesic domes, which have interlocking circles on the surface of a partial sphere.

Buckyballs were thought to float around in space, but had escaped detection until now.

“We found what are now the largest molecules known to exist in space,” said astronomer Jan Cami of the University of Western Ontario, Canada, and the SETI Institute in Mountain View, California.

“We are particularly excited because they have unique properties that make them important players for all sorts of physical and chemical processes going on in space.”

Cami authored a paper about the discovery that appeared last Thursday in the journal Science.

Buckyballs are made of 60 carbon atoms arranged in three-dimensional, spherical structures. Their alternating patterns of hexagons and pentagons match a typical black-and-white soccer ball.

The research team also found the more elongated relative of buckyballs, known as C70, for the first time in space. These molecules consist of 70 carbon atoms and are shaped more like an oval rugby ball.

Both types of molecules belong to a class known officially as buckminsterfullerenes, or fullerenes.

Spotted in an ageing star system

The Cami team unexpectedly found the carbon balls in a planetary nebula (a cloud of gas) named Tc 1. Planetary nebulae are the remains of stars like the Sun, which shed their outer layers of gas and dust as they age.

A compact, hot star, or white dwarf, at the centre of the nebula illuminates and heats these clouds of material that has been shed.

The buckyballs were found in these clouds, perhaps reflecting a short stage in the star’s life, when it sloughs off a puff of material rich in carbon.

The astronomers used the Spitzer Space Telescope’s spectroscopy instrument to analyse infrared light from the planetary nebula and see the spectral signatures of the buckyballs.

Spectrum of Tc 1 showing the signatures of buckyballs

Spectral data from NASA's Spitzer Space Telescope show the signatures of buckyballs in space.

These molecules are approximately room temperature; the ideal temperature to give off distinct patterns of infrared light that Spitzer can detect.

According to Cami, Spitzer looked at the right place at the right time. A century from now, the buckyballs might be too cool to be detected.

The data from Spitzer were compared with data from laboratory measurements of the same molecules and showed a perfect match.

We did not plan for this discovery,” Cami said. “But when we saw these whopping spectral signatures, we knew immediately that we were looking at one of the most sought-after molecules.”

Intriguing molecules

In 1970, Japanese professor Eiji Osawa predicted the existence of buckyballs, but they were not observed until lab experiments in 1985.

Researchers simulated conditions in the atmospheres of aging, carbon-rich giant stars, in which chains of carbon had been detected. Surprisingly, these experiments resulted in the formation of large quantities of buckminsterfullerenes.

The molecules have since been found on Earth in candle soot, layers of rock and meteorites.

The study of fullerenes and their relatives has grown into a busy field of research because of the molecules’ unique strength and exceptional chemical and physical properties. Among the potential applications are armour, drug delivery and superconducting technologies.

Sir Harry Kroto, who shared the 1996 Nobel Prize in chemistry with Bob Curl and Rick Smalley for the discovery of buckyballs, said, “This most exciting breakthrough provides convincing evidence that the buckyball has, as I long suspected, existed since time immemorial in the dark recesses of our galaxy.”

Previous searches for buckyballs in space, in particular around carbon-rich stars, proved unsuccessful. A promising case for their presence in the tenuous clouds between the stars was presented 15 years ago, using observations at optical wavelengths. That finding is awaiting confirmation from laboratory data.

More recently, another Spitzer team reported evidence for buckyballs in a different type of object, but the spectral signatures they observed were partly contaminated by other chemical substances.

Adapted from information issued by NASA / ESA / STScI / JPL-Caltech / University of Western Ontario.

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Dragon of deep space

Visible and infrared images of M17 Swex

Before and after. The top half shows a visible light image of the region of space known as M17 Swex, while the bottom half is an infrared image of the same region, taken with the Spitzer Space Telescope. Details are revealed that are completely unseen at visible wavelengths.

A new infrared image from NASA’s Spitzer Space Telescope (above) shows what appears to be a dragon-shaped cloud of dust flying out from a bright explosion in space (bottom half), a creature that is entirely cloaked in shadow when viewed in visible part of the spectrum (top half).

