Discover Gliese 581g - Just 20 Light-Years Away!

[DaveC426913]

Just look how misleading this is:



http://www.jb.man.ac.uk/~drl/publications/clf+00.pdf"

What a terrible article.

Apparently, hey have already decided its composition is "...rocky with liquid water and atmosphere..."

And I like this comment: "It takes just 37 days to orbit its sun which means its seasons last for just a few days."

The one-face Gliese planets do not have seasons.

Nevermind the fact that they give no details about the mysterious light.

 

[Gaius Baltar]

Completely Agree Dave.

It just goes to show, the Media and other sources of news outlets will stop at nothing to promote lies & fear mongering. Shame 60% of people who read, believe...

**Sigh...**

 

[stevebd1]

I mean, 6 years trip sounds pretty optimistic. I wonder if there's any propulsion tech that is close to getting this achieved.

While it's not hard science, I thought this was a great website for ideas and suggestions regarding long distance space travel-

http://www.projectrho.com/rocket/rocket3aj.html

 

[GlieseWorm]

Amazing discovery. Carl Sagan would be thrilled to read this article. Gliese 581g is only 20 light-years away. It would make a nice weekend getaway spot.

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

what planet do you live on where 40yrs equates to a weekend? Christ , this is a physics site not Miils n Boom.

 

[GlieseWorm]

could someone offer a physics answer as to when the Gliese 581g existence are due to be officially confirmed or contra-confirmed?

 

[JaredJames]

what planet do you live on where 40yrs equates to a weekend? Christ , this is a physics site not Miils n Boom.

It was a bit of light hearted humour. No need to be so harsh, perhaps a bit less attitude.

could someone offer a physics answer as to when the Gliese 581g existence are due to be officially confirmed or contra-confirmed?

Not entirely sure what else you're looking for here, the above discussion covers things nicely.

 

[lpetrich]

could someone offer a physics answer as to when the Gliese 581g existence are due to be officially confirmed or contra-confirmed?

When someone observes Gliese 581 with a spectroscope with a resolution better than 1 m/s, to translate the Doppler shift into velocity for visible light. Currently, the purported detection of 581g is borderline; improving the spectroscope resolution will make it less borderline.

About spectroscopes better than 1 m/s, I don't know if any are in the works.

There's also the question of how far one can go. Is 1 m/s the limit, or some smaller velocity value?

 

[GlieseWorm]

When someone observes Gliese 581 with a spectroscope with a resolution better than 1 m/s, to translate the Doppler shift into velocity for visible light. Currently, the purported detection of 581g is borderline; improving the spectroscope resolution will make it less borderline.

About spectroscopes better than 1 m/s, I don't know if any are in the works.

There's also the question of how far one can go. Is 1 m/s the limit, or some smaller velocity value?

i have only read of one blip being recorded and the next time they looked the blip didnt appear. to me , if me reading so far is correct, then this would seem to suggest that the confirmation is lacking and that the so called planet is an artefact. combined with the other data that suggests 4 planets not 6, it seems a bit early to come to conclusions about the planet being tidally locked.

if the 'planet' only has a year of 37days, then we should have been seeing a lot more blips by now, and i am not sure we need to request a new spectroscope when what we need is apparently a calendar ?

 

[GlieseWorm]

Some issues on tidal locking:
quoting Wikipedia from yesterday, my additions in bold:
"An estimate of the time for a body to become tidally locked can be obtained using the following formula:[4]

t,lock=wa^6IQ/3Gm^2,pk,2R^5

where
w is the initial spin rate (radians per second)
a is the semi-major axis of the motion of the satellite around the planet
I is the moment of inertia of the satellite (Gliese 581g of course).
Q is the dissipation function of the satellite.
G is the gravitational constant
(m,p) is the mass of the 'planet' (Gliese 581 itself)
(m,s)is the mass of the satellite

k2 is the tidal Love number of the satellite
R is the radius of the satellite.
Q and k2 are generally very poorly known except for the Earth's Moon which has k2 / Q = 0.0011. However, for a really rough estimate one can take Q≈100 (perhaps conservatively, giving overestimated locking times), and

k2=1.5/(1+(19μ/2pgR)

where
p is the density of the satellite
g is the surface gravity of the satellite
μ is rigidity of the satellite. This can be roughly taken as 3×1010 Nm−2 for rocky objects and 4×109 Nm−2 for icy ones.
As can be seen, even knowing the size and density of the satellite leaves many parameters that must be estimated (especially w, Q, and μ), so that any calculated locking times obtained are expected to be inaccurate, to even factors of ten. Further, during the tidal locking phase the orbital radius a may have been significantly different from that observed nowadays due to subsequent tidal acceleration, and the locking time is extremely sensitive to this value."

 

[GlieseWorm]

Some issues on tidal locking:
quoting Wikipedia from yesterday, my additions in bold:
"An estimate of the time for a body to become tidally locked can be obtained using the following formula:[4]

t,lock=wa^6IQ/3Gm^2,pk,2R^5

where
w is the initial spin rate (radians per second)
a is the semi-major axis of the motion of the satellite around the planet
I is the moment of inertia of the satellite (Gliese 581g of course).
Q is the dissipation function of the satellite.
G is the gravitational constant
(m,p) is the mass of the 'planet' (Gliese 581 itself)
(m,s)is the mass of the satellite

k2 is the tidal Love number of the satellite
R is the radius of the satellite.
Q and k2 are generally very poorly known except for the Earth's Moon which has k2 / Q = 0.0011. However, for a really rough estimate one can take Q≈100 (perhaps conservatively, giving overestimated locking times), and

k2=1.5/(1+(19μ/2pgR)

where
p is the density of the satellite
g is the surface gravity of the satellite
μ is rigidity of the satellite. This can be roughly taken as 3×1010 Nm−2 for rocky objects and 4×109 Nm−2 for icy ones.
As can be seen, even knowing the size and density of the satellite leaves many parameters that must be estimated (especially w, Q, and ), so that any calculated locking times obtained are expected to be inaccurate, to even factors of ten. Further, during the tidal locking phase the orbital radius a may have been significantly different from that observed nowadays due to subsequent tidal acceleration, and the locking time is extremely sensitive to this value."

so what i would like to know is for all these claims of tidal locking, what are the estimates or calculated figures used, including errors, plus an experts personal estimates of probability of tidal locking.
any takers?

