The Hill Star Map and Exoplanets

antonioparis
reply to post by tanka418

 

Interesting post. Setting aside whether the Hill story is a hoax or not, you have factor in if a "grey" could function properly on Earth. Any habitable extrasolar planet would need to have the same and/near gravitational influence as on earth. This is called gravitational biology. Our specific gravity on earth had a direct result in human evolutionary processes. The cells in our bodies, for example, are adapted to 9.78 m/s². This is why we cannot function outside of earth without a spacesuit.

Therefore, any extraterrestrial visiting earth would have to have come from a planet with a similar gravity, in this case 9.78 m/s². If not, they would not be able to function properly on earth. Thus far, astronomers have not found any extrasolar planets orbiting Z1 or Z2 ... let alone an extrasolar planet with a gravity close to 9.78 m/s². This goes for reptilians, Nordics, etc. too.

Great topic guys.

Good points...

Have you ever driven a "muscle car"? When I was young I has a 1966 Chevy with a 427 in it; the damn thing would do wheel stands in there gears. Was quite a surprise wen I first experienced that.

Now, Imagine that car, capable of acceleration far in excess of Earths gravity. Just how do you suppose I could have driven that car at it's max acceleration. I mean it must have been nearly 1.5 - 1.75 G's

How do you suppose the astronauts get by when being boosted into space at nearly 5 g?

Yes entering a gravity well different than what One evolved in can be challenging, but, it is far from impossible.

If either of us were to attempt to work in space we would learn what every inhabitant of the Space Station learns very quickly; how to perform in zero G. If we were to go to a planet where the gravity is more than Earth's; we would learn to handle it. After all; we are intelligent sentient creatures, we are capable of adapting.

antonioparis
reply to post by tanka418

 

Interesting post. Setting aside whether the Hill story is a hoax or not, you have factor in if a "grey" could function properly on Earth. Any habitable extrasolar planet would need to have the same and/near gravitational influence as on earth. This is called gravitational biology. Our specific gravity on earth had a direct result in human evolutionary processes. The cells in our bodies, for example, are adapted to 9.78 m/s². This is why we cannot function outside of earth without a spacesuit.

Therefore, any extraterrestrial visiting earth would have to have come from a planet with a similar gravity, in this case 9.78 m/s². If not, they would not be able to function properly on earth.

That's incorrect.

The reason space suits are needed have nothing to do with gravity but rather things like temperature, atmospheric pressure, and of course breathable air. The same is true in reverse: ie: A terraformed Mars would still have less gravity than the Earth.

There is no reason why a species from a similar planet in terms of temperature and atmospheric makeup but with a higher gravitational field (ie: a habitable zone Super Earth) could not function on our planet.

Having evolved in a higher gravity they would find it easier to move around as we do on the moon or will on Mars. They might be able to for instance take larger leaps or scale walls fairly easier as their bodys muscles would have evolved in an environment where they'd have to be more efficient in turning chemical energy (ie: food) into kinetic energy (ie: motion).

When we went to the moon we took huge leaps because of 1/6th the Earth Gravity. If the moon somehow had a breathable atmosphere and atmospheric pressure with no temperature extremes, we would have been able to do the same without a space suit.

Where it would get trickier is if a species like us tried to operate in a 2-G environment. We'd find it tougher to move around in their world because our muscles evolved in a 1-G world so it would be like running on a treadmill or walking around while lifting weights, but we'd manage.

Again: Space suits have nothing to do with gravity. They don't make gravity, nor do they shield us from it. They are environmental suits that provide air, maintain a livable temperature and atmospheric pressure.

Thus far, astronomers have not found any extrasolar planets orbiting Z1 or Z2 ...

It's more like "thus far, astronomers have ruled out any large gas giants on short period orbits around Zeta Reticuli", which actually is a good thing. If Jupiter orbited one of the stars of Zeta Reticuli in an orbit smilar to Jupiter does in our solar system we would not have found it yet.

If Zeta Reticuli has a whole bunch of terrestrial, P and M class planets in their habitable zones (HZ) we wouldn't have found those either yet as the instruments we've been using are not sensitive enough to find them yet. That is why it is key that TESS and other instruments get built and launched.

let alone an extrasolar planet with a gravity close to 9.78 m/s².

Also incorrect. Kepler 78 (just announced on Saturday) would have identical gravity as the Earth. Several of the planets announced yesterday would as well. And there are plenty of non-Kepler world which have gravity identical to the Earth or close to it.

