Near Earth-sized planet found in habitable zone: Gliese 581C

[heyscottie]

[Cut and paste from Space.com news]<br /><br />An Earth-like planet spotted outside our solar system is the first found that could support liquid water and harbor life, scientists announced today. <br /><br />Liquid water is a key ingredient for life as we know it. The newfound planet is located at the "Goldilocks" distance-not too close and not too far from its star to keep water on its surface from freezing or vaporizing away.<br /><br />And while astronomers are not yet able to look for signs of biology on the planet, the discovery is a milestone in planet detection and the search for extraterrestrial life, one with the potential to profoundly change our outlook on the universe.<br /><br />"The goal is to find life on a planet like the Earth around a star like the Sun. This is a step in that direction," said study leader Stephane Udry of the Geneva Observatory in Switzerland. "Each time you go one step forward you are very happy."<br /><br />The new planet is about 50 percent bigger than Earth and about five times more massive. The new "super-Earth" is called Gliese 581 C, after its star, Gliese 581, a diminutive red dwarf star located 20.5 light-years away that is about one-third as massive as the Sun.<br /><br />Smallest to date<br /><br />Gliese 581 C is the smallest extrasolar planet, or "exoplanet," discovered to date. It is located about 15 times closer to its star than Earth is to the Sun; one year on the planet is equal to 13 Earth days. Because red dwarfs, also known as M dwarfs, are about 50 times dimmer than the Sun and much cooler, their planets can orbit much closer to them while still remaining within their habitable zones, the spherical region around a star within which a planet's temperature can sustain liquid water on its surface.<br /><br />Because it lies within its star's habitable zone and is relatively close to Earth, Gliese 581 C could be a very important target for future space missions dedicated to the search for extraterrestrial life, said study team me

 

[MeteorWayne]

The formula's in a Mars thread around here somewhere.... <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

Mrom heyscottie in the Mars gravity thread in AtA:<br /><br /><font color="yellow"> The equation for gravity is F = G*m1*m2/(r^2). <br /><br />We can get rid of G because we are doing relative calculations here. </font><br /><br />So if Im reading it right, m2= a human (negligible), M1 is the planet mass.<br /><br />Now let me look up what the units are for the calculation <img src="/images/icons/smile.gif" /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

So m1=5 and r=1.5 for relative measurements<br /><br />So it equals 5/ square 1.5<br /><br />That comes out to 2.2222 times earth's. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[abq_farside]

<font color="yellow"><i>An Earth-like planet spotted outside our solar system is the first found that could support liquid water and harbor life, scientists announced today...... </i></font>/i><br /><br />Very cool!<br /> <div class="Discussion_UserSignature"> <p> </p><p><em><font size="1" color="#000080">Don't let who you are keep you from becoming who you want to be!</font></em></p> </div>

 

[zazaban]

This is so wonderful, I have never felt so happy to be alive. <br /><br />This is better than sex.

 

[logicize]

This makes for great headlines, and it's fun to imagine. But I think it takes a great leap of faith to say that we know the size a planet, that we really can't even see, and we know that it has liquid water and may host life currently. All this when we don't even know the size or composition of Sedna, which we can see and it's in our solar system.

 

[mithridates]

Seconded. And at a relatively near distance of 20 ly too. I'm trying to find out this star's radial velocity right now, whether it's moving towards us or away. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[robnissen]

We do, however, know the minimum size to a high confidence level. <br /><br />What I am curious about is whether the planet is tidally locked. Also, would the fact that there is a "hot jupiter," nearby make it less likely that the planet is tidally locked. I assume with three fairly large planets fairly close to a small star, the gravitational calculations are probably pretty complex.

 

[mithridates]

