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

[rhm3]

According to this exoplanet encyclopedia, Gliese 581 is 4.3 billion years old...slightly younger than the Sun. <br /><br />http://exoplanet.eu/planet.php?p1=Gl+581&p2=c<br /><br />I hadn't previously heard of an actual age estimate for the star (other than at least 2 billion years old which is vague)...so I figured it was worth posting.

 

[robnissen]

<font color="yellow"> Gliese 581 is 4.3 billion years old...slightly younger than the Sun. </font><br /><br />So, IF this new planet is earth like, and IF evolution proceeds at the same pace on all Earth like planets, then this planet should just about be ready to start the AGE of REPTILES. I guess it sux to be SETI. <img src="/images/icons/smile.gif" />

 

[summoner]

This is just too cool. I just can't suck up the info fast enough. ...beating fists on the desk chanting TPF...TPF... <div class="Discussion_UserSignature"> <p> </p><p> </p><p> </p><p> <br /><table cellpadding="0" cellspacing="0" style="width:271px;background-color:#FFF;border:1pxsolid#999"><tr><td colspan="2"><div style="height:35px"><img src="http://banners.wunderground.com/weathersticker/htmlSticker1/language/www/US/MT/Three_Forks.gif" alt="" height="35" width="271" style="border:0px" /></div>

 

[deapfreeze]

I think this i very cool. I hope there is life, water and everything to be kind of like earth. I don't care if the life isn't like ours just that its there and then I will be able to tell everyone I know I told you so.. LOL ( We will find life elsewhere) optimism <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#0000ff"><em>William ( deapfreeze ) Hooper</em></font></p><p><font size="1">http://deapfreeze-amateur-astronomy.tk/</font></p><p> </p> </div>

 

[derekmcd]

This is just absolutely fantastic news! I see i'm a little late catching wind of it. Can't wait to learn more about it. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[doubletruncation]

<blockquote><font class="small">In reply to:</font><hr /><p>According to this exoplanet encyclopedia, Gliese 581 is 4.3 billion years old...slightly younger than the Sun.<br /><br />http://exoplanet.eu/planet.php?p1=Gl+581&p2=c<br /><br />I hadn't previously heard of an actual age estimate for the star (other than at least 2 billion years old which is vague)...so I figured it was worth posting.<p><hr /></p></p></blockquote><br /><br />If you follow the references, I think they got Gliese 581 mixed up with HD 4308 (another HARPS target with a Neptune mass planet). The paper with the star measurements for Gliese 581 is here: http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0509/0509211v1.pdf<br /><br />In that paper they give a /> 2 billion years for the age estimate. Getting ages for isolated main sequence M-dwarfs is an incredibly difficult thing to do. Since the star barely changes over billions of years, you can't use the temp/luminosity to infer the age (unless it's less than a few 100 Myr old, in which case it'll still be settling on to the zero-age main sequence. Note that this means that for a good 100 Myr or so at the beginning of its life the planet would have been on the inside of the habitable zone - any water it had might have boiled off). The only real way to do it is to measure the rotation period (from starspots) or the activity level and use empirical relations between activity/age. The impression that you get from the paper is that they don't have a very firm measurement of the activity - they can only say that it's a very low level, and hence the age must be > 2 Gyr. But there's no R_HK listed, or a limit on it listed, so it's hard to really say. In any case, I wouldn't put too much confidence in the R_HK ages... there is some evidence that they can be off by as much as 50%. <div class="Discussion_UserSignature"> </div>

 

[qso1]

Makes more sense to me. I always thought red dwarfs were supposed to be considerably older than the sun. <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>

 

[lost_shaman]

doubletruncation : <font color="yellow">If you follow the references, I think they got Gliese 581 mixed up with HD 4308 (another HARPS target with a Neptune mass planet). The paper with the star measurements for Gliese 581 is here: http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0509/0509211v1.pdf </font><br /><br />If you read the second Paper, describing Gliese 581c, you'll see that they had already announced Gliese 581b in 2005, that's where they noticed the perturbations that led to the discovery of Gliese 581d and Gliese 581c, today's announcement.<br /><br /> <br />

