First image of newborn planet 'PDS 70b' captured by Very Large Telescope
New Delhi : Astronomers have spotted the very first image of a newborn planet orbiting a star just 370 light-years from Earth. They have captured the image using the European Southern Observatory’s Very Large Telescope (VLT) in Chile. Termed as PDS 70b, the huge planet is the first-ever to be seen orbiting within a disc of planet, forming material. The new discovery will possibly help scientists to know more about solar system and planets form around stars.
PDS 70b is a gas giant with a mass which is believed to be several times that of Jupiter. It orbits a very young star called PDS 70, which is about 10 million years old and is encircled by a dense protoplanetary disc of dust and gas. The snap captured highlights void near its centre, which has probably been vacant by the young planet. Astronomers have known about such voids for decades and have long guessed that they are associated with young planets.
“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,” explains Miriam Keppler of Germany’s Max Planck Institute of Astronomy in Heidelberg, who led the team that discovered PDS 70b. She adds, “The problem is that until now, most of these planet candidates could just have been features in the disc”.
The discovery of PDS 70b planet inspired a follow-up study that was led by Keppler’s Heidelberg-based colleague André Müller and looked more closely at PDS 70b and how it interacts with the planetary disc. This revealed that the planet is orbiting in the middle of the void at a distance of about 22 au from the star, which in the solar system would put it just beyond Uranus.
Astronomers say that the surface temperature of PDS 70b is about 1000 °C and the radius of the planet is 1.4-3.7 times that of Jupiter. According to Müller and colleagues, the upper limit is fairly greater than expected for the age of the planet, which they estimate to be 5.4 million years. Spectroscopic studies of light from the planet indicate that it has a cloudy atmosphere.
Scientists have used SPHERE, a planet-hunting instrument on the VLT that was used by two astronomical survey programmes to study PDS 70. One project is named as SHINE which aims to take near infrared images of 600 nearby young stars in a search for new planets. The other is called DISK, which looks at young planetary systems and protoplanetary discs.
‘SPHERE’ detects the pale light from planets by first blocking the much brighter light from the parent star using a coronagraph. Then a series of images is taken of the system over time. It is obvious that the position of the planet changes slightly as it moves in its orbit, while the star appears motionless. By looking at how the image changes with time, astronomers can pull out the light from the planet and decline light from the star.
