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Discovery of non-transiting exo planets possible?
Kepler uses dip in light curves of stars to determine the existence of
exo-planets, but that presumption is that these "exo" solar systems have their ecliptics aligned with us so that transits are observable, but there must be far more systems that do not fit that criterion than do. So are there any telescopes in the works that can not only detect reflected light from exo-planets but can use light arcs around their home stars to detect them? Just curious. |
#2
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Discovery of non-transiting exo planets possible?
On Sunday, December 17, 2017 at 4:26:54 AM UTC-7, David Spain wrote:
Kepler uses dip in light curves of stars to determine the existence of exo-planets, but that presumption is that these "exo" solar systems have their ecliptics aligned with us so that transits are observable, but there must be far more systems that do not fit that criterion than do. So are there any telescopes in the works that can not only detect reflected light from exo-planets but can use light arcs around their home stars to detect them? Just curious. Several exoplanets have been discovered by other means, the latest being one orbiting Proxima Centauri: https://en.wikipedia.org/wiki/Proxim...anetary_system [[Mod. note -- To answer answer to the poster's original question: No current telescope can directly resolve the "light arc" produced when an extrasolar planet acts as a gravitational lens for a background star. But this phenomenon also *brightens* the background star, and this brightening is detectable. A number of extrasolar planets have in fact been discovered via this "microlensing" technique: https://en.wikipedia.org/wiki/Gravit...olar _planets -- jt]] |
#3
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Discovery of non-transiting exo planets possible?
On Sunday, December 17, 2017 at 6:26:54 AM UTC-5, David Spain wrote:
Kepler uses dip in light curves of stars to determine the existence of exo-planets, but that presumption is that these "exo" solar systems have= their ecliptics aligned with us so that transits are observable, but there must be far more systems that do not fit that criterion than do. So are there any telescopes in the works that can not only detect reflected light from exo-planets but can use light arcs around their home stars to detect them? Just curious. Our planets rotate on the similar plain to our galaxy. Lets call the odds of most of our planets orbiting on the same plain as our galaxy 50 to 1 , ruff estimate. This would mean that the odds of other solar systems in our galaxy also being on the same plain as our galaxy high. This improves the possibility of sensing a dip in brightness caused by a planet in front of it's star if the telescope is pointed in the direction of our galaxy on the same plain. However the arcs would be nice. I would venture a guess the planet reflected light is too small and added to this being very close to a bright star. It would exceed the dynamic range of the light sensor. A 16 bit A/D would have a hard time telling the difference between a bright star and a dim planet. [[Mod. note -- 1. No, the planets in our solar system do NOT orbit in the plane of our galaxy. 2. The author is correct that directly imaging an extrasolar planet requires a HUGE dynamic range. To this end, attempts to do this generally include a coronagraph to block almost all of the host star's light. There's a bit of discussion of coronagraph designs in Wikipedia: https://en.wikipedia.org/wiki/Coronagraph Even with a coronagraph, scattered light from the host star is still the #1 problem in direct detection of extrasolar planets. -- jt]] |
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Discovery of non-transiting exo planets possible?
In article , John
Heath writes: Kepler uses dip in light curves of stars to determine the existence of= exo-planets, but that presumption is that these "exo" solar systems hav= e their ecliptics aligned with us so that transits are observable, but there must be far more systems that do not fit that criterion than do. So are there any telescopes in the works that can not only detect reflected light from exo-planets but can use light arcs around their home stars to detect them? Just curious. Our planets rotate on the similar plain to our galaxy. Nope. If so, the Milky Way would lie along the ecliptic. It's almost perpendicular to it. Sometimes you can discover interesting stuff by just looking at the sky. :-) |
#5
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Discovery of non-transiting exo planets possible?
In article ,
[[Mod. note -- 1. No, the planets in our solar system do NOT orbit in the plane of our galaxy. Indeed: the Galactic latitude of the north ecliptic pole is about 29.8 deg. It would be 90 deg if the two planes were aligned. 2. The author is correct that directly imaging an extrasolar planet requires a HUGE dynamic range. To this end, attempts to do this generally include a coronagraph to block almost all of the host star's light. There's a bit of discussion of coronagraph designs in Wikipedia: https://en.wikipedia.org/wiki/Coronagraph Even with a coronagraph, scattered light from the host star is still the #1 problem in direct detection of extrasolar planets. -- jt]] Nevertheless, planets have been directly detected in a few systems. I _think_ the first was beta Pictoris (Lagrange et al. 2010): http://science.sciencemag.org/content/329/5987/57.full HR 8799 shows three planets (Marois et al. 2010): http://www.nature.com/articles/nature09684 There are other examples; those are just two I happened to find. A recent article by Meshkat et al. (2017) http://iopscience.iop.org/article/10...81/aa8e9a/meta reports a systematic but unsuccessful search of stars known to have debris disks. Their Introduction gives references to prior successful imaging studies. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Discovery of non-transiting exo planets possible?
On 12/17/2017 6:26 AM, David Spain wrote:
So are there any telescopes in the works that can not only detect reflected light from exo-planets but can use light arcs around their home stars to detect them? Just curious. Well to be honest I was thinking in terms of "arcs" of reflected light off a resolved planet more or less acting as a point of light that would be seen over a long duration plot to detect orbital travel. I wasn't thinking in terms of gravitational lensing at all. But of course that might be a better way to go if you don't have the dynamic range to detect such faint images. Will the Webb telescope provide any additional capabilities in this area? Forgive the naive question, astronomy is my hobby not my profession. David Spain |
#7
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Discovery of non-transiting exo planets possible?
In article ,
David Spain writes: I was thinking in terms of "arcs" of reflected light off a resolved planet more or less acting as a point of light that would be seen over a long duration plot to detect orbital travel. Exposure times are short compared to orbit times, so when planets are directly imaged, they show up as point sources. My previous message gave some examples, and the Introduction section in the Meshkat article gives references to others. I wasn't thinking in terms of gravitational lensing at all. But of course that might be a better way to go if you don't have the dynamic range to detect such faint images. The idea is that when a foreground star lenses a background one, if the foreground star has a planet, it can add to the lensing signal. The timescale is much shorter, though, because the planet's mass is much smaller than the star's mass. You might do web searches on "Einstein radius" and on "microlensing." Will the Webb telescope provide any additional capabilities in this area? The Near Infrared Camera has a coronagraph, which is intended to block light from the star and allow planets to be imaged. (The coronagraph has uses for other projects as well.) Together with the large telescope aperture, which gives high angular resolution, it should be possible to image planets much closer to their primary stars than can be done now. Of course the planets have to be there and be either large and shiny or large and hot, but there should be some very nice images coming. I see there is one Early Release Science project that includes imaging of one exoplanet: https://jwst.stsci.edu/files/live/si...86-hinkley.pdf The main goal of this project is to test the instrument; I'm sure there will be more projects done. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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