In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and how they interact with their surroundings.

Using NASA’s Chandra X-ray Observatory, astronomers have studied one particular explosion that may provide clues to the dynamics of other, much larger stellar eruptions.  

A team of researchers pointed the telescope at GK Persei, an object that became a sensation in the astronomical world in 1901 when it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite GK Persei as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star.

A nova can occur if the strong gravity of a white dwarf pulls material from its orbiting companion star.  If enough material, mostly in the form of hydrogen gas, accumulates on the surface of the white dwarf, nuclear fusion reactions can occur and intensify, culminating into a  cosmic-sized hydrogen bomb blast. The outer layers of the white dwarf are  blown away, producing a nova outburst that can be observed for a period of months to years as the material expands into space.

Classical novas can be considered to be “miniature” versions of supernova explosions. Supernovas signal the destruction of an entire star and can be so bright that they outshine the whole galaxy where they are found. Supernovas are extremely important for cosmic ecology because they inject huge amounts of energy into the interstellar gas, and are responsible for dispersing elements such as iron, calcium and oxygen into space where they may be incorporated into future generations of stars and planets.

Although the remnants of supernovas are much more massive and energetic than classical novas, some of the fundamental physics is the same. Both involve an explosion and creation of a shock wave that travels at supersonic speeds through the surrounding gas.  

The more modest energies and masses associated with classical novas means that the remnants evolve more quickly. This, plus the much higher frequency of their occurrence compared to supenovas, makes classical novas important targets for studying cosmic explosions.

Chandra first observed GK Persei in February 2000 and then again in November 2013. This 13-year baseline provides astronomers with enough time to notice important differences in the X-ray emission and its properties.

This new image of GK Persei contains X-rays from Chandra (blue), optical data from NASA’s Hubble Space Telescope (yellow), and radio data from the National Science Foundation’s Very Large Array (pink). The X-ray data show hot gas and the radio data show emission from electrons that have been accelerated to high energies by the nova shock wave. The optical data reveal clumps of material that were ejected in the explosion. The nature of the point-like source on the lower left is unknown.

Over the years that the Chandra data span, the nova debris expanded at a speed of about 700,000 miles per hour. This translates to the blast wave moving about 90 billion miles during that period.

One intriguing discovery illustrates how the study of nova remnants can provide important clues about the environment of the explosion. The X-ray luminosity of the GK Persei remnant decreased by about 40% over the 13 years between the Chandra observations, whereas the temperature of the gas in the remnant has essentially remained constant, at about one million degrees Celsius. As the shock wave expanded and heated an increasing amount of matter, the temperature behind the wave of energy should have decreased. The observed fading and constant temperature suggests that the wave of energy has swept up a negligible amount of gas in the environment around the star over the past 13 years. This suggests that the wave must currently be expanding into a region of much lower density than before, giving clues to stellar neighborhood in which GK Persei resides.

A paper describing these results appeared in the March 10th issue of The Astrophysical Journal. The authors were Dai Takei (RIKEN, Spring-8 Center Japan), Jeremy Drake (Smithsonian Astrophysical Observatory), Hiroya Yamaguichi (Goddard Space Flight Center), Patrick Slane (Smithsonian Astrophysical Observatory), Yasunobu Uchimaya (Rikkyo University, Japan), Satoru Katsuda (Japanese Aerospace Exploration Agency).

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

› Read More from NASA’s Chandra X-ray Observatory

Image Credit: NASA/CXC/RIKEN/D.Takei et al

Janet Anderson
Marshall Space Flight Center, Huntsville, Ala.
256-544-0034
janet.l.anderson@nasa.gov

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu via NASA http://ift.tt/1Ax4qhr

One of the Vanguard satellites is checked out at Cape Canaveral, Florida in 1958. Vanguard 1, the world’s first solar-powered satellite, launched on St. Patrick’s Day (March 17) 1958. It was designed to test the launch capabilities of a three-stage launch vehicle and the effects of the environment on a satellite and its systems in Earth orbit. Vanguard 1 was the second U.S. satellite in orbit, following Explorer 1, and remains the oldest artificial object orbiting Earth to this day. Vanguard began as a program at the Naval Research Laboratory in Washington and transferred over to NASA (along with many of its personnel) after the agency was founded by the National Aeronautics and Space Act of 1958.

Image Credit: NASA via NASA http://ift.tt/1GjmbEQ

From afar, Saturn’s rings look like a solid, homogenous disk of material. But upon closer examination from Cassini, we see that there are varied structures in the rings at almost every scale imaginable.

Structures in the rings can be caused by many things, but often times Saturn’s many moons are the culprits. The dark gaps near the left edge of the A ring (the broad, outermost ring here) are caused by the moons (Pan and Daphnis) embedded in the gaps, while the wider Cassini division (dark area between the B ring and A ring here) is created by a resonance with the medium-sized moon Mimas (which orbits well outside the rings). Prometheus is seen orbiting just outside the A ring in the lower left quadrant of this image; the F ring can be faintly seen to the left of Prometheus.

This view looks toward the sunlit side of the rings from about 15 degrees above the ringplane. The image was taken in red light with the Cassini spacecraft wide-angle camera on Jan. 8, 2015.

