It is possible that most of the planets confirmed thus circling far TRAPPIST-1 could be in the star's habitable zone. The inner 6 planets are probably rocky in composition and may be just the right temperature for liquid water to exist (between 0 - 100 degrees C) - if they have any water, that is. The outermost 7th planet still needs some more observations to nail down its orbit and composition.
I appreciate the excitement in scientific circles but, as I understand it, TRAPPIST-1 only barely classifies above a Brown Dwarf. That makes for very tight orbits to make for a thermal 'goldilocks zone'.The problem I've always had with these dim red dwarf 'habitable zone' planets is that all the other physical characteristics are likely to make them sterile, most notably being tidally locked, really close to the photosphere (and thus likely to be bathed in lethal X- and UV-radiation levels) and probably without atmosphere due to lack of magnetic field )due to said tidal locking) and close proximity to the primary. They make for useful studies and doubtless have their own unique charms (Pluto has taught us that there is no such thing as an 'uninteresting planetary body'). I guess I just have difficulty hyping these bodies up in my mind.In my mind, with current sensing capabilities, the optimum habitable target world we're likely to find would be a hypothetical Galilean Moon-sized object orbiting a detected 'Warm Jupiter' in the habitable zone of a K- to A-class primary.
Anyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.
Quote from: Alpha_Centauri on 02/22/2017 12:31 pmAnyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.I doubt "b" ... given the resonances, I expect it's Io-like due to tidal heating. On the plus side, this means those nearer the ice line may be warmer than just flux would suggest, though I haven't run any numbers.On planets around M dwarfs in general, like Ben, I'm sceptical due to both locking and desiccation when the stars are young.--- Tony
Is that all we're going to do be downbeat about this, no wonder those in society who devalue science are having so much success these days.
The exoplanets around TRAPPIST-1 are almost all very nearly the same mass or slightly more massive than the Earth, so we should expect they would be likely to have an atmosphere.
Quote from: Alpha_Centauri on 02/22/2017 12:31 pmAnyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.I doubt "b" ... given the resonances, I expect it's Io-like due to tidal heating. On the plus side, this means those nearer the ice line may be warmer than just flux would suggest, though I haven't run any numbers.
Quote from: Star One on 02/22/2017 01:24 pmIs that all we're going to do be downbeat about this, no wonder those in society who devalue science are having so much success these days.Why do you think this is downbeat? I'm sceptical over the habitability of planets around M dwarfs. That doesn't make them uninteresting or even mean there aren't plenty of habitable planets around other types of star.It also doesn't mean I'm ruling it out, just that there are good reasons to doubt that just because a planet is in the HZ means it is at all close to being Earth-like or habitable. Much depends on system formation, and most models don't allow enough volatiles for atmosphere / water to survive the initial flare activity.--- Tony
Did I imagine it or did I read that they had spent 1500h observing this system using the HST.
Quote from: Star One on 02/22/2017 03:25 pmDid I imagine it or did I read that they had spent 1500h observing this system using the HST.I missed the article when it was up, but there's no way they could've gotten anywhere close to that number of hours.edit: I think 1500 hours refers to total time with all telescopes including Spitzer, on which they did get several hundred hours. A quick look at accepted proposals shows about 40 orbits of HST observations.
edit: I think 1500 hours refers to total time with all telescopes including Spitzer, on which they did get several hundred hours. A quick look at accepted proposals shows about 40 orbits of HST observations.
Owing to over 1500 hours of monitoring including a recent 20-d long follow-up with the Spitzer Space Telescope, we have now constrained the architecture of TRAPPIST-1's system up to its ice line
Other researchers are already using the Hubble Space Telescope to hunt for atmospheres on the TRAPPIST-1 planets. Kepler is also observing the system and will gather data that can better pin down the planetary masses, says Courtney Dressing, an astronomer at the California Institute of Technology in Pasadena. And the TRAPPIST team is building four new 1-metre-diameter telescopes in Chile to continue the work.“For all the worlds that we see in science fiction, these are even more extraordinary,” says Hannah Wakeford, an exoplanet scientist at Goddard.
The Hubble Space Telescope characterized the atmospheres of TRAPPIST-1B and TRAPPIST-1C, finding that the two worlds probably aren't encircled by hydrogen and helium rich atmospheres, meaning their atmospheres could resemble our own. Researchers will be able to get an even better look at these worlds in the future.NASA's James Webb Space Telescope (JWST) — Hubble's telescope successor expected to launch in 2018 — should be able to peer deeply into the atmospheres of alien planets to try to see if they really could be like our own.