How Dead Stars Make Planets

Rings of debris formed in the aftermath of stellar explosions could fuel the birth of new, rocky planets around dead stars. They could also provide an alternative way to make black holes, scientists said today.

Using NASA's Spitzer Space Telescope, researchers detected a cool disk of material glowing in infrared light around a young X-ray pulsar, a type of neutron star that sends out regular, directed pulses of radiation like a lighthouse beam. A neutron star is a dead star that has lost most of its material in an explosion.

New methods

Stars with about eight to 20 solar masses become neutron stars when they die. The stars run out of fuel as they age and their central cores collapse under their own immense weights.  Protons and electrons in the cores get compressed into a tight sphere of neutrons with about 1.5 solar masses all packed into a region the size of a city.

When infalling matter from the imploding star's outer layers reaches this neutron core, it bounces back and generates a powerful shockwave that blasts away the star's outer mantle in a stellar explosion called a supernova.

If material cast off from the explosion doesn't have enough velocity to escape the star's gravitational grasp, it will stall and fall back.

"It's like throwing a baseball straight up into the air," said study team-member Deepto Chakrabarty from the Massachusetts Institute of Technology (MIT). "Unless you're throwing it really, really fast, it's eventually going to fall back down on you."

This so-called "fallback" material can land back on the neutron star's surface or coalesce into a spinning debris disk around the star.

If the fallback material lands back onto the neutron star, it can cause the star to become a black hole. Scientists think this happens when a neutron star exceeds about three solar masses.

"Suppose you form a neutron star that is close to the upper limit. If enough stuff falls back, it'll push the star over this limit and a black hole will form," Chakrabarty told SPACE.com.

Black holes are typically thought to form from the gravitational collapse of stars that have more than about 20 solar masses. These stellar giants bypass the supernova explosions and the neutron star stage to immediately become black holes.

New worlds

If the fallback material instead forms a spinning disk around the neutron star, it can become fodder for the formation of new planets, the scientists say.

"This discovery demonstrates that the planet-creation process is a very robust and a very universal one," said Aleksander Wolszczan, an astrophysicist from Penn State University who was not involved in the finding.

In 1992, Wolszczan's team discovered a trio of rocky worlds around a fast-spinning pulsar. The finding was the first confirmed detection of planets beyond our solar system.

Planet formation around neutron stars would work similar to young stars, except that rocky planets would be favored over gas giants and the entire process would happen more quickly.

One reason for this is that material in the debris disk of neutron stars is more chemically evolved than material created in younger stars.

"The stuff that explodes from a supernova has all been processed through the nuclear engine in the middle of a star so you end up with lots of heavy elements," said study team member David Kaplan, also from MIT.

Moon, Mars and Marshall

Exploration of the moon and Mars will be an enduring legacy to future generations, confirming America's desire to explore, learn, and progress. NASA's Marshall Space Flight Center is playing a vital role in the design and development of the systems that not only will take us there but also help us support life in these unique environments.

The moon is a fundamental stepping stone for more distant human space exploration. Robotic missions will yield important knowledge, making it possible for humans to prepare to live in the moon’s harsh environment and to survive extreme conditions on distant planets. Marshall is managing a series of robotic orbiter and lander missions that will gather information to create an accurate atlas of the moon's features and identify resources needed to establish a lunar outpost. For example, water ice found on the moon could provide a source of oxygen and hydrogen for future inhabitants.

NASA will rely on a fleet of robust, cost-effective launch vehicles, the new Ares rockets, to carry astronauts and cargo to the moon and eventually beyond. Marshall is responsible for development and overall integration of the Ares I crew launch vehicle and for development of the Ares V cargo launch vehicle, both essential components of NASA’s Constellation Program for exploration. The center will also develop propulsion and life support elements for the Altair lunar lander, and support the development of lunar surface life support syatems, resource systems, lunar dust management methods, habitats, and structures.

Marshall Space Flight Center also manages exciting science missions that not only dramatically advance understanding of our solar system, but allow NASA to further refine America’s exploration of space beyond low Earth orbit.

Bringing together government, industry, and academic partners, Marshall links science and exploration to open new frontiers for human and robotic exploration and to provide many significant benefits here on Earth.

future space suit

NASA Loves A Good Challenge - Not Business As Usual

NASA's pioneering use of prize competitions and innovation challenges is a dramatic departure from government's traditional "business as usual." The agency's innovation and technology challenges include prizes that encourage independent teams to race to achieve bold goals - without any upfront government funding. NASA benefits from private sector investments many times greater than the cash value of prizes, and the agency only pays for results.
"NASA prize competitions unlock the extraordinary, sometimes untapped potential of U.S. students, private companies of all sizes and citizen inventors," said NASA Chief Technologist Bobby Braun at NASA Headquarters in Washington.
"These individuals and teams are providing creative solutions to NASA challenges while fostering new technology, new industries and innovation across the United States."
NASA has a history of broad and successful experiences with prize challenges. The agency is a leader in government-sponsored competitions that solve problems to benefit the space program and nation. Since 2005, NASA has conducted 20 Centennial Challenges in six areas and awarded $4.5 million to 13 teams. Each challenge is managed by non-profit organizations in partnership with NASA.

In July, NASA announced three new challenges and is seeking non-profit organizations to manage them. The challenges are:

+ The Nano-Satellite Launch Challenge is to place a small satellite into Earth orbit, twice in one week, for a prize of $2 million. The goals of this challenge are to stimulate innovations in low-cost launch technology and encourage commercial nano-satellite delivery services.
+ The Night Rover Challenge is to demonstrate a solar-powered exploration vehicle that can operate in darkness using its own stored energy. The prize purse is $1.5 million. The objective of this challenge is to stimulate innovations in energy storage technologies for extreme space environments, such as the surface of the moon, or for electric vehicles and renewable energy systems on Earth.
+ The Sample Return Robot Challenge is to demonstrate a robot that can locate and retrieve geologic samples from varied terrain without human control. This challenge has a prize purse of $1.5 million. The objective is to encourage innovations in automatic navigation and robotic technologies.
NASA's Centennial Challenges program has an impressive track record for generating novel solutions from student teams, citizen inventors and entrepreneurial firms outside the traditional aerospace industry. NASA is putting the innovations to work, as the agency recently announced awards to two small aerospace firms for flight testing rocket vehicles based on designs that won prizes in the Lunar Lander Challenge.
NASA's Green Flight Challenge offers $1.5 million for an aircraft with unprecedented fuel-efficiency. At least 10 teams are preparing to compete next summer in the challenge. Other agency challenges are focused on wireless power transmission and super-strong materials.
In addition to the Centennial Challenges, NASA sponsors innovation challenges, posing problems via the Internet to people around the world.
NASA uses open innovation platforms, or crowd sourcing, to take advantage of group power from outside the agency to help solve problems or to bring in new ideas. Current challenges seek innovative solutions to health and medical problems of astronauts living in space, the forecasting of solar storms and exercise equipment for crews aboard the International Space Station. Solutions are submitted in return for prizes or recognition by the space program.
NASA recently inaugurated an employee challenge called NASA@Work. This collaborative problem-solving program will connect the collective knowledge of experts from around the agency using a private Web-based platform. NASA "challenge owners" can post problems for review by internal "solvers." The solvers who deliver the best innovative ideas will receive a NASA Innovation Award.