(Illustration: This picture depicts a distant hypothetical solar system that is similar in age to our solar system.) Looking inward from the outer edge of the system, a circle of dusty debris can be seen, in which planets orbit a star the size of a sun. Source: NASA)
(Illustration: This picture depicts a distant hypothetical solar system that is similar in age to our solar system.) Looking inward from the outer edge of the system, a circle of dusty debris can be seen, in which planets orbit a star the size of a sun. Source: European Space Agency)
For years, scientists have been probing planets around mature stars and imaging dust disks around young stars, respectively. A powerful theory has been formed—that planets are formed by disks of residual material from these star-forming processes.
In other investigations, the researchers observed lumpy objects in young star systems that are thought to be forming planets.
However, there is a serious problem with observations: Perhaps because these dust disks have thinned to almost imperceptible levels, while mature stars with planets and dust disks remain elusive.
Fortunately, some of the recently announced observations fill these gaps.
(Pictured: NASA's Spitzer Space Telescope captures a glowing star in an opaque dark sphere.) Image source; NASA)
NASA's space telescope Spitzer has detected dust disks around mature sun-like stars with planets. The dust is located on the periphery of the system and is presumably produced by collisions between objects, as happened in the Kuiper Belt beyond Neptune in our solar system.
The six star systems spatzer analyzed contain gas giant planets. Perhaps rocky, Earth-sized planets also exist in them, but current technology cannot find them.
The findings suggest that the theory of planet formation, including the solar system, holds promise — a star is born in a cloud of gas and dust. The remaining material rotates, forming a relatively flat disk that orbits the rotating star. Dust and chemicals accumulate and form rocks and some icy objects that collide. Some material forms comets, asteroids and planets. The Spitzer telescope also detected dust from other subsequent collisions.
Charles Bechmann of NASA's Jet Propulsion Laboratory and the principal investigator of the study said the new results "fit the theoretical picture we've built about how star and planetary systems form."
"Spitzer has established the first direct link between planets and dust disks," Bechman said. "Now, we can look at the relationship between the two."
(Illustration: The Hubble Space Telescope observes the ring of debris around the North Gate.) The inner edge of the disc may have been formed by the orbit of the North Gate b in the lower right corner. Source: NASA)
Another new observation from the Hubble Space Telescope reveals an important dust disk around a young star that is between 50 million and 250 million years old. And importantly, this star resembles our sun.
"The new Hubble image allows us to best observe the reflection of light from the dust disk around the star." David Adira, head of hubble research at Johns Hopkins University, said. "It basically shows some possible past of our own solar system."
Both results were announced in a conference call with reporters at NASA on Thursday afternoon.
Alycia Weinberger, an astronomer at the Carnegie Institution in Washington, argues that dust around stars is like bricks on a construction site. Previous observations found "bricks," she said, while others showed completed "houses," though the two were not found in the same location.
"The new observation ends the previous confusion. Because they show us planets and dust disks at the same time. Weinberg said.
Related knowledge
Planet (Latin: planeta) usually refers to celestial bodies that do not emit light themselves and orbit stars. Its direction of rotation is often the same as that of the orbiting star[1] (from west to east). In general, planets need to have a certain mass, and the mass of the planet should be large enough (relative to the Moon) and approximately spherical to be stellar in its own way to undergo nuclear fusion reactions. In May 2007, a MIT space science research team discovered the hottest known planet (2040 degrees Celsius). With the discovery of some sun-sized objects, the scientific definition of the term "planet" seems more urgent. Historically, planetary names derive from their position (as opposed to the position of the star) from the fact that they were not fixed in the sky, as if they were walking in the starry sky. The five planets in the solar system that are visible to the naked eye, Mercury, Venus, Mars, Jupiter and Saturn, have been discovered by humans since prehistory. After the 16th century, heliocentrism replaced geocentrism, and humanity learned that the earth itself was a planet. After the invention of the telescope and the discovery of gravity, humans discovered Uranus, Neptune, Pluto (excluded from the ranks of planets after 2006, reclassified as a Pluto-like object in 2008, a type of dwarf planet) and a number of asteroids. At the end of the 20th century, humans also discovered planets in star systems outside the solar system, and as of July 12, 2013, humans have discovered more than 2,000 planets in the extrasolar milky way.
BY: Robert Roy Britt
FY: Gigi Wei
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