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New Horizons Parallax Program Targets Proxima Centauri, Wolf 359

In a few short months, New Horizons will be almost 8 billion kilometers out, a distance that still boggles the mind until we remember that Voyager 1 has reached 22.2 billion kilometers (over 148 AU). Then, of course, we’re humbled again with the thought that the inner Oort Cloud is thought to be between 2,000 and 5,000 AU from the Sun, with an outer edge that could extend as far as halfway to the nearest star. That star, Proxima Centauri, is 268,770 AU from us.

As New Horizons hunts Kuiper Belt objects for the next flyby, the spacecraft is now being used to perform parallax studies to detect the apparent ‘shift’ in the relative position of nearby stars as compared with what we see on Earth. Earth’s orbit is about 300 million kilometers in diameter, so we see that apparent shift by comparing observations taken half a year apart. That’s a pretty decent baseline, but if we extend the baseline, as now with New Horizons, we can see better parallax effects, and thus tighten the distance measurements we make from them.

The most celebrated name in parallax studies is German astronomer and mathematician Friedrich Bessel, who in 1838 obtained the first stellar parallax measurements to determine the distance of the star 61 Cygni. Here again it’s humbling to reflect that the distances to the nearest stars are almost half a million times greater than the baseline offered by Earth’s orbit, which makes Bessel’s feat all the more impressive. Bessell worked out a distance of about 10 light years, not all that far off the 11.4 light year distance modern astronomers have estimated for 61 Cygni.

I might mention that Bessell (1784-1846) was also the first astronomer to predict the existence of an unseen companion around another star, announcing from his study of Sirius that deviations in its motion indicated a companion that we now know as the white dwarf Sirius B.

But back to New Horizons. On April 22 and 23, the spacecraft will take images of Proxima Centauri and Wolf 359. These can be used in combination with Earth-based images taken on the same dates to yield what the New Horizons team is calling ‘a record-setting parallax measurement,’ one that will be made in coordination with Earth-based observatories and a public observing campaign. Amateur astronomers with a camera-equipped, 6-inch or larger telescope are invited to participate. Says New Horizons principal investigator Alan Stern:

“These exciting 3D images, which we’ll release in May, will be as if you had eyes as wide as the solar system and could detect the distance of these stars yourself. It’ll be a truly vivid demonstration of the immense distance New Horizons has traveled, and a cool way to take advantage of the spacecraft’s unique vantage point out on the very frontier of our solar system!”

Image: Color images of the Wolf 359 (top) and Proxima Centauri star fields, obtained in late 2019. The large proper motions of both stars (at the center of each image) will cause them to shift by over an arcsecond by April 2020, when NASA’s New Horizons spacecraft, nearly five billion miles (8 billion kilometers) from Earth, will image them. A green circle provides a rough estimate of where both stars will appear in the New Horizons images. Credit: William Keel/University of Alabama/SARA Observatory.

A new way to find our way around nearby interstellar space? New Horizons science team member Tod Lauer (National Science Foundation Optical-Infrared Astronomy Research Laboratory) points out the method’s history and its future promise:

“For all of history, the fixed stars in the night sky have served as navigation markers. As we voyage out of the solar system and into interstellar space, how the nearer stars shift can serve as a new way to navigate. We will see this for the first time with New Horizons.”

More details are available here for those interested in participating in the New Horizons Parallax program. I’m anxious to see the results, and also reminded how limited parallax measurements have historically been when confined to Earth’s orbit around the Sun. New Horizons points the way to a future in which we extend the baseline even further. Imagine a mission like Claudio Maccone’s FOCAL, an observing instrument collecting light at distances greater than 550 AU, where the gravitational lensing effects of the Sun become observable. And who knows, perhaps one day we’ll have a baseline as far as the Alpha Centauri stars to help map the Orion Arm.

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{ 35 comments… add one }
  • kzb February 3, 2020, 9:27

    How will this accuracy compare to GAIA?
    I recall asking about using the Voyagers for this purpose, and it was said Voyager cameras were designed for planetary imaging, not parallax measurements. The Voyager baseline is nearly X3 that of New Horizons, was this purpose designed into NH from the start?

  • neutrino78x February 3, 2020, 9:57

    Wolf 359??? A mement of silence for the brave souls who perished there in the battle against the Borg. ;-)

    • Tod Lauer February 5, 2020, 2:08

      That hasn’t happened yet.

      • lepton February 7, 2020, 2:56

        All the past, present and future are embedded inside the spacetime continuum. We might haven’t experienced it, but they are all there.

