Pink alien planet is smallest yet to be photographed with an orbit around a sun



Nasa believes the planet, GJ 504b is a magenta colour, based on infrared data from the Subaru Telescope in Hawaii

The pink planet orbits its star at nearly nine times the distance Jupiter orbits the sun to challenge theoretical ideas of how giant planets form

GJ 504b is about four times the mass of Jupiter and its star can be seen without a telescope in the constellation Virgo

Astronomers at Nasa have discovered a pink alien planet orbiting a star like our sun 57 light-years away that they said is the smallest by mass photographed so far.

Scientists believe the planet, GJ 504b, is thought to be a magenta colour, based on infrared data from the Subaru Telescope in Hawaii.

While GJ 504b is the the lowest-mass planet ever detected around a star using direct imaging techniques, but it is still several times the mass of Jupiter and similar in size.



The planet, GJ 504b (pictured) is the smallest exoplanet by mass orbiting a star like our sun, some 57 light-years away. It is thought to be a magenta colour, based on infrared data from the Subaru Telescope in Hawaii

Michael McElwain, a member of the discovery team at NASA's Goddard Space Flight Centre in Greenbelt, Maryland, said: 'If we could travel to this giant planet, we would see a world still glowing from the heat of its formation with a color reminiscent of a dark cherry blossom, a dull magenta.'

'Our near-infrared camera reveals that its color is much more blue than other imaged planets, which may indicate that its atmosphere has fewer clouds.'

GJ 504b orbits its star at nearly nine times the distance Jupiter orbits the sun, which poses a challenge to theoretical ideas of how giant planets form.



According to the most widely accepted theory, called the core-accretion model, Jupiter-like planets begin their life in the gas-rich debris disk that surrounds a young star, Francis Reddy of Nasa explained.



This composite combines Subaru images of GJ 504 using two near-infrared wavelengths (orange, 1.6 micrometers, taken in May 2011 and blue, 1.2 micrometers, April 2012). Once processed to remove scattered starlight, the images reveal the orbiting planet, GJ 504b

A core produced by collisions among asteroids and comets provides a 'seed' and when this core reaches sufficient mass, its gravitational pull rapidly attracts gas from the disk to form the planet.



While this theory holds true for planets in our solar system out to where Neptune orbits, it is more problematic for worlds located farther from their stars.



Pink planet GJ 504b lies at a projected distance of 43.5 astronomical units from its star - which is around one-and-a-half times the distance Neptune is from our sun.

Markus Janson, a Hubble postdoctoral fellow at Princeton University in New Jersey said: 'This is among the hardest planets to explain in a traditional planet-formation framework.'



'Its discovery implies that we need to seriously consider alternative formation theories, or perhaps to reassess some of the basic assumptions in the core-accretion theory.'



The astronomers said GJ 504b is about four times the mass of Jupiter and has a temperature of around 237 Celsius. Its star, GJ 504 also known as 59 Virginis (circled) is slightly hotter than the sun and can be seen in the constellation Virgo in this chart and can be seen without using a telescope, according to Nasa

The research is part of the Strategic Explorations of Exoplanets and Disks with Subaru (SEEDS), a project to directly image extrasolar planets and protoplanetary disks around several hundred nearby stars using the Subaru Telescope on Mauna Kea, Hawaii.



The five-year project began in 2009 and is led by the National Astronomical Observatory of Japan (NAOJ).



While direct imaging is arguably the most important technique for observing planets around other stars, it is also the most challenging.



Masayuki Kuzuhara at the Tokyo Institute of Technology, who led the discovery team, said: 'Imaging provides information about the planet’s luminosity, temperature, atmosphere and orbit, but because planets are so faint and so close to their host stars, it's like trying to take a picture of a firefly near a searchlight.'

The astronomers said GJ 504b is about four times the mass of Jupiter and has a temperature of around 237 Celsius.

Its star is slightly hotter than the sun, which can be seen in the constellation Virgo.