Aug 3 2016
From The Space Library
RELEASE 13-232 NASA's Hubble Finds Telltale Fireball After Gamma Ray Burst
NASA's Hubble Space Telescope recently provided the strongest evidence yet that short-duration gamma ray bursts are produced by the merger of two small, super-dense stellar objects.
The evidence is in the detection of a new kind of stellar blast called a kilonova, which results from the energy released when a pair of compact objects crash together. Hubble observed the fading fireball from a kilonova last month, following a short gamma ray burst (GRB) in a galaxy almost 4 billion light-years from Earth. A kilonova had been predicted to accompany a short-duration GRB, but had not been seen before.
"This observation finally solves the mystery of the origin of short gamma ray bursts," said Nial Tanvir of the University of Leicester in the United Kingdom. Tanvir lead a team of researchers using Hubble to study the recent short-duration GRB. "Many astronomers, including our group, have already provided a great deal of evidence that long-duration gamma ray bursts (those lasting more than two seconds) are produced by the collapse of extremely massive stars. But we only had weak circumstantial evidence that short bursts were produced by the merger of compact objects. This result now appears to provide definitive proof supporting that scenario."
The team's results appear Saturday, Aug., 3 in a special online edition of the journal Nature.
A kilonova is about 1,000 times brighter than a nova, which is caused by the eruption of a white dwarf. The self-detonation of a massive star, a supernova, can be as much as 100 times brighter than a kilonova. Gamma ray bursts are mysterious flashes of intense high-energy radiation that appear from random directions in space. Short-duration blasts last at most a few seconds, but they sometimes produce faint afterglows in visible and near-infrared light that continue for several hours or days. The afterglows have helped astronomers determine that GRBs lie in distant galaxies.
Astrophysicists have predicted short-duration GRBs are created when a pair of super-dense neutron stars in a binary system spiral together. This event happens as the system emits gravitational radiation, creating tiny waves in the fabric of space-time. The energy dissipated by the waves causes the two stars to sweep closer together. In the final milliseconds before the explosion, the two stars merge into a death spiral that kicks out highly radioactive material. This material heats up and expands, emitting a burst of light.
In a recent science paper Jennifer Barnes and Daniel Kasen of the University of California at Berkeley and the Lawrence Berkeley National Laboratory presented new calculations predicting how kilonovas should look. They predicted the same hot plasma producing the radiation also will block the visible light, causing the gusher of energy from the kilonova to flood out in near-infrared light over several days.
An unexpected opportunity to test this model came June 3 when NASA' s Swift space telescope picked up the extremely bright gamma ray burst, cataloged as GRB 130603B. Although the initial blast of gamma rays lasted just one-tenth of a second, it was roughly 100 billion times brighter than the subsequent kilonova flash.
From June 12-13, Hubble searched the location of the initial burst, spotting a faint red object. An independent analysis of the data from another research team confirmed the detection. Subsequent Hubble observations on July 3 revealed the source had faded away, therefore providing the key evidence the infrared glow was from an explosion accompanying the merger of two objects.
MEDIA ADVISORY M16-094 NASA Invites Media to Journey to Mars Showcase on Aug. 18
Media are invited Thursday, Aug. 18, to interview experts from across NASA and industry about the science, technology and human spaceflight activities that are making the agency’s Journey to Mars possible.
The day will begin at NASA’s Michoud Assembly Facility in New Orleans, where the core stage of the Space Launch System (SLS) rocket and parts of the Orion spacecraft are being manufactured, and will end the day at a test firing of SLS’s powerful RS-25 engine at the agency’s Stennis Space Center, near Bay St. Louis, Mississippi. Transportation will be provided for media travelling between Michoud and Stennis to cover both parts of this showcase event.
To participate, media must contact Kathryn Hambleton for credentials at 202-358-1100 or kathryn.hambleton@nasa.gov no later than 5 p.m. EDT, Friday, Aug. 12.
NASA experts will be available for one-on-one interviews with media about technologies needed to explore the Red Planet, including SLS, Orion and ground systems operations, as well as habitat and lander development, landing site selection, propulsion, advanced manufacturing, robotic exploration, and more.
Media will have the opportunity to:
- get a behind-the-scenes look at what NASA is doing in science, technology, and human spaceflight to prepare for deep space travel
- view manufacturing of the core stage, the largest part of NASA's new deep space rocket
- see the next Orion structure being manufactured -- the Orion that will be used for structural testing of the design which will take humans beyond Earth orbit
- speak with representatives from NASA and industry partners creating the capabilities to send humans to Mars
- witness a firing of the RS-25 engine, part of the SLS core stage
- tour rocket engine facilities at Stennis
- visit the B-2 test stand that is being renovated for SLS core stage testing
NASA is on an ambitious Journey to Mars that includes sending humans to the Red Planet in the 2030s. The agency’s robotic spacecraft are leading the way on Mars with two active rovers, three active orbiters, the planned launch of the InSight lander in 2018, and development of the Mars 2020 rover. SLS and Orion will launch together, for the first time, in 2018 and be capable of sending humans farther from Earth than ever before, including to an asteroid and Mars.