The view was obtained at a distance of approximately 566,000 miles (911,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 37 degrees. Image scale is 34 miles (54 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://ift.tt/Jcddhk or http://ift.tt/ZjpQgB . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL-Caltech/Space Science Institute via NASA http://ift.tt/1x8r3ND

The United Launch Alliance Atlas V rocket with NASA’s Magnetospheric Multiscale (MMS) spacecraft onboard launches from the Cape Canaveral Air Force Station Space Launch Complex 41, Thursday, March 12, 2015, Florida. NASA’s MMS mission studies the mystery of how magnetic fields around Earth connect and disconnect, explosively releasing energy via a process known as magnetic reconnection. MMS consists of four identical spacecraft that work together to provide the first three-dimensional view of this fundamental process, which occurs throughout the universe.

Photo Credit: NASA/Aubrey Gemignani via NASA http://ift.tt/1BdPCU5

The United Launch Alliance Atlas V rocket with NASA’s Magnetospheric Multiscale (MMS) spacecraft onboard launches from the Cape Canaveral Air Force Station Space Launch Complex 41, Thursday, March 12, 2015, Florida. NASA’s MMS mission studies the mystery of how magnetic fields around Earth connect and disconnect, explosively releasing energy via a process known as magnetic reconnection. MMS consists of four identical spacecraft that work together to provide the first three-dimensional view of this fundamental process, which occurs throughout the universe.

Image Credit: NASA/Aubrey Gemignani via NASA http://ift.tt/1Bz1uVA

The Soyuz TMA-14M spacecraft is seen as it lands with Expedition 42 commander Barry Wilmore of NASA, Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos) and Elena Serova of Roscosmos near the town of Dzhezkazgan, Kazakhstan on Wednesday, March 11, 2015 (Thursday, March 12, Kazakh time). NASA astronaut Wilmore, Russian cosmonauts Samokutyaev and Serova returned to Earth after almost six months onboard the International Space Station where they served as members of the Expedition 41 and 42 crews. The spacecraft touched down safely at approximately 10:07 p.m. EDT.

Image Credit: NASA/Bill Ingalls via NASA http://ift.tt/1C8KTbW

The Soyuz TMA-14M spacecraft is seen as it lands with International Space Station Expedition 42 commander Barry Wilmore of NASA, Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos) and Elena Serova of Roscosmos near the town of Zhezkazgan, Kazakhstan. The landing took place on the evening of Wednesday, March 11 in the U.S, and early in the morning on Thursday, March 12, in Kazakhstan.

The three crew members returned to Earth after a 167-day mission on the orbital outpost that included hundreds of scientific experiments and several spacewalks to prepare the orbiting laboratory for future arrivals by U.S. commercial crew spacecraft.

Credit: NASA/Bill Ingalls via NASA http://ift.tt/1GH5vuc

The largest, most powerful rocket booster ever built successfully fired up Wednesday for a major-milestone ground test in preparation for future missions to help propel NASA’s Space Launch System (SLS) rocket and Orion spacecraft to deep space destinations, including an asteroid and Mars.

The booster fired for two minutes, the same amount of time it will fire when it lifts the SLS off the launch pad, and produced about 3.6 million pounds of thrust. The test was conducted at the Promontory, Utah test facility of commercial partner Orbital ATK, and is one of two tests planned to qualify the booster for flight. Once qualified, the flight booster hardware will be ready for shipment to NASA’s Kennedy Space Center in Florida for the first SLS flight.

More information.

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Engineers at Orbital ATK prepare to test the largest, most powerful booster ever built for NASA’s new rocket, the Space Launch System (SLS), which will fire up for a ground test at 11:30 a.m. EDT on Wednesday, March 11, at Orbital ATK Propulsion Systems’ test facilities in Promontory, Utah.

The two-minute static test is a significant milestone for the SLS as part of NASA’s journey to Mars, and follows years of development. It is one of two ground tests to qualify the booster for flight. A second test is planned for early 2016. Once qualification is complete, the hardware will be ready to help send the rocket, along with NASA’s Orion spacecraft, on its first flight test. When completed, two five-segment, solid-rocket boosters and four RS-25 main engines will power the SLS as it begins its deep space missions. The boosters operate in parallel with the main engines for the first two minutes of flight, providing more than 75 percent of the thrust needed for the rocket to escape Earth’s gravitational pull.

The first flight test of the SLS will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system. As the SLS is updated, it will provide an unprecedented lift capability of 130 metric tons (143 tons) to enable missions even farther into our solar system.

Live coverage of the test on NASA TV begins on Wednesday at 11:00 a.m. EDT.

Image Credit: Orbital ATK via NASA http://ift.tt/1FFwByi

Engineers across the country have been busy taking a closer look at NASA’s Orion spacecraft and the data it produced during its successful flight test in December 2014. Inside the Launch Abort System Facility at NASA’s Kennedy Space Center in Florida, Orion was lifted using a special crane for removal of its heat shield on Feb. 13, 2015. In the background, technicians move the heat shield on a work stand. The spacecraft’s heat shield protected Orion as it reentered Earth’s atmosphere at searing temperatures. Removing the back shell allows the team to get a closer look at Orion’s systems to see how they fared during the trip to space. The heat shield was removed in preparation for shipment to NASA’s Marshall Space Flight Center in Huntsville, Alabama, where special equipment will be used to remove its ablative material. From there, the heat shield will be shipped to NASA’s Langley Research Center in Hampton, Virginia, where it will be outfitted on a test article for water impact testing.

Meanwhile, NASA and Lockheed Martin, the prime contractor for Orion, continue to take a look at the data the flight test produced to validate pre-flight models and improve the spacecraft’s design. Analysis of data obtained during its two-orbit, four-and-a-half hour mission Dec. 5 will provide engineers detailed information on how the spacecraft fared.

Photo Credit: NASA/Jim Grossmann via NASA http://ift.tt/1GjNJtF