Hubble Discovers a Hundred New Planets 395
Spudley writes "The BBC is reporting that the Hubble Telescope has discovered over a hundred new exoplanets - a number which almost doubles the total known. Apparently they are also expecting to be able to analyse the atmospheres of up to 20% of them. The discovery will be confirmed within the next seven days."
Re:Class M (Score:5, Informative)
None. If you RTFA, you'll see that the method used is to measure a dimming of a star, which can (but doesn't have to) be from a planet passing in front of it. For this to be measurable over the natural fluctuations of a star, the planet will have to be a giant.
Of course, the precense of one or more giant planets in a system increases the chance of habitable planets, as the giants acts like vacuum cleaners, keeping the smaller ones relatively undisturbed.
Regards,
--
*Art
Found It!! (Score:5, Informative)
So how many of those 200-odd planets that we know of are capable of supporting carbon-based life? You crunch the numbers . . .
Re:Too bad... (Score:5, Informative)
But it's not too bad since there will only be a 4 year gab (or so) between both satelites.
How do they analyze the atmospheres of... (Score:3, Informative)
Re:WHAT... (Score:0, Informative)
Re:Atmosphere? (Score:2, Informative)
Re:MUST SHUT DOWN HUBBLE! (Score:5, Informative)
Hopefully the upgrades will be good enough to complement the James Webb Space Telescope [nasa.gov] scheduled to launch in 2011. I can't wait to see if they redo "deep field" picture with this, it would be truely stunning.
Re:Atmosphere? (Score:5, Informative)
But once you've found a planet that big, you can look even more closely and see what color changes you observe during the dim period. You can chalk that up to wavelengths of light absorbed by the planet's atmosphere, which you can use to hazard a guess as to what the planet's made of.
In all likelihood it's pretty much the same as Jupiter, which is to say pretty much like the sun itself: mostly hydrogen and some helium. But you might be able to detect faint signals of nitrogen, oxygen, maybe some carbon, and perhaps a bit of ammonia. The ratios of hydrogen to helium will suggest a lot about the way the planet was formed.
Re:How do they analyze the atmospheres of... (Score:3, Informative)
Re:Too bad... (Score:5, Informative)
However, the new telescope won't see in the visible spectrum like Hubble does.
This makes the new telescope less interesting to me.
Re:WHAT... (Score:3, Informative)
The up to date list (minus these recent 100) can be found at exoplanets.org [exoplanets.org]
Submitter misread article (Score:5, Informative)
This is incorrect, probably based on a misreading of this quote: "If this is confirmed, in seven days we will have doubled the number of planets known in nine years."
The article states that Kailash Sahu, the astronomer who made the discovery, did so during an observation period of seven days. According to the director of the Space Telescope Science Institute, they don't expect final results until September or October.
Re:Too bad... (Score:4, Informative)
A minor correction: VLT and adaptive optic systems allow ground-based systems to do better than Hubble in the visible portion of the spectrum. For IR and UV stuff that never makes it thru the atmosphere, a space-based telescope is the only option.
Re:Found It!! (Score:5, Informative)
Although it's certainly an interesting equation to think about, its main problem is that we don't really know what most of the factors are. You can support guesses that result in anything from hundreds of thousands of civilizations in the galaxy, down to it being suprising that there's even one.
Rather than predicting the number of these planets that have life, the observations are more likely to help us get a better idea of what some of those factors are. Actually, though I didn't RTFA, my understanding is that most or all of the planets they discover are gas giants, often bigger than Jupiter. So, it's unlikely that any of them have life on them -- at least, life as we expect to find it. However, it will give us a better idea of how many stars have planetary systems, and studying their atmospheres might give us some clues as to whether the system would contain planets suitable for life.
Re:And we are retiring this why? (Score:5, Informative)
Hubble is still profoundly useful, and even its proposed successor, the James Webb Space Telescope, cannot probe the same regions as HST. The reason has to do with the filters hooked up to it. James Webb is designed to view the highest redshift objects, so its filters are very red. The "bluest" light it can observe is about 600 nm, which appears yellowish-orange to our eyes, up to about 2000 nm, far into the infrared. HST can observe wavelengths between ~200 nm (ultraviolet) and ~850 nm (near infrared). I don't know why people keep spouting off that the James Webb is a superior replacement to HST, because it probes an entirely different type of light.
It's also worth noting that all of these extra-solar planets are gas giants, comparable to Jupiter-sized objects. The reason people are interested as far as life goes is not that they expect to find life on these planets, but that these planets may be indicators of other, Earth-type planets, in the same solar system.
