Study Identifies Possible Origins of “Differentiated” Celestial Objects
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reader!
It
follows an article published day (04/02) in the english website of the Agência
FAPESP noting that a study led by Brazilian Researchers identifies possible
origins of “differentiated” celestial objects.
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Articles
Study Identifies Possible Origins of
“Differentiated” Celestial Objects
By Elton Alisson
April 2, 2014
(illustration: NASA)
An
international group of researchers
led by Brazil locates possible sources of
asteroid fragments with basaltic crust.
|
Agência FAPESP – In the Solar
System’s main belt of asteroids, located between Mars and Jupiter, there is a
small group of celestial objects known as V-type asteroids. These are,
supposedly, fragments of the Vesta asteroid, the second largest object in the
belt and one of the group of celestial bodies having a basaltic crust.
In recent years, an additional 127 V-type asteroid candidates have been identified.
Although their origin is not very well understood, they are found in the
central part of the main belt. Astronomers think it is very unlikely that they
are all fragments of the Vesta asteroid because of the orbital position in
which they are found.
A study conducted by researchers at the Universidade Estadual Paulista
(UNESP) in Guaratinguetá, in collaboration with colleagues from the National Institute
for Space Research (INPE), the University of Namur in Belgium, the Paris
Observatory, and the Pierre and Marie Curie University in France, has
demonstrated that these new V-type asteroids in the main belt may be derived
from other differentiated asteroids and not from the Vesta.
Differentiated celestial bodies are those that underwent processes by
which they were structurally divided into layers that were geologically and
chemically different from one another and have a basaltic crust, mantle, and
nucleus.
The findings of the study, conducted under the scope of the project “Orbital mobility caused by close encounters with more than one massive
asteroid”, funded by FAPESP, will be published in the journal Monthly
Notices of the Royal Astronomical Society (MNRAS).
“It’s very likely that there have been other differentiated objects that
gave rise to these new V-type asteroids, but we don’t know how many,” Valério
Carruba, Unesp professor and first author of the study, told Agência FAPESP.
“If we could determine the minimum number of differentiated objects that
gave rise to these new asteroids, we would be able to better understand their
origin and dynamic evolution,” he projected.
According to Carruba, the V-type asteroids are sparsely distributed
throughout the main belt. The researchers have proposed the division of the
central main belt into three regions where families of asteroids associated
with the formation of V-type objects are situated, namely, Hansa, Eunomia, and
Merxia and Agnia.
In making this division, the researchers determined that the V-type
asteroids that originated from these families “respect the perimeter” in which
they are situated.
“A V-type asteroid in the region of Hansa, for example, would hardly
migrate to the Eunomia region,” Carruba explained. “It’s also highly unlikely
that a V-type asteroid from the Eunomia region would migrate toward the regions
of the Merxia and Agnia families.”
Sources of V-Type Asteroids
The researchers also demonstrated in the study that three different
sources of asteroids – such as those of Eunomia, Merxia and Agnia, and Hansa –
are enough to establish populations of V-type objects in the central main belt,
where at least one more differentiated body, in addition to Vesta, is supposed
to have existed.
The researchers hypothesize that the object that gave rise to the
Eunomia family, for example, could have previously been a differentiated or
partially differentiated body.
“The idea is that, in the past, the main body that gave rise to the
family of Eunomia had a volcanic basaltic crust that was completely destroyed
and scattered throughout the main belt,” said Carruba. “Other studies have also
suggested that the Merxia and Agnia families could also have originated from
differentiated bodies.”
The patterns of formation of these differentiated objects are based on
parameters that are, as yet, not well understood, such as the minimum size for
the differentiation, the shape of the region in which they were formed, and the
efficiency with which they were scattered throughout the main belt.
According to these models, the number of differentiated objects that
could have reached the main belt varies from two to a few hundred. “We still do
not know how many differentiated objects were formed and when they reached the
main belt,” said Carruba. He further stated that “establishing limits on these
numbers can help us better understand the scenarios that led to the formation
of the Solar System.”
The version of the article Dynamical evolution of V-type asteroids in
the central main belt, by Valério Carruba and others, which will be
published in the journal Monthly Notices of the Royal Astronomical Society,
may be viewed at arxiv.org/abs/1401.6332.
Source: English WebSite of the Agência FAPESP
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