Science News

Massive Young Stars Trigger Stellar Birth

Massive Young Stars Trigger Stellar Birth

About 4,000 light years from Earth lies RCW 108, a region where stars are actively forming within the Milky Way galaxy. The region contains young star clusters, including one that is deeply embedded in a cloud of molecular hydrogen. By using data from different telescopes, astronomers determined that star birth in this region is being triggered by the effect of nearby, massive young stars.

This image is a composite of X-ray data from Chandra (blue) and infrared emission detected by Spitzer (red and orange). More than 400 X-ray sources were identified in Chandra’s observations of RCW 108. About 90% of these X-ray sources are thought to be part of the cluster and not stars that lie in the field-of-view either behind or in front of it. Many of the stars in RCW 108 are experiencing the violent flaring seen in other young star-forming regions such as Orion. Gas and dust blocks much of the X-rays from the juvenile stars located in the center of the image, explaining the relative dearth of Chandra sources in this part of the image. The Spitzer data show the location of the embedded star cluster, which appears as the bright knot of red and orange just to the left of the center of the image. Some stars from a larger cluster, known as NGC 6193, are also visible on the left side of the image. Astronomers think that the dense clouds within RCW 108 are in the process of being destroyed by intense radiation emanating from hot and massive stars in NGC 6193.

Taken together, the Chandra and Spitzer data indicate that there are more massive star candidates than expected in this several areas of this image. This suggests that pockets within RCW 108 underwent localized episodes of star formation.

Image Credit: X-ray: NASA/CXC/CfA/S.Wolk et al; IR: NASA/JPL-Caltech

The Jules Verne

The Jules Verne

After completing its mission to re-supply the International Space Station, the European Space Agency’s Jules Verne Automated Transfer Vehicle (ATV) entered the Earth’s atmosphere, where researcher’s captured images of its fiery end.

In the early morning hours of Sept. 29, 2008, the ATV entered the atmosphere above an uninhabited section of the Pacific Ocean, southwest of Tahiti. Researchers captured visible, infrared, ultraviolet and spectroscopic data during the re-entry. NASA’s primary goal of the airborne project was to study the spacecraft’s re-entry and compare it to meteor fragmentation.

The image was taken from high-definition video footage captured during the mission.

Image Credit: NASA/ESA/Bill Moede and Jesse Carpenter

Bone parts don’t add up to conclusion of Palauan dwarfs

Greg Nelson. Photo by Jim Barlow

Misinterpreted fragments of leg bones, teeth and brow ridges found in Palau appear to be an archaeologist’s undoing, according to researchers at three institutions. They say that the so-called dwarfs of these Micronesian islands actually were modern, normal-sized hunters and gatherers.

In a paper published Aug. 27 in PLoS ONE, an open access journal of the Public Library of Science, scientists from the University of Oregon, North Carolina State University and the Australian National University refute the conclusion of Lee R. Berger and colleagues that Hobbit-like little people once lived there.

“Our evidence indicates the earliest inhabitants of Palau were of normal stature, and it counters the evidence that Berger, et al, presented in their paper indicating there was a reduced stature population in early Palau,” said University of Oregon anthropologist Greg C. Nelson. “Our research from whole bones and whole skeletons indicates that the earliest individuals in Palau were of normal stature but gracile. In other words, they were thin.”

Berger, an American-raised paleoanthropologist at the University of the Witwatersrand in Johannesburg, South Africa, stunned archaeologists in March with his claim — based on skeletal fragments collected from two caves exposed to tidal activity — that small-bodied humans may have lived in isolation and suffered from insular dwarfism on the islands 1,000 to 3,000 years ago. Berger initially found fragmented human remains while vacationing in Palau, and returned later for excavations under a grant from the National Geographic Society.

Nelson and NCSU anthropologist Scott M. Fitzpatrick, who earned his doctorate at the UO and based his dissertation on Palauan culture, reviewed full skeletal remains and cultural evidence dating back to almost 3,500 years ago. Their Australian co-author Geoffrey Clark also has studied multiple Palauan cultural sites dating to approximately 3,000 years ago.

They argue that Berger, an expert on much earlier humans dating to the Pleistocene, failed to review existing documentation, much of it published by Nelson or Fitzpatrick. Much of their rebuttal comes from remains unearthed by Fitzpatrick and Nelson at Chelechol ra Orrak, only miles from Berger’s two sites. Among these whole remains are bone pieces that match — some are even smaller that fragments found by Berger — and come from much larger bodies than those claimed by Berger.

“I think Berger’s primary mistakes were his not understanding the variation in the skeletal population in which he was working, using fragmentary remains again in a situation where he didn’t understand variation, and stepping outside his own area of expertise, which, I think all scientists try not to do but sometimes we do,” Nelson said.

University of Oregon

Ius Chasma

Ius Chasma

The Red Planet is home to Valles Marineris, the solar system’s largest canyon. Within this canyon lies Ius Chasma. This image, which spans the floor of its southern trench,m was taken by the Mars Reconnaissance Orbiter. The canyon is well-known for its fine stratigraphic layers modified by wind and water.

The outcrops contain interchanging layers of dark and bright rocks. The layered deposits consist of dark basalt lava flows and bright sedimentary layers. The sediments are likely to be from atmospheric dust, sand or alluvium from an ancient water source. The layers are visible on the gentle slopes above the canyon floor, in pitted areas, and in small mesa buttes. The floor of the canyon is littered with megaripples that are aligned in a north-south direction.

Ius Chasma is believed to have been shaped by a process called sapping when water seeped from the layers of the cliffs and evaporated before it reached the canyon floor. Ius Chasma also has several structural features such as east trending normal faults and grabens that deformed the canyons. Recent geomorphological events include avalanches and minor sapping from gullies that continued to erode the canyon walls.

Image Credit: NASA/JPL-Caltech/Univ. of Arizona

Obscure Moon

Obscure Moon

Just before Rhea slipped behind Saturn, the Cassini spacecraft captured the moon in its disappearing act.

Along with the partly obscured Rhea (949 miles, or 1,528 kilometers across) are Tethys (665 miles, or 1,071 kilometers across), at right, and Enceladus (314 miles, or 505 kilometers across), left of Tethys.

At the wavelength in which this image was taken, absorption of sunlight by methane gas in Saturn’s atmosphere is strong, causing the planet to appear darker than at other wavelengths.

This view looks toward the unilluminated side of the rings from about 4 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Nov. 9, 2007 using a spectral filter sensitive to wavelengths of infrared light centered at 890 nanometers. The view was acquired at a distance of approximately 1.7 million miles (2.8 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 44 degrees.

Image Credit: NASA/JPL/Space Science Institute