Re:Too bad... (Score:3, Informative)
Re:Found It!! (Score:3, Informative)
Also, life-supporting planets is only one factor of many in the Drake equation. Others are _much_ more contentious, like proportion on which life arises, and proportion of life bearing planets that give rise to civilization. Disagreements on those two tend can be in large orders of magnitude.
Re:Too bad... (Score:5, Informative)
Re:Wow. (Score:3, Informative)
The observation wasn't done directly, ie Hubble didn't see bodies orbiting stars. Hubble can see pretty well, but it can't see that well.
How the observation is done is by analyzing minute Doppler variation patterns in the spectral signature of the stars, filtered through an iodine spectral mask.
As the spectral signature of the star drifts from left to right you can determine how many bodies are orbiting, and the approximate masses of those bodies. When you get an occultation (planet passing in front of the star) you can register the difference in the direct spectral pattern of the star to determine the atmospheric characteristics of the occulting planet (ie, the star's spectral signature is mostly hydrogen, and for a little while we see traces of heavier elements as the occulting planet's atmosphere filters a bit of the starlight reaching us).
Re:Too bad... (Score:5, Informative)
Second, the new JWST will only work in the near infra-red. That is fantastic for cosmology, star formation and certain other sciences, but will not help with the optical and near-UV science that HST can provide.
And finally, while adaptive optics at most new ground based telescopes are doing great things, there are still _severe_ limitations to their use: only small fields of view are available and bright stars need to be nearby in the sky (this greatly limits the fraction of the sky that can be viewed by these systems). Note: yes, sodium laser-based AO systems can fix some of these problems, but the lasers are currently highly problematic and the systems have very low observing efficiency (i.e. useful scientific data per unit of telescope time).
So bottom line is that HST will be sorely missed by astronomers/astrophysicists. And yes, as a professional astronomer, I will be one of those missing it (even though most of my work is in the radio).
Re:Wow. (Score:5, Informative)
They have considered it, thanks. Also scopes on the Antartic high ice cap, and earth-trailing, and at 5 AU, and at L2.
Why is there always an assumption that the folks at NASA are idiots? Or is that just the usual
It's incredibly expensive to softland devices on the moon, compared to orbiting them in space. There's no solar power for two weeks at a time, so you'd have to use nuclear, which limits the amount of power you can get (and nuclear power generators are heavy, so you can't just launch more). Assuming it's a visible wavelength telescope (IR just seems impossible with the temp variations), when you're in the shade, you have to keep things warmed up to room temp, and when you're in the sun, you have to shield them from the sun without blocking your aperture. Being on the moon severely limits pointing capabilities - you have to point where ever the moon is pointing (L2 satellites have to point anti-sun but that's less restrictive). In fact, when the sun is shining down your aperture, can you observe at all? There's no soft lander infrastructure in place (you can't call up Boeing and order a Delta IV with the moon soft landing option), so you'd have to develop that also. It would include landing a multi-ton very precise, irreplaceable mirror and deploying in a gravity field. Just seems like a design, cost, and risk nightmare. All this is robotic of course, unless you also want to pay for the infrastructure to put humans up there. Which would cost about the same as 5 or 10 Hubble equivalents. That would make the telescope the flea on the elephant's back and the first thing to be cut when the inevitable overruns happened.
Now where are the advantages? Or did you just say that because you think there are some but you really haven't thought about what they are, but hey, Hubble on the moon! That sounds cool! Right up there with "move the Hubble to the ISS" in terms of bad choices.
Uh, no. (Score:5, Informative)
For those who follow this field, I'll remind you of the OGLE project, which has been doing the same thing from the ground. They found 60 likely planetary candidates (out of a similar number of stars monitored), but only two of those actually look like they could be planets. All the rest are either grazing-incidence binaries or blended binaries. The higher resolution of Hubble may help the blend problem to an extent, but I highly doubt the number of actual planets is anywhere near 100.
They also have little chance of confirming whether these are actually planets, as you need to do extremely high-resolution spectroscopy in order to confirm its existence via the radial velocity method. Even Keck can only do that for stars down to ~16th magnitude, and according to the observing proposal [stsci.edu], this survey is going down to 23rd. They might be able to get precise-enough light curves to reject false positives based on color-curve changes, but I'd like to see it before I believe it.
Original Hubble Proposal for this project (Score:3, Informative)
http://www.stsci.edu/observing/phase2-public/9750
A big aspect of this proposal *not* mentioned in the BBC article is the importance of metallicity on star formation - in other words, what star environments (old vs. young) form more planets.