And like I said, it would be easy for a species from a higher gravity world to operate on our Earth just as it will be easier for us to move around on a terraformed Mars or a smaller, yet temperate and breathable exoplanet.

9.78 meters a second is not some magic barrier to operating on another planet with different gravity (within reason - its hard to see how we could operate somewhere with 5 Gs or above luckily, the only planets that are like that are Gaseous worlds full of volatiles (think Neptune) we'd not be interested in trying to land on anyway)

Great topic guys.

Thanks.

It seems that Zeta 1 and Zeta 2 Reticuli may not be low in metallicity after all. This could increase the chances of terrestrial planets in this system, as well as providing ample resources for a technical civilization.
The site linked below gives a summary of the relevant paper by Da Silva and Foy, plus a link to the paper itself.

This paper also mentions an observed abundance of helium in the stars, twice that found in the Sun. It is remarked that this would slow their process of stellar evolution across the main sequence.
This abundance could be a natural occurrence or possibly the result of technological mixing of the stellar material in order to prolong the life of the star. If hydrogen is sent back into the core of the star with this aim in mind, it would presumably render helium more abundant, in proportion, in the outer layers. www.bibliotecapleyades.net/andromeda/esp_andromedacom_7d.htm

Ross 54
It seems that Zeta 1 and Zeta 2 Reticuli may not be low in metallicity after all. This could increase the chances of terrestrial planets in this system, as well as providing ample resources for a technical civilization.
The site linked below gives a summary of the relevant paper by Da Silva and Foy, plus a link to the paper itself.

This paper also mentions an observed abundance of helium in the stars, twice that found in the Sun. It is remarked that this would slow their process of stellar evolution across the main sequence.
This abundance could be a natural occurrence or possibly the result of technological mixing of the stellar material in order to prolong the life of the star. If hydrogen is sent back into the core of the star with this aim in mind, it would presumably render helium more abundant, in proportion, in the outer layers. www.bibliotecapleyades.net/andromeda/esp_andromedacom_7d.htm

edit on 6-11-2013 by Ross 54 because: improved paragraph structure

edit on 6-11-2013 by Ross 54 because: improved paragraph structure

Great find Ross!

One of the things I have been keeping an eye on is the correlation between stellar metallicity and the likelihood of terrestrial planets and its implications.

As far as the helium abundance of Zeta Reticuli is concerned, it's said to be twice that of the Sun. I read that the Sun is about 26 % helium by mass, and that figures within a couple of percent of this are typical for stars in general. I'm probably misunderstanding something here, but does that mean that Zeta Reticuli is 52% helium? If so, this would appear to make it a very unusual star in yet another way.

I put together a video on this, such as it is.

I show all the stars and the improbable distribution of stellar class.
What is most interesting is that 'IF" One were to be given a map by ET; it would look just like this.



This "map" and experience have been greatly undervalued for a very long time.

tanka418
I put together a video on this, such as it is.

I show all the stars and the improbable distribution of stellar class.
What is most interesting is that 'IF" One were to be given a map by ET; it would look just like this.

Cool video. It looks you agreed with my research that a likely replacement for Gliese 67 is Upsilon Andromedae.

There are a number of problems with your video's conclusion though.

You did not mention selection bias in the original model.

The focus on G, F and K stars was done by Marjorie Fish herself. She excluded M-class (red dwarf) stars from the models because they were thought not to be places that life could evolve since any habitable planets would be tidally locked and back then they thought the atmosphere would be burned off on one side and frozen solid on the other.

The reality is that we know that is probably not the case. Sophisticated models show that the atmosphere would circulate enough so that these planets could themselves have a temperate habitable zone.

We call these "Eyeball Earths" (google it).

So while the percentage of G-stars on the map is interesting it is due to selection bias on the part of Ms. Fish.

Now, that being said a couple of the stars on the map do have red dwarf or brown dwarf companions.There are other reasons the map is interesting though.

When I ran a matching algorithm using Hipparcos data which included M-stars as well as all other classes of stars the stars on the map still were the best fit.

I did not intend for this to be the result. Initially I thought other good fits would emerge from nearby stars but out of over 2,000 combinations tried, this still was the best fit. The next one isn't even close.

This "map" and experience have been greatly undervalued for a very long time.

Agreed.

I guess I should let you have a sneak peek at the video I am putting together for a new thread on this subject. Right now I am waiting for Stanton Friedman to get back from a speaking tour because I want to include a segment on who Marjorie Fish was and why her analysis, given the tools she had at her disposal at the time has stood the test of time and various challenges. I'd have posted by now but I thought it better to include that segment towards the end since she constructed the models which all this research is based off of and she just passed away this past summer so it is fitting that she is remembered.


