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Stargazing Where can I find high resolution photos of distant stars?

  1. Jun 8, 2017 #1
    Hello

    I've been digging around for high resolution photos of distant stars now for awhile. The search has been pretty difficult.

    If what I've been reading is correct then there appears to be a limit to viewing small objects like stars, if this is true can someone help me understand the reason for this? I (think I) understand it has to do with light diffraction and the lens diameter. Also is there a foreseeable way this will be improved in the future of astronomy? Is the new telescope that's going up next year to replace Hubble going to help with this?

    Thanks for your time and interest
     
  2. jcsd
  3. Jun 8, 2017 #2

    1oldman2

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    I'd have to start by recommending http://hubblesite.org/
     
  4. Jun 8, 2017 #3
    Naturally I tried Hubble's website but most of the images are planets, galaxies, nebula, etc. I haven't really found one of just a star itself. Maybe I'm looking in the wrong spot but then I read this on https://www.spacetelescope.org/about/faq/

    But I'm not sure if this or something similar applies to stars as well.
     
  5. Jun 8, 2017 #4

    1oldman2

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    Ah! unfortunately I'm not the guy to discuss optical physics with, however you are in luck as this site has plenty of talent that should answer your questions. I did notice that today's Hubble image is a white dwarf, if its downloaded at full resolution and you zoom in it doesn't look too shabby, still not what your looking for but it is rather cool to look at. :smile:
    http://hubblesite.org/image/4043/gallery
    white dwarf.PNG
     
  6. Jun 8, 2017 #5
  7. Jun 8, 2017 #6

    Drakkith

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    Yes, all of those are artists conceptions, not real images.
    On page 5 of this link, you can see an image of the star Betelgeuse by the HST (Panels A and G). These images are diffraction limited and represent the maximum resolving power of the HST in UV light.
     
  8. Jun 8, 2017 #7
    Nice. Just what I was looking for (in a sense)

    I'll try to find out more about the resolving power of the HST or of future equipment. If any one knows any good articles regarding this it would be appreciated.
     
  9. Jun 8, 2017 #8

    davenn

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    surprised no-one has mentioned the obvious yet ..... you wont find cause basically they don't exist ......
    there may be a few random intergalactic stars but I think you will find 99% of stars are within galaxies

    so your two choices are ....either all the individual stars in the sky you see visually or through telescope are ones in our galaxy ( the Milky Way). Or you can look at images of other galaxies for which stars are resolved Say M 31, Andromeda Galaxy


    Dave
     
    Last edited: Jun 8, 2017
  10. Jun 8, 2017 #9

    OmCheeto

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    I just read that the JWST has the same resolution as the HST, and given the following from Drakkith's reference;

    "The bright supergiant Betelgeuse (5a Orionis 5 HD 39801) has long been a favorite candidate for interferometric studies, speckle imaging, and aperture-masking techniques because it possesses the largest apparent diameter of any star beyond the Sun."

    I doubt you will find any better images of stars in the near future(20 years).

    Though, a couple of hours of googling indicate that, as always, science is on the move:

    Current Hubble CCD pixel physical size: 21 µm
    Sensor size: 1024 x 1024
    [ref]
    Pixels: ≈1 million [maths]

    Purported recently{2015} achieved sensor pixel size: 50 nm [ref]
    Theoretical sensor size: 430,000 x 430,000 [my maths]
    Pixels: ≈185,000 million​

    Whether or not this will work on Hubble? I have not a clue.

    My 2 hours of googling indicated to me that once again, I will be long dead before I understand all of this stuff. But the maths is fun.

    ps. If it did work, the resolution would be about the same as Hubble imaging Mars, when it's ≈80,000,000 km from Earth. [ref] [and my always suspicious maths]
     
  11. Jun 8, 2017 #10
    Even the very closest stars can't be resolved to more than a few pixels by Hubble.
    https://www.nasa.gov/image-feature/goddard/2016/hubbles-best-image-of-alpha-centauri-a-and-b
    However prior to that, all stars were only observable as a single point source, the reason being that they are so far away.
    When JWST goes into service it will provide somewhat better resolution, though not radically better.
    It will also be much more sensitive in Infrared.
    Nevertheless, more distant stars are still only going to be resolvable as a few pixels.
    It may well discover plenty of small red dwarfs that previously were unknown, despite seeing only a pixel or two though.
     
