There has been so much excitement since the discovery of a system where seven Earth-sized rocky planets orbit a cool star known as TRAPPIST-1. Those that are in the habitable zone are three planets, the region of space where liquid water can flow on the surface of the planets. Two new studies, however, by scientists in the University of Arizona's Lunar and Planetary Laboratory may lead astronomers to redefine the habitable zone for TRAPPIST-1.
It is possible that the three planets in the habitable zone are facing a formidable opponent to live which is the high-energy particles spewed from the star. For the first time, Federico Fraschetti and a group of scientists from the Center for Astrophysics I Harvard and Smithsonian have calculated how hard these particles are hitting the planets. They published their study - Tides between TRAPPIST-1 planets - in the Astrophysical Journal.
In the meantime, a graduate student in the Lunar and Planetary Laboratory, Hamish Hay, has discovered that the gravitational tug-of-war the TRAPPIST-1 planets are playing with one another is raising tides on their surfaces, possibly driving volcanic activity or warming ice-insulated oceans on planets that are otherwise too cold to support life.
TRAPPIST-1A, the system's star, is a less massive, smaller and 6,000 degrees Fahrenheit more cooling than the sun with 10,000-degree. It is also extremely active, meaning that it emits vast amounts of high-energy protons - the same particles that cause auroras on Earth.
The researchers simulated the journey of these high-energy particles through the magnetic field of the star. What Fraschetti and his team discovered was the fourth planet, the innermost of the worlds inside the TRAPPIST-1 habitable zone may be experiencing a powerful bombardment of protons.
Fraschetti explained that the flux of these particles in the TRAPPIST-1 system could be up to 1 million times more than the particles flux on Earth.
This new development surprised the scientists, even when the planets are much closer to their star than Earth is to the sun. High-energy is carried through space along magnetic fields, and the magnetic field of TRAPPIST-1A is tightly wound around the star.
Explaining further, Fraschetti said that the expectation is that the particles would get trapped in these tightly wrapped magnetic field lines, but there is tendency they can escape with the application of turbulence and move perpendicularly to the average stellar-field.
The magnetic field will be turbulent through the flare on the surface of the star, and it will allow the protons to sail away from the star. Where the particles head depends on how the magnetic field of the star is angled away from its axis of rotation. In the TRAPPIST-1 system, the most likely alignment of this field will bring energetic protons directly to the fourth planet's face where they could break apart complex molecules that are needed to build a life, or perhaps they could serve as catalysts for the creation of these molecules.
