Tag Archives: protoplanet

Astronomers scout metal-rich asteroid thought to be worth 10,000 quadrillion dollars

Most asteroids are made of plain rock or ice — but not ’16 Psyche’.

Representation of the Psyche asteroid. Image credits: Arizona State University.

According to recent observations perform using NASA’s Hubble Space Telescope, the chunky asteroid from the solar system’s main asteroid belt between Mars and Jupiter is mostly made of nickel and iron. This makes it an extremely atypical asteroid and a very valuable one — it’s worth as much as $10,000 quadrillion in raw resources by some estimates, or almost 70,000 times the value of the global economy in 2019.

Billionaires: ‘hold my beer’

Psyche spans 140 miles (225 km) in diameter, making it one of the largest objects in the main asteroid belt. In fact, Psyche is so large it was easily discovered using 19th-century technology in 1852.

The novelty is that now scientists have reported in The Planetary Science Journal the asteroid’s composition.

Scientists previously had some hints that Psyche is a dense, largely metallic object. This assumption has now been confirmed thanks to observations at two specific points in the asteroid’s rotation that offered a view of both sides of Psyche at ultraviolet wavelengths.

For the first time, astronomers have recorded iron oxide ultraviolet absorption bands in any asteroid. This is a clear indication that oxidation is occurring on the surface of the asteroid. Its high density suggests that the oxidated metals are nickel and iron. In fact, the entire asteroid might be the leftover core of a failed planet that never succeeded in forming into one.

“We’ve seen meteorites that are mostly metal, but Psyche could be unique in that it might be an asteroid that is totally made of iron and nickel,” Dr. Tracy Becker, Southwest Research Institute planetary scientist and co-author of the new study, said in a statement. “Earth has a metal core, a mantle and crust. It’s possible that as a Psyche protoplanet was forming, it was struck by another object in our solar system and lost its mantle and crust.”

The oxidation is believed to be caused by the solar wind. This flow of charged particles from the sun’s corona is responsible for the beautiful tails of comets, the formation of auroras in Earth’s atmosphere, and, in this case, the space weathering of Psyche.

Such metal asteroids are extremely rare, which is why Psyche was shortlisted in 2017 for a mission to study it closely using a spacecraft. The mission, which will be operated by NASA, is slated for a 2022 launch on a SpaceX Falcon Heavy rocket. The unmanned spacecraft would become the first to visit a body almost entirely made of metal, learning more about the asteroid as well as the solar system.

Since Psyche is believed to be as old as the solar system itself, findings from the mission could enrich our understanding of how planets form. Besides the scientific value of the mission, if you take into account the size of the asteroid and its metal composition, its total economic value could add up to $10,000 quadrillion, or $10 million trillion. That’s quite the incentive to visit the asteroid — provided, of course, we one day develop the technology to mine and retrieve metals from such asteroids.

“To understand what really makes up a planet and to potentially see the inside of a planet is fascinating,” Becker said.

“Once we get to Psyche, we’re really going to understand if that’s the case, even if it doesn’t turn out as we expect … any time there’s a surprise, it’s always exciting,” he added.

How to “Weigh” Baby Planets

Similar to how stars are formed, the most popular theory among today’s scientists regarding the creation of planets is that they are a result of a nebula breaking down. During the long evolution of the deteriorating gaseous cloud, the nebula transforms into a structure called a protoplanetary disk, with a newly-formed star at its center. Such a disk provides a place of incubation for developing planets.

Just recently, for the first time on record, young planets-to-be (also referred to as protoplanets) developing in one of these protoplanetary disks were actually “weighed”. Several scientific papers published earlier this month as inclusions in the Astrophysical Journal Letters discuss a new mode of operation which can be employed to calculate various physical attributes of these protoplanets. It’s also rather accurate and dependable.

One group of astronomers headed by Richard Teague was responsible for the discovery of two young planets having a mass close to the size of the mass of Jupiter, the largest planet in our solar system. The two bodies orbit a star which has been labeled HD 163296. This four-million-year-old ball of burning gas is still a youngster as a star the size of our Sun would have a normal life expectancy of about 10 billion years and beyond.

A Developing Star System. Source: SciTechDaily.

But a separate party of scientists, this one based in Australia and headed by Christophe Pinte, was also spending time examining the same system. They noticed a third protoplanet in a revolution around the very same star. However, the finding attributed to Pinte’s team was a young planet nearly twice as massive as the gas giant Jupiter.