  12. Jun 8, 2017 #11

    Drakkith

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    If I understand things correctly, the resolving power of the HST is limited by diffraction, not the size of the pixels on the sensor. From the link I gave above:

    The pixels of the FOC already have a resolution of about 14.35 mas in the near-uv, which is less than the PSF of 38 mas. In other words, the FOC can distinguish between objects/details separated by 38 mas but the pixels already capture information at half this angle. Decreasing the pixel size would have little effect on resolving power. You're image would just be less blocky and more blurry.

    And that increased resolution is mostly in the IR band. Since the JWST can't see UV, the best resolving power it can get is less than you'd expect.
    For comparison:

    Theoretical Resolving Power of HST: ##27 mas## at ##λ=255 nm##
    Theoretical Resolving Power of JWST: ##23 mas## at ##λ=600nm##
    Theoretical Resolving Power of HST in near-IR: ##63 mas## at ##λ=600 nm##

    Real-world values will be less (higher value). Note that this doesn't take into account special techniques often used to increase the resolving power, especially various image processing techniques developed in the last few decades.
     
    Last edited: Jun 9, 2017
  13. Jun 8, 2017 #12
    Should be R = √(telescope optical resolution2 + pixel size2)
    R = √(0.02622 + 0.04022) = 0.048 arcseconds
     
  14. Jun 13, 2017 #13
    There are plenty of high resolution images of a star available on the web - it's called the Sun ! SDO and other sattelites show the surface in detail and ground based observatories do quite a good job as well.
     
  15. Jun 13, 2017 #14
    The OP was interested specifically in distant stars, though observations of the Sun probably do assist our understanding of stars in general.
     
  16. Jun 26, 2017 #15
    Heh, I should specify what I mean by distant stars. Distant stars as in stars not in our own solar system. 8 light-minutes is significant but hardly anything compared to 4.22-46.6 *109 light-years

    It should be interesting looking at those photos as well though.

    Thanks for the replies everyone. Any future updates will be appreciated.
     
  17. Jun 27, 2017 #16

    1oldman2

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  18. Jul 4, 2017 #17
    "Where can I find high resolution photos of distant stars?"
    Photographs are taken by cameras, but there are no cameras used from outside of Earths atmosphere by any of the instruments examining stars. What you are looking for is images, created by using information from instruments that gather spectral data that has been processed by computers utilising various software. Hubble is not a camera.
     
  19. Jul 4, 2017 #18

    russ_watters

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    This is confusing -- Hubble is a telescope and to collect data, it has cameras.
     
  20. Jul 4, 2017 #19
    Hubble is not so simple. These are perhaps what you imagine Hubble to be, but no telescope with camera attached has ever been tried from orbit. If it were so simple then China, Japan, Russia or India would have their own space telescopes by now.

    Testbed Paves Way for Amateur Space Telescope
    http://www.skyandtelescope.com/astronomy-news/testbed-paves-way-for-amateur-space-telescope/

    An Amateur Space Telescope
    http://adsabs.harvard.edu/abs/1982S&T....64..127S

    http://www.drewexmachina.com/2014/04/16/vintage-micro-the-amateur-space-telescope/
     
  21. Jul 4, 2017 #20

    russ_watters

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    This is confusingly put: Please say exactly what you are meaning to say it is instead of saying what you think it is not. Because the way I see it, Hubble is a pretty simple instrument - a Cassegrain type telescope with a camera at the end (actually, several cameras at the end), very similar to the one in my avatar photo.
    Simple doesn't mean cheap. They don't do it, because it is expensive.
     
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