A Supernova Cocoon Breakthrough

Observations with NASA’s Chandra X-ray Observatory have provided the first X-ray evidence of a supernova shock wave breaking through a cocoon of gas surrounding the star that exploded. This discovery may help astronomers understand why some supernovas are much more powerful than others.

On Nov. 3, 2010, a supernova was discovered in the galaxy UGC 5189A, located about 160 million light years away. Using data from the All Sky Automated Survey telescope in Hawaii taken earlier, astronomers determined this supernova exploded in early October 2010 (in Earth’s time-frame). 

This composite image of UGC 5189A shows X-ray data from Chandra in purple and optical data from Hubble Space Telescope in red, green and blue. SN 2010jl is the very bright X-ray source near the top of the galaxy. 

A team of researchers used Chandra to observe this supernova in December 2010 and again in October 2011. The supernova was one of the most luminous that has ever been detected in X-rays. 

In optical light, SN 2010jl was about ten times more luminous than a typical supernova resulting from the collapse of a massive star, adding to the class of very luminous supernovas that have been discovered recently with optical surveys. Different explanations have been proposed to explain these energetic supernovas including (1) the interaction of the supernova’s blast wave with a dense shell of matter around the pre-supernova star, (2) radioactivity resulting from a pair-instability supernova (triggered by the conversion of gamma rays into particle and anti-particle pairs), and (3) emission powered by a neutron star with an unusually powerful magnetic field. 

In the first Chandra observation of SN 2010jl, the X-rays from the explosion’s blast wave were strongly absorbed by a cocoon of dense gas around the supernova. This cocoon was formed by gas blown away from the massive star before it exploded. 

In the second observation taken almost a year later, there is much less absorption of X-ray emission, indicating that the blast wave from the explosion has broken out of the surrounding cocoon. The Chandra data show that the gas emitting the X-rays has a very high temperature — greater than 100 million degrees Kelvin – strong evidence that it has been heated by the supernova blast wave. 

The energy distribution, or spectrum, of SN 2010jl in optical light reveals features that the researchers think are explained by the following scenario: matter around the supernova has been heated and ionized (electrons stripped from atoms) by X-rays generated when the blast wave plows through this material. While this type of interaction has been proposed before, the new observations directly show, for the first time, that this is happening. 

This discovery therefore supports the idea that some of the unusually luminous supernovas are caused by the blast wave from their explosion ramming into the material around it. 

In a rare example of a cosmic coincidence, analysis of the X-rays from the supernova shows that there is a second unrelated source at almost the same location as the supernova. These two sources strongly overlap one another as seen on the sky. This second source is likely to be an ultraluminous X-ray source, possibly containing an unusually heavy stellar-mass black hole, or an intermediate mass black hole. 

These results were published in a paper appearing in the May 1st, 2012 issue of The Astrophysical Journal Letters. The authors were Poonam Chandra (Royal Military College of Canada, Kingston, Canada), Roger Chevalier and Christopher Irwin (University of Virginia, Charlottsville, VA), Nikolai Chugai (Institute of Astronomy of Russian Academy of Sciences, Moscow, Russia), Claes Fransson (Stockholm University, Sweden), and Alicia Soderberg (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA). 

Credits: X-ray: NASA/CXC/Royal Military College of Canada/P.Chandra et al); Optical: NASA/STScI

Expedition 31 Prepares For Launch

The Soyuz rocket is seen in the monitor of a video camera moments before Soyuz Commander Gennady Padalka and flight engineers Joseph Acaba and Sergei Revin arrived to board the rocket at the Baikonur Cosmodrome in Kazakhstan for their flight to join their crew mates already aboard the International Space Station. The craft successfully launched at 11:01 p.m. EDT, Monday, May 14, 2012. 

The trio will dock to the station’s Poisk Mini-Research Module at 12:38 a.m. Thursday, bringing Expedition 31 to its full six-member complement.

