The birth of a planet has been caught on camera for the first time, by an international team of astronomers led by a group at the Max Planck Institute for Astronomy in Heidelberg, Germany. The picture was published in Astronomy & Astrophysics on Monday.
The baby exoplanet, named PDS 70b after its star, PDS 70, is the bright spot to the right of the black center in the picture shown above.
PDS 70 is forming about three billion kilometers from the central star, about the same as the distance between Uranus and the Sun, the astronomers say.
That black center is an artifact masking the star's corona. That is necessary for observation, because stars shine shines so brightly that dimmer sources of light – such as starlight reflected from the surface of planets – cannot otherwise be observed. "Without this mask, the faint light from the planet would be utterly overwhelmed by the intense brightness of PDS 70," the scientists spell out.
The photograph also shows empty space next to the protoplanetary disc, "sculpted" out of the cloud by the forming planet as it absorbs matter.
Actually the proto-planet seems to be part of a whole solar system forming around PDS 70, which is itself a young dwarf star. This system taking shape is thought to be about 50 million years old, an infant in cosmological terms.
Not quite like Terra
Though "Earth-like" planets are all the rage, this one is anything but. It seems to be a gas giant, like Jupiter and Uranis, which is as opposed to a rocky planet. That doesn't mean however that gas giants don’t have solid cores: they may do, made of the heavier elements.
In this case, the dimensions and characteristics of PDS 70b dwarf anything in our vicinity.
The baby planet has a mass several times that of Jupiter, which is the biggest planet orbiting our Sun. Jupiter is estimated to have mass 300 times that of Earth.
PDS 70b's surface temperature is around 1000°C, the scientists estimate. That is twice as hot as the maximal estimated surface temperature on Mercury (around 430°C) and Venus (around 467°C).
Again for the sake of comparison, while this newly forming planet is estimated to be 3 billion kilometers from its star - Mercury is 58 million kilometers from the Sun.
The extraordinary snapshot was achieved using a device called SPHERE which was installed on a device usefully called the Very Large Telescope, which the scientists say is one of the most powerful planet-hunting instruments in existence. They needed one, since the light from any star is too bright to see dimmer emanations anywhere in the vicinity.
Solar systems are believed to form when, due to some impetus or other – such as a nearby supernova - a cloud of gas and dust in space begins to contract and spin on its own axis. As the cloud collapses, it spins faster; the central mass becomes denser and denser and hotter too, forming the star. Material not swallowed up into the star itself forms a flat disk around the star, from which planets accrete over time, explains Prof. Tsvi Piran of Hebrew University.
"These discs around young stars are the birthplaces of planets, but so far only a handful of observations have detected hints of baby planets in them," says coauthor Miriam Keppler, who led the team behind the discovery of the still-forming planet. "The problem is that until now, most of these planet candidates could just have been features in the disc."
This glimpse at the dust-shrouded planetary birth was enabled by SPHERE, which studies exoplanets and discs around nearby stars using high-contrast imaging. After the starlight is blocked (using a coronagraph), SPHERE employs data processing to weed out the signal of the faint planetary companions.