I’m surprised that HD 154345 seems to exhibit so much jitter though — we’re following it very closely to see if it is, in fact, due to inner planets.

Tom wrote: “Is that a typical error margin for the eccentricity of an exoplanet or is that higher in this case than normal?”

These errors in the eccentricity are typical for signals as weak as this one. For more massive or more close-in planets, the errors are correspondingly smaller. Check our Catalog of Nearby Exoplanets for examples of typical eccentricity uncertainties (http://exoplanets.org).

Tom wrote: “Regarding the search strategy for life, with only two hundred or so exoplanets being known to date (I’m sure the number might climb drastically in the future) is there really a problem with scanning them all with the new space telescopes?”

It’s not just a problem of time (and, yes, 200 targets could easily be too many for something like TPF, depending on the design), it’s also a problem of engineering specifications. These telescopes have to be optimized to some goal. Generally, that goal is detecting a 1 earth-mass planet at 1 AU from a G star. There are trade-offs that make observing other kinds of planets more difficult (although in general, more massive planets are always easier to detect). In addition, the instruments being developed are optimized to look for water and other chemicals indicative of life on Earth. We can’t just look for “anything out of the ordinary”, we have to give the engineers very specific guidance for what sort of signals their looking for.

Tom wrote: “I would agree with the idea of starting with stellar systems similar to ours, or perhaps with planets we think are in the habitable zone (e.g., Gliese 581c) if logistical considerations are a block. On the other hand, I would also pursue a space probe to the seas of Titan (even though they are not water seas, but rather methane seas) since we know that life is a manifestation of the liquid state of matter.”

I, too, am excited at the possibility of looking more carefully at Titan, as well as Europa. Again, it’s a resources issue. If NASA tells us that we can look carefully at either Titan or Mars with a fixed budget (which isn’t how it actually works, but bear with me), then do you look at the closer (and thus much-cheaper-to-get-to) body with a history of liquid water, or the much more distant and costlier body with extraordinary cold ethane lakes?

If money were no object, I think you’d see plenty of missions to find life in some very exotic places. I know several astronomers who have put in proposals to search for life in places even you might find unlikely (supermassive black holes, for instance).

This would be the J.T. Wright listed as an author on the paper? It’s a real pleasure communicating with you, sir. I did not mean to come off as dissing your paper. The more data we can have on exoplanets the better IMHO.

Now that you explain the combination of parameters that HD 154345b has, I didn’t realize that nothing like that had been found before. But I do note in reading the article that you list the eccentricity as being 4.4 percent but with an error of plus or minus 4.6 percent, is that right? So the eccentricity could be as high as 9 percent and still be consistent with your data. Is that a typical error margin for the eccentricity of an exoplanet or is that higher in this case than normal?

Regarding the search strategy for life, with only two hundred or so exoplanets being known to date (I’m sure the number might climb drastically in the future) is there really a problem with scanning them all with the new space telescopes? I would agree with the idea of starting with stellar systems similar to ours, or perhaps with planets we think are in the habitable zone (e.g., Gliese 581c) if logistical considerations are a block. On the other hand, I would also pursue a space probe to the seas of Titan (even though they are not water seas, but rather methane seas) since we know that life is a manifestation of the liquid state of matter.

You’re right that long-period planets are not new — though this is one of the longest periods yet discovered. You’re also right that HD 154345b is not particularly low mass, though it is the smallest of all of the planets you list. You’re also right that circular orbits are not unknown outside the Solar System — though they are pretty rare and HD 154345b is by far the most circular on your list. But this system is the first to have all of those properties at once, and the first to look almost exactly like our Sun would look if we were observing it from a distant star with present technology.

As for the charge of chauvinism, I think that all of the exoplanets are interesting. On the other hand, it has long been an outstanding problem that so few long-period exoplanets have circular orbits like our planets.
Your cut of e=0.3 for “circular-ness” is rather generous — half of all exoplanets have e < 0.3, but the (now) eight planets in our Solar System all have eccentricities much less than that. It’s important to planet formation theory to see that there are other exceptions as well.

Finally, as for the life thing, most astronomers will enthusiastically agree that we have very little idea what form extraterrestrial life will have if and when we eventually discover it (and we’re pretty imaginative people!). But throwing up our hands and saying “it could be anywhere!” does not lead to a plan for finding it. Building space telescopes costs billions of dollars and requires detailed specifications, so we have to have very specific targets in mind. Lacking anything else to go on, prudence dictates that we look in the most likely places first, and based on the quick development of life on Earth in water, that means oceans on rocky planets. In short, the reason we look for Earth analogs isn’t that we can’t imagine where else life would form. The reason is that we have limited resources and have to start somewhere.