The image has revealed that this dark cloud, called M17 SWex, is forming stars at a furious rate but has not yet spawned the most massive type of stars, known as O stars.

Such stellar behemoths, however, light up the M17 nebula at the image’s centre and have also blown a huge “bubble” in the gas and dust to the left of M17.

See the full-size infrared image here (1.1MB, will open in a new window).

The stars and gas in this region are passing though the Sagittarius spiral arm of the Milky Way (moving from right to left), touching off a galactic star-forming “domino effect.”

Stars are formed when interstellar gas clouds collapse in on themselves, often driven by pressure or shockwaves from outside.

The youngest episode of star formation is playing out inside the dusty dragon as it enters the spiral arm. Over time, this area will flare up like the bright M17 nebula to the left of the dragon, glowing in the light of young, massive stars.

The remnants of an older burst of star formation blew the bubble in the region to the far left, called M17 EB.

The different parts of M17 Swex

Stars and gas are moving through the Sagittarius spiral arm, sparking off star formation episodes.

The visible-light view of the area clearly shows the bright M17 nebula, as well as the glowing hot gas filling the “bubble” to its left. However the M17 SWex “dragon” is hidden within dust clouds that are opaque to visible light.

It takes an infrared view to catch the light from these shrouded regions and reveal the earliest stages of star formation.

Cold spacecraft takes hot pictures

The Spitzer Space Telescope comprises a 0.85-metre diameter telescope and three science instruments that perform imaging and spectroscopy in the 3–180 micron wavelength range.

Since infrared is primarily heat radiation, detectors are most sensitive to infrared light when they are kept extremely cold. Using the latest in large-format detector arrays, Spitzer has made observations that are more sensitive than any previous mission.

Artist's impression of the Spitzer Space Telescope

Artist's impression of the Spitzer Space Telescope (left) and a diagram showing its component parts.

Spitzer launched on 25 August 2003, but its coolant fluid has now run out. Now in an extended mission phase known as the Spitzer Warm Mission, the telescope continues to operate, but with some small limitations due to its not-as-cold-anymore status.

The telescope is surrounded by an outer shell that radiates heat to cold space in the anti-Sun direction, and is shielded from the Sun by the solar panel assembly. Intermediate shields intercept heat from the solar panel and the spacecraft bus, or main structure.

The outer shell and inner, middle, and outer shields were vapour cooled—ie. the cold helium vapour from the helium tank was used to carry away the heat from these structures—prior to the expiration of the coolant fluid.

The spacecraft bus contains the subsystems required for housekeeping and control engineering: telecommunications, reaction control, pointing control, command and data handling, and power. The star tracker and gyro package is mounted on the spacecraft bus. The main antenna is located at the rear of the spacecraft bus. Control thrusters are located on outriggers from the spacecraft bus.

Adapted from information issued by NASA / JPL-Caltech / Penn State / DSS.

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New star-forming regions found

The Orion Nebula

The Orion Nebula, an example of an H II gas cloud, where hydrogen gas is ionised and glows.

  • Previously-unknown star forming regions found
  • Scattered through the Milky Way
  • Hold chemical clues to stellar evolution

Astronomers studying the Milky Way have discovered a large number of previously-unknown regions where massive stars are being formed. Their discovery provides important new information about the structure of our home Galaxy and promises to yield new clues about the chemical composition of the Galaxy.

“We can clearly relate the locations of these star-forming sites to the overall structure of the Galaxy,” said Thomas Bania, of Boston University.

“Further studies will allow us to better understand the process of star formation and to compare the chemical composition of such sites at widely different distances from the Galaxy’s centre.”

Bania worked with Loren Anderson of the Astrophysical Laboratory of Marseille in France, Dana Balser of the US National Radio Astronomy Observatory (NRAO), and Robert Rood of the University of Virginia.

Gas clouds hidden from view

Artist's impression of the Milky Way looking from above

Our current understanding of the major components of our galaxy, the Milky Way (artist's impression shown here). Astronomers have found dozens more star-forming regions known as H II clouds.