I'm curious about that too. Here's a link to an article written in 2001 about the possibility of planets being around red dwarf stars:<br />http://www.kencroswell.com/reddwarflife.html<br /><br />My favourite part:<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>And there is good reason to believe that the first extraterrestrial civilisation that we find will differ greatly from our own. Ten years ago, when astronomers knew no planets beyond the Solar System, they believed that other solar systems would resemble our own. Then, in 1991, they accidentally discovered the first extrasolar planets, circling not a living star like the Sun but a type of dead star known as a pulsar. And in 1995, when they found the first extrasolar planet around a Sun-like star, it took them completely by surprise. In our Solar System, giant planets like Jupiter and Saturn orbit far out from the Sun. But this giant was astonishingly close to its star, and astronomers have since found many others like it.<br /><br />Which leads to an intriguing thought. Any planets that circle red dwarfs may have given rise to astronomers as parochial as those on Earth. These alien observers may have concluded that only red dwarfs can support life, blessed as they are with stable planets where suns never set and seasons never disrupt the climate. Indeed, their SETI programs may ignore Sun-like stars altogether. After all, they might argue, any temperate planet orbiting such a star would lie so far out that it would rotate freely, subjecting life to a relentless cycle of light and dark. Any tilt of the axis would cause severe summers and winters, and changes in axial tilt might induce ice ages, with mighty glaciers smothering much of the globe. How on Earth could life possibly arise on such a hostile world?<p><hr /></p></p></blockquote> <br /><br />Here's another article with a few more images, including an artist's impression of the s <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[chyten]

<b>Here's another article with a few more images, including an artist's impression of the sky there: <br /><br />http://www.thisislondon.co.uk/news/article-23393718-details/Found:+The+New+Earth/article.do </b><br /><br />Quote: "Gliese 581: A star, a third the size of our Sun - and 50 times colder"<br /><br />I assume they meant "50 times dimmer". 50 time colder than Sun is about 120 Kelvin. That would be an iceball, not a star. <img src="/images/icons/smile.gif" />

 

[Aetius]

Red dwarf solar systems are wicked cool! If Gliese 876 and Gliese 581 both have super-Earths <i>and</i> gas giants, it says that many examples of this common star type may also have solar systems.<br /><br />Regarding the super-Earth type worlds' failure to develop into gas giants, maybe somehow not enough material was available at the proper time. Gliese 876 lacks an Edgeworth-Kuiper Belt analog, and has its own super-Earth (though perhaps super-Venus might be a more appropriate name in this case), Gliese 876d.

 

[mithridates]

I still can't seem to find the relative motion of this star compared to ours. Anybody know whether it's moving towards or away from us? <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[mithridates]

Wait, just found it. It's radial velocity is -9.5 km/s, so it's moving towards us.<br /><br />Link<br /><br /><i>Edited to shorten the length of the posted link</i> <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[mithridates]

Its diameter is 50% greater:<br /><br />http://www.news.com.au/dailytelegraph/story/0,22049,21618354-5001021,00.html<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>The new planet, which orbits a small, red star called Gliese 581, is about one-and-a-half times the diameter of the Earth. <br /><br />...The surface gravity is probably around twice that of the Earth and the atmosphere could be similar to ours. <p><hr /></p></p></blockquote> <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[qso1]

Zazaban:<br />This is better than sex.<br /><br />Me:<br />Lol, I'm not so sure about that.<br /> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

logicize:<br />But I think it takes a great leap of faith to say that we know the size a planet, that we really can't even see, and we know that it has liquid water and may host life currently.<br /><br />Me:<br />Gotta read the article a little closer and keep in mind that its written by a space.com writer/reporter rather than the scientists themselves. The reporter tends to jazz things up a bit to make for an exiting news story.<br /><br />Lets look at a passage:<br /><br />Excerpt from article:<br />"An Earth-like planet spotted outside our solar system is the first found that could support liquid water and harbor life, scientists announced today".<br />End Excerpt.<br /><br />The scientists are saying could support water...not that it has liquid water. Another passage below:<br /><br />Excerpt from article:<br />"Possible waterworld<br /><br />Computer models predict Gliese 581 C is either a rocky planet like Earth or a waterworld covered entirely by oceans".<br />End excerpt.<br /><br />Note possible waterworld as opposed to definite waterworld and note the extremely wide range the computer model encompasses. Bottom line, we really are not seeing anything that definitive. I could have made up that range of worlds without a computer.<br /><br />As for size, this can be fairly accurately measured even at these distances and different techniques are used to determine the size of objects that are visible like Sedna, and far off like this exoplanet. Even so, nobody has pinned the size down to kilometers, just that its 1.5 times earth sized and one day some of the data we now have on exoplanets will be refined as new data replaces it.<br /><br />In fact, this field of research will really begin to percolate once we can image some of these worlds and start to see what they look like and what their spectra tell us. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[mithridates]

This reminds me, wasn't COROT supposed to start showing its first concrete results around April or May? <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[qso1]

http://smsc.cnes.fr/COROT/<br /><br />According to this link, the first observing run began just this past February 8th. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[3488]

