Exoplanet Stats

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Helio, apologies if I am missing something, but I cannot see distance from Earth. My interest is possibility of communication, which is partly based on the time factor (2c turnaround of messages) . . . . . . but also, of course, on durability of possible civilisations (= temporal coincidence).
That report was to show that the 10 exoplanets are not the best 10 choices I would use. Post #53 should be the better list, which shows distance for each.

I tried to enhance the Excel program to list those that meet the equilibrium test only, but Excel says the program is now too large to compile. Anyone know how to get past this hiccup? [I can run a separate program if I have to.]

iPad
 
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Catastrophe

"There never was a good war, or a bad peace."
Helio, I replied to that on #57. As it is on a previous "page", I will repeat:

I have not considered anything around 10 parsecs, which leaves only M type.

I have provisionally discounted low temperatures, as we are looking for solid, liquid and gaseous water simultaneously somewhere on the surface. I am not sure how the stated temperature would work with this condition.

That leaves only Ross 128b -7° (3.38 parsecs 11 LY) and Wolf 1061c +1°C. (4.29 parsecs 14 LY ).

Please correct me if I have misunderstood anything, but it seems to me very unlikely that any communication would be likely between Earth and either of these planets. 22 and 28 year turnaround communications seem very long to actually happen. That would assume simultaneity of relatively advanced civilisations.

Cat :)
 
I have provisionally discounted low temperatures, as we are looking for solid, liquid and gaseous water simultaneously somewhere on the surface. I am not sure how the stated temperature would work with this condition.
But this ignores the insulation effects of expected atmospheres. Th low temperature range is established for the three phases of water. These HZ temperature requirements are not surface temperatures, AFAIK.

Distance will always be a big issue, but the eye on the price is for life.
 
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Catastrophe

"There never was a good war, or a bad peace."
Helio, Quite apart from distance apart, measured in LY, people in general seem to totally ignore the time and duration in time of a potentially contactable alien civilisation. There might have been a dozen advanced civilisations on the Centauri system during the last 12 billion years, when we were atoms in the disc, molecules in primeval mud, or fighting with stone axe heads.

Cat :)
 
Update, but nothing really new.

Applying the eccentricity factor (more ecc --> more heat --> more distance from star), gains us one HZ exoplanet within the planetary radius limits (shown in header of 2nd image).



 
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Catastrophe

"There never was a good war, or a bad peace."
Helio,
May I, first of all, express our thanks for all the work you are putting into this subject. Your provision of information is much appreciated.

May I make a small suggestion, which relates to communication with any advanced inhabitants with exoplanets? We have already touched on this question. Taking a considered limit - of perhaps 25 LY (open to consideration) - would it be possible have a small section, updated to current status, of HZ exoplanets within that distance. This would, of course, include considerations of temperature and atmosphere.

The 25 LY suggestion is, of course, based on a communication exchange in 50 years. I note today that communication via X-rays or quantum considerations have been suggested as possible modes. We would first have to recognise communication when it is attempted.

I would guess that this would be a small list, which might be accessed via a top menu. If such an option is already available in readily accessible form, then I apologise for my lack of observation, and look forward to being enlightened.

Cat :) :) :)
 
Hi Cat,

Here is the current list. I included a few exoplanets that don't meet the normal HZ criteria but do meet the equilibrium temp. for the HZ. This latter method (blue highlighted cells) takes the Bond albedo into consideration, whereas the others don't. [This tells me we just don't have the best equations yet to determine HZs, else all three methods should be much closer to one another.]



These exoplanets, save one, have no known radii, though this will change with more research. [It's possible a NASA has this info that exoplanet.eu does not.]
 
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I tried to enhance the Excel program to list those that meet the equilibrium test only, but Excel says the program is now too large to compile. Anyone know how to get past this hiccup? [I can run a separate program if I have to.]
FWIW, the answer to this problem seems to be to write or move code into a subroutine located within a separate module. I should be able to cut and paste a large chunk of the program into a new subroutine and give it a new name. Then use the Call command to call it. Simple. It seems I can make the common variables work be declaring them public, or I can simply dimensionalize them in the new routine. I'll learn more as I go, but I'm no hurry quite yet.
 
