Stars like our sun?!

[c8lindawn]

Hi Guys,<br />I'm totally new, but LOVE astronomy. Just have a very amateur question. HOw many stars, other than our sum are presently believed to have planets orbiting them?<br />I'm tried looking around the internet, but I haven't found a consistant figure yet.<br />Thanks so much everyone!<br />-Caitlin

 

[unlearningthemistakes]

plenty are the stars this universe have. You can try comparing them to all the particles of sand in all the beaches of this earth.<br /><br />There are lots of stars with planets/planetoids around them. <br />But something like this earth? <br />yet to be found... <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[formulaterp]

The number currently stands at 155 planets orbiting around 133 stars, but it depends on how recently a given database is updated. Also there may have been cases where suspected planets were later ruled out during follow-up observations.<br /><br />The best website to keep track of this is probably http://planetquest.jpl.nasa.gov/index.cfm<br />

 

[newtonian]

c8lindawn - We don't know.<br /><br />Note that many stars are like our sun in having planets, but are unlike our sun in many other ways.<br /><br />Likewise, with many different types of solar systems with planets.<br /><br />For example, many of the observed solar systems have very large planets in close solar orbits which would destroy any earthlike planets in orbits similar to ours.<br /><br />Jupiter's stable fairly circular distant orbit is at a very good distance to protect earth from comets and asteroids.<br /><br />This is not your typical solar system!

 

[mooware]

<font color="yellow">This is not your typical solar system! </font><br /><br />Fact of the matter is we do not know that. We have only observed the tiniest fraction of stars in an immense universe. We detect massive planets in tight orbits around their stars because that's all our technology will allow for, for the moment.<br /><br />

 

[newtonian]

mooware - Hi!<br /><br />Good point - I should have been more humble - sorry about that.<br /><br />Haven't we detected an earthlike planet recently?<br /><br />My point is based partly on observation and partly on extrapolation of probability.<br /><br />For example, what would the probability be for a Jupiter size gas giant to be in such a benevolent orbit for an earthlike planet in an orbit conducive to life as we know it?<br /><br />Compare, for example, Drake's equation.<br /><br />Note also elliptical gas giant orbits actually observed.

 

[rhodan]

<i>For example, what would the probability be for a Jupiter size gas giant to be in such a benevolent orbit for an earthlike planet in an orbit conducive to life as we know it?</i><br /><br />A Jupiter size gas giant may also have moons that may be conductive to life. Our own Jupiter size planet -Jupiter <img src="/images/icons/wink.gif" />- has a moon that may harbour life: Europa. A Jupiter size planet inside a star's ecosphere may proof to be a candidate for life, intelligent life even.<br />

 

[mooware]

<font color="yellow">Haven't we detected an earthlike planet recently? </font><br /><br />If memory serves it's earthlike in the fact that it's rocky. It's supposed to be something like 13 times more massive than Earth.<br /><br /><font color="yellow">My point is based partly on observation and partly on extrapolation of probability. <br /><br />For example, what would the probability be for a Jupiter size gas giant to be in such a benevolent orbit for an earthlike planet in an orbit conducive to life as we know it? </font><br /><br />Difficult to come up with any a probability one way or the other, based on the limited data. Again, our observation methods are in thier infancy.<br /><br /><br /><br />As for the Drake equation. You could really just plug in any number you want. Alot of the variables are unknown.<br /><br /><font color="yellow"> Note also elliptical gas giant orbits actually observed </font><br /><br />Again, our observation is a tiny fraction of what is out there, and our technology does not currently allow for better observation.<br />

 

[newtonian]

rhodan - True.<br /><br />I was more thinking of human type life. The discovery of extremophiles has changed our expectations of environments that can support earth type life.<br /><br />I am aware that intelligent life forms can be totally different in form than earth-life. E.g.: angels.

 

[mooware]

<font color="yellow"> am aware that intelligent life forms can be totally different in form than earth-life. E.g.: angels</font><br /><br />How about sentient beings that are not angels or demons or any of their ilk

 

[newtonian]

mooware - How about considering that angels = superior extraterrestrial life forms?<br /><br />In which case we are talking about the same thing but with different words - aka semantics.<br /><br />I hope you do not think all superior life forms are necessarily good instead of bad (as in angels vs. demons)!<br /><br />That would be a very dangerous assumption to make!

