 |
|
Astronomers detect echoes from ancient supernovae
December 22, 2005A team of astronomers has found faint visible "echoes" of three ancient supernovae by detecting centuries-old light reflected by interstellar gas clouds hundreds of light-years removed from the original explosions.
Located in a nearby galaxy in the southern skies, the three exploding stars flashed into short-lived brilliance at least two centuries ago, and probably longer. The oldest is likely to have occurred more than 600 years ago.
Just as a sound echo can occur when sound waves bounce off a distant surface and reflect back toward the listener, a light echo can be seen when light waves traveling through space are reflected back toward the viewer.
The light echoes were discovered by comparing images of the Large Magellanic Cloud (LMC) taken years apart. By precisely subtracting the common elements in each image and analyzing what variable objects remain, the team looked for evidence of dark matter that might distort the light of stars in a transitory way, as part of a second-generation sky survey called SuperMACHO. SuperMACHO builds on the discoveries of the MACHO project, which started at Lawrence Livermore National Laboratory in 1989.
"The exciting thing for me is that the light echo discovery was serendipity," said Livermore astronomer Kem Cook, a co-author on the paper that appears in the Dec. 22, 2005, edition of Nature. "We are carrying out a large wide-field, time-domain survey looking for the signature of dark matter, and as a bonus we are discovering unexpected things like these light echoes. Serendipitous discoveries are a key element of large surveys and will likely be an important element of even larger future surveys in which LLNL is involved, such as the Large Synoptic Survey Telescope."
The careful image analysis also revealed a small number of concentric, circular-shaped arcs that are best explained as light moving outward over time, and being scattered as it encounters dense pockets of interstellar dust. Team members then fit perpendicular vectors to the curves of each arc system, which were found to point backward toward the sites of three recent supernovae remnants found previously via their X-ray glow by the orbiting Chandra X-ray Observatory.
"Without the geometry of the light echo, we had no way of knowing just how old these supernovae were," said astronomer Armin Rest of the National Optical Astronomy Observatory (NOAO), lead author of the paper. "Some relatively simple mathematics can help us answer one of the most vexing problems that astronomers can ask - exactly how old is this object that we are looking at?"
This technique can be applied to famous supernovae in history. "Imagine seeing light from the same explosion first seen by Johannes Kepler some 400 years ago, or the one recorded by Chinese observers in 1006," said Christopher Stubbs of the Harvard-Smithsonian Center for Astrophysics (CfA), co-author of the paper and principal investigator for the SuperMACHO program. "These light echoes give us that possibility."
In principle, astronomers can split the light echo into a spectrum to investigate what type of supernova occurred. "We have the potential with these echoes to determine the star's cause of death, just like the archaeologists who took a CT scan of King Tut's mummy to find out how he died," said co-author Arti Garg of CfA.
Astronomers also can use supernova light echoes to measure the structure and nature of the interstellar medium. Dust and gas between the stars are invisible unless illuminated by some light source, just as fog at night is not noticeable until lit by a car's headlights. A supernova blast can provide that illumination, lighting up surrounding clouds of matter with its strobe-like flash.
"We see the reflection as an arc because we are inside an imaginary ellipse, with the Earth at one focus of the ellipse and the ancient supernovae at the other," explained Nicholas Suntzeff of NOAO. "As we look out toward the supernovae, we see the reflection of the light echo only when it intersects the outer surface of the ellipse."
An unusual aspect of the arcs is that they generally appear to move much faster than the speed of light. This does not violate the cosmic speed limit, which states that no object can move faster than light. "What our telescopes see is the reflection moving, and not any physical object," Suntzeff said. "It is also very exciting that our observations confirm the visionary prediction of Fritz Zwicky in 1940 that light from ancient supernovae could be seen in echoes of the explosion."
The Livermore portion of the work is funded by National Nuclear Security Administration.
Other co-authors of the paper are Mark Huber and Sergei Nikolaev of Lawrence Livermore, Knut Olsen and Chris Smith of the Cerro Tololo Inter-American Observatory in Chile, Jose Luis Prieto of Ohio State University, Douglas Welch of McMaster University, Ontario, Canada, Andrew Becker and Gajus Miknaitis of the University of Washington, Marcel Bergmann of the Gemini Observatory, and Alejandro Clocchiatti and Dante Minniti of Pontifica Universidad Católica de Chile.
Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.
Lawrence Livermore National Laboratory
The light echoes were discovered by comparing images of the Large Magellanic Cloud (LMC) taken years apart. By precisely subtracting the common elements in each image and analyzing what variable objects remain, the team looked for evidence of dark matter that might distort the light of stars in a transitory way, as part of a second-generation sky survey called SuperMACHO. SuperMACHO builds on the discoveries of the MACHO project, which started at Lawrence Livermore National Laboratory in 1989.
