What's the farthest object as determined only by parallax?

  • I'm wondering what the farthest object we know of, as measured only by parallax methods, from either earth or satellite based telescopes, and at either visible light or radio wavelengths.



    Basically, if we had no other way of measuring distances,
    what would be the farthest object we knew about? I'm guessing this measurement would probably be one from Gaia, it being the latest telescope to measure such things TTBOMK.


    "Hipparcos is only able to measure parallax angles for stars up to about 1,600 light-years away, a little more than one percent of the diameter of the Milky Way Galaxy." https://en.wikipedia.org/wiki/Stellar_parallax "The European Space Agency's **Gaia** mission,....is able to measure parallax angles to an accuracy of 10 microarcseconds, thus mapping nearby stars (and potentially planets) up to a distance of tens of thousands of light-years from Earth."

    @WayfaringStranger - indeed. However, "Capable" is not the same as measured.

    @nbubis Yes, someone needs to do a sort of Hipparcos by distance. I doubt the object has much of a name. Still early days for Gaia.

  • ProfRob

    ProfRob Correct answer

    5 years ago

    It depends what parallax uncertainty you are prepared to tolerate. Very Long Baseline Interferometry (VLBI) at long wavelengths currently provides the most precise parallaxes. Parallaxes to bright radio sources measured in this way can have precisions of around 10 microarcseconds (see for example Reid et al. (2014).



    According to the review by Reid & Honma (2014), the most distant source with a VLBI-based trigonometric parallax is the star forming region W49N. The source has a parallax of $90\pm 6$ microarcseconds and a corresponding distance of $11.1 \pm 0.8$ kpc (Zhang et al. 2013).



    The precision of these parallaxes is similar to what is likely to be possible with Gaia for the brightest stars (e.g 5-16 microarcseconds according to https://www.cosmos.esa.int/web/gaia/science-performance ). Only the most luminous giants will be this bright at distances of $>10$ kpc.


    How does that agree with the previous answer that given a maximum distance of 7 Mpc?

    @nbubis It doesn't. That answer is citing a distance estimate (70 Mpc) that is not achieved by measuring a parallax. It measures the velocities (and accelerations) of maser sources.

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