  • Harry R Ray February 3, 2020, 10:54

    “That star, Proxima Centauri is 268,770 AU from us.” It just blows my mind that we know WITH PRECISION, the distance of an object > 1 parsec away from us to just within a couple hundred million miles(i.e., 268,769 – 268,771 AU, 1 AU being ~93 million miles). Of course, that distance changes with time as Proxima Centauri orbits Alpha Centauri A and Alpha Centauri B and(currently)receeds from us. That orbit can be refined by TRIANGULATING New Horizons images, Earth based images, and Gaia images(at L2)taken SIMULTANEOUSLY provided, ONE: New Horizon’s camera is NOT turned off(like the Voyagers cameras were)after its primary mission is over, in order to conserve energy, and; TWO: Gaia’s fuel supply is CONSERVED so that it can operate well into the next decade.

  • Alex Tolley February 3, 2020, 13:04

    I would certainly love to see the parallax with my own eyes, seeing the stars in 3D space. SciFi movies and Star Trek have given us a sense of the galaxy as a 3D object rather than a 2D projection in t4eh heavens. We have seen 3D diagrammatic representations of our stellar neighborhood in 2D. But to see the nearer stars in 3D, that would be a new experience, and one worth having.

    • Harry R Ray February 4, 2020, 10:40

      The best way to achieve this is, ironically, via a blink comparator of Clyde Tombaugh and Pluto fame. I am not sure whether a 3d blink comparator exists or not, but it would be a mind blowing experience if it did. Hmmm, is this worthy of a tech-savvy Centauri Dreams reader(not me, unfortunately)to file a patent if one does not already exist?

    • Michelangelo February 4, 2020, 17:05

      You can easily experience this with SpaceEngine pro. The software can be used with a VR Headset, and you can change the distancie between you eyes in the visualization. I think even GaiaSky allows for this.

  • Charley February 3, 2020, 14:29

    “As New Horizons hunts Kuiper Belt objects for the next flyby,…” Mister Gilster, do we know for sure that there WILL BE another flyby at this point in time? Have you heard anything that indicates they located a suitable target?

    • Paul Gilster February 3, 2020, 22:23

      I haven’t checked recently, but as far as I know, the New Horizons team is still hoping to find a good target for a flyby while continuing studies of the Kuiper Belt. I don’t know if any targets particularly stand out at this point.

  • Spaceman February 3, 2020, 14:39

    This is really cool! Nice images :-) A couple of questions:

    1). Is Wolf 359 currently being observed by any of the ongoing planet hunting campaigns?

    2). Will these new parallax measurements using New Horizons help us improve the accuracy of the so-called cosmic distance ladder?

    • Antonio February 4, 2020, 4:29

      1) CHEOPS is not observing it. GAIA yes, but has found nothing. HARPS, HIRES, UVES and PFS found 2 candidate planets, but results are still not confirmed. Since the star is quite dim and these are the best spectrographs today, probably we will not have a confirmation soon and no observing campaign is ongoing.

    • Antonio February 4, 2020, 4:34

      I forgot to say: of course, TESS is not observing it either, since its targets are bright stars.

      • Harry R Ray February 4, 2020, 10:44

        Kepler-K2 observed Wolf 359 for 72 days and found nothing.

    • Tod Lauer February 5, 2020, 15:44

      The New Horizons Parallax program provides both an excellent demonstration of instantaneous stellar parallaxes and the great distance that the spacecraft has traveled, but despite the large baseline the measurements can’t come anywhere near to the sensitivity of Gaia.

  • Ashley Baldwin February 3, 2020, 14:53

    Yes. As I recall, it was 2D thinking that ultimately did for the protagonist in the epynomous “Wraith of Khan”.

    Just goes to show what you can achieve with a good quality telescope and digital camera . Wherever they are. In terms of this experiment – well done the Long Range Reconnaissance Imager. It has been already used for this purpose before – in massively improving the parallax on KBO JR-1 in 2015/2016 .

    Just an 8.2 inches aperture but more than enough to provide the necessary accuracy required ( and limiting magnitude ) to do parallax of two close by late M dwarfs – with peak emission conveniently around the 850nm upper band pass limit . It should be noted as a reference point that the citizen science programme running in parallel from Earth only requires a 6 inch aperture telescope .

    LORRI, designed to work in dim light anyway and within the relatively short exposures allowed by the propellant driven spacecraft targeting. Ironically had New Horizons possessed a separate targeting platform it probably wouldn’t be functioning by now . Be interesting to see just how much precious propellant this experiment uses up. And how much is left to allow New Horizons able to point it’s dish at Earth.