Both of the teams employed data from the Atacama Large Millimeter/submillimeter Array (ALMA). This is a system of radio telescopes located in Chile, South America. The two teams of astronomers closely examined the motion of the nebulous gas. Both managed to develop a process of measuring the gas’s velocity by observing the change in the wavelength of light emitted by carbon monoxide molecules.

The gravitational pull of a planet would best explain the gaseous movements. Richard Teague thinks this method of measurement could be used effectively in observing many other stars and protoplanets. In this way, he hopes scientists will be able to discover what types of protoplanets are most common in the cosmos.

Meteorites Not Responsible For Building Solar System, Study Finds

For decades, astronomers have believed that meteorites are the building blocks of our solar system – the lego blocks for planets. But a new study from scientists at MIT and Purdue University suggests that this may not be the case after all – and we’ve given meteorites too much credit.

meteorite

An artist’s rendering of a protoplanetary impact. Early in the impact, molten jetted material is ejected at a high velocity and breaks up to form chondrules, the millimeter-scale, formerly molten droplets found in most meteorites. These droplets cool and solidify over hours to days.
Credit: NASA/California Institute of Technology

Meteorites are solid pieces of debris  asteroids or comets, that originate in outer space and survive the impact with the Earth’s surface. The name meteorite is typically used when the object enters Earth’s atmosphere and survives the fall and the crash to the Earth’s surface. If it doesn’t enter our planet’s atmosphere, the strictly correct term is meteoroid.This new study, based on computer simulations, concluded that there’s no way meteorites could have been the building blocks of planets. Instead, the research concluded that meteorites are just debris resulting from proto-planetary collisions during the early days of the Solar System. If this is true, then studying meteorites won’t yield information about how the planets were like in their early stages, as was previously believed.

“This tells us that meteorites aren’t actually representative of the material that formed planets – they’re these smaller fractions of material that are the byproduct of planet formation,” says Brandon Johnson of MIT’s Earth, Atmospheric and Planetary Sciences department. “But it also tells us the early solar system was more violent than we expected: You had these massive sprays of molten material getting ejected out from these really big impacts. It’s an extreme process.”

Johnson and his colleagues, including Maria Zuber, the E.A. Griswold Professor of Geophysics and MIT’s vice president for research, have published their results this week in the journal Nature.

 

[Also Read: The Only Carving from a Meteorite]

Collision models indicate that astral bodies like our Moon (and others of similar sizes) likely formed way earlier than was previously believed, and way before chondrites formed. Chondrites are stony (non-metallic) meteorites that have not been modified due to melting or differentiation of the parent body.

“If this finding is correct, then it would suggest that chondrites are not good analogs for the building blocks of the Earth and other planets,” said University of Chicago Associate Professor of Planetary Science, Fred Ciesla. “Meteorites as a whole are still important clues about what processes occurred during the formation of the Solar System, but which ones are the best analogs for what the planets were made out of would change.”

If this finding is true, then we should reanalyze what we know about the early stages of the Solar System. Image via IOP.

If this is the case, then meteorites are in fact byproducts, and not building blocks, and we’ll have to revise what we think about the early stages of the solar system.

“Chondrules were long viewed as planetary building blocks,” Zuber notes. “It’s ironic that they now appear to be the remnants of early protoplanetary collisions.”

However, not all computer simulations are accurate, and this is going to need some confirmation before it is viewed as a fact, but it casts a big shadow over something which was regarded as a near certainty for the longest of time.

“This would be a major shift in how people think about our solar system,” says Ciesla, who did not contribute to the research. “If this finding is correct, then it would suggest that chondrites are not good analogs for the building blocks of the Earth and other planets. Meteorites as a whole are still important clues about what processes occurred during the formation of the Solar System, but which ones are the best analogs for what the planets were made out of would change.”

Journal Reference:

  1. Brandon C. Johnson, David A. Minton, H. J. Melosh & Maria T. Zuber. Impact jetting as the origin of chondrules. Nature, 2014 DOI: 10.1038/nature14105

 

Taking a peak inside a planetary womb

Astronomers using ESO’s Very Large Telescope have obtained what is likely the first direct observation of a forming planet still embedded in a thick disc of gas and dust. If the finding is confirmed, it could significantly boost what we already know about forming planets.

protoplanet

An international team led by Sascha Quanz (ETH Zurich, Switzerland) has studied the disc of gas and dust that surrounds the young star that goes by the name of HD 100546, located some 330 light years from Earth. They were surprised to see that, from their original observations, it appears that the planet is in its initial stages of formation – an event not captured by astronomers so far.