Interesting link here: Gliese 581 / HO Librae.<br /><br />I think some perspective needs to be put here. A planet with five times the mass of Earth with a 50% greater diameter & just over twice the surface gravity is not Earth like. <br /><br />It is not like anything in our own solar system, but falls in the size / mass gap between Earth & Uranus.<br /><br />It is interesting that it has been pointed out that it seems strange that this planet has not accumulated a huge dense hydrogen atmosphere (it will be cold enough to hold on to such).<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[Boris_Badenov]

First off, FIX THAT LINK!!!<br /><br />The local morning news show just reported; "scientists have discovered a planet with oceans & an Earthlike atmosphere."<br /> Thats just the laugh I needed first thing in the morning. <img src="/images/icons/laugh.gif" /><img src="/images/icons/laugh.gif" /><img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[3488]

Hi Boris1961.<br /><br />Not mithridates's fault. The Daily Telegraph article clearly stretches this find far too far. Fairly typical for the British Press.<br /><br />I would like to thank heyscottie for starting this thread in the first place. The Gliese 581 system is turning out to be a real fascinating one.<br /><br />Of course, we know nothing of the physical characteristics of the planet in question, other than its mass & now possibly size. <br /><br />Questions are:<br /><br />1). Does it have an atmosphere.<br /><br />2). Is it tidally locked to Gleise 581 (i.e keep the same face turned towards its Red Dwarf sun)?<br /><br />3). Is it geologically active (have volcanoes, tectonics, or is it dead & covered in impact craters)?<br /><br />4). Is it differentiated like the Earth, Venus, Mars, Io, Ganymede (with a core, mantle & crust, or is it a homogenous object like Callisto)?<br /><br />5). Does it have any moons, if so how many, size & mass ranges.<br /><br />6). Does it have a magnetosphere?<br /><br />7). Is there liquid water, or is it ice, or is there any water there at all?<br /><br />These questions (which need to be answered to understand this object) along with many others , will not be answered for a very, very long time!!!<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[heyscottie]

Let's review what we really DO know about this system.<br /><br />Star:<br />Gliese 581<br />Distance 20.4 LY<br />Mass about 31% solar masses<br />Luminosity about 1% sun's, but is a VARIABLE star<br />Composition has only about 50% metallic content of sun<br /><br />-------------------------------<br />Gliese 581 b:<br />Semimajor Axis 0.041 AU<br />Eccentricity ~0<br />Orbital period .015 years<br />Mimimum Mass 15.7 earths<br />Class: Hot Neptune? Hot rocky planet?<br />Discovered August 2005<br />-------------------------------<br />Gliese 581 c:<br />Semimajor Axis 0.073 AU<br />Eccentricity ~0<br />Orbital period .035 years (about 13 days)<br />Mimimum Mass 5.1 earths<br />Class: Super Earth<br />Discovered April 2007<br />-------------------------------<br />Gliese 581 d:<br />Semimajor Axis 0.25 AU<br />Eccentricity ~0<br />Orbital period .231 years (about 84 days, like Mercury)<br />Mimimum Mass 8.2 earths<br />Class: Super Earth/Uranus like<br />Discovered April 2007<br />-------------------------------<br /><br />What can we surmise or predict about Gliese 581 c?<br /><br />1) It is located within the star's potential habitable zone, with mean temperatures somewhere between 0 and 40 C<br />2) If we assume an earth-like density and a true mass of about 5.1 earths, then its radius would be 1.72 that of earth. This would give 1.7g gravity at the surface. Note that this minimum mass and earth-like density are both almost certainly incorrect, though neither are unreasonable numbers.<br /><br />That is all! I'd love to know the answers to some of 3488's questions, but as he says, we will not know many of them for quite a long time.

 

[MeteorWayne]

brandohall,<br /><br />Good point I hadn't considered. radius vs volume.<br /><br />Headline articles are so lacking in detail <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[rhm3]

Research paper on Gliesse 581 and its planets (including the new one)...<br /><br />http://exoplanet.eu/papers/udry_terre_HARPS-1.pdf<br /><br />Worth pointing out that the star is one of the least active of the sampled M class...and the new earthlike planet is on a low-eccentricity orbit which ensures a stable system. <br /><br />Anyone have any ideas or reasonable guesses as to whether it is tidally locked or not?