Gliese 581g

[tblaxland]

How long did the orbit take to become stable and what was it's eccentricy when it became stabile. I would like to know so i can ajust it's orbit to make things as realistic as possible.

Its eccentricity was not stable, it continually varied between about 0 to 0.1 IIRC. Try it out for yourself (requires Tony's Gravity Simulator): http://orbiter-forum.com/images/tblaxland_images/Gliese%20581%20d.gsim

 

[RisingFury]

That's what happened. Period changes in eccentricity and a steady precession of LAN and Arg Pe.

Its eccentricity was not stable, it continually varied between about 0 to 0.1 IIRC. Try it out for yourself (requires Tony's Gravity Simulator): http://orbiter-forum.com/images/tblaxland_images/Gliese 581 d.gsim

Yea! Wonko orbit! It fluctuates from 0 to 0.1 because the 3:5 resonance is pretty symmetrical overall. But if you have a 2:1 or 3:1 resonance, things can go real bad real fast. The "tug" on the orbit always happens when the inner moon is in one place, which means it's like a rocket with with an ion engine that turns the engine on at periapsis every second orbit.


Don't misunderstand, 5:3 resonance is stable. The orbit will dance around, but it won't eject anyone. The problem in this case is that of the two satellites that are present here, one has formed with the planet, the other was captured. But for it to circularize it's it's orbit, it'd have to take a long time and could not be "recently captured".

The third one that crosses orbit with the inner most satellite would be unstable for the rather obvious reasons...

 

[donatelo200]

I can't make the resonace show unfortunatly with out it being flung out on hard time accel.

I also guess the angle i showed earlier didn't show it's inclanation relative to to GI 581 d and d I thats why i said it was captured.

 

[Orbinaut Pete]

Aliens? :blink:

SPACE.com: "Claim of Alien Signal from Planet Gliese 581g Called 'Very Suspicious'".

Discovery News: "Gliese 581g and the Question of Intelligent Life".

 

[Orbinaut Pete]

Astrobiology Magazine: "Doubt Cast on Existence of Habitable Alien World".

:blink:

 

[T.Neo]

Oh darn... we don't want to have our dreams crushed.

 

[donatelo200]

We'll I'm pretty shure it exists because why in the hell would they publish it without being 100% certant it exists. If it does end up not being real I'll be but I'll still be updating just without F and G.:dry:

 

[Hielor]

We'll I'm pretty shure it exists because why in the hell would they publish it without being 100% certant it exists. If it does end up not being real I'll be but I'll still be updating just without F and G.:dry:

Part of science is being wrong. That's what makes it science, not religion.

 

[T.Neo]

Hmm... I will also be if these findings are reported to be false, but at least it'll save me a bit of work that I've been procrastinating on.

 

[donatelo200]

It will kill the work that i have finished witch including the moons i have placed around planet f. G and F i have already finished.

 

[Cairan]

Just release it as a "alternate" star system... Just like those of Sol with a Blue Mars...

 

[donatelo200]

Eh sounds like a plan.

 

[T.Neo]

It is unconfirmed... nobody has said yet that it doesn't exist.

I don't find the idea of "alternate" systems too pleasing... I suppose I could release a system where Mars replaced the Moon...

 

[Orbinaut Pete]

SPACE.com: "Astronomer Stands By Discovery of Alien Planet Gliese 581g Amid Doubts".

 

[Columbia42]

Well if they haven't discovered the planet until now, it must not be that easy to find even if you know where to look. That's probably why people are saying it doesn't exist.

 

[RisingFury]

Ragbir Bhathal, a scientist at the University of Western Sydney, claimed to have detected a suspicious pulse of light nearly two years ago, that came from the same area of the galaxy as the location of Gliese 581g, according to the U.K.'s Daily Mail online.

Don't trust Daily Mail when it comes to science. They have a high track record of misunderstanding what papers mean, then inventing a sensationalist claim, then years later they turn around to fight the hype they started...

 

[Unstung]

Apparently the planet has been confirmed to likely exist according to Universe Today, but I can't find many other sources. They don't seem very trustworthy. I wonder if more sources will report on it in the coming days.


Universe Today: "Exoplanet Gliese 581g Makes the Top 5"

University of Puerto Rico at Arecibo: "Five Potential Habitable Exoplanets Now"

Now the original discoverers of Gliese 581g, led by Steven S. Vogt of UC Santa Cruz, present a new analysis with an extended dataset from the HARPS instrument that shows more promising evidence for its existence. The new analysis strength their original assumption that all the planets around Gliese 581 are in circular and not elliptical orbits as currently believed. It is under this likely assumption that the Gliese 581g signal appears in the new data.

Another source - Herald Sun: "SUPER EARTH: Scientists discover life-supporting planet 'right at Earth's front door'"

 

[RisingFury]

Tidally locked could be a good thing:

http://www.space.com/scienceastronomy/earth-like-exoplanet-possibly-habitable-100929.html

EDIT: FWIW, from what I can find about the physical size, surface gravity would range from 1.5g to 2.8g

Any tidally locked system also tends to decrease the orbital eccentricity. Obviously that helps to stabilize the climate because you have no instances of increasing and decreasing solar flux and because you have no summer and winter cycles.

