Results 1 to 3 of 3

Thread: Planet with a thin atmosphere and radical water cycle

  1. #1
    Join Date
    Mar 2019
    Posts
    4

    Planet with a thin atmosphere and radical water cycle

    Ok so I have a question.
    let us say a planet exists that is 50 percent Earths radius and 13 percent Earths mass.
    This planet is around 3 billion years old and has a magnetic field.
    The planet is in the habitable zone of its G8V type star and receives around 0.95 percent the sunlight Earth does.
    The atmosphere is 0.15 bar.
    The rotation rate is 36 hours.
    The tilt is 25 degrees
    The eccentricity is 0.05
    Could the planet in this state have liquid water or would the planet essentially have a steam atmosphere in the summer and be ice in the winter?
    I am thinking it would be an interesting scenario to think about.


    I put in details because I think every detail helps

  2. #2
    Join Date
    Mar 2007
    Location
    Falls Church, VA (near Washington, DC)
    Posts
    8,653
    Quote Originally Posted by ktevolved365123 View Post
    Ok so I have a question.
    let us say a planet exists that is 50 percent Earths radius and 13 percent Earths mass.
    This planet is around 3 billion years old and has a magnetic field.
    The planet is in the habitable zone of its G8V type star and receives around 0.95 percent the sunlight Earth does.
    The atmosphere is 0.15 bar.
    The rotation rate is 36 hours.
    The tilt is 25 degrees
    The eccentricity is 0.05
    Could the planet in this state have liquid water or would the planet essentially have a steam atmosphere in the summer and be ice in the winter?
    I am thinking it would be an interesting scenario to think about.


    I put in details because I think every detail helps
    The water phase diagram a little under halfway down in this Wiki article is your friend.
    https://en.wikipedia.org/wiki/Triple_point
    At your hypothetical pressure of 0.15 bar, liquid water can exist between 0oC and about 50oC. You are describing something about the size of Mars with much higher atmospheric pressure. In such a thought exercise we can vary the atmospheric composition, and thus the amount of greenhouse effect, to set the temperature to this range. Planetary scientists have inferred that Mars once had such conditions, including surface water. Perhaps the magnetic field on your planet will protect it from atmospheric depletion from the solar wind.

  3. #3
    Join Date
    Feb 2009
    Posts
    2,206
    Quote Originally Posted by Hornblower View Post
    The water phase diagram a little under halfway down in this Wiki article is your friend.
    https://en.wikipedia.org/wiki/Triple_point
    At your hypothetical pressure of 0.15 bar, liquid water can exist between 0oC and about 50oC. You are describing something about the size of Mars with much higher atmospheric pressure. In such a thought exercise we can vary the atmospheric composition, and thus the amount of greenhouse effect, to set the temperature to this range. Planetary scientists have inferred that Mars once had such conditions, including surface water. Perhaps the magnetic field on your planet will protect it from atmospheric depletion from the solar wind.
    Or you are observing a young planet whose atmosphere has not yet been depleted - how long did rivers flow on Mars?
    Or the star, stated as G8, has less wind than G2 Sun.
    Or the planet is just slightly denser than Mars:
    Mars - 53 % Earth radius, 10,7 % Earth mass, 45 % Earth escape speed
    the planet - 50 % Earth radius, 13 % Earth mass, 51 % Earth escape speed
    and that makes the difference between rivers lasting 2 Gyr or 6 Gyr?

    What was young Mars like? The rivers were mapped, and found to be quite wide. But how much permanent gases was in Martian atmosphere when rivers flowed? How much ice?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •