[meteorite-list] Young Stars in Orion
From: Dave Coleman & Sarah Kennedy-Coleman <jensan_at_meteoritecentral.com>
Date: Thu Apr 22 09:48:56 2004
Dear Ron and listees,
Very interesting finding from Chandra.
I wonder though, whether the exotic decay products in the CAI's are
pre-solar OR infant-solar....how is it that they are found only in the
primitive carbonaceous meteorites, and not also in the more numerous
samples of primitive chondrites? Is Eros, now known to be primitive, but
not carbonaceous, expected to harbor them?
If the source of the altered material was indiscriminate in the making
of it within the solar nebula (a nearby supernova must be the very
definition of a "shotgun effect" at the scale of our solar
system)....why are the CAI exotics more difficult to find than the gold
atoms made in the same explosion?
Got to go for a bit, or this nearby lightning will be the cause of MY
Ron Baalke wrote:
> Office of Public Information
> Eberly College of Science
> Pennsylvania State University
> University Park, Pennsylvania
> Eric Feigelson, 814-865-0162, efeigelson_at_astro.psu.edu
> Barbara K. Kennedy (PIO), 814-863-4682 or 814-863-8453, science_at_psu.edu
> 6 September 2001
> Young Stars in Orion May Solve Mystery of Our Solar System
> Scientists may have to give the Sun a little more credit. Exotic isotopes
> present in the early Solar System -- which scientists have long-assumed
> were sprinkled there by a powerful, nearby star explosion -- may have
> instead been forged locally by our Sun during the colossal solar-flare
> tantrums of its baby years.
> The isotopes -- special forms of atomic nuclei, such as aluminum-26,
> calcium-41, and beryllium-10 -- can form in the X-ray solar flares of young
> stars in the Orion Nebula, which behave just like our Sun would have at
> such an early age. The finding, based on observations by the Chandra X-ray
> Observatory, has broad implications for the formation of our own Solar
> Eric Feigelson, professor of astronomy and astrophysics at Penn State, led
> a team of scientists on this Chandra observation and presents these results
> in Washington, D.C., today at a conference entitled "Two Years of Science
> with Chandra".
> "The Chandra study of Orion gives us the first chance to study the flaring
> properties of stars resembling the Sun when our solar system was forming,"
> said Feigelson. "We found a much higher rate of flares than expected,
> sufficient to explain the production of many unusual isotopes locked away
> in ancient meteorites. If the young stars in Orion can do it, then our Sun
> should have been able to do it too."
> Scientists who study how our Solar System formed from a collapsed cloud
> of dust and gas have been hard pressed to explain the presence of these
> extremely unusual chemical isotopes. The isotopes are short-lived and had
> to have been formed no earlier than the creation of the Solar System, some
> five billion years ago. Yet these elements cannot be produced by a star as
> massive as our Sun under normal circumstances. (Other elements, such as
> silver and gold, were created long before the creation of the solar system.)
> The perplexing presence of these isotopic anomalies, found in ancient
> meteoroids orbiting the Earth, led to the theory that a supernova
> explosion occurred very close to the Solar System's progenitor gas cloud,
> simultaneously triggering its collapse and seeding it with short-lived
> Solar flares could produce such isotopes, but the flares would have to be
> hundreds of thousands of times more powerful and hundreds of times more
> frequent than those our Sun generates.
> Enter the stars in the Orion Nebula. This star-forming region has several
> dozen new stars nearly identical to our Sun, only much younger. Feigelson's
> team used Chandra to study the flaring in these analogs of the early Sun
> and found that nearly all exhibit extremely high levels of X-ray flaring --
> powerful and frequent enough to forge many of the kinds of isotopes found
> in the ancient meteorites from the early solar system.
> "This is a very exciting result for space X-ray astronomy," said Donald
> Clayton, Centennial Professor of Physics and Astronomy at Clemson University.
> "The Chandra Penn State team has shown that stellar-flare acceleration
> produces radioactive nuclei whether we want them or not. Now the science
> debate can concentrate on whether such irradiation made some or even all
> of the extinct radioactivities that were present when our solar system was
> formed, or whether some contamination of our birth molecular cloud by
> external material is also needed."
> "This is an excellent example of how apparently distant scientific fields,
> like X-ray astronomy and the origins of solar systems, can in fact be
> closely linked," said Feigelson.
> The Orion observation was made with Chandra's Advanced CCD Imaging
> Spectrometer, which was conceived and developed for NASA by Penn State
> and Massachusetts Institute of Technology under the leadership of Gordon
> Garmire, the Evan Pugh Professor of Astronomy and Astrophysics at Penn
> State. The Penn State observation team includes Pat Broos, James Gaffney,
> Gordon Garmire, Leisa Townsley and Yohko Tsuboi. Collaborators also include
> Lynne Hillenbrand of CalTech and Steven Pravdo of the NASA Jet Propulsion
> Isotopes are atoms whose nuclei have different numbers of neutrons. Many
> isotopes are unstable, or radioactive, and decay into other elements. A
> famous example is carbon-14 whose decay gives scientists the opportunity
> to date organic materials over thousands of years.
> A rare type of ancient meteorite called carbonaceous chondrites, which are
> rocks from the Asteroid Belt whose orbits are perturbed and fall to the
> Earth, date back to the formation of our Solar System 4.55 billion years
> ago. Studying carbonaceous chondrites gives us a unique window on
> conditions in the solar nebula when the Sun and Solar System were forming.
> Certain portions of carbonaceous chondrites, small melted pebbles called
> Calcium-Aluminum-rich Inclusions or CAIs, have unusually high abundances
> of decay products of rare, short-lived isotopes. These include
> beryllium-10, calcium-41, 26-aluminum and 53-manganese, among others.
> Explaining the presence of these short-lived isotopes, which do not appear
> anywhere else in solar system material, has been one of the toughest
> challenges of solar system science. The favored explanation has been that
> a star exploded in a supernova and triggered a nearby cloud of dust and
> gas to collapse to form our Sun and planetary system. But conditions have
> to be carefully adjusted for this model, and it cannot be widely applied
> to all stars. The principal alternative model is that energetic particles
> from violent flares hit particles in the solar nebula and transformed some
> of their atoms to radioactive isotopes. A drawback to this model has been
> that the level of flaring needed, around 100,000 times the flaring level
> of the Sun today, was thought to be impossibly high. However, the X-ray
> observations reported here give direct evidence for just this high level
> of flaring. In addition, this model readily applied to all young stars and
> solar systems, not just a few.
> Check out the new Meteorite Central logo wear at http://www.cafepress.com/cp/store/store.aspx?storeid=meteorites
> Meteorite-list mailing list
Received on Thu 06 Sep 2001 03:01:51 PM PDT