 

[mooware]

Never said anywhere or implied that extra-terrestrial, Not necesarily superior, were all good.<br /><br />No we are not talking about the same thing. You are implying that all superior life forms are angels, or demons or whatever. I'm suggesting leaving angels and demons out of the equation.<br /><br />Is it not also a dangerous assumption to make, that all superior life is either and angel or a demon..? Provided of course superior life is found, or any other life for that matter.<br /><br /><br />

 

[newtonian]

mooware - How did I imply angels and demons are the only superior life forms out there?<br /><br />Absence of evidence is not evidence of absence!<br /><br />I have no idea how many extraterrestrial life forms were created in our universe and other universes.<br /><br />Angels are the most superior life forms out there, but they are so far superior to us (I do not know the math ratio, btw) that this leaves open the possiblity of a googol (to pick a number from the hat) of life forms in between our intelligence, power, etc. and that of angels.<br /><br />And there are likely many forms of angels (besides cherubs and seraphs, for example).<br /><br />Consider, for example, this implication (implications can be misread or misinterpreted, btw):<br /><br />(1 Corinthians 13:1) 13 If I speak in the tongues of men and of angels but do not have love, I have become a sounding [piece of] brass or a clashing cymbal. . .<br /><br />If (if is a BIG word) there are plural languages (= tongues) of angels, than it may logically follow that there are plural types of angelic life forms. <br /><br />BTW - this subject belongs on SETI - it is way off thread theme!!!

 

[rogerinnh]

Stars like our sun ???<br /><br />That's wrong. Stars do not like our Sun. In fact, stars are very jealous of our Sun.

 

[mooware]

You didn't imply ALL life forms apart from our own are angles, but you did bring the whole angel thing up. We weren't even talking about them. <br /><br />We were talking about stars that are sunlike, then someone brought up life, then you tossed in angels. <br /><br />My point is can we have a conversation regarding other sun like stars, and other probability of life without bringing up the supernatural?<br /><br />

 

[formulaterp]

mooware,<br /><br />There is very little to be gained by arguing wih him about this. We live in a pluralistic society where tolerance is paramount. You just have to learn to respect other people's superstitions.

 

[newtonian]

mooware - And it also helps to have a sense of humor - you posted:<br /><br />"You didn't imply ALL life forms apart from our own are angles,"<br /><br />It does indeed help in scientific research to consider different angles.<br /><br />Seriously, this tangent is due to one reason for astronomers search for earthlike planets around stars like our sun, namely: extraterrestrial life.<br /><br />And the fact that extraterrestrial life may well be quite different in form from earth-based life.<br /><br />In other words, how different can solar systems be and still harbor life?

 

[newtonian]

formulaterp - Thank you - sort of.<br /><br />Tolerance is indeed important.<br /><br />However, you should note that those of my faith reject the common superstitions involved with angels and demons - including those involved in Halloween.<br /><br />We do, however, accept the Bible as scientifically accurate.<br /><br />For example, in regards to the differences in stars:<br /><br />(1 Corinthians 15:41) . . .in fact, star differs from star in glory.<br /><br />The context compares the variety in life forms on earth - which indeed has amazing variety!<br /><br />Is the Bible really accurate in comparing the degree of variety in earth's life forms with the variety of radiant glory of stars?<br /><br />Astronomers are finding this is true - with more and more types of variety being found.<br /><br />Take, for example, our sun's radiant magnetic glory. Astronomers have found that our star's (sun's) corona is extremely hot due to many magnetic fields "floating" from deep in the interior (possibly all the way from the core) to the surface.<br /><br />The extreme power of these magnetic fields is caused by some sort of dynamo type propagation - likely ions in motion.<br /><br />While observations of other stellar magnetic fields is limited, it is known that there is great variety in the strengths of these fields.<br /><br />In fact, some stars have such strong magnetic fields that they evolve (=change) into magnetars!<br /><br />See the relatively recent article in Scientific American on Magnetars.<br /><br />There really is amazing variety out there - and this variety causes an equally amazing variety of stellar nebulae such as those caused by Novae or Supernovae.<br /><br />It never ceases to amaze me how beautiful some of those Hubble photographs of this variety are!

