Mysterious stellar absorption lines could illuminate 90-year puzzle

Nov 02, 2011

The discovery of 13 diffuse interstellar bands with the longest wavelengths to date could someday solve a 90-year-old mystery.

Astronomers have identified the new bands using data collected by the of stars in the center of the Milky Way.

Nature reports on its website today findings that support recent ideas about the presence of large, possibly carbon-based —"carriers"—hidden in interstellar dust clouds. The paper will also appear in the Nov. 10 print issue of the journal.

"These diffuse interstellar bands—or DIBs—have never been seen before," says Donald Figer, director of the Center for Detectors at Rochester Institute of Technology and a co-author of the study. "Spectra of stars have absorption lines because gas and dust along the line of sight to the stars absorb some of the light."

"The most recent ideas are that diffuse interstellar bands are relatively simple carbon bearing molecules, similar to amino acids," he continues. "Maybe these are amino acid chains in space, which supports the theory that the seeds of life originated in space and rained down on planets."

"Observations in different Galactic sight lines indicate that the material responsible for these DIBs 'survives' under different physical conditions of temperature and density," adds Paco Najarro, scientist in the Department of Astrophysics in the Center of Astrobiology in Madrid.

The low-energy absorption lines Figer and his colleagues discovered provide constraints for determining the nature of diffuse interstellar bands. Future theoretical models that predict wavelengths absorbed by these mysterious particles now must accommodate these lower energies, Figer notes.

"We saw the same absorption lines in the spectra of every star," Figer says. "If we look at the exact of the features, we can figure out the kind of gas and dust between us and the stars that is absorbing the light."

Diffuse interstellar bands have remained a puzzle since their initial 90 years ago. The 500 bands identified before this study mostly occur at visible and near-infrared wavelengths. The observed lines do not match predicted lines of simple molecules and cannot be pinned to a single carrier.

"None of the diffuse interstellar bands has been convincingly identified with a specific element or molecule, and indeed their identification, individually and collectively, is one of the greatest challenges in astronomical spectroscopy," says lead author Thomas Geballe, from the Gemini Observatory. "Recent studies have suggested that DIB carriers are large carbon-containing molecules."

The newly discovered infrared bands can be used as probes of the diffuse interstellar medium, especially in regions in which thick dust and gas obscure observations in the optical and shorter wavelength bands.

Studying the stronger emissions in the group may lead to an understanding of their molecular origin. Some day laboratory spectroscopy could be used to identify the infrared diffuse interstellar bands. No one has been successful yet at reproducing the interstellar bands in laboratory, Figer notes, due to the multitude of possibilities and the difficulty of reproducing the temperatures and pressures the gas would experience in space.

In addition to Geballe, Najarro and Figer, co-authors of the paper included Najarro's student Diego de la Fuente and former Gemini science intern Barrett Schlegelmilch.

Explore further: A new approach in the search for extraterrestrial intelligence: targeting alien polluters

Related Stories

NASA scientists on the trail of mystery molecules

May 25, 2011

(PhysOrg.com) -- Space scientists working to solve one cosmic mystery at NASA's Ames Research Center, Moffett Field, Calif., now have the capability to better understand unidentified matter in deep space. Using a new facility ...

Clocking the mosh pit of interstellar space

Oct 05, 2011

(PhysOrg.com) -- The space between the stars in the Milky Way and all other galaxies is full of dust and gas, the raw materials from which stars and planets are made.

Recommended for you

Lives and deaths of sibling stars

11 hours ago

This beautiful star cluster, NGC 3293, is found 8000 light-years from Earth in the constellation of Carina (The Keel). This cluster was first spotted by the French astronomer Nicolas-Louis de Lacaille in ...

Fermi finds a 'transformer' pulsar

Jul 22, 2014

(Phys.org) —In late June 2013, an exceptional binary containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed. The pulsar's radio beacon vanished, while at ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

omatumr
1 / 5 (3) Nov 02, 2011
These diffuse interstellar bandsor DIBshave never been seen before: Carbon-based organic molecules"carriers"hidden in interstellar dust clouds


These carbon-based molecules are products of Helium burning, i.e.,

a.) 3 He-4 => C-12
b.) 4 He-4 => O-16
c.) etc., etc

What is mysterious?

Oliver K. Manuel

Vendicar_Decarian
not rated yet Nov 03, 2011
Mysterious? Abundance, distribution... etc...

LKD
not rated yet Nov 03, 2011
Space whales and space squids, mystery solved. :D