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Catastrophe

"There never was a good war, or a bad peace."
Helio, thank you for that information. It seems to me, at first sight, that communication based on "c" suggests that contact is unlikely, unless longevity of our species is attainable - perhaps to hundreds of years. And this is subservient to the "time gap" issue. Such exo-civilisations might have/will develop(ed) within the "distance gap", but they could "miss us" by millions of years either way. From pre Solar System to Red Giant phase.

Please note that I am not pre-empting anything. I am just giving my initial reaction. I do not wish to introduce SF complications, but suggested quantum communication, could overturn the "distance gap" issue, but not the "time gap" issue.

Cat :)
 
Helio, thank you for that information. It seems to me, at first sight, that communication based on "c" suggests that contact is unlikely, unless longevity of our species is attainable - perhaps to hundreds of years. And this is subservient to the "time gap" issue. Such exo-civilisations might have/will develop(ed) within the "distance gap", but they could "miss us" by millions of years either way. From pre Solar System to Red Giant phase.

Please note that I am not pre-empting anything. I am just giving my initial reaction. I do not wish to introduce SF complications, but suggested quantum communication, could overturn the "distance gap" issue, but not the "time gap" issue.
Agreed.

We still might be able to learn a great deal about a distant civilization by zooming-in on their broadcast transmissions, just at they would do for us. [Hopefully they are < 100 lyrs away so the powerful Hitler broadcast has already passed them. ;)]

This would give us time to study whether or not they would pose a threat to us.
 
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Catastrophe

"There never was a good war, or a bad peace."
Helio,
"We still might be able to learn a great deal about a distant civilization by zooming-in on their broadcast transmissions, just at they would do for us."

I entirely agree. But, first we have to encrypt them. Then they may be so far away that they might be dead before they receive our reply.

I saw recently, the suggestion that messages might be sent in X-ray wavelengths, or even quantum coding. Are we even looking in these suggested areas?

Cat :)

Ref:

Aliens could send us interstellar quantum messages using X-rays ...
https://dailynewstoday.org › aliens-could-send-us-inters...


Quantum communication technology may allow for information to be securely sent through interstellar space without being disrupted by gravity or solar winds ...
 
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I saw recently, the suggestion that messages might be sent in X-ray wavelengths, or even quantum coding. Are we even looking in these suggested areas?

Ref:
Aliens could send us interstellar quantum messages using X-rays ...
https://dailynewstoday.org › aliens-could-send-us-inters...


Quantum communication technology may allow for information to be securely sent through interstellar space without being disrupted by gravity or solar winds ...
The link doesn't reference a full article, I think. I suspect that there is quantum messaging that is being developed that offers great security but does not involve FTL entanglement, so it still works at light speed, apparently.

The x-rays shorter wavelength increases the amount of data that this carrier can transmit.

If FTL entanglement could be made to work, perhaps likely exoplanets could be sent this stream of entangled photons far in advance to using them. So if we discover life on an exoplanet, say, 20 lyrs, away, that has received these entangled photons, we could instantly communicate some things with them to get established. They, in turn, could send us their entangled particles and we can all be entangled with one another. :)
 
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Catastrophe

"There never was a good war, or a bad peace."
Oooooooh! That sounds great. Helio, you are truly a fount of knowledge :)

Yes, New Scientist does limit non-subscriber access. I assume you got this bit?
If aliens wanted to send us messages from 30 light years away, their best bet may be to use X-rays and quantum technology.

On Earth, researchers have previously encoded information into the quantum states of particles of light, or photons. Using the photons’ special properties, they have transmitted that information securely. Research teams have sent the data to other labs around the world – as a proof of concept for a quantum internet – and to satellites orbiting Earth.
I understand what you are saying, but, on discovery, we would have to send, wait, and see if they decode it 20 years later. I suppose, putting the boot on the other foot, we might have been sent any number of potential communication items, without finding or understanding them. How would we actually go about looking for them? I don't know.

