BBC: Tiny rock excites astrochemists. (Via: Universe Today)
A "unique" micrometeorite found in Antarctica is challenging ideas about how planets can form.Gounelle, M., et al., A Unique Basaltic Micrometeorite Expands The Inventory of Solar System Planetary Crusts, Proceedings of the National Academy of Sciences, 2009
Detailed analysis has shown that the sample, known as MM40, has a chemical composition unlike any other fragment of fallen space rock.
This, say experts, raises questions about where it originated in the Solar System and how it was created.
It also means that astrochemists must expand their list of the combinations of materials in planetary crusts.
The detailed analysis of MM40 was led by Matthieu Gounelle from the Laboratory of Mineralogy and Cosmochemistry at the French Natural History Museum.
Published in PNAS, the analysis revealed the "unique" chemical composition of MM04 despite it being only 150 microns across as its widest point - about half the width of a written full stop.
Dr Caroline Smith, curator of meteorites at the Natural History Museum, London, UK, said the sample was important because of the role that the study of meteorites played in our understanding of Solar System and planetary formation.
MM40 was a basaltic achondritic micrometeorite, said Dr Smith.
Achondritic meteorites were formed when the Solar System's planets were coming into being. The substances in such meteorites and the processes they have undergone can give clues about how the larger bodies were formed.
By contrast, chondritic meteorites were formed during the the Solar System's early days before material had accreted into planets. They have not been altered by the melting and re-crystalisation that has utterly transformed the nature of, say, Earth rocks.
Dr Mahesh Anand, an astrochemist from the department of Earth & Environmental Sciences at the Open University, said: "It is fascinating as to how much information can be retrieved about the processes involved in planetary formation from tiny fragments of extra-terrestrial material that routinely arrive on Earth anonymously."
For Dr Smith, the excitement of MM40 lay in the mystery of its origins.
"We have basaltic meteorites that are thought to come from an asteroid called 4 Vesta and we also have basaltic meteorites from the Moon and Mars," said Dr Smith.
"But [MM40's] chemistry does not match any of those places," she said. "It has to be from somewhere else."
While its ultimate origins are a mystery it does have implications for the ways that astrochemists thought planets could be formed. The analysis of MM40 showed that the "inventory" of such processes must be expanded, said Dr Smith.
"Micrometeorites are often seen as the 'poor man's space probe'," said Dr Smith "They land on Earth fortuitously and we do not have to spend millions of dollars or euros on a robotic mission to get them."
Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.
-759725.jpg){kind=link}
2 comments:
HOW PLANETS CAN FORM IS AN ECHO OF HOW BINARY PAIRS OF STARS FORM
"Modern" astronomy claims to know how stars and planets form and evolve, but do they?
Space.com(March 22, 2009) -- "A massive star a million times brighter than our sun exploded way too early in its life, suggesting scientists don't understand stellar evolution as well as they thought. 'This might mean that we are fundamentally wrong about the evolution of massive stars, and that theories need revising,' said Avishay Gal-Yam of the Weizmann Institute of Science in Rehovot, Israel."
Apparently, the stars are failing to behave as predicted by the gravity "only" model.
Reports are being made on a regular basis that throw doubt on the idea that "modern" astronomy knows how stars are formed.
Space.com (March 1, 2005) -- "The best look ever inside a womb of star birth reveals a force at work astronomers were not aware of."
Further:
"Some previously unrealized energetic process, likely related to magnetic fields, is superheating parts of the cloud, nudging it to become a star, scientists said. The detection of X-rays from the cold stellar precursor surprised astronomers. The observations reveal that matter is falling toward the core 10 times faster than gravity could account for."
Magnetic fields and thus electric currents are critical to star formation.
ScienceDaily (September 10, 1999) -- "Observations by a University of Illinois astronomer have shown that magnetic fields are a critical component controlling when and how stars form."
"Understanding the physics governing the structure and evolution of dense interstellar clouds is a necessary part of understanding the fundamental astrophysical process of star formation," said Richard Crutcher, a professor of astronomy at the U. of I. "Theoretical studies have suggested that magnetic fields play a vital role in the evolution of interstellar clouds and in the formation of stars, but those studies needed to be compared with observational data."
Clearly, electrotmagnetism phenomenon is present in star forming regions.
Science knows that the Sun has both an electromagnetic torus surrounding it like a big donut (as does Earth, Jupiter, and Saturn), and it also has a heliospheric current sheet that results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium.
Science has been able to observe new and forming stars, and what it has observed is spiral flares coming off the star.
And, a partial torus has been observed around a new star as well.
Interestingly Kristian Birkeland as part of his terrela experiments was able to create a remarkable similar electromagnetic spiral flare out from a magnetized sphere.
Compare the actual observations of young stars and Birkeland's picture, the similarity is remarkable.
Birkeland was able to create the toroidal donut around the magnetic sphere as well (notice the ionized haze around the sphere in the shape of a donut).
Kirstian Birkeland was the first scientist to do astrophysics experiments in a laboratory.
Birkeland currents are named in his honor.
(This is where the post and the comment are tied together.)
What these pictures suggest is that when a star is new and energetic, toruses can form around it and spiral electromagnetic flares can emerge and follow the heliospheric current sheet out away from the young star.
And since these flares are electromagnetic in nature, they can form plasmoids along there path where initially a binary star pair can form or later in the process planets can form. See, this schematic of a plasmoid. And in a process known as Marklund Convection can draw in plasma into a concentrated area and form neutral matter until gravity can play a role.
The "accetion disk", whether as used in planet formation, star formation, or surrounding a "black hole" is a faulty hypothesis.
Plasma Cosmology provides both observational confirmation and laboratory replication.
"Modern" astronomy provides neither.
How many surprises does it take before "modern" astronomy begins to question its own assumptions and actively consider alternative explanations?
How many different kinds of "dark" whatever can "modern" astronomy inject into its gravity "only" model before the dead weight drags down the model?
How much "pixie dust" can Peter Pan, the "modern" astronomer, sprinkle on his Never Never Land?
How long can "modern" astronomy stand in willful denial?
How hard will "modern" astronomy be run into the ground?
And will the pure mathematicans who dominate "modern" astronomy, today, ever come to their senses?
Post a Comment