Also I had to revisit one of the stars on the map in light of a newly published paper which draws the inner edge of a habitable zone closer to the star.


82 Eridani d (HD 20794 d) is potentially habitable.

ArXiv: Towards Minimum Inner Edge Distance of the Habitable Zone

• The number of potentially habitable con-firmed/validated exoplanets significantly increases.

The potentially habitable super-Earth exoplanets are Gliese 581c, Gliese 667Cc, Gliese 163c, HD
85512b, HD 20794c and [b[HD 20794d, HD 40307f and HD 40307g, Kepler 61b, Kepler 52c, Kepler 55b and Kepler 55c, Kepler 62e and Kepler 62f,Kepler 69c, and Kepler 22b. The microlensing exoplanet OGLE-2005-BLG-390Lb could also be habitable, if its atmosphere is hydrogen-rich.

A good layperson summary of that paper can be read here:

Astrobites: How Hot is Too Hot?

Also you'll notice HD 40307f could join HD 40307g on the habitability list.

Good thing I waited. If 82 Eri d is habitable then that star system being on the map makes more sense.

I'll be revising the video and the posts I am preparing for the new thread accordingly.

Have you had a look at Terence Dickinson's work on the map in the 1970s? There was a very good back and forth between him and Carl Sagan in the pages of Astronomy magazine back then. I have the report which includes the letters that were published in Astronomy.

Its a fascinating read in hindsight based on what we now know about exoplanets, etc.

I found it on Amazon.com for about $10 USD.




An avenue of interest which you picked up on is to keep track of how many of those stars have habitable zone planets. Data is incomplete there as many of those stars have not really been studied in great detail for planets due to being southern hemisphere stars but that is going to change very soon.

It will be interesting to note if the percentage of habitable zone planets on the map is significantly higher than what would be expected from a random group of stars.

If you are interested in working on this together over the next years let me know and we'll keep in touch.

JadeStar

Cool video. It looks you agreed with my research that a likely replacement for Gliese 67 is Upsilon Andromedae.

There are a number of problems with your video's conclusion though.

You did not mention selection bias in the original model.

Yes, well Upsilon Andromeda "seemed" like a good fit, so I didn't argue (an I'll admit; I was being lazy).

And, again, yes; I did fail to take into account that being an armature astronomer, Ms Fish, probabilistically speaking would tend to select stars she thought would be more suited. However; In the actual map we find that these stars are also of an appropriate distance as well. n fact the only questionable star(as far as distance goes) is Upsilon Andromeda at 66ly. Until like yesterday, I was thinking that 66ly may be too far, but, I'm in the process of revising that estimate.

By the way; One's conclusions always need revision. (that should be somebody's "first law" of something).

When I ran a matching algorithm using Hipparcos data which included M-stars as well as all other classes of stars the stars on the map still were the best fit.

Hmmmm...yo gots an algorithm for finding stars....

maybe, y'all are quite as primitive as I thought (astronomers, that is) Course the real next question is "what constitutes near by"?

Then again, I don't know just what and how your software works (not that there are a "lot" of ways to do that). So perhaps you [I]can[/I] perform semi automated searches where mine are "sort of" manual. I actually write an SQL query to find what I want; your "algorithm" does the same thing and the program serves as a wrapper. Yours is way easier and doesn't require knowledge of the "SQL" language.

I did not intend for this to be the result. Initially I thought other good fits would emerge from nearby stars but out of over 2,000 combinations tried, this still was the best fit. The next one isn't even close.

This I don't quite get though; 2000 combinations? Of what?

Yesterday I was conducting a search for a potentially habitable that could be "mistaken" as Sirius. I drew a 2D box around Sirius and told my machine to search that box for stars (distance was left out of this search). The issues with this method is "how big of a box?".

The problem here, for other sciences, is the fact that Astronomy uses a silly coordinate system. The conversion from time to degrees and then to decimals is a bit awkward at best.

The situation of intelligent, technologically adept life on planets around some of the more massive, shorter-lived
F stars could be especially challenging. At about the time space travel became possible to them, their ever-growing star, nearing the end of its life on the main sequence could be threatening their continued existence. A really very strong incentive to develop interstellar space travel, or perhaps stellar engineering, to prolong the stable life of their star.

It looks like a bunch of the stars on the map will get a good look by an ESA planet characterization space telescope called PLATO if it is approved next year for a 2017 launch (same year TESS which also may study these stars launches):