New images of
beta Pictoris planet
DR EMILY BALDWIN
Posted: 04 March 2011
New observations of beta Pictoris’ giant planet confirm its movement around the star, as well as establishing the planet’s mass and temperature.
Beta Pictoris b imaged in 2003 (left image), October 2009 (middle) and in March 2010. The planet’s motion is clearly seen between 2003 and 2009. Published in Astronomy & Astrophysics, 2011, vol. 528, L15.
Located 63.4 light years from our Sun, beta Pictoris is a 12 million year old star, and the first star to have its dust disc directly imaged. Its planet, beta Pictoris b, orbits within the disc between 8 and 15 astronomical units from the star.
Using the NaCo instrument on the Very Large Telescope (VLT), astronomers have now observed the system at a wavelength of 2.8 micrometres; previous measurements were made at four micrometres. The observations again confirm the planet’s orbit around the star, and enabled the astronomers to determine the planet’s mass at 7-11 times the mass of Jupiter. They also estimate an effective temperature of 1,100 to 1,700 degrees Celsius (the effective temperature of a planet is the surface temperature it would have if it absorbed all the radiation coming from its star and re-emitted it all back into space).
The observation that beta Pic b is still warm implies that it has retained most of the heat it acquired during its formation. The next step for observations of beta Pic b will be to determine atmospheric properties of the planet, as well as further details on the interaction of the planet with the disc material, to learn more about the formation of planets in other solar systems.