 

[mooware]

Angles, Angels. Uh, I'll mark that one down to a long day..<br /><br />

 

[mooware]

<font color="yellow">We live in a pluralistic society where tolerance is paramount</font><br /><br />Of that I am certainly thankful. I believe that's our greatest strength. Unlike other societies which don't need to be discussed here.<br /><br /><font color="yellow">You just have to learn to respect other people's superstitions</font><br /><br />Certainly, Mr. Newtonian is entitled to believe what he pleases. I believe he is aware that I do respect his right to believe, as I have certainly told him before. However, while I respect his rights. I don't necesarily have to agree with them.<br /><br /><font color="yellow">There is very little to be gained by arguing wih him about this</font><br /><br />I know, it a lesson in futility. But sometimes can't help myself.<br />

 

[newtonian]

mooware - I would suggest actually addressing some of the scientific references - like Scientific American on Magnetars.<br /><br />I think you will learn some fascinating things that way!<br /><br />And I don't mind your disagreeing on various points - thats how one refines understandings and avoids errors - by weighing, analyzing, different viewpoints, models, theories, data, etc.

 

[mooware]

<font color="yellow">I would suggest actually addressing some of the scientific references - like Scientific American on Magnetars</font><br /><br />What has that to do with considering angels as actual life forms, and your probability of Sun like solar systems low? Remember, there is little evidence to suggest our system is rare, or abundant based on what we have gathered thus far.<br /><br />

 

[newtonian]

mooware - Thread theme: Stars like our sun.<br /><br />Relevancy: will stars like our sun turn into Magnetars?<br /><br />Or are stars that turn into Magnetars quite unlike our sun?<br /><br />I am simply noting there are many ways stars can be unlike one another, i.e. different from our sun.<br /><br />A related way, also relevant, is the variant temperatures of other stars coronas relative to their surface temperatures - which relates more to how stellar magnetic fields propagate than to the mere strength of stellar magnetic fields.<br /><br />Our sun generates magnetic fields by internal dynamoes involving ions in motion, probably from the core to the surface.<br /><br />This also involves the specific tidal interactions of the sun with the earth, which is causing earth's orbit to recede slighty (add this to the recession caused by the rate of loss of mass of our sun - another factor very variable among different stars).<br /><br />Internal motion of our sun, which generates magnetic fields, also effects tidal interactions, and is effected by tidal interactions.<br /><br />One can expect, for example, that stars with massive planets nearer to them will have much stronger tidal interactions and much more effect on said star's internal motions. <br /><br />All of this is relevant to thread theme.

 

[formulaterp]

Newtonian,<br /><br />How exactly is the tidal interaction between the Earth and the Sun affecting the Sun's magnetic field?<br /><br />Do you have a link for further info?<br /><br />Regarding the main thread topic: As mooware has pointed out, we do not have enough info at present to say that our Solar System is either rare or commonplace. The technology to detect other star systems such as ours does not exist yet. There are however, a number of initiatives under way which will provide this capability in the coming years such as the planned Kepler and Terrestrial Planet Finder missions.

 

[raghara2]

Some notes<br /><br />Actually the nearest bi/trinary star system could have two perfectly habitable zones. IIRC < 3 AU from the nearest star. Because alpha is pretty simillar to sun you can easily plug all important numbers into the equation. Of course deviation from the plane described by rotation of A and B would highly decrease stability of orbits, however such orbits are less likely anyway so why worry.<br /><br />Also note that retrograde orbiting planets have much smaller restrictions (irregularities in the combined gravity field would affect them much less). Of course such planets would probably appear by interaction in stellar nurseries, so they might have any orbits close to the plane.<br /><br />And when we look at trinary systems, we might look at figure eight orbits as well. Sufficiently lose, or close, figure 8 orbits could have habitable planets as well. <br /><br />Red dwarfs are more likely to have flares, but planets around red dwarfs are also more likely to be tidally locked as well. This means complex behaviour of flora tailored to survive regular flares might emerge, by for example sending seeds into superrotating streams, and when things will calm down reseed the inward side. So flares might be something as bad as winter, nobody likes them, but they are survivable.