"The exciting thing for me is that the light echo discovery was serendipity," said Livermore astronomer Kem Cook, a co-author on the paper that appears in the Dec. 22, 2005, edition of Nature. "We are carrying out a large wide-field, time-domain survey looking for the signature of dark matter, and as a bonus we are discovering unexpected things like these light echoes. Serendipitous discoveries are a key element of large surveys and will likely be an important element of even larger future surveys in which LLNL is involved, such as the Large Synoptic Survey Telescope."
The careful image analysis also revealed a small number of concentric, circular-shaped arcs that are best explained as light moving outward over time, and being scattered as it encounters dense pockets of interstellar dust. Team members then fit perpendicular vectors to the curves of each arc system, which were found to point backward toward the sites of three recent supernovae remnants found previously via their X-ray glow by the orbiting Chandra X-ray Observatory.
"Without the geometry of the light echo, we had no way of knowing just how old these supernovae were," said astronomer Armin Rest of the National Optical Astronomy Observatory (NOAO), lead author of the paper. "Some relatively simple mathematics can help us answer one of the most vexing problems that astronomers can ask - exactly how old is this object that we are looking at?"
This technique can be applied to famous supernovae in history. "Imagine seeing light from the same explosion first seen by Johannes Kepler some 400 years ago, or the one recorded by Chinese observers in 1006," said Christopher Stubbs of the Harvard-Smithsonian Center for Astrophysics (CfA), co-author of the paper and principal investigator for the SuperMACHO program. "These light echoes give us that possibility."
In principle, astronomers can split the light echo into a spectrum to investigate what type of supernova occurred. "We have the potential with these echoes to determine the star's cause of death, just like the archaeologists who took a CT scan of King Tut's mummy to find out how he died," said co-author Arti Garg of CfA.
Astronomers also can use supernova light echoes to measure the structure and nature of the interstellar medium. Dust and gas between the stars are invisible unless illuminated by some light source, just as fog at night is not noticeable until lit by a car's headlights. A supernova blast can provide that illumination, lighting up surrounding clouds of matter with its strobe-like flash.
"We see the reflection as an arc because we are inside an imaginary ellipse, with the Earth at one focus of the ellipse and the ancient supernovae at the other," explained Nicholas Suntzeff of NOAO. "As we look out toward the supernovae, we see the reflection of the light echo only when it intersects the outer surface of the ellipse."
An unusual aspect of the arcs is that they generally appear to move much faster than the speed of light. This does not violate the cosmic speed limit, which states that no object can move faster than light. "What our telescopes see is the reflection moving, and not any physical object," Suntzeff said. "It is also very exciting that our observations confirm the visionary prediction of Fritz Zwicky in 1940 that light from ancient supernovae could be seen in echoes of the explosion."
The Livermore portion of the work is funded by National Nuclear Security Administration.
Other co-authors of the paper are Mark Huber and Sergei Nikolaev of Lawrence Livermore, Knut Olsen and Chris Smith of the Cerro Tololo Inter-American Observatory in Chile, Jose Luis Prieto of Ohio State University, Douglas Welch of McMaster University, Ontario, Canada, Andrew Becker and Gajus Miknaitis of the University of Washington, Marcel Bergmann of the Gemini Observatory, and Alejandro Clocchiatti and Dante Minniti of Pontifica Universidad Católica de Chile.
Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.
Lawrence Livermore National Laboratory
Supernovae News and Current Supernovae Events RSS'Cosmic ghost' discovered by volunteer astronomer
When Yale astrophysicist Kevin Schawinski and his colleagues at Oxford University enlisted public support in cataloguing galaxies, they never envisioned the strange object Hanny van Arkel found in archived images of the night sky.
The quiet explosion
A European-led team of astronomers are providing hints that a recent supernova may not be as normal as initially thought. Instead, the star that exploded is now understood to have collapsed into a black hole, producing a weak jet, typical of much more violent events, the so-called gamma-ray bursts.
In Unique Stellar Laboratory, Einstein's Theory Passes Strict, New Test
Taking advantage of a unique cosmic configuration, astronomers have measured an effect predicted by Albert Einstein's theory of General Relativity in the extremely strong gravity of a pair of superdense neutron stars. Essentially, the famed physicist's 93-year-old theory passed yet another test.
Supernova birth seen for first time
Astronomers have seen the aftermath of spectacular stellar explosions known as supernovae before, but until now no one has witnessed a star dying in real time.
A scientific first: A supernova explosion is observed in real time
An ordinary observation with NASA's Swift research satellite recently led to the first real-time sighting of a star in the process of exploding. Astronomers have surveyed thousands of these supernova explosions in the past, but their observations have always begun some time after the main event is underway.
Observation of X-rays from birth of supernova leads to all-out effort to record stellar death
The lucky capture in January of an X-ray outburst from the very beginning of a supernova allowed astronomers around the world to quickly follow up with ground-based telescopes and collect a wealth of new information on early processes in stellar explosions, according to a paper newly submitted to The Astrophysical Journal.
NASA's Swift satellite catches first 'normal' supernova in the act of exploding
Thanks to a fortunate observation with NASA's Swift satellite, astronomers, for the first time, have caught a normal supernova at the moment of its birth--the first instant when an exploding star begins spewing its energy into space, transforming into a supernova that during its brief lifetime will shine brighter than billions of stars combined.