Cat :)
 
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Catastrophe

"There never was a good war, or a bad peace."
Here are some refs:

Viability of quantum communication across interstellar distances
https://arxiv.org › quant-ph


by A Berera · 2022 — Abstract: The possibility of achieving quantum communication using photons across interstellar distances is examined.

Aliens could send us interstellar quantum ... - Scooploop
https://www.scooploop.com › thread › aliens-could-sen...


Quantum communication technology may allow for information to be securely sent through interstellar space without being disrupted by gravity.

We could detect alien civilizations through their interstellar ...
https://phys.org › Astronomy & Space › Astronomy


29 Apr 2021 — Townes of the Institute of Defense Analyses (IDA) in Washington D.C. In their paper, "Interstellar and Interplanetary Communication by Optical ...
Cat :)

P.S. Sorry, second goes back to former link above, but the other two should work.
 
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I confess I understand very little about the quantum world. My understanding, however, is that there currently is no way to offer FTL communication, even over short distances. Any outside influence on an entangled pair causes them to be untangled faster than pulling out a single strand of wet spaghetti. :)

The nice paper you referenced introduces inducing problems with long distance transmission (to stars) that would create, perhaps, noise or deterioration effects, though I only read part of the abstract, admittedly.

Perhaps someone more knowledgeable can help us here with terms like decoherence, and entanglement, especially as applied to communication.
 
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Update: Total is now 5120 and climbing. :)

The exoplanet numbers continue to rise, slowly at the moment. [Will the JWST study a large group so that a large number will flow into the list, similar to Kepler?]


View: https://imgur.com/Bj5Xhsz


Here are 9 that are somewhat Earth-sized. Note that the outer boundary is bumped as a function of eccentricity. It moves the outer boundary proportional to eccentricity out to e=0.4 (13.8% increase in the outer HZ limit).

View: https://imgur.com/Bj5Xhsz
 
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I read where the JWST is supposed to study about 30 exoplanets. But, perhaps, we will get a trove of new exoplanets (confirmed) from all those candidates from TESS. The TESS web page, for instance, shows that only 230 exoplanets are confirmed out of 5740 candidates.
 
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Update. 5,146 exoplanets confirmed. No change in estimated HZ exoplanets or Earth-sized HZ exoplanets. Only about 199,999,995,000 more exoplanets to go for our galaxy, give or take 50 billion. ;)
 
Update... 9/8/22...

Another likely HZ exoplanet has been discovered (LP 890-9c, aka TOI-4306c).

2 of the three test methods put it about 1/4 of the way into the HZ, but one shows it is too hot.

Worse is that it orbits a, likely, M7 red dwarf with an orbital period of only 8-1/2 days, so tidally locked.

But the total count continues to improve. Total exoplanets now number 5162.

Congrats to all those hunters!
 
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There is yet another method for determining HZ exoplanets. It's found in a paper from 2013, but it was corrected in 2014. Here This is an elaborate atmospheric greenhouse method, but limits the exoplanet mass to a range, that I use, from about 0.25 Earths to 7.5 Earths.

I abbreviate the heading in the following list with "Kop". Notice that this method adds a few more exoplanets that don't fit the other method's calculations. This is due mainly to the limited masses used in the "Kop" method.

Notice also that we now have 10 exoplanets in the HZ and close to the size of Earth, ignoring the Kop additions.

View: https://imgur.com/SRXJ82a
 
Why are we considering planets with freezing temperatures as habitable?
Good question.

These temps. aren’t surface temperatures. They are equilibrium temperatures. The atmospheric effects are assumed to be additive to produce an inner HZ limit to be at the freezing point and an outer limit where liquid water becomes vapor.
More Here.

Until more data can be acquired for many exoplanets, there doesn’t seem to be any one master equation that nails the zone.

This is why I show what seems to be the better known methods to get a better picture of those more favorable, hopefully, of being in the HZ.

The equilibrium model is quite simple, so I’m inclined to think the “Kop” model may be a more serious attempt instead. Their 2013 paper was many pages dealing with dozens of atmospheric layers. It includes more than a dozen coefficients, though the 2013 values were corrected in 2014.

I don’t really know what is used by planetary scientists, but perhaps an amateur’s attempt can be helpful because it’s a broad approach.
 
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