The habitable zone of a planet(s)

This is my unprofessional view. I do stand by it with my best knowledge of this field in planetary science. My knowledge might be outdated or wrong, resulting in me getting the wrong conclusions in this article. You have been warned.

The problem with the habitable zone of a planet

I dislike it when I see the news that a planet has been found around a star. Only to see later in that same news that the planet is a dwarf star giving out minimal amount of light and heat. There seems to be minimal requirement for live to exist in the universe. I don’t know if this has been studied in any details or if there have been any study into this matter in recent years. There is a lower limit on were life can exist and there is a upper limit on this same scale.

The lower limit and the upper limit

In my personal view this star classes can support life. There are limits within those classification.

Lower limit

Class M (?)
Class K
Class G
Class F
Class A
Class M (red giants, supergiants)

Lower limit

The lower limit of stars might support life if the conditions allow for it. This might not happen in majority of any star system that falls into the lower limit. If life exists around such planet in a star system that falls into the lower limit that life might only be plants that can deal with cold temperatures and long winters. Animal life on such planet should be expected to be limited to not existing at all. This goes both for ocean and land animal life.

Upper limit

All of this classes might have their own limit and not all star systems that have planets support life due to random reasons. No dwarf stars (class L, Y, T, M). Any star that is at the end of its life span might have had life in the past, it however should be expected to be extinct at this point in the star life cycle. The upper class of stars is more complicated as they radiate more energy out and have a shorter life span than smaller stars. A life can evolve around such star but in the time needed for it to evolve to a civilization levels are limited because of the time needed until that happen.

There’s no guarantee for life in a star system

While a star might be favourable to life that alone is not a guarantee in any way that a star system is going to have any life. A lot of things can go wrong in a planet formation that results in no life or atmosphere that can support life. I don’t know what starts life in a star system but it is a sequence of events that has to happen each time life gets going on a planet in any star system that has life.

The complex life problem

While life might exist in a star system it does not have to be animal life. There might be planets out there with nothing but plants and insects on them and no animals. What path evolution takes on each planet is based on random factors that are impossible to predict.

The Venus problem

Venus is a dead planet in more than just one way. When it formed something did go horribly wrong during its formation or soon after it formed. This seems to have happened early on and there is a good chance that life never took hold on Venus and it never had any water to start the carbon cycle. According to this article and based on measurements Venus magnetic field flares up for a short period of time, this suggests that whatever happened to Venus is related to the planet core and issues that it is having. In our solar system Venus should be full of jungle life today and possibly hosting a civilisation on its own. Something like humans or perhaps not. Whatever happened resulted in Venus resulted in Venus being a dead planet and he has remained like this for billions of years.

The Mars problem

Mars never had any life. Its too small as a planet to support life and due to a large eruption in its past its core died and along with it everything that might have been on its surface. There is a chance that before the core of Mars core died due to the eruption of Olympus Mons and other volcano activity. Other reasons for Mars core dying are also possible, among them greater heat loss due to Mars being a smaller planet. Being a greater distance from the Sun in our solar system Mars never had any chance of supporting life. In other solar systems where the planetary evolution is different and Mars sized planet might be closer to its star there is a small chance a life might exists for as long the planet is able to maintain its magnetic sphere.

The planet problem

There are many factors that have to add up for a life to happen in a solar system. Sometimes those factors exist in a solar system and sometimes they are missing in the formation process. How and why are not known to anyone and it is the biggest question that humans have unanswered. An answer might appear in the centuries ahead if humans survive current global warming crises.

KIC 8462852 (Tabby’s Star / Boyajian’s Star)

The star called Tabby’s Star / Boyajian’s Star but has the science name of KIC 8462852 dimmed few days ago, it’s increasing its brightness again as I write down this words. While it is not known what is creating this dimming. It is my view that following ideas are not possible, because they are just in the realm of fiction and are going to stay there.

Impossible

  • Dyson sphere is the idea that a space able civilisation is able to build a sphere of some type around its host star to shield it and the planets inside it. This idea has several flaws, one of the biggest is gravity, as such sphere would inflict a gravity equal to its size (squared). Then there is question about planet orbits, some planets have orbit that would cross such sphere path and other things. Then there are things like comets, space weather and wind.

What might be possible

  • Some type of alien┬ácivilisation has built other types of mega structures around the star. This seems unlikely as such structure would require massive resources. This seems unlikely, as such activity might be detectable by RF signal activity. No RF signal activity has been detected by SETI so far, making this a unlikely option.
  • Draining the star of its energy (hydrogen). It might be possible that some alien civilisation is draining the hydrogen from the star for energy use propose. Such activity would not leave a lot or any RF signal activity. But I find it quite difficult to imagine the scale of such activity to drop the star light by 20%.*

* I think this is mostly my idea that I was discussing on Ars Technica forum. It didn’t go well into the people there that didn’t understand the concept of what I was talking about. If this is the case, a helium flare might appear soon as the hydrogen is drained from the star (it might not happen due to this type of star). To my knowledge that has not yet happened. Making this idea improbable, but not impossible at the moment. Time is soon going to tell if this is the case, as older data suggests that current behaviour has been going for at least 100 years, possibly longer.

Like the rest of the science community I don’t have any idea about what is going on at KIC 8462852. Only research and observation is going to make that clear. Based on earlier pattern, a short dip that happened few days ago is soon followed by a longer dip in brightness. I’ll try to monitor the news reports once that happens to see if I can get any new data about what is going on at this star.

The light year distance to KIC 8462852 is around 1300 years, so current sequence of events took place around the year 717 on Earth.