 

[3488]

Hi qso1.<br /><br />Not ALL Red Dwarfs. There are many within the Pleiades (M45), only about 80 million years old & Proxima Centauri may be only 800 million years old (where as Alpha Centauri A & B are about 6.3 billion years old, somewhat older than our Sun, suggesting that Proxima is a captured body).<br /><br />I think that there will be a lot more on Gliese 581, when the observations are compiled. I for one am looking forward to it.<br /><br />APOD today Gliese 581. <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>

 

[qso1]

Hey there 3488. Your right, I'd forgotten about the much younger red dwarf stars but when you mentioned Proxima, that jogged my memory. I wouldn't be surprised if Proxima is still in the capture process. We have only known about it since what...1915? Yet its orbital period is millions of years so we really haven't seen much of its orbit.<br /><br />As for Gliese 581, I definetely agree that there will be a lot more to learn about that system, and the planets including of course, the most famous one now...581c. I'm already imagining some kind of microbiological life forms concentrated along a wide path either side of the terminator of the planet because the ideal temps are probably there. <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]

If this planet has an atmosphere (which is highly likely IMO), it will likely effect the surface temperature. <br /><br />Other questions that need to be answered have occured to me (a bit slow I am)!!!<br /><br />1). Although the Red Dwarf sun Gliese 581 appears stable now, did it have eruptive flares in the past?<br /> <br />2). Does Gliese 581 have a solar / star spot cycle & if so, how active does it become at starspot maximum?<br /><br />3). Does the orbit of Gliese 581 (& its planets) around the galactic centre, take it close to the galactic centre, or does it stay in the outer suburbs like our Sun?<br /><br />4). Does the Gliese 581 system have a large number of comets & asteroids that can impact the planets?<br /><br />5). What is the rotational period of Gliese 581. If slower than the planet's year, could it lead to orbital decay (like Phobos & Mars) & that Gliese 581 C may have once orbited much further out, thus being extremely cold, only warming up relatively recently .<br /><br />Like my last load of questions yesterday, I expect that it will be a very long time before these can be answered.<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>

 

[kelvin_zero]

Isnt the news here really ''hey we are getting good enough to find pretty small planets now?".<br /><br />Our own solar system has 3 worlds around the habitable zone. I havent heard any argument that this is atypical.<br /><br />Would you agree we can expect a stream of better and closer candidates as detection methods improve?

 

[MeteorWayne]

Well, not when they're young <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>

 

[3488]

I understand that the Red Dwarf Kapteyn's Star is one of the oldest in our neighbourhood, possibly 12 billion years old!!! <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>

 

[robnissen]

Its not that Red Dwarfs are older than the sun, its that so far, no Red Dwarf has ever died a natural death. While a few may have wandered into black holes or had some other violent death, it takes around 100 Billion years for a red dwarf to live its natural life. Thus, red dwarfs won't start dying natural deaths fo another 87 billion years or so. <br /><br />But as most stars are red dwarfs, most new stars are also red dwarfs, so there will be many red dwarfs that are younger than the sun.

 

[mithridates]

Planets like these are also interesting in how they provide a different climate either for or against space travel. I suspect that we wouldn't have been so quick to want to get into space if we didn't have a moon right there to explore for example. A planet like this would have an escape velocity of 25 km/s compared to our 11. A world with the same gravity as Mars however has a bit under half that. Since a rocket is a rocket that might not seem like much but if our gravity had been lower and atmospheric pressure somewhat higher (ignoring everything else that comes along with a lower gravity and higher atmospheric pressure of course) we might have been capable of launching rockets into orbit sometime before WWII instead of over a decade after it ended. I wonder how much these environmental circumstances contribute to the quick formation of a space-faring society. Imagine half our gravity, twice the atmospheric pressure, and two moons of 500 km or so each with a high albedo in an orbit only 50000 km or so above the surface. I suspect intelligent creatures in an environment like that would be quick to develop the necessary technology to go see what's up there. These factors could also be included as we find more and more of these planets and try to ascertain which destinations are worth paying the most attention to. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[derekmcd]