Re:Too bad... (Score:2, Informative)
I think you'll find that just about everything that gets into space at this point was basically designed decades ago. The ISS dates from the later 70s/early 80s. The shuttle was late and it's first flight was in 1980. The Soyuz hasn't changed all that much since the 60s.
I'll admit that it's a combination of factors that do it. Between cost of development and the reliability of "tried and true" designs, older designs have the upper hand. Then there's the construction time. These things are assembled by hand, it's not surprising that the design will be old by the time it's actually is ready to launch. Then there's NASA's budget problems, which effect scientific instruments more than, say, communication satellites. I'm sure there are a dozen half constructed project just hanging around because their budgets got cut or even fully constructed ones that they couldn't get fit into the launch schedule.
Hubble is definitely old, but it's also all that we've got.
Re:Atmosphere? (Score:2, Informative)
There are several methods of detecting extra-solar planets. One of the first was detecting the extremely small wobble of the parent star as the planet orbits it. This works for planets less than the size of a "brown dwarf" (15-80 times the mass of Jupiter) down to around the size of Jupiter. As an example of the size of the wobble we detect, at 10 parsecs from the Sun, the wobble due to the orbit of Jupiter would be something like (if memory serves me correctly) three tenths of an arc-second.
Another method that also uses this wobble measures the Doppler shift of the light from the star as it comes towards us and away from us due to the planet's rotation. According to this [arxiv.org] paper, these velocities of the star are on the order of meters per second, so we're talking about extremely tiny Doppler shifts.
The method used in this study measures the slight dimming of the light of the star as the planet transits the star. This still generally works for larger, close-in planets. However, by studying the spectrum of the light that comes from the star and passes through the atmosphere of the planet, we can figure out what the atmosphere of the planet is made of.
For much smaller planets, it is possible to detect a slight localized brightening of the parent star when the planet is transiting across it. This brightening is due to the same gravitational lensing that we use to see far-away galaxies. The gravity of the planet focuses the light very slightly near it, and so we see a slightly bright spot on the star. This technique, called gravitational microlensing, has been used to discover planets of roughly the same size as the Earth.
Re:Planets passing in front of stars? (Score:3, Informative)
Probably not, the planet only has to pass in front of the star's corona for us to notice, and a lot of these might be hot giants (orbiting very close to the star) - which I'm leery to count as a real discovery.
In addition, a greater majority of planetary orbits will be laying on the galactic plane. Our system isn't, which means that we also have a bit more range to work with.
Re:Too bad... (Score:3, Informative)
The recent Hubble Ultra Deep Field images--which were very popular with the public--were generated using the ACS (Advanced Camera for Surveys) and NICMOS (Near Infrared Camera and Multi-object Spectrometer). As the name implies, NICMOS is an infrared camera. ACS is sensitive from deep in the UV through visible wavelengths up into the near infrared.
In other words, the Hubble Deep (and Ultra Deep) Field images are false-colour images. Indeed, most of the most impressive Hubble images are false-colour. The famous 'Pillars of Creation' [skyimagelab.com] would actually appear pinkish and relatively unremarkable in a photograph.
SOHO images of the Sun are almost exclusively false-colour. Once again, some of them are quite eye-catching [nasa.gov]. COBE's measurements of the microwave background are also (obviously) false-colour [nasa.gov]--but they still made headlines.
As long as you can take a picture of something at some wavelength, it can be represented in the visible. With a little bit of talent, that representation can be made 'pretty'. There are many arguments for and against the JWST and its specific instrumentation choices--but an inability to produce newsworthy pictures is not one of them.
Re:More like... (Score:2, Informative)
Also, there are many micro-sized meteorits [teachersource.com] and other space dust that will happily punch holes in anything that flies around (which makes long space flights nearly impossible)
And radiations...
And comets...
And stars...
And stuff...
And a 100 new planets...
And us...
Re:WHAT... (Score:3, Informative)
The first exoplanets were discovered by Alexander Wolszczan in 1991, around PSR B1257+12.
They're pulsar planets, yes, but they're planets. Give the guy credit.
Story here [psu.edu]. Curious that the first discovered planets were Earth-sized. Also the planetary system is very much like Earth's. Dead, yes, but still encouraging.
Re:Too bad... (Score:3, Informative)
As for UV or IR a lot of that gets blocked by the atmosphere, space telescope is the best option.
As for most of the pretty pics you see they are enhanced and shifted so you can see it.