The Hyakutake Comet
Click on image for full size
Michael Brown (University of Melbourne), Chris Fluke (University of Melbourne) and Mount Stromlo and Siding Spring Observatories
DISCOVERED! X-rays from comet Hyakutake
A bit of background
A small portion of the solar wind is comprised of minor ions, atoms of oxygen, carbon, and neon, that have been nearly stripped of their electrons. Dr. Thomas Cravens of University of Kansas theorizes that these minor ions found in solar wind can steal electrons from neutral atoms found in comets. These stolen electrons start off in the excited state and fall into lower orbitals. For an electron to fall down to a lower orbital, it must get rid of energy, often in the form of radiation. When this occurs in a comet this excess energy can be given off in the form of x-ray radiation. So by detecting this x-ray emission, we have a new and exciting way to track comets and solar wind phenomena.
The details of the discovery
On March 27, 1996, observations were taken of the Comet Hyakutake by Germany's ROSAT satellite. X-ray emissions (the first from any comet) were detected at this time. A simulation of these emissions was conducted using an Earth sciences super computer at the NASA Goddard Space Flight Center. The computer simulation showed that the x-ray emissions depend mainly on the solar wind composition, not on the comet. Because of this independence, researchers can determine where the comet's nucleus is in relation to the comet's atmosphere.
"Cometary X-rays present a potentially powerful new tool to
monitor comet activity far from Earth, as well as the
composition and flux of the solar wind," said co-author
Dr. Tamas Gombosi of the University of Michigan, Ann Arbor. "By
capturing these X-rays' detailed energy spectrum, it might be
possible to monitor the propagation and evolution of spectacular solar wind phenomena, such as the coronal mass
ejections seen this January and April."
This new theory of cometary x-ray emission will be tested on the Comet Hale-Bopp using Japan's ASCA x-ray satellite in September.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science
You might also be interested in:
Hale-Bopp continues to offer surprises as astronomers study the comet. Using the Hubble Space Telescope and the International Ultraviolet Explorer, astronomers have found that there are distinctly different...more
Six spacecraft flew by Halley's comet in 1986. There were two spacecraft launched from Japan, Suisei and Sakigake, and two from the Soviet Union, Vega 1 & 2. One spacecraft, ICE, from the United States...more
Comets are observed to go around the sun in a long period of time or a short period of time. Thus they are named "long-period" or "short-period" comets. One group of short-period comets, called the Jupiter...more
Scientists have learned a great deal from the crash of comet Shoemaker-Levy 9. Scientists traced the orbit of the comet backwards in time to guess its origin. This calculation, along with the discovery...more
Mathematical theory suggests that comet Shoemaker-Levy 9 was likely a short-period comet which was captured into orbit around Jupiter in 1929 and began to execute the trajectory plotted in this diagram....more
As the ices of the comet nucleus evaporate, they expand rapidly into a large cloud around the central part of the comet. This cloud, called the coma, is the atmosphere of the comet and can extend for millions...more
When evaporation begins, the gas is propelled from the nucleus at supersonic speed (depicted by arrows in the figure). Because of the low gravity in space, this means that the molecules from the nucleus...more