HD 163296, a star about twice the mass of our sun and only an estimated 5 million years old has two newly formed planets. The planets have been observed at a distance of about 400 light years from Earth in the direction of the constellation Sagittarius.

By way of comparison, the earth is at least 4.5 billion years old (based on measurements of radioactive elements in an ancient Australian rock, and may be even older. Virtually all other stars found with planets (about 2100 planets around nearly 1300 stars so far) are about the same age as the Earth so finding planets in the act of being created is a remarkable find.

Planets still being formed

The question people always ask about newly discovered planets is whether they could support life.

That is, so far, impossible to answer about those planets found in the Goldilocks regions (not too hot, not too cold) but it is certain there is no life abound these two planets because they haven’t even completely formed yet, being in the gas and rock cloud which is thought to be the birthplace of every planet.

The pair of cosmic infants were found by researchers using data collected by The National Radio Astronomy Observatory, a facility of the National Science Foundation. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers say they found compelling datum showing the two Saturn-sized likely gas giants in the process of being formed in the dust and gas clouds which form the protoplanetary disk which is thought to surround nearly every young star during its early life.

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Since a serious search for extrasolar planets began in 1988 astrophysicists (the fancy name for astronomers) have been astounded to discover nearly every star which is close enough to be observed has one or more planets ranging from Earth-sized rocky planets to gas giants larger than Jupiter.

Young stars with planets

Observations of a few even younger stars including HK Tauri, which is about 1 million years old, show the protoplanetary disks and even gaps in the clouds which are thought to be the earliest indication of planetary bodies being formed by aggregating the dust and gasses into large masses. Those stars, as well as the newly discovered half-formed planets around HD 163296 have caused astronomers to rethink some of their assumptions about planetary formation because it was previously thought that stars only a million years old were far too young to begin forming planets.

Planets are almost certainly formed around young stars out of the dust and gas clouds left over from the giant cloud which condensed to form the star itself.

As larger masses in the orbiting cloud begin to attract more and more gas and other material due to their weak but growing gravitational attraction the planets, asteroids, and comets are formed with the planets creating large gaps in the cloud.

What is ALMA

Unlike optical observatories ALMA is a radio telescope which can “see” the glow of carbon monoxide gas in stellar clouds and those observations show three prominent gaps in the protoplanetary disk at a distance of 60 AUs, 100 AU, and 160 AU. An AU or astronomical unit is 93 million miles - the distance from Earth to the sun, placing these new planets far beyond what would be the orbit of Pluto if they were in our solar system. The confirmation of planetary formation in the disk has been projected based on ALMA’s ability to measure both the gas and dust concentrations to approximately the same resolution. Earlier studies showed gaps in the gas clouds around young stars but that might have been due to some other process. Having both the CO gas and dust being swept up in the same region is a strong indication that this really is an early picture of two large planets in the process of formation.