“So far, planet formation has mostly been a topic tackled by computer simulations,” says Sascha Quanz. “If our discovery is indeed a forming planet, then for the first time scientists will be able to study the planet formation process and the interaction of a forming planet and its natal environment empirically at a very early stage.”

Initially, they just noticed a faint blob in the outer regions of the system, about 60 times further out from its star than the Earth is to the Sun. According to current theory, giant planets grow by capturing some of the gas and dust that remains after the formation of a star, and so far, astronomers have captured a few ideas that support this theory. Structures in the dusty circumstellar disc, which could be caused by interactions between the planet and the disc, were revealed close to the detected protoplanet. This discovery has many astronomers jumping around at the unique chance presented to them. Adam Amara, another member of the team, is one of them:

“Exoplanet research is one of the most exciting new frontiers in astronomy, and direct imaging of planets is still a new field, greatly benefiting from recent improvements in instruments and data analysis methods. In this research we used data analysis techniques developed for cosmological research, showing that cross-fertilisation of ideas between fields can lead to extraordinary progress.”

Hawaii astronomer takes picture of youngest planet

An astronomer working at the University of Hawaii captured the first ever pictures of a planet forming around a star.

In order to do it, he used the 10-metre Keck telescopes on Mauna Kea and a system of mirrors; the main problem with taking pictures such as these ones is that the planet’s star usually outshines the planet, so there is a need to obstruct the starlight.

The protoplanet, or planetary embryo, was named LkCa 15 b; the hot mass of dust and gas will become a giant, much like Jupiter and Saturn. It is currently the youngest planet ever found.

‘LkCa 15 b is the youngest planet ever found, about 5 times younger than the previous record holder,’ said Adam Kraus, who made the discovery. ‘This young gas giant is being built out of the dust and gas. In the past, you couldn’t measure this kind of phenomenon because it’s happening so close to the star. But, for the first time, we’ve been able to directly measure the planet itself as well as the dusty matter around it.’

Upon analyzing images at different wavelengths, researchers were surprised by the complexity of the phenomenon.

‘We realized we had uncovered a super Jupiter-sized gas planet, but that we could also measure the dust and gas surrounding it. We’d found a planet at its very beginning,’ said Kraus.

When Worlds Collide

worlds collide
Not a Hollywood movie or something like that; not even a pun. The title is in the most literal fashion it could be. But how could this be? Worlds can’t collide, can’t they? Hard to say. Anyway astronomers have announced that a mystery object orbiting a star 170 light-years from Earth might have formed from the collision and merger of two protoplanets.

This object has puzzled them as it just seems to not be physically posible because its temperature, luminosiry, age and location just don’t match with any theory. “This is a strange enough object that it needs a strange explanation,” said Eric Mamajek of the Harvard-Smithsonian Center for Astrophysics (CfA). The object (let’s call it so) is called 2M1207B and it orbits a 25-Jupiter-mass brown dwarf called 2M1207A seen in the direction of the constellation Centaurus. Computer models show that 2M1207A is very young, only about 8 million years old; therefore its companion should also be 8 million years old. Everything sounds ok until here.

But the thing is that at that age it should have lowered its temperature to less than 1300 degrees Fahrenheit (1000 Kelvin). But observations have showed that in fact it has a temperature of about 2400 degrees F (1600 K) and this temperature could very well be the result of a protoplanetary collision.

“Most, if not all, planets in our solar system were hit early in their history. A collision created Earth’s moon and knocked Uranus on its side,” explained Mamajek. “It’s quite likely that major collisions happen in other young planetary systems, too.”

Also they were expecting a certain luminosity from it it is 10 times fainter than expected. In our solar system planets are assembled from dust, rock, and gas, gradually growing larger over millions of years. In this way this object could be the result of a collision between a gas giant about the size of Saturn and a planet about three times as big as the Earth; they were so big that they just got stuck together forming a larger world still boiling from the heat generated in the collision.

“The Earth was hit by something one-tenth its mass, and it’s likely that other planets in our solar system were too, including Venus and Uranus,” explained Meyer. “If that one-tenth scale holds in other planetary systems, then we could be seeing the aftermath of a collision between a 72 Earth-mass gas giant and an 8 Earth-mass planet, even though such collisions are very unlikely.”

It is not a certitude that it was formed due to a collision but that theory is very probable. They are currently making some tests and we are probably going to find the answer a year or two from now.