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Johns Hopkins UniversityArts and Sciences Magazine

Research Briefs

A New Type of Dwarf

NASA's Galaxy Evolution Explorer has found a surprisingly simple recipe for dwarf galaxies: just a little pristine gas, likely leftover from the early universe.

These dwarf galaxies—relatively small collections of stars that often orbit around larger galaxies—are springing up out of gas that lacks both dark matter and metals, while most galaxies form in association with one or the other. Though never seen before, this new type of dwarf galaxy may be common throughout the more distant and early universe, when pristine gas was more pervasive.

The new findings, reported in the Feb. 19 issue of Nature, were uncovered by a team of astronomers led by David Thilker, a research scientist in the Department of Physics and Astronomy. The team spotted the unexpected galaxies forming inside the Leo Ring, a huge cloud of hydrogen and helium that traces a ragged path around two massive galaxies in the constellation Leo. The cloud is thought to be an ancient remnant of material that has remained relatively unchanged since the very earliest days of the universe.

For decades scientists have studied the Leo Ring with world-class telescopes operating at radio and optical wavelengths but nothing except the gas was ever detected. No stars at all, young or old, were found. "But when we looked at the ring with the Galaxy Evolution Explorer, which is remarkably sensitive to ultraviolet light, we saw telltale evidence of recent massive star formation," Thilker says. "It was really unexpected."

The Galaxy Evolution Explorer, launched in 2003, is an orbiting space telescope that captures observations to measure the history of star formation in the universe across about 10 billion years of cosmic history.

 

 

Ozone Levels May Never Rebound

Increasing greenhouse gases could delay or postpone indefinitely the recovery of stratospheric ozone in some regions of Earth, which could take a toll on public health.

Research led by Darryn W. Waugh, chairman and professor in the Morton K. Blaustein Department of Earth and Planetary Sciences, suggests that climate change could provoke variations in the circulation of air in the lower stratosphere in tropical and southern mid-latitudes (a band of the Earth including Australia and Brazil). Such circulation changes could cause ozone levels in those areas never to return to levels that were present before decline began, even after ozone-depleting substances have been wiped out from the atmosphere.

This could have an effect on the health of people living in the tropics and southern mid-latitudes, raising the risk of skin cancer in countries like Australia, New Zealand, Chile, and Argentina.

While scientists have long suspected that climate change might be altering the dynamics of stratospheric ozone recovery, Waugh's team is the first to estimate the effects of increasing greenhouse gases on the recovery of ozone by region. The team's findings were published in the Feb. 5 issue of Geophysical Research Letters, a publication of the American Geophysical Union.

Supercomputing Storage Champs

Supercomputing guru Alexander Szalay, Alumni Centennial Professor in the Department of Physics and Astronomy, led his team to victory in the Storage Challenge at SC08, the eighth annual Conference for Higher Performance Computing, Networking, Storage, and Analysis.

Szalay's team, which includes several other scientists and staff members from Johns Hopkins, as well as experts from Microsoft; the University of Illinois, Chicago; the University of Hawaii; and Dell, designed a computer facility called the GrayWulf System that combines inexpensive hardware and software into a single innovative platform that can analyze and process petabyte-scale data sets (a petabyte is equal to 1,000 terabytes, or 1 quadrillion bytes).

In the competition, GrayWulf was able to sift through information gathered in the Sloan Digital Sky Survey to locate quasars in 12 minutes—a search that took other computing systems 13 days.

Szalay says competitions such as SC08 impact the way future science and engineering research—both of which are generating tremendous data sets—will be conducted. Tools for data-intensive science in one field, such as astrophysics, can be generalized and applied to other fields, Szalay says.

Funding for GrayWulf was provided by the Gordon and Betty Moore Foundation, Microsoft Research, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS).

Born of primordial gas, a new type of dwarf galaxy. See a detail of this image.