The Concept of a Habitable Zone on Exoplanets

The Concept of a Habitable Zone on Exoplanets Q & A

by Ju Boo Lim - Friday, 25 October 2019, 9:37 AM

Number of replies: 15

Calculations on the Goldilocks Zone where Earth-like environment around a star may be possible:

Given the relative sizes of the Habitable Zones around stars which are relatively 0.25, 0.5, 5 and 10 times the luminosity of the Sun

Applying the equations for the given luminosity of the Sun

The Habitable Radius around a star:

0.25 x the luminosity of the Sun, it would 0.47 AU (inner radius), and 0.68 AU (outer radius)

0.5 x the luminosity of the Sun, it would 0.67 AU (inner radius), and 0.97 AU (outer radius)

5.0 x the luminosity of the Sun, it would be 2.13 AU (inner radius) and 0.3.0 AU (outer radius)

10 x the luminosity of the Sun, it would be 3.0 AU (inner radius) and 4.34 AU (outer radius)

AU = Astronomical Unit is Earth-Sun distance

 = 1.495 978 707×1011 metres, or about 150 million kilometres (93 million miles).

However in my personal thinking this may just be a theoretical mathematical-physical  concept, because for life to be possible in another planet it is not just the physical Earth-like environment like heat, light and water that are just right, but I think we also need to consider the presence of complex organic compounds in their correct constituents and configurations to start jump life.

Not just the presence of carbon, nitrogen, hydrogen and oxygen to form amino-acids and other organic compounds as in Miller and Harold Urey experiment, but much more complex than that, which is the ability for organic molecules to form DNA which is still not life, but merely the chemical foot-prints of life.

What I strongly believe than just the synthesis of nucleic acids and DNA, is the presence of “the spark of life” (whatever that is residing inside a living body) to “ignite” these chemical substances into life itself in order for any exoplanet or even planets in our own Solar System (other than our own Earth) to give rise to life itself, and continue to support it as on Earth.

Although I don’t mean to show disrespect to these mathematical formulae given by astronomers, I am only expressing the freedom of my own (scientific) thinking that the Goldilocks Zone is only a zone that may mimic Earth-like physical environments on an (exo)planet  if it is not too near or too far away from a parent star.

I hope I will not be penalized for my independent thinking

Thank you.

Lim ju boo

In reply to Ju Boo Lim

Re: The Concept of a Habitable Zone on Exoplanets Q & A

From Dr. Grant Miller University of Oxford  - Friday, 25 October 2019, 6:36 PM

Hi Lim,

Good post! You raise some important points. Of course just finding a planet in the "habitable zone" does not mean it will actually be inhabited. This depends on many other factors, but it's a good first step on the search. The one thing that underpins all life on Earth is the need for liquid water, so first we look for places where liquid water can exist, and everything else comes after that.

Now you may say that there's a possibility that life exists in some other way in the Universe without the presence of liquid water, but that is such a big unknown that it makes a lot more sense to start the search with what we do know and expand from there.

I hope that makes sense!

Cheers,

Grant