 

[Keatah]

It would be interesting to see what sort of evolution happens on a tidally locked planet..

You might get strong winds on the terminator. And dwellings for creatures might be aerodynamic. This is assuming the atmosphere rises on the hot side and condenses on the cold side.

This convection action might take all the water and deposit it as snow on the dark side. Could that cause an imbalance and cause some type of super-long-term precession as weighty snow deposits on one side? How would that effect tidal lock?

What kinds of politics and society would develop in a narrow habitable band?

Would the habitable band be variable based on the solar fluctuations? More variable than on earth? Might it move back and forth between hot side and cold side?

How would a culture develop religions? And what about space travel? Would they have a more difficult time than galileo or copernicus and kepler in figuring out how their solar system works?

 

[garyw]

Gliese 581's planets don't exist.

The world is breathing a collective sigh of relief today as interstellar war with life from the well-known prospective so "Goldilocks" worlds orbiting the star Gliese 581 has been averted – because the planets didn't actually exist.

In the heady early days of the search for planets in the habitable zones of nearby stars, Gliese 581, an M-class dwarf star located just 20 light years away in the Libra constellation, was something of a standout. Various boffinries originally found six planets orbiting in the system, with no less than three sitting in the sweet spot from the sun where liquid water is possible.

One Goldilocks world (so called as its “not too hot and not too cold” to support life), Gliese 581f, was quickly disproved, but hopes were so high that the system could support intelligent life that clapped-out social network Bebo – quite popular at the time – reckoned spamming Gliese 581 with a load of old teenage tosh was a great idea.

Obviously, this was actually a terrible idea because if there was someone listening, they would no doubt think it incumbent upon them to rid the Universe of this blot of inanity, this sore of narcissism, this boil of solipsism, which apparently thought its first meeting with intelligent aliens should be marked by such comments as:

I love Television. We watch animated cartoons and real-life drama on it. I could sit and watch Television all day.

Hi im nicole ... someday i would love to appear on the west end stage, in a hit show.i also wouldnt mind doing a few television programs whether it is as a extra or a main part i dont mind i would love to appear on doctor who as i love it. anyway laters. Nicole x

However, the enthusiasm was short-lived as scientists immediately started to question the results that lined up these planets in the Goldilocks zone. There were questions about whether the worlds could in fact support life at all and also questions about whether the original data supporting their discovery could be backed up.

So it’s with bittersweet relief (no interstellar war = good, no aliens = boo) that the world greets the latest research on the system, which indicates that Gliese 581’s g and d planets, the last two options for Earthlike living, don’t actually exist.

Picking Earthlike planets out of the sky is no easy task. Boffins can’t actually see the worlds themselves, but instead infer their existence from changes to the way the light from their host star changes in appearance. Irritatingly, having a planet pass in front of the star is not the only way the light may be dimmed or altered – it could also be caused by activity in the sun itself.

Scientists use various tricks to try to confirm their “sightings” of exoplanets, one of the most obvious being waiting for the planet to come round again if they can. Planets have periodic orbits and the fact that it comes this way every x number of days is a relatively good indication that it’s a real world, not just a blip.

But stellar activity can be periodic as well. Sunspots can sit on the surface of a star and rotate in and out of view and flaring activity can have cycles like our own Sun’s 11-year activity cycle. To try to compensate for these false positives, boffins apply different filters to what they’re seeing.

Commonly, researchers will measure the emission of calcium at the blue edge of the visible spectrum, but because small, cool M dwarf stars have such a low temperature, they emit very little light at the blue end of the spectrum. In the latest study, researchers have figured out that Gliese 581d and Gliese 581g don’t exist by using redder absorption lines like sodium D and hydrogen alpha. They used the data from these results to correct for the effects of magnetic activity on the star and ran the numbers again from the start.

Both the planets in the habitable zone turned out to be nothing more than some sunny activity, but the boffins were able to confirm with much more certainty that the other three worlds exist. This doesn’t help the Gliese 58 system with its lifelessness, but it will help researchers to get rid of future false positives.

"Our improved detection of the real planets in this system gives us confidence that we are now beginning to sufficiently eliminate Doppler signals from stellar activity to discover new, habitable exoplanets, even when they are hidden beneath stellar noise,” said lead author Paul Robertson, a post-doctoral fellow at the Penn State's Centre for Exoplanets and Habitable Worlds.

"While it is unfortunate to find that two such promising planets do not exist, we feel that the results of this study will ultimately lead to more Earthlike planets."

The full study, "Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581", was published in Science.

Source: http://www.theregister.co.uk/2014/07/04/gliese_581_habitable_worlds_dont_exist/

and

http://www.sciencemag.org/content/e...ract?sid=4fe55744-0e21-49f3-9389-7eef196a3e1f