 

[GlieseWorm]

is it possible that gliese581g has a twin and that the two are locked together in tango in what i understand to be the pluto/charon combination, hence we need to wider our search?
in which case the tidal locking calculation could be a double waste of time , beyond math quiz.

 

[GlieseWorm]

Just look how misleading this is:



http://www.jb.man.ac.uk/~drl/publications/clf+00.pdf"

http://en.wikipedia.org/wiki/47_Tucanae"

Just goes to show, research goes a long way...

What a terrible article.

Apparently, hey have already decided its composition is "...rocky with liquid water and atmosphere..."

And I like this comment: "It takes just 37 days to orbit its sun which means its seasons last for just a few days."

The one-face Gliese planets do not have seasons.

Nevermind the fact that they give no details about the mysterious light.

guys i am a bit confused here, so i have done some reading around the net; the conclusion i have come to is that you are quoting a newspaper article which was based on Ragbir Bathals laser-like one-off signal from 47 Tucanae, a galaxy "about 16,700 light years away from Earth" (wikipedia). GLiese 581g is 20light years away need i remind you all. However according to a rival forum, the http://setiathome.berkeley.edu/forum_thread.php?id=61590&sort=7
the error lies in the delay that Prof Ragbir Bathal reported his findings and a mistaken belief that they were the same signal i presume.
in fact, the signals were from different parts of the sky, and so Prof Ragbir Bathals group have no link to GLiese581 at all as far as i can tell and certainly not Gliese 581g.

Thus, DaveC426913, with all due respect, it appears that you are quoting the wrong article in your criticism of the conclusions about the nature of the planet, as you have referenced Camilo et al (2000). I can't see how it could be referring to any planets as there have yet to be any planets detected in this entire galaxy, again according to Wikipedia today.

 

[Radrook]

Well, since the planet is gravitationally locked with one side always in perpetual darkness and the other in light then the only habitable zone tempertature-wise would be the line between shadow and light (known as the "terminator"). The planet's almost circular orbit will tend to keep this zone fairly stable. However, having a mass three to four times that of Earth means that we weigh more there and will probably have to exert ourselves considerably more just to get about. Neither is a twenty light year distance a paltry consideration in view of our present technology since it would take a spacecraft traveling at Voyager speed well over 70,000 years to get to Alpha Centauri which is apprtox 4 ly away and approx. 350,000 years to get to Gliese.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Excerpt:

horseshoe7 Wrote:

However, if my calculations are correct, my 200lb body would feel like about 867lbs on the surface of Gliese 581 d... even if I went on a crash diet to get to ~150lbs, I'd STILL weigh about 650 pounds there!... maybe we need to "continue the seach" for more suitable habitable planets? ... hopefully, there is a more Earth-sized planet Gliese 581 f that is right in the middle of the habitable zone of the Gliese 581 system?


https://www.physicsforums.com/showthread.php?t=359589

 

[lpetrich]

i have only read of one blip being recorded and the next time they looked the blip didnt appear. to me , if me reading so far is correct, then this would seem to suggest that the confirmation is lacking and that the so called planet is an artefact. combined with the other data that suggests 4 planets not 6, it seems a bit early to come to conclusions about the planet being tidally locked.

Strictly speaking, it's not a burst of something, it's spectroscopic data.

One uses spectroscopy to measure a star's radial velocity, repeating the measurements over several hours or days or weeks or months or years. One then tries to fit the effect of an orbiting planet to what one observes.

The problem with Gliese 581g is that it does not produce a very strong effect, if it exists. It's barely above the noise.

 

[Radrook]

Before we get too excited, red dwarfs have some problems. One is that many of them - perhaps half - are UV Ceti variables, also called flare stars. They have sporadic flares which are much more dangerous than solar flares - both because they are more energetic (especially in X-rays) and because their planets are closer.

Unfortunately, Gl 581 falls into this category. (When looking it up, it's also NSV 7023. NSV stands for New Suspected Variable)

Unfortunately, the closest star to earth, Proxima Centauri, also falls under that unpredictable red dwarf variable category.

 

[FtlIsAwesome]

Emphasis added in quote.

Thus, DaveC426913, with all due respect, it appears that you are quoting the wrong article in your criticism of the conclusions about the nature of the planet, as you have referenced Camilo et al (2000). I can't see how it could be referring to any planets as there have yet to be any planets detected in this entire galaxy, again according to Wikipedia today.

Huh? We've already detected hundreds of exoplanets in the Milky Way, starting in 1992.
http://en.wikipedia.org/wiki/Exoplanet_detection
http://en.wikipedia.org/wiki/PSR_B1257+12
http://en.wikipedia.org/wiki/Extrasolar_Planet

There are 538 such planets that have been confirmed as of March 11, 2011.

Of course, the number of known exoplanets was lower at the time of your post, but much higher than 0.

 

[DaveC426913]

Huh?

Yeah. Who knows what he means...