Image Credit: NASA/Bill Ingalls

The Swan Glowing in Flight

Best known as a swan winging its way across the night, the constellation Cygnus is easily seen in the northern hemisphere’s summertime sky. This new view of the Cygnus-X star-forming region by the Herschel Telescope highlights chaotic networks of dust and gas that point to sites of massive star formation. This image combines far-infrared data acquired at 70 micron (corresponding to the blue channel); 160 micron (corresponding to the green channel); and 250 micron (corresponding to the red channel). The observations were made on May 24, 2010, and Dec. 18, 2010. 

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. 

Image Credit: ESA/PACS/SPIRE/Martin Hennemann & Frederique Motte, Laboratoire AIM Paris-Saclay, CEA/Irfu — CNRS/INSU — Univ. Paris Diderot, France

Active Black Hole Squashes Star Formation

New data from the Herschel Space Observatory shows that galaxies with the most powerful, active, supermassive black holes at their cores produce fewer stars than galaxies with less ones.

Supermassive black holes are believed to reside in the hearts of all large galaxies. When gas falls upon these monsters, the materials are accelerated and heated around the black hole, releasing great torrents of energy. In the process, active black holes often generate colossal jets that blast out twin streams of heated matter.

Inflows of gas into a galaxy also fuel the formation of new stars. In a new study of distant galaxies, Herschel helped show that star formation and black hole activity increase together, but only up to a point. Astronomers think that if an active black hole flares up too much, it starts spewing radiation that prevents raw material from coalescing into new stars.

This artist concept of the local galaxy Arp 220, captured by the Hubble Space Telescope, helps illustrate the Herschel results. The bright core of the galaxy, paired with an overlaid artist’s impression of jets emanating from it, indicate that the central black hole’s activity is intensifying. As the active black hole continues to rev up, the rate of star formation will, in turn, be suppressed in the galaxy. Astronomers want to further study how star formation and black hole activity are intertwined.

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes, with important participation by NASA. 

Image Credit: NASA/JPL-Caltech

Saturn’s Brightly Reflective Moon Enceladus

A brightly reflective Enceladus appears before Saturn’s rings, while the planet’s larger moon Titan looms in the distance.

Jets of water ice and vapor emanating from the south pole of Enceladus, which hint at subsurface sea rich in organics, and liquid hydrocarbons ponding on the surface on the surface of Titan make these two of the most fascinating moons in the Saturnian system.

Enceladus (313 miles, or 504 kilometers across) is in the center of the image. Titan (3,200 miles, or 5,150 kilometers across) glows faintly in the background beyond the rings. This view looks toward the anti-Saturn side of Enceladus and the Saturn-facing side of Titan. The northern, sunlit side of the rings is seen from just above the ringplane.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on March 12, 2012. The view was acquired at a distance of approximately 600,000 miles (1 million kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 36 degrees. Image scale is 4 miles (6 kilometers) per pixel on Enceladus.

Image credit: NASA/JPL-Caltech/Space Science Institute

Dragon’s Crew Accommodations

Space Exploration Technologies (SpaceX) has finished an important evaluation of a prototype Dragon spacecraft designed to carry people into orbit. This key milestone is part of SpaceX’s partnership with NASA under a funded Space Act Agreement to advance the design of crew transportation vehicles.

The primary goal of the tests was to determine whether the layout will allow astronauts to maneuver effectively in the vehicle. Several veteran space shuttle astronauts and NASA engineers conducted the evaluation during a pair of two-day-long reviews. 

On top, from left, are NASA Crew Survival Engineering Team Lead Dustin Gohmert, NASA astronauts Tony Antonelli and Eric Boe, and SpaceX Mission Operations Engineer Laura Crabtree. On bottom, from left, are SpaceX Thermal Engineer Brenda Hernandez and NASA astronauts Rex Walheim and Tim Kopra.