The star-forming regions the astronomers sought, called H II regions, are sites where hydrogen atoms are ionised, or stripped of their electrons, by the intense radiation of the massive, young stars. To find these regions hidden from visible-light detection by the Milky Way’s gas and dust, the researchers used infrared and radio telescopes.

“We found our targets by using the results of infrared surveys done with NASA’s Spitzer Space Telescope and of surveys done with the US National Science Foundation’s (NSF) Very Large Array (VLA) radio telescope,” Anderson said. “Objects that appear bright in both the Spitzer and VLA images we studied are good candidates for H II regions.”

The astronomers then used the NSF’s giant Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, an extremely sensitive radio telescope. With the GBT, they were able to detect specific radio frequencies emitted by electrons as they recombined with protons to form hydrogen.

This evidence of recombination confirmed that the regions contained ionised hydrogen and thus are H II regions.

Our Galaxy’s chemical mix

Further analysis enabled the astronomers to determine the locations of the H II regions.  They found concentrations of the regions at the end of the Galaxy’s central elongated region and in its spiral arms. Their analysis also showed that 25 of the regions are farther from the Galaxy’s centre than the Sun.

“Finding the ones beyond the [Sun’s location] is important, because studying them will provide important information about the chemical evolution of the Galaxy,” Bania said. “There is evidence that the abundance of heavy elements changes with increasing distance from the Galactic centre.”

“We now have many more objects to study and improve our understanding of this effect.”

Adapted from information issued by NRAO / NASA / JPL-Caltech / R. Hurt (SSC-Caltech) / HHT (AURA / STScI / NASA).

A planet that “tastes” funny

Artist's concept of an unusual, methane-free planet

A distant planet is partially eclipsed by its star in this artist's concept. NASA's Spitzer Space Telescope has found evidence that the hot, Neptune-sized planet lacks methane — an ingredient common to many planets in our own Solar System.

NASA’s Spitzer Space Telescope has discovered something odd about a distant planet — it lacks methane, an ingredient common to many of the planets in our Solar System.

“It’s a big puzzle,” said Kevin Stevenson, a planetary sciences graduate student at the University of Central Florida in Orlando, lead author of a study appearing in the journal Nature.

“Models tell us that the carbon in this planet should be in the form of methane. Theorists are going to be quite busy trying to figure this one out.”

The discovery brings astronomers one step closer to probing the atmospheres of distant planets the size of Earth.

The methane-free planet, called GJ 436b, is about the size of Neptune, making it the smallest distant planet that any telescope has successfully “tasted,” or analysed.

Eventually, a larger space telescope could use the same kind of technique to search smaller, Earth-like worlds for methane and other chemical signs of life, such as water, oxygen and carbon dioxide.

“Ultimately, we want to find bio-signatures on a small, rocky world. Oxygen, especially with even a little methane, would tell us that we humans might not be alone,” said Stevenson.

Plots from NASA's Spitzer Space Telescope showing light from GJ 436b, and its star, measured at six different wavelengths.

The Spitzer Space Telescope measured the light from a distant planet, GJ 436b, and its star, at six different wavelengths, before, during and after the planet circled behind the star. The dips tell astronomers how much light is coming from the planet itself. The differences at different wavelengths give clues as to what gases are in the planet's atmosphere.

“In this case, we expected to find methane not because of the presence of life, but because of the planet’s chemistry. This type of planet should have cooked up methane. It’s like dipping bread into beaten eggs, frying it, and getting oatmeal in the end,” said Joseph Harrington of the University of Central Florida, the principal investigator of the research.

Does methane indicate the presence of life?

Methane is present on our life-bearing planet, manufactured primarily by microbes living in cows and soaking in waterlogged rice fields.

All of the giant planets in our Solar System have methane too, despite their lack of cows. Neptune is blue because of this chemical, which absorbs red light.

Methane is a common ingredient of relatively cool bodies, including “failed” stars, which are called brown dwarfs.

