Astronomers Develop New Model to Explain the Formation of Mars
Hello
reader!
It
follows an article published day (06/25) in the english website of the Agência
FAPESP noting that Astronomers develop new model to explain the formation of
Mars.
Duda
Falcão
Articles
Astronomers
Develop New Model
to Explain the Formation of Mars
By Elton
Alisson
Junho 25,
2014
(Image: NASA)
International
study led by Brazilian
researchers analyzes the density of the cloud that formed the Solar System to explain the size of the Red Planet. |
Agência FAPESP – Models of formation of the Solar System’s
rocky planets developed in the past two decades have been successful in
explaining the origin of Venus and Earth, which are similar in size, as well as
that of Mercury, which has only 5% of the Earth’s mass.
High-resolution computer simulations, however, have still failed to
explain how Mars formed and why the planet has only 10% of the Earth’s mass.
According to researchers, this is an intriguing question because the
four planets are all products of similar planetary embryos – celestial bodies
with sizes similar to the current planets – that merged over tens of millions
of years ago.
An international team– made up of researchers from Brazil, the United
States, Germany and France, and led by the Orbital Dynamics and Planetology
Group of the São Paulo State University (Unesp), Guaratinguetá campus –
recently performed a series of simulations, demonstrating that the size of Mars
may be related to the density of the protosolar nebula – the cloud of gas and
dust that gave rise to the Solar System – in the planet’s orbit.
Findings from the FAPESP-funded thematic project, “Orbital dynamics of minor bodies,” were
described in an article published in February 2014 in The Astrophysical
Journal from the American Astronomical Society.
The study was cited by John Chambers, researcher in the Department of
Terrestrial Magnetism of the Carnegie Institution for Science, in the United
States, in an article published in the May issue of the journal Science.
“Most simulations of terrestrial planet formation are unable to generate
a Mars-sized body in its orbit, which is situated at a distance of 1.5
astronomical units [AU, equivalent to approximately 150 million kilometers]
from the Sun,” Othon Cabo Winter, researcher in the Orbital Dynamics and
Planetology Group and project coordinator, told Agência FAPESP.
“These models typically produce a Mars-like body in the orbit of Mars at
approximately the mass of the Earth, much larger than its actual mass,” said
the researcher, author of the article together with André Izidoro, who is
currently a post-doc at the Observatoire de la Côte d'Azur (OLCD) in Nice,
France.
Grand Tack
According to Winter, one of the models already proposed to try to explain
the formation of Mars is what is known as “Grand Tack,” developed by
researchers at the OLCD.
The model holds that during the formation of the Solar System, 4.5
billion years ago, the orbit of Jupiter, the giant planet closest to Mars,
migrated from its current position at 5 AU from the sun closer to the orbit of
the red planet, 2 AU from the sun.
As it approached Mars’ orbit, Jupiter may have crossed the asteroid belt
and swept away most of the planetesimals (solid bodies made of cosmic dust and
ice, similar to asteroids and comets) and planetary embryos found in the
asteroid belt or near the red planet’s orbit, closer to the Sun.
As a result, according to the Grand Tack model, the mass of Mars and the
asteroid belt were reduced and the planetesimal and planetary matter ultimately
formed Earth and Venus.
Because of gravitational interactions with the solar nebula and Saturn,
however, Jupiter would have returned to its current orbit. “This model is valid
but quite questionable because it is unlikely that this really would have
happened,” Winter said.
Alternative Model
To develop an alternative model to the Grand Tack, the Brazilian
researchers, in cooperation with colleagues at the OLCD, along with the
Astrobiology Institute of the US National Aeronautics and Space Administration
(NAI, NASA, USA) and the Institute of Astronomy and Astrophysics at the
University of Tübingen, in Germany, conducted a series of simulations of the
gas and dust flows within the protosolar nebula during its formation.
The simulations suggest that the matter flowed in the direction of the
Sun, moving at different speeds, at varying distances from the star. In the
region between 1 and 3 AU from the Sun, the protosolar nebula could have
suffered a loss or reduction (depletion) of matter equivalent to between 50%
and 75% of its density.
The model assumes that the loss of this volume of “planetary
construction blocks” by the protosolar nebula in this region near Mars’ orbit
would have caused a reduction of the final mass of Mars and the growth of the
Earth and Venus.
“We’ve studied a number of parameters and concluded that if there were a
50% to 70% mass-depletion of the protosolar nebula in the region of between 1
and 3 AU, there is over a 50% chance that a planet with a similar mass on the
current orbit of Mars, in addition to Earth, Venus and a few objects in the
asteroid belt, would have been formed,” Winter said.
“The model is very complete because it addresses the formation of Mars
and, in addition, maintains and is able to generate the other terrestrial
planets at their mass and current orbit,” he went on to say.
Possible Contributions
In Winter’s estimation, the new model closed a gap in the previous model
of the formation of the Solar System, indicating that the profile of mass density
of the protosolar cloud had not been uniform and had undergone depletions.
“These data could have implications for studies that attempt to explain such
things as the formation of the asteroid belt,” he said.
The model could also contribute to research studies in the area of
astrobiology, a field of knowledge that constitutes the interface between
astronomy, biology, chemistry, geology and atmospheric sciences, among other
things, related to objects from Mars moving toward Earth, in addition to studies
about extrasolar planets, he said.
The article “Terrestrial planet formation in a protoplanetary disk
with a local mass depletion: a successful scenario for the formation of Mars”
(doi: 10.1088/0004-637X/782/1/31), by Winter and colleagues, can be read by
subscribers to The Astrophysical Journal at: iopscience.iop.org/0004-637X/782/1/31/article?fromSearchPage=true.
The article “Forming terrestrial planets” (doi:
10.1126/science.1252257) by John Chambers can be read by subscribers to Science
at: www.sciencemag.org/content/344/6183/479.summary?sid=3325c543-db93-448f-b8e4-37409996da5c.
Source: English WebSite of the Agência FAPESP
Comentários
Postar um comentário