Soccer balls in interstellar space

Mar 15, 2013
Figure 1: The structure of fullerene C60. Credit: NAOJ

An international team of astronomers led by Masaaki Otsuka (Academia Sinica Institute of Astronomy and Astrophysics or ASIAA) has detected the C60 fullerene (molecules of carbon with 60 atoms arranged in patterns resembling a soccer ball) in the dying star M1-11. Data from the Subaru Telescope, the Spitzer Space Telescope (SST), the Very Large Telescope (VLT), the 1.88 m telescope at the Okayama Astrophysical Observatory (OAO), and the Japanese infrared astronomy satellite AKARI all contributed to this finding, which takes scientists closer to understanding the prevalence and formation of C60 in space.

Interstellar space is teeming with solid, called "dust", a large fraction of which are rich in carbon that was formed in the cores of solar-type stars. When are ejected into interstellar space from dying stars, they are catalysts for the formation of the next generation of stars. Therefore, an investigation into the amount and composition of the dust produced by dying stars as well as its subsequent return to interstellar space is a crucial step in understanding and the chemical evolution of galaxies.

The C60 fullerene is a molecule consisting of 60 , with a that resembles the seams on a (Figure 1). It is particularly interesting since C60 is an extremely stable molecule, which easily forms in laboratories on Earth, and probably exists in abundance in . However, its detection in space has only been recent (2010) and elusive, having been found in about 20 objects. Scientists do not know yet how prevalent it is or what sort of environment is necessary to produce it.

Figure 2: Detection of C60 in M1-11. Arrows indicate the postions of the C60 emissions at 17.3 and 18.9 microns. Credit: NAOJ

How much C60 exists in space? Since C60 is very stable, could there be much more C60 in than on Earth? To answer these queries, the team focused on a class of dying stars called "planetary nebulae" (Note 2), because cosmic C60 has previously been detected in these objects. Otsuka analyzed all of the relevant spectroscopic data taken by the SST and analyzed spectral data from more than 300 planetary nebulae, checking each carefully for evidence of C60 infrared wavelengths. The team identified C60 in several planetary nebulae, including the first detection of C60 in M1-11 (Figure 2). Otsuka also found evidence for C60 in the archived spectra of M1-11 taken by the VLT and proceeded to estimate the total amount and the temperature of C60 in M1-11. Using data obtained with the SST and AKARI, he also investigated the dust grain composition in M1-11 and obtained the amount in each component. Although M1-11 is rich in carbon-bearing molecules and minerals, C60 makes up only 0.01 percent of the total dust mass. Therefore, he concluded that C60 is very rare in the interstellar medium.

Figure 3: Detailed analysis of the spectra of M1-11 taken by the Subaru Telescope's High Dispersion Spectrograph (HDS) (upper panel) and the 1.88 m Okayama telescope's near-infrared imager and spectrograph (ISLE) (lower panel). The emission lines from the carbon (C) and the phosphorous (P) are indicated by the blue characters; those from hydrogen (Paβ), helium (He), and oxygen (O), are indicated by black characters. In the ISLE spectrum, molecular hydrogen (H2) is also noted. Credit: NAOJ

How, then, did C60 form in space? Characterizing the physical conditions in the environments that contain C60 is an important step in understanding this process. Otsuka applied the method of elemental abundance analysis to unveil the evolutionary status of M1-11's nebula and its progenitor star, which were largely unknown until his research. The team used the 8.2 m Subaru Telescope's High Dispersion Spectrograph (HDS) and the Okayama 1.88 m telescope's near infrared imager and spectrograph (ISLE) to precisely measure line strengths of chemical elements such as carbon (C), phosphorous (P), and krypton (Kr). Detailed analysis of the spectra (Figure 3) revealed the relative amounts (abundances) of eleven elements. The team found that M1-11 is a very young planetary nebula, which formed from material ejected by the star ~1000 years ago; and it evolved from a star 50% more massive than the Sun. The obtained values in M1-11, namely, the C60 mass and temperature, the elemental composition of the gas in the nebula, the mass of the progenitor star, and the evolutionary status, are very similar to those seen in other planetary nebulae containing C60, e.g., Tc1, where the cosmic C60 was detected for the first time by the SST (Note 3). The team concluded that C60 is likely to form in carbon-rich dusty objects such as M1-11. They believe that chemical processing and the destruction of HAC (hydrogenated amorphous carbon) by the radiation as well as the strong wind from the central star of a planetary nebula produce the cosmic C60.

Using the 's Cooled Mid-Infrared Camera and Spectrometer (COMICS), Otsuka has recently started a new project to investigate the spatial distribution of C60 in planetary nebulae to verify the C60 formation scenario. As Otsuka stated, "These new Subaru observations will further clarify the C60 formation process".

Explore further: Computers beat brainpower when it comes to counting stars

More information: The research paper was published in The Astrophysical Journal (Otsuka et al." The Detection of C60 in the Well-Characterized Planetary Nebula M1-11" The Astrophysical Journal, 764:77 (20pp), 2013 February 10).

Related Stories

Has graphene been detected in space?

Aug 11, 2011

( -- A team of astronomers, using the Spitzer Space Telescope, have reported the first extragalactic detection of the C70 fullerene molecule, and the possible detection of planar C24 ("a piece of graphene ...

Graphene decoupling of organic/inorganic interfaces

Jun 19, 2012

( -- Cryogenic ultrahigh vacuum scanning tunneling microscopy (STM) was employed by researchers in the Center for Nanoscale Materials Electronic & Magnetic Materials & Devices Group at the Argonne ...

Fullerene crystals with bimodal pore architectures

Feb 22, 2013

A research group headed by MANA Scientist Dr. Lok Kumar Shrestha of the Supermolecules Unit, for the first time demonstrated template-free novel mesoporous carbon material: fullerene (C60) crystals with bimod ...

The origin of organic magnets

Mar 02, 2012

Electrical engineers are starting to consider materials made from organic molecules -- including those made from carbon atoms -- as an intriguing alternative to the silicon and metals used currently in electronic ...

Recommended for you

ESO image: A study in scarlet

18 hours ago

This new image from ESO's La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that ...

Astronomers: 'Tilt-a-worlds' could harbor life

Apr 15, 2014

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...

Pushy neighbors force stellar twins to diverge

Apr 15, 2014

( —Much like an environment influences people, so too do cosmic communities affect even giant dazzling stars: Peering deep into the Milky Way galaxy's center from a high-flying observatory, Cornell ...

Image: Multiple protostars within IRAS 20324+4057

Apr 14, 2014

( —A bright blue tadpole appears to swim through the inky blackness of space. Known as IRAS 20324+4057 but dubbed "the Tadpole", this clump of gas and dust has given birth to a bright protostar, ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 15, 2013
1 of nature's perfect shapes...

More news stories

Meteorites yield clues to Martian early atmosphere

( —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Let's put a sailboat on Titan

The large moons orbiting the gas giants in our solar system have been getting increasing attention in recent years. Titan, Saturn's largest moon, is the only natural satellite known to house a thick atmosphere. ...

Red moon at night; stargazer's delight

Monday night's lunar eclipse proved just as delightful as expected to those able to view it. On the East Coast, cloudy skies may have gotten in the way, but at the National Science Foundation's National Optical ...