Average Seperation

[Basil]

Re: Average Seperation

 

Does it mention any trend as to the types of stars that have planets?

 

Well, the smaller-mass stars react more to any planet orbiting them, so I'd imagine the smaller-mass ones are more likely the ones being looked at. Of course, there are more small-mass stars than large-mass stars.

 

All-in-all, if there's any "trend" it may (or may not) be a result of the search method rather than a result of the actual presense/absense of planets.

 

Oh, and nothing in the article mentioned any "trend". It is more a "Yahooooo!!! Look at all those planets!" sort of article.

[Basil]

Re: Average Seperation

 

You'll probably find tons of info about that on the 'net. One thing' date=' though: the as-yet-detected planets are almost all of the gas giant variety. AFAIK, only one "terrestrial planet" (which means "a ball of rock") could be located, and they're not sure whether it is that or just a very small gas giant.[/quote']

Actually, the article I mentioned says there are two bodies they believe are terrestrial, the smaller of which is still 14 times the mass of Earth.

 

The problem with detecting extraterrestrial planets with curent technology is that one cannot spot them directly with a tetelscope or something- they simply look at the star and try to see when it is dragged a tiny bit towards a direction were it douldn't be dragged' date=' thus assuming that there must be some planetary body whose gravity well draws thestars towards them. The exact size of that (_very_...) tiny bit tells the astronomers how large and heavy the planet is. Humanity will need a lot better telescopes for directly spotting extraterrestrial planets.[/quote']

Two things:

1) One aspect of depending on the star's "wiggle" to detect planets: the planet has to be extermely massive (usually a gas giant) and it has to be orbitting very very fast (on the order of a couple weeks, maximum). The period has to be that short so that the "wiggle" repeats quickly enough that it can be shown to be from an orbiting body, rather than just a random fluctuation (which could be a one-time event, an error in measuring, etc.)

 

2) The article talks about a few groups of astronomers who are working on various ways to "block" the light of the star, so as to see planets directly. IMO, in a just few years, someone will take the first picture of an extrasolar planet. Cool stuff!

[Basil]

Re: Average Seperation

 

Nyrath: thanks for the link to www.extrasolar.net! I just spent over an hour there. Which is why I don't have time to check out your other link tonight. I'll get to it tomorrow.

[Bucky]

Re: Average Seperation

 

Two things:

1) One aspect of depending on the star's "wiggle" to detect planets: the planet has to be extermely massive (usually a gas giant) and it has to be orbitting very very fast (on the order of a couple weeks, maximum). The period has to be that short so that the "wiggle" repeats quickly enough that it can be shown to be from an orbiting body, rather than just a random fluctuation (which could be a one-time event, an error in measuring, etc.)

 

2) The article talks about a few groups of astronomers who are working on various ways to "block" the light of the star, so as to see planets directly. IMO, in a just few years, someone will take the first picture of an extrasolar planet. Cool stuff!

 

1) True but only sorta. It depends on how long you look at the star. The longer you look, the longer period of a planet you can pick up. If you look at the sites mentioned, you will find planets with much longer orbits.

 

The shorter the orbital period, the easier it is to find the planet. But the longer period planets are still findable. It just takes longer.

 

2) And there is also interferonmeters being built to do the same trick without cancelling the light from the central star (Or rather, canceling it out via a different method.) This is great because once you get an optical image of the star, you can run it through a spectroscope and determine if it has an oxygen atmosphere.

 

You got an oxygen atmosphere, you got life.

[Basil]

Re: Average Seperation

 

1) True but only sorta. It depends on how long you look at the star. The longer you look, the longer period of a planet you can pick up. If you look at the sites mentioned, you will find planets with much longer orbits.

 

The shorter the orbital period, the easier it is to find the planet. But the longer period planets are still findable. It just takes longer.

Jupiter's siderial period of revolution is ~11.9 years. Watching for a similar planets is going to take decades. After all, you'll need a few revolutions to get enough data to prove it's an orbiting body, not a hiccough in the data.

 

2) And there is also interferonmeters being built to do the same trick without cancelling the light from the central star (Or rather' date=' canceling it out via a different method.)[/quote']

That just one of the methods the article discusses. That's why I put "block" in quotation marks.

 

This is great because once you get an optical image of the star, you can run it through a spectroscope and determine if it has an oxygen atmosphere.

 

You got an oxygen atmosphere, you got life.

I think you meant to say "...an optical image of the planet..."

And oxygen is not the only possible "life-formed" chemical to look for. There's also free clorine & fluorine, hydrogen sulfide (IIRC, it reacts quickly enough to disappear from an atmosphere), and I believe others that won't be around in a equilibrium atmosphere.

[Bucky]

Re: Average Seperation

 

I think you meant to say "...an optical image of the planet..."

And oxygen is not the only possible "life-formed" chemical to look for. There's also free clorine & fluorine, hydrogen sulfide (IIRC, it reacts quickly enough to disappear from an atmosphere), and I believe others that won't be around in a equilibrium atmosphere.

Oh yes, bad typo.

 

I stick with oxygen, because it is my, well, "studied opinion", that life out there will be pretty much like it is here. Carbon based, oxygen breathing, etc. And if you have an intelligent species, it will be pretty much some kind of bipedal critter, much like humans are. You need long chain polymers, which means carbon. Silicon is just not reactive enough. (Carbon dioxide is a gas at standard temperature and pressure, silicon dioxide is sand.) Oxygen usage provides something like 10 times the energy that using Hydrogen sulfide does.

 

And it appears you need a bipolar liquid medium to, well, "grow" life. The range of chemicals, let alone naturally occuring ones that fit that bill are severally limited. Water is great. Other liquids, not so much. Either the range in which they are liquid is too narrow, or they lack even the essential bipolar nature that water has.

 

You are right that evidence of clorine, flourine and hydrogen sulfide in an atmosphere might indicate life, as these chemicals would be depleted without it. But I don't think it would be anything but basic bateria. And definitely not a place I would want to spend my vacation at.

[Nyrath]

Re: Average Seperation

 

Professor Steven A. Benner maintains that water is not an essential ingredient for life, though Isaac Asimov could have told you that back in 1963.

[Bucky]

Re: Average Seperation

 

I am familiar with those arguments. I think there is a problem in that, without such a liquid, (i.e a bipolar one) you don't get lipid formation required to make cell walls. Without cell walls, well, you don't really get life forms.

 

Look at the temperature ranges for those other liquids. You see they are all far more narrow than those of water (with the exception of molten sulfer).

 

The problem with silicon life forms is that silicon compounds are too stable. Whatever life that arrose using such chemistry would be incredibly slow.

 

Funny you should mention Asimov, as it was another of his essays that got me thinking like this. About how, if life is out there, it pretty much has to follow the same chemistry as here.