In fact, any world with the common atmospheric mix of hydrogen, carbon and oxygen, and a temperature up to 730 degrees Celsius is expected to have a large amount of methane and a small amount of carbon monoxide. The carbon should “prefer” to be in the form of methane at these temperatures.

At 530 degrees Celsius, GJ 436b is supposed to have abundant methane and little carbon monoxide. Spitzer observations have shown the opposite. The space telescope has captured the planet’s light in six infrared wavelengths, showing evidence for carbon monoxide but not methane.

“We’re scratching our heads,” said Harrington. “But what this does tell us is that there is room for improvement in our models. Now we have actual data on faraway planets that will teach us what’s really going on in their atmospheres.”

Aiming to find Earth-like planets

GJ 436b is located 33 light-years away. It rides in a tight, 2.64-day orbit around its small star, an “M-dwarf” much cooler than our sun. The planet transits, or crosses in front of, its star as viewed from Earth.

Artist's impression of the Spitzer Space Telescope

Artist's impression of the Spitzer Space Telescope, which made the observations.

Spitzer was able to detect the faint glow of GJ 436b by watching it slip behind its star, an event called a secondary eclipse. As the planet disappears, the total light observed from the star system drops — this drop is then measured to find the brightness of the planet at various wavelengths.

The technique, first pioneered by Spitzer in 2005, has since been used to measure atmospheric components of several Jupiter-sized exoplanets, the so-called “hot Jupiters“, and now the Neptune-sized GJ 436b.

“The Spitzer technique is being pushed to smaller, cooler planets more like our Earth than the previously studied hot Jupiters,” said Charles Beichman, director of NASA’s Exoplanet Science Institute at NASA’s Jet Propulsion Laboratory and the California Institute of Technology.

“In coming years, we can expect that a space telescope could characterise the atmosphere of a rocky planet a few times the size of the Earth. Such a planet might show signposts of life.”

Adapted from information issued by NASA / JPL-Caltech / K. Stevenson (U. of Central Florida).

Young stars shine in Orion

Part of the Orion Nebula

Part of the Orion Nebula, imaged by NASA's Spitzer Space Telescope. The region contains many young stars.

Astronomers have their eyes on a hot group of young stars, watching their every move like the paparazzi.

A new infrared image from NASA’s Spitzer Space Telescope shows the bustling star-making colony of the Orion nebula, situated in the hunter’s sword of the famous constellation.

Like Hollywood starlets, the cosmic orbs don’t always shine their brightest, but vary over time. Spitzer is watching the stellar show, helping scientists learn more about why the stars change, and to what degree planet formation might play a role.

“This is an exploratory project. Nobody has done this before at a wavelength sensitive to the heat from dust circling around so many stars,” said John Stauffer, the principal investigator of the research at NASA’s Spitzer Science Centre, located at the California Institute of Technology in Pasadena.

“We are seeing a lot of variation, which may be a result of clumps or warped structures in the planet-forming [clouds].”

The new image was taken after Spitzer ran out of its coolant in May 2009, beginning its extended “warm” mission. The coolant was needed to chill the instruments, but the two shortest-wavelength infrared channels still work normally at the new, warmer temperature of –243 Celsius.

In this new phase of the mission, Spitzer is able to spend more time on projects that cover a lot of sky and require longer observation times.

One such project is the “Young Stellar Object Variability” programme, in which Spitzer looks repeatedly at the same patch of the Orion nebula, monitoring the same set of about 1,500 variable stars over time. It has already taken about 80 pictures of the region over 40 days. A second set of observations will be made in late 2010.

The region’s twinkling stars are about one million years old. This might invoke thoughts of wrinkle cream to a movie star, but in the cosmos, it is quite young. Our middle-aged Sun is 4.6 billion years old.

The hottest stars in the region, called the Trapezium cluster, are bright spots at centre right in the image. Radiation and winds from those stars has sculpted and blown away surrounding dust. The densest parts of the cloud appear dark at centre left.

Adapted from information issued by NASA / JPL-Caltech.