Image Credit: SpaceX

The Bluest Sky

The main parachutes deploy for Boeing’s crew capsule during a parachute drop test on May 2, 2012. This is the second successful parachute drop test for its Crew Space Transportation (CST) spacecraft, part of Boeing’s effort to develop commercial crew transportation capabilities that could ferry U.S. astronauts to and from low-Earth orbit and the International Space Station.

To accomplish the task, a helicopter lifted the CST-100 crew capsule to about 10,000 feet above the Delmar Dry Lake Bed near Alamo, Nev. A drogue parachute deployment sequence was initiated, followed by deployment of the main parachute. The capsule descended to a smooth ground landing, cushioned by six inflated air bags.

Image Credit: Boeing

Dream Chaser

The Dream Chaser model with its Atlas V launch vehicle is undergoing final preparations at the Aerospace Composite Model Development Section’s workshop for buffet tests at the Transonic Dynamics Tunnel at NASA Langley. The scale model is being tested as part of NASA’s Commercial Crew Development program to regain the American capability to launch astronauts safely to the International Space Station. The lifting body reusable spacecraft would carry as many as seven astronauts to the space station. Sierra Nevada Space Systems is developing the craft under a Space Act Agreement with NASA.

With the help of hundreds of pressure transducers, engineers from Sierra Nevada Corporation, the United Launch Alliance and NASA Langley will look at the pressure fluctuations the model and launch vehicle stack experience during the critical ascent to orbit, especially at transonic speeds. Shock-waves form on launch vehicles as they approach the speed of sound and may result in regions of highly unsteady flow. Within these regions of the Dream Chaser and launch vehicle, the resulting buffet forces and high frequency acoustic noise must be clearly understood as part of the vehicle design process. Transonic wind-tunnel testing of large, highly instrumented scale models is the only method of determining the buffet environments of launch vehicles with complex shapes.

Image Credit: NASA EDGE/Ron Beard

Black Hole Caught Red-handed in a Stellar Homicide

This computer-simulated image shows gas from a star that is ripped apart by tidal forces as it falls into a black hole. Some of the gas also is being ejected at high speeds into space. 

Using observations from telescopes in space and on the ground, astronomers have gathered the most direct evidence yet for this violent process: a supermassive black hole shredding a star that wandered too close. NASA’s orbiting Galaxy Evolution Explorer (GALEX) and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were used to help to identify the stellar remains. 

A flare in ultraviolet and optical light revealed gas falling into the black hole as well as helium-rich gas that was expelled from the system. When the star is torn apart, some of the material falls into the black hole, while the rest is ejected at high speeds. The flare and its properties provide a signature of this scenario and give unprecedented details about the stellar victim. 

To completely rule out the possibility of an active nucleus flaring up in the galaxy instead of a star being torn apart, the team used NASA’s Chandra X-ray Observatory to study the hot gas. Chandra showed that the characteristics of the gas didn’t match those from an active galactic nucleus. 

The galaxy where the supermassive black hole ripped apart the passing star is known as PS1-10jh and is located about 2.7 billion light years from Earth. Astronomers estimate the black hole in PS1-10jh has a mass of several million suns, which is comparable to the supermassive black hole in our own Milky Way galaxy. 

Credits: NASA, S. Gezari (The Johns Hopkins University), and J. Guillochon (University of California, Santa Cruz)

Engine Test With a Cyclonic Twist

Water forms an interesting cyclonic twist as it is intentionally sucked into the test engine of a U.S. Air Force C-17 transport aircraft during the VIPR project engine health monitoring tests conducted by NASA Dryden. The water was contained on a special platform built by NASA Dryden’s Fabrication Branch for the tests. NASA’s Aviation Safety Program is developing technology for improved sensors to help spot changes in vibration, speed, temperature and emissions which are symptomatic of engine glitches.

These advanced sensors could alert ground crews to problems that can be eliminated with preventive maintenance before becoming serious safety concerns. Ultimately, the sensors could alert pilots to the presence of destructive volcanic ash particles too small for the eyes to see, giving more time for evasive action to prevent engine damage in flight.

Image Credit: NASA / Tony Landis