"<i>I'm already imagining some kind of microbiological life forms concentrated along a wide path either side of the terminator of the planet because the ideal temps are probably there.</i>"<br /><br />You are assuming the terminator is static which would mean it is tidally locked. I don't think we know this yet. I hope it is not locked, though I think it is more likely than not. A planet being tidally locked would make it very difficult for life to flourish. <br /><br />I don't really have high hopes for discovering life here, but I am really excited we found another planet besides our own with the potential. For me, the excitement is about the skills and the technology improving to such a degree that I am confident more will be found. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[serak_the_preparer]

<i>. . . questions that need to be answered have occured to me...</i><br /><br />This world might also be tidally locked with respect to its star, which still might not necessarily spell doom for any life there. An article by Ken Croswell included two years ago as part of the last post to this thread discusses the possibility of life on worlds orbiting red dwarf suns.<br /><br />Once upon a time, red dwarfs were considered bad candidates for planets with biospheres. Then some people spent some time rubbing their chins and reconsidered. As the article's opening line puts it:<br /><br /><i>It was always thought that any planet orbiting a red dwarf would be an extremely unlikely place to find life. But it now looks as though these dim red suns could harbour most of the Galaxy's life-bearing worlds....</i>

 

[heyscottie]

I always said "GLEECE", but it seems I've heard radio broadcasts saying something more like "GLAYsah"

 

[heyscottie]

derekmcd has pinned it down for me. While this planet is, in itself, a potentially fantastic discovery, the real benefit is likely to be the fact that there are probably going to be a bunch of these found now, so many that we may stop taking notice.<br /><br />When we stop being amazed because of the frequency of new earthlike planet discoveries, that is when the fun begins. When our catalog of potentially habitable worlds gets big, we will start devoting resources and new methods to learn more about these worlds. When some of that information starts coming back, we'll start a whole new cycle of amazement...

 

[mithridates]

Since it's the name of a German astronomer sounds like 'cheese' with a g instead of a ch and a bit of pronunciation of the e at the end. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[heyscottie]

GEEZeh???

 

[ianke]

Is the L silent? <div class="Discussion_UserSignature"> </div>

 

[mithridates]

Sorry, gl instead of ch. The l isn't silent. *^^* <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[rhm3]

Here is another paper I stumbled upon: Detailed Models of super-Earths: How well can we infer bulk properties?<br /><br />In attempt to connect dots...<br /><br />As the paper notes, super-Earths with a large core mass fraction, large ice mass fraction, but low mantle mass fraction are unlikely to exist:<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><br />To explore scenario (2) mentioned above, we contemplate late-stage processes that might<br />influence the final accretionary state of a planet starting from a ’normal’ embrio. Any process<br />that induces the escape of preferentially light elements (solar wind, gravitational escape) will<br />deplete the planet from volatiles, H2O and perhaps silicates forming terrestrial planets (core,<br />mantle+core planets). Conversely, any process that targets heavy elements to be excluded<br />from accretion (like formation of the Moon after the Mars-sized impact onto a proto-Earth<br />(Canup 2004)) would deplete the planet from Fe and silicates forming a light planet (mantle,<br />mantle+water ocean planets). It is difficult to imagine a process that would preferentially<br />retain the heavy and light elements simultaneously and blow-off or prevent from accreting<br />the medium density components (silicates).<br />Based on these arguments we expect that planets with large CMF and IMF and small<br />or non-existent mantles are very unlikely. Thus, the shaded region in Fig 1 is unlikely to be<br />populated.<br /><p><hr /></p></p></blockquote><br /><br />So the idea that Gliese 581c is either a super-Mercury (large iron core, no more surface water than Earth)...OR an ocean planet with lighter core but extensive covering of water...is correct. But the two don't intertwine. <br /><br />Some estimates of the radius yield a planet with a density approaching that of iron, leading to the idea that its an oversized terrestrial planet with a dense iron