Searching the heavens
A new space mission, due to launch this month, is going to shed light on some of the most extreme astrophysical processes in nature - including pulsars, remnants of supernovae, and supermassive black holes.
Compact galaxies in early Universe pack a big punch
Using the Near Infrared Camera and Multi-Object Spectrometer onboard of the Hubble NASA/ESA Hubble Space Telescope, astronomers have made observations of young, surprisingly compact galaxies, each only 5,000 light-years across, but weighing 200 billion times the mass of the Sun.
Jekyll-Hyde neutron star discovered by researchers
Like something out of a Robert Louis Stevenson novel, researchers at NASA and McGill University discovered an otherwise normal pulsar which violently transformed itself temporarily into a magnetar, a stellar metamorphosis never observed before.
More Supernovae News Articles
 | Mysterious Universe: Supernovae, Dark Energy, and Black Holes (Scientists in the Field) by Ellen Jackson The universe is rapidly expanding. Of that much scientists are certain. But how fast? And with what implications regarding the fate of the universe?Ellen Jackson and Nic Bishop follow Dr. Alex Fillippenko and his High-ZSupernova Search Team to Mauna Kea volcano in Hawaii, where they will study space phenomena and look for supernovae, dying stars that explode with the power of billions of hydrogen... |
 | Supernovae and Nucleosynthesis (Princeton Series in Astrophysics) by David Arnett This book investigates the question of how matter has evolved since its origin in the Big Bang, from the cosmological synthesis of hydrogen and helium to the generation of the complex set of nuclei that comprise our world and our selves. A central theme is the evolution of gravitationally contained thermonuclear reactors, otherwise known as stars. Our current understanding is presented... |
 | Cosmic Catastrophes: Exploding Stars, Black Holes, and Mapping the Universe by J. Craig Wheeler From supernovae and gamma-ray bursts to the accelerating Universe, this is an exploration of the intellectual threads that lead to some of the most exciting ideas in modern astrophysics and cosmology. This fully updated second edition incorporates new material on binary stars, black holes, gamma-ray bursts, worm-holes, quantum gravity and string theory. It covers the origins of stars and their... |
 | Supernovae: and How to Observe Them (Astronomers' Observing Guides) by Martin Mobberley This book is intended for amateur astronomers who are readers of Sky and Telescope magazine or similar astronomy periodicals – or are at least at the same level of knowledge and enthusiasm. Supernovae, the subject of this book, represent the most violent stellar explosions in the universe. It is a unique guide to supernova facts, and it is also an observing/discovery guide, all in one... |
 | Stardust: Supernovae and Life --- The Cosmic Connection by John Gribbin, Mary Gribbin We are made of stardust--and so is all life as we know it. Every chemical element on earth except hydrogen and helium has been scattered across the universe in great stellar explosions and recycled into new stars, planets, and parts of us. In this engrossing book, John and Mary Gribbin explain how developments in astronomy from the 1920s to the present day have led to this startling... |
 | The Biggest Bangs: The Mystery of Gamma-Ray Bursts, the Most Violent Explosions in the Universe by Jonathan I. Katz Gamma-ray bursts are the most violent events since the birth of the universe. They are about ten times more energetic than the most powerful supernovae. At their peak, gamma-ray bursts are the brightest objects in space, about 100,000 times brighter than an entire galaxy. And yet until recently these titanic eruptions were the most mysterious events in astronomy. In The Biggest Bangs,... |
 | Observing Variable Stars, Novae, and Supernovae by Gerald North, Nick James Gerald North's complete practical guide and resource package instructs amateur astronomers in observing and monitoring variable stars and other objects of variable brightness. Descriptions of the objects are accompanied by explanations of the background astrophysics, providing readers with real insight into what they are observing at the telescope. The main instrumental requirements for observing... |
| Nucleosynthesis in massive stars and supernovae, by William A Fowler | |
 | Exploding Superstars: Understanding Supernovae and Gamma-Ray Bursts (Springer Praxis Books / Popular Astronomy) by Alain Mazure, Stéphane Basa In Exploding Superstars, Alain Mazure and Stephane Basa show how great stellar explosions have become extremely important in recent years to cosmologists trying to understand the evolution of our universe since the Big Bang and the scale of that universe. Recently supernovae and gamma-ray bursters have been used, for example, as "standard candles," illuminating their immediate environs like... |
 | The Extravagant Universe: Exploding Stars, Dark Energy, and the Accelerating Cosmos (Princeton Science Library) by Robert P. Kirshner One of the world's leading astronomers, Robert Kirshner, takes readers inside a lively research team on the quest that led them to an extraordinary cosmological discovery: the expansion of the universe is accelerating under the influence of a dark energy that makes space itself expand. In addition to sharing the story of this exciting discovery, Kirshner also brings the science up-to-date in a... |
| © 2008 BrightSurf.com |