Kepler Reveals New Worlds
NASA Releases Kepler Survey Catalog with Hundreds of New Planet Candidates
“NASA’s Kepler space telescope team has released a mission catalog of planet candidates that introduces 219 new planet candidates, 10 of which are near-Earth size and orbiting in their star’s habitable zone, which is the range of distance from a star where liquid water could pool on the surface of a rocky planet. With the release of this catalog, derived from data publically available on the NASA Exoplanet Archive, there are now 4,034 planet candidates identified by Kepler. Of which, 2,335 have been verified as exoplanets. Of roughly 50 near-Earth size habitable zone candidates detected by Kepler, more than 30 have been verified.”
So, if that is 50 Earth-like planets for $550M, that’s working out to $11m per Earth-like planet.
Bargain.
One of the most useful and valuable Discovery Program missions ever done.
It sure has changed my daily routine!
Or, only $136k per exoplanet candidate many of which are just as interesting scientifically as the Earth-like ones. It really is a bargain.
Measuring the value of a scientific endeavor in the short term as you do ignores the long term value of the knowledge gained from the investment.
If such analysis were the standard, almost no one would invest in primary scientific research.
What’s the data on the ten new near-Earth-size planets they found? Are they orbiting sun-like stars, or are they red dwarf planets like most of them?
I’m not finding a wealth of information on the web sites linked to the press release or the Kepler project’s web page. I suspect it’s a mix. Red dwarf stars are very common, and I wouldn’t expect the new data to change the trend of most planets orbiting them. Possibly a slight shift in the trend: Planets in the habitable zone of larger stars are, inherently, on longer period orbits. That means more observing time is required to detect them, and transit observations like Kepler are less likely to see them.
Personally, I think they should rethink this term, “near Earth-analogs”. Currently, it’s based on the planet’s mass (times sin(i)…) or its radius (relative to the star’s radius and a few other things) and a guess at the temperature (actual temperature measurements are extremely rare at the moment.) It is worth noting that Europa, a favored target for astrobiology within our solar system, fails the temperature and size criteria. One could easily argue that tidal locking to the star is an equally important to habitability. Or being a large, close moon of a distant gas giant. So the “analogs” mentioned in this press release may not be terribly relevant analogies.
Oh. Wait. I’ve just said something about how to classify planets. With all the fuss over Pluto, maybe that’s a place I don’t want to go…
I don’t think “near-Earth analogs” is bad. Maybe if we were saying these were “habitable planets” it would be, because Europa and Enceladus suggest that worlds that are very un-Earthlike can potentially have biospheres (or at least we’ll find out if that’s true when we get around to sending new probes out there). But “near-Earth analog” is fine.
I’m hoping at least a few of them are around G- or K-class stars, and that they actually are close to Earth in radius. There’s been some previous releases where they referred to planets with “two times Earth radius or less” as “Earth analogs”, and that just strikes me as wrong – a lot of the modeling and data suggests that we should hesitate to call anything with a radius greater than 1.5 times Earth “earth-like” or even “rocky”, and a fair number of planets might be “sub-Neptunes” down to about 1.2 times Earth’s radius (and that’s not even getting into outer solar system potential gas giant “cores” that migrated inward before they could grab much hydrogen gas, and thus have giant water mantles).
IIRC There are limits to how big of moons can accrete around gas giants, such that even a single large moon around a planet with ten times Jupiter’s mass wouldn’t be much more massive than Mars. Then there’s the tidal effects, the weird light/darkness cycle, the gas giant’s gravity well pulling stuff in that then might impact the moon, etc. I’m not really convinced about them potentially being earth-like, unless they’re oceanic under-ice ecosystems.
That’s why I ended my comment with a remark about Pluto and classications of planets. The terms have implications and baggage which mean different things to different people. To some people, a “near Earth analogue” means a place where life could have evolved. To others, it simply means certain, specific physical similarities. Trying to make the technical criteria match the wildly varying implications people have is a mess. In a very different subject, someone once used the term “a maze of mirrors” to describe a similarly messy problem.
When I wrote, “large, close moons” I was thinking of Europa or Titan-sized ones, with potentially habitable, subsurface oceans. (And I’m still trying to get people to call the one in Europa the Mediterranean, since that’s almost literally correct.) But I wouldn’t rule out Earth-sized ones. We don’t really understand how large moons in our own solar system formed. Any theoretical limit on the size of a moon is a bit dubious.
Europa is a target by default, there being no obviously-hospitable solar system cranny. It’s a bit like the last hope.
In a sense, it’s also an unending hope. That ocean is awfully hard to get to, and transport of material from the ocean to the surface (by natural processes) may be very slow and limited. It may take a century before we can really say anything definitive about life in that ocean. That’s a paradise for theory and speculation.
“a paradise for theory and speculation”
Sorta like Mission to Mars, one supposes.
You can find orbit and stellar parameters for new planets in this latest Kepler release from the NASA Exoplanet Archive. You can just read the numbers off the “Habitable Planet Candidates” graphic and search for them. Looks like they orbit a variety of stellar spectral types from M to G.
https://exoplanetarchive.ip…
The Kepler News site also did a post specifically on the 10 planets, including a chart showing them in size, stellar insolation, and star surface temperature.
They are only planet-candidates, but three of them look really promising.
1. KOI 7711.01 is 1.31 times Earth’s radius (with an error range), around a sun-like star. That’s a bit bigger than the 1.2 times Earth radius threshold, but there’s still a very good chance that it’s a rocky planet. The error range on the size and solar insolation is a bit troubling, but it still seems good.
2. KOI 7923.01 is nearly an Earth-twin in radius, at 0.97 times Earth’s radius (with a small error range) – closer than Venus!. They must have screwed up the size chart on that one, because it’s showing as bigger than that on the chart versus the size they give at your link. Only downside is that it gets about 0.44 times the solar insolation of Earth – that’s not much more than Mars.
3. KOI 8174.01 is about 20% bigger than Mars, with significantly stronger sunlight.
The others are either too big or too close to their stars, or in the case of KOI 8012.01 too small and cold.
well, you pulled a lot of info from one slide ! I found a bunch of data at caltech’s exoplanetarchive.ipac site (if you know the koi number). 7923 is very much an earth twin.
That’s why I said the chart screwed up. They portrayed the planet on the chart as bigger than Earth, even though it’s a near-Earth twin that is very likely smaller than Earth (barely).
If it gets confirmed at roughly the same radius and solar intensity, it’s hands-down the most promising potential exo-Earth. The size is right, the sunlight is acceptable, even the year is close to Earth’s (395 days in the year vs 365 for Earth). It’s a pity it’s probably too far away for a plausible direct imaging mission in the future to further study.
The more worlds Kepler discovers, the more we see how lucky the Earth is to be in the Solar System it is in. It appears to be a very stable one, which is unusual, and the Earth is also lucky to have a large moon to stabilize it. No wonder the search for SETI has had such poor results.
If the planet doesn’t have a large moon, there’s no point in getting excited.