Red dwarfs with planets: low metallicities

[newmoon]

From KenCroswell.com:<br /><br />Three of the nearest red dwarf stars with planets all have LESS iron than the Sun, say astronomers in Texas. The discovery is a surprise, because heavy elements like iron make up the bulk of most planets in the solar system.

 

[djtt]

thats 3 out of god knows how many though

 

[qso1]

Proving once again, astronomy is full of suprises that the astronomers are willing to admit so to speak, suprises them. <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>

 

[alokmohan]

Fine,Universe is stranger thanwe can imagine.But the web says M dwarfs may have life.Premature to suggest.

 

[qso1]

I agree with that. It is premature to suggest planets orbiting M dwarfs may have life. I would want to see spectroscopy of a planet orbiting an M dwarf or any star for that matter at the very least and even spectroscopy wouldn't constitute proof. It would be quite compelling however if the spectral data resembled earths spectrum. But at the same time. The statement was probably made because the scientists cannot say Mdwarfs cannot have planets that support life. <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>

 

[mikeemmert]

I read the link and did not see any mention of life whatsoever. The article talked only about metallicity and spectra. Perhaps the author edited it? I made sure I scrolled all the way down and also checked the advertisements (which don't really count, anyway. Money's money.)<br /><br />The article said that red dwarves in general don't have planets. If these are pathological cases, there's no real way to tell what went on at this stage of the investigation.

 

[alokmohan]

Too many pop ups.I shall tell you later.

 

[alokmohan]

I was mistaken.Sorry.

 

[mikeemmert]

I would tend to agree that it's too early to tell if red dwarf systems have planets, but many were included in the initial surveys looking for extrasolar planets, enough to make a preliminary, general statement that is not arm-waving.

 

[3488]

Hi all,<br /><br />It is an interesting find indeed. It was always assumed that planets would form around stars with high metallicities (due to the abundance of elements heavier than Helium). <br /><br />Do we know what these planets are likely to be? <br /><br />Regarding life on a terrestrial planet in orbit around a M type dwarf? I would say forget it. <br /><br />The planet would have to orbit so close to the Red Dwarf (to get enough warmth), that for one, it would likely to have a synchronous rotation (i.e keep one face turned towards its host star all the time, due to the proximity) & two, because of this, the day side would be very hot & the night side, probably slumming around at only a few degrees Kelvin. <br /><br />Also the planet would probably be very close to the Roche Limit, so any major impacts with any asteroids or comets orbiting the Red Dwarf, could smash it.<br /><br />However, an object like Europa or Enceladus orbiting the Red Dwarf or a planet in orbit around the red dwarf, who knows!!!!<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>

 

[newmoon]

<blockquote><font class="small">In reply to:</font><hr /><p>thats 3 out of god knows how many though<p><hr /></p></p></blockquote><br /><br />It's three out of three. The astronomers studied all three of the known planet-bearing red dwarfs. All had lower metallicities than the Sun. In contrast, most Sunlike stars with planets have higher metallicities than the Sun.<br /><br />Since those observations, I've seen a report of a fourth red dwarf with planets.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>But the web says M dwarfs may have life.Premature to suggest.<p><hr /></p></p></blockquote><br /><br />It's surely not premature to suggest the mere possibility.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>I read the link and did not see any mention of life whatsoever.<p><hr /></p></p></blockquote><br /><br />The author bio at the end of the article contains a link to a New Scientist article on the topic.<br /><br /><p><hr />"Red dwarf stars in general do not have planets."<br /><br />Curious. One wonders if the author has sent out several hundred probes and found that out or knows of some alien, space faring species which has. <p><hr /><br /><br />The article doesn't say that. It simply says that astronomers have discovered few planets around red dwarfs. However, if most red dwarfs have only small planets--as might be the case, since these are small stars--then astronomers would not have detected them.<br /><br />Also, note the statement from Gregory Laughlin: he says metallicity should influence the presence of Saturn- and Jupiter-mass planets, but not Neptune-mass and smaller planets.</p></p>

 

[mithridates]

This is a bit of an old article but just in case anybody has missed it it's a good read:<br /><br />http://www.kencroswell.com/reddwarflife.html<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Although it now looks as if a planet orbiting a red dwarf can offer oceans, atmospheres, and a mild climate, such a world would still differ greatly from Earth. It would have no seasons, because the tidal pull of the star would prevent its spin axis from tilting. And one side would be in perpetual light, while the other was in perpetual darkness.<br /><br />The hottest part of a red dwarf planet would be just one spot on the equator--the centre of the day side, where the sun is overhead. On a habitable planet, the temperature at the hot spot might soar to 100 or 120 Fahrenheit. Moving away from this spot, temperatures would drop, falling towards freezing near the dividing line between the day and night sides. On the night side there would be an ice cap covering the coldest part, directly opposite the hot spot.<br /><br />"The daylight hemisphere is going to be where the action is," says Heath. "For one thing, it's going to be pretty cold on the dark side. We know that there are organisms that can sit in water pockets in the ice and carry out photosynthesis, but they can't do that if there's no light getting there."<p><hr /></p></p></blockquote><br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>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 fr</p></blockquote> <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[qso1]

stevehw33:<br />But, and this a big caveat, we do NOT know, that is we have NOT confirmed, that the spectral characteristics of stars in terms of metallicity ALSO allows us to conclude that there are few or many rocky planets/moons around such a star.<br /><br />Me:<br />Agreed. We will have to simply be able to confirm planets exist with larger scopes such as the GMT and I for one look forward to that telescope going into service. Thats about the best I can hope for nowadays since I'm getting up there in years. I won't be around for unmanned star probes. I share your enthusiasm for this telescope and any telescope that will allow for more direct detection including imaging of extrasolar worlds.<br /><br />I tend to think planets probably orbit red dwarfs but they are not likely to harbor life...at least life as we currently understand it. <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>

 

[alokmohan]

Dicussion on this planet is not the article.It is in our mind.I made this mistake.Others have followed.MIKE DETECTED MY MISTAKE.

 

[alokmohan]

Discussion on this planet is not the article.It is in our mind.I made this mistake.Others have followed.MIKE DETECTED MY MISTAKE.

 

[qso1]

Thats good. The discussion about possible planets around Mdwarf stars was still interesting. <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>

 

[alokmohan]

steve,brown dwarfs are my favourite.But will they not be too hot?Epsilon erdiani was a favourite candidate long back,now it has lost its flavour.When Daniken brought aliens to make them God,possibly epsilon erdiani came to mind.Any way mars expedition is not too near,leave aside goimg to stars.Another favorite canditate those days was fomalho(spelling I forget ,sorry).And poor bernard star ,none talks of it.Wish good luck for stellar life.See you in red dwarf or our own yellow dwarf.

 

[qso1]

Whether mars or stars, IMO its going to take a major discovery to send humans. I agree with you on the prospect of sending humans to mars, bleak at best. But for mars, discovery of possible microbiological activity would probably generate enough interest in a mars mission. For the stars, detection of an earthlike world accompanied by a spectrum that strongly suggests life has developed on such a world would likely generate much interest.<br /><br />Of course, this scenario assumes private enterprise/industry does not achieve or has little effect on human spaceflight beyond LEO. <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>

 

[alokmohan]

Mars is our future.Zubrin will be Washington for the new world.

 

[qso1]

I hope so. And though I sound a bit pessimistic, the future often unfolds in unexpected manner. What seems bleak today may well be accomplishment tomorrow. <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>