TRAPPIST-1. Are We Alone? 

Credit: NASA 

#trappist1 #space #astrophysics

Recently NASA announced the prescence of 7 terrestrial planets around the TRAPPIST- 1 star. Most stars we see in the night sky have planets orbiting them. What makes this discovery particularly special? After all, planets are confirmed almost every day with many more thousands awaiting confirmation thanks to The Keplar Space Observatory. 

Briefly, planets are found orbiting stars by observing stars for a long period of time. If there is a dip in starlight observed, this is evidence of a planet passing in front of the star. 

Credit : NASA/Kepler Space Observatory.

So back to Trappist 1, it can be found in the constellation Aquarius and it isnt visible to the naked eye. In fact its barely visible through a telescope! So what is so special about the star itself? The answer is…..pretty much nothing. It is an ultra cool red dwarf star which is only slightly larger in size than Jupiter but 84 times more massive

TRAPPIST is only around 8% the mass of our own sun and 11% of the radius so it is quite a small star among the heavenly bodies. Interesingly, the spectroscopy testing failed to detect the presence of lithium. The star is fusing hydrogen the same as our sun. It is incredibly dim and has a surface temperature of 2550 Kelvin and is at least 500 million years old. To compare, our Sun is about 4.6 billion years old and has a temperature of 5778 K. So TRAPPIST-1 is a baby among the stars. 

Due to the fact TRAPPIST-1 has such a low luminosity, it uses much less power and has the ability to live for up to 12 trillion years. Our sun is a main sequence star half way through its life. Our sun is fusing Hydrogen to Helium at a much higher rate which will cause its expansion and subsequent supernova much more quickly. 

Should there be life on one of these planets, they will be living in the terrifying era of the universe called The Degenerate Era when no new stars are forming and existing stars are exploding, the beginning of the end of our universe.

The star is quite metal rich with a metallicity 109% of our solar amount. The majority of light emitted from the star is in the form of infared light. 

So lets answer the million dollar question. What are the chances of life on these planets? Firstly, the 7 planets are quite close together, they are all rocky planets with varying masses and a year on the innermost star would be around 36 hours! The outermost planet orbits in 19/20 days. A dizzying orbit, although the planets are very close to the star itself. 

Relative to us, the 7 planets would fit inside the orbit of Mercury. Planets E, F and G are considered to be within the “habitable zone” and could support liquid water on the surface. 

Credit : The Telegraph

Interestingly, the planets are all tidally locked. The same as our moon, we only see one side of it. There are two viable options for these planets; the first being that one side of the planets is forever in darkness whilst the other is eternal sunshine and second being the light reflected from the nearby planets could illuminate the dark sides. It is difficult to say at this point.

From the surface of any of the planets, you would see the other 6 in stunning detail. The James Webb Telescope is sure to examine them more to find their chemical composition in the hope of finding oxygen signatures, key to biological activity. 

Hold on! It isn’t all good news. There is a reasonable chance that the star being closeby has eroded the planet’s atmospheres via solar radiation and UV rays. Similiar to what happened to Mars. A lack of a magnetic field on a planet can leave it incredibly vulnerable to cosmic ray damage. Our magnetic field protects us from severe solar damage. The rotation of the Earth creates a magnetic field. Venus’ day is longer than its year as it rotates very slowly. Slower than it orbits the Sun.

These things will have to be studied further although I must say, this is an incredibly exciting discovery. 

Im sure radio signals have been sent there on their 39.5 year journey and unless they have found a way to communicate faster than light, we wont actually have communication in our lifetime. I maintained that Saturn’s moon Titan was the number 1 candidate for life. I have now moved my beloved Titan to number two.

Credit : NASA Artist Impression of the surface of TRAPPIST 1f.

Jude Morrow.

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