Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: alfa015 on 09/02/2019 01:18:48

Title: Do you think Tau Ceti e is inhabited?
Post by: alfa015 on 09/02/2019 01:18:48
Hi!

Guys do you think Tau Ceti e is inhabited?

It was recently confirmed (https://twitter.com/i/web/status/1084742558041993216) and it is considered a potentially habitable exoplanet (http://phl.upr.edu/projects/habitable-exoplanets-catalog)

I made a video about it, just in case someone is interested:
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: yor_on on 09/02/2019 08:44:58
Sounds good to me :) Did you say we could reach it in twenty years?
How?
==
And no, not by any species able to communicate the same way we do over the EM spectrum. Because that should be noticeable, shouldn't it?  Inhabited by living organisms and flora, why not? Life seems pretty persistent to me.
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: Janus on 09/02/2019 16:55:29
From what data I can find, it seems more likely to be a Venus type world than an Earth like one.  Its minimum estimated mass is ~4 times that of the Earth.  It orbits fairly close to Tau Ceti. Enough so, that with an Earth like atmosphere, its average temp is over 150 F.   Even if it was the same density as the Earth, it would have ~ 1.5 times the surface gravity and ~2.5 times the escape velocity (and being more massive, if of comparable to Earth make up, it would likely be denser, which would drive down the radius and drive up the surface gravity and escape velocity.)   

It's greater gravity makes it easier for it to hold on to its atmosphere, which increases the chances of it having a thicker one than the Earth. A thicker atmosphere can lead to higher surface temps, driving it into a greenhouse runaway.

I wouldn't get my hopes up.
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: yor_on on 10/02/2019 11:44:22
Ouch, but if you look at https://iopscience.iop.org/article/10.3847/2041-8213/aa5f13/meta Janus?

And I still hope for a answer to how we're supposed to get there :)
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: Janus on 10/02/2019 15:47:37
Ouch, but if you look at https://iopscience.iop.org/article/10.3847/2041-8213/aa5f13/meta Janus?

And I still hope for a answer to how we're supposed to get there :)
Tau Ceti e has an eccentricity of 0.18 ( a bit less than Mercury's).  The 90% value alluded to in the abstract isn't reached until the eccentricity approaches 1 (Just short of a parabolic trajectory).  Looking at the graph provided in the paper, you can just barely make out the difference at 0.18 eccentricity.   Call it 99%. 99% of 150 is  148.5. ( and I rounded down to the nearest 10 with the 150 value)   
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: chiralSPO on 10/02/2019 17:32:01
Call it 99%. 99% of 150 is  148.5.

Sorry to be the pedant, but are you scaling a temperature? In F?!?

150 F

At the very least, please use an absolute temperature scale (Kelvin or Rankine) before multiplying temperatures by any factor, otherwise we end up with such silly results, like: "50% hotter than 32 F (0 C) is 48 F (8.9 C), but 50% hotter than 0 C is, still 0 C?" or even worse: "50 % hotter than 20 F (6 C) is 30 F (1.1 C)..."

Even with absolute temperatures, scaling is somewhat nonsensical, but at least the maths work out.
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: Janus on 10/02/2019 18:58:47
Call it 99%. 99% of 150 is  148.5.

Sorry to be the pedant, but are you scaling a temperature? In F?!?

150 F

At the very least, please use an absolute temperature scale (Kelvin or Rankine) before multiplying temperatures by any factor, otherwise we end up with such silly results, like: "50% hotter than 32 F (0 C) is 48 F (8.9 C), but 50% hotter than 0 C is, still 0 C?" or even worse: "50 % hotter than 20 F (6 C) is 30 F (1.1 C)..."

Even with absolute temperatures, scaling is somewhat nonsensical, but at least the maths work out.

Yeah your right.  Silly mistake on my part.
(https://fstatic1.mtb-news.de/img/photos/1/3/1/0/6/8/_/medium/Yet_another_Picard_facepalm.jpg?0)

  Using the same numbers gives ~ 144 F.  For difference of 6F.  But then again, I was being generous with the 99% estimate.   At the highest resolution of the graph in the paper, you might get 99% of circular orbit equilibrium temp at an eccentricity of 0.4, better than twice the eccentricity of Tau Ceti e, and its on a curve that flattens out as you approach 0 eccentricity. 

So despite my embarrassing lapse, I still don't think that this is enough to significantly increase the chances of Tau Ceti e being habitable
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: Ophiolite on 11/02/2019 18:01:12
Yeah your right.  Silly mistake on my part.
Janus, having benefited from your concise, informed posts on this and number of other forums for several years it was a relief (and a delight :)) to discover that you are, nevertheless, human!
Title: Re: Do you think Tau Ceti e is inhabited?
Post by: chiralSPO on 11/02/2019 19:47:10
Yeah your right.  Silly mistake on my part.

Yes, we all make mistakes--those of us who can admit to them lose nothing, and those who learn from them come out on top.

I don't think the error changes the conclusions of your analysis much, I just couldn't resist making the correction (you managed to find one of my pet peeves  :P )