    • Tod Lauer February 5, 2020, 0:01

      The amount of propellant to be used is an extremely small fraction of the remaining supply and is considerably less than that being used for the on-going program of distant KBO photometry.

  • Ioannis Kokkinidis February 3, 2020, 15:14

    One of the aims of near future interstellar probes, like the one being currently studied by JHUAPL for the upcoming Heliophysics decadal survey, is long baseline parallax survey. Thus this New Horizons campaign is a prototype for such a future mission. Gaia sends huge amounts of data back to earth, being responsible for a very large fraction of ESTRACK time every day. Should we try to do an actual long baseline parallax mission, considering also just how data limited New Horizons is, it would require massive improvement on the spacecraft communication gear compared to New Horizons and to earth receiving equipment. Indeed it is very interesting to see what this experiment would bring both for the science aspect and the engineering aspect

  • John walker February 3, 2020, 15:42

    I just want to say how much I appreciate Paul’s frequent inclusion of the merits of long past and sometimes sadly recently passed figures in the astronomical community. Here Bessel’s accomplishments in the early 1800’s are astounding considering the technical limits of the day. Koenigsberg Observatory was located quite close to the center of the town which already had a population of over 70,000. Though I imagine the conditions in pre-electric, largely pre-gas lighting Koenigsberg were still very dark in that small city that spawned so many stellar intellectuals.

  • Juraj February 3, 2020, 15:55

    Would it be feasible to try this with stars further away that have uncertain parallax for various reasons – like Polaris which is too bright for GAIA?

    • wdk February 4, 2020, 2:07

      Juraj,
      The case you site is an interesting example since it sits overhead the equatorial plane – rather than the ecliptic. But going back to the cases of Wolf 359 and Proxima Centauri, it should be noted that the parallax
      value for one arc second can be translated into a light year or astromical unit distance that is very precise ( e.g. 180/pi *3600 AUs for 1 arc second = 206,264.8 AUs to 7 significant figures). And then a fraction of an arc second becomes an even further distance because of the inverted relation. But what lies in the background is how many significant figures can we take a 1 AU baseline parallax to an arc second or less angle measure? Having a high resolution camera out around 100 AUs will certainly improve the accuracy, maybe 100 times.

      Also, the objects under discussion do have some proper motion; they will change their position some wrt the background stars over several years. But if they have planets orbiting at right angles to the line fo sight, astrometry might be used a way to detect them. Habitable zone
      oscillations should be cycles of days or weeks for these less bright stars.

      As for Alpha Centauri A and B, being visual binaries of near 80 year period, astrometric measurement would have to look for oscillations of a very small nature ( their brighter and more massive) superimposed on their elliptic paths. Worth a try.

    • Ashley.Baldwin February 4, 2020, 14:01

      If I recall , Gaia’s sensors have a lower limiting magnitude of 3. For greatest accuracy. Special measures ( whatever they are !) allow for astrometry of brighter ( and generally though not invariably – thinking Proxima and Wolf 3589- nearer) stars . But at the cost of astrometric accuracy. As the LORRI telescope/camera on New Horizons is optimised for dim targets I suspect it will be subject to these same limitations as Gaia. Indeed more so, as constrained by its limited pointing capacity it has to image targets near the plane of the ecliptic. Gaia has much larger apertures of 2 X 1 by 0.5m telescopes versus LORRI’s humble singleton 0.2m. So much less stray light bouncing around within the scope to mess up its observations.

  • Frank February 3, 2020, 18:05

    @Alex Tolley – you can produce 3D views of the stars using two images taken decades apart. Josep Comas i Solà did this with images of the Pleiades. Since it’s a relatively close cluster, the stars pop out.

    • Alex Tolley February 3, 2020, 23:46

      That wouldn’t be the same, would it? Wouldn’t a distant star moving faster across the sky appear closer than a nearer star moving more slowly?

      When pairs of aerial photo-reconnaissance images are used to create 3D images of objects on teh ground, a moving object like a train or vehicle just looks like it is in 2 places, rather than in the air.

      Do you have a link for that Pleiades cluster, or something analogous?

      • Frank February 6, 2020, 16:21

        Alex – It was the Hyades, not the Pleiades that Comas Sola used to make 3D views.
        It works for open clusters since the member stars will be co-moving and they should pop out from the background.

        It can probably be re-created by taking two images of the Hyades separated by a few decades, adjusting the images so that matching stars in both images appear equally bright.

        Stars with large proper motion will appear closer.

  • Robert Flores February 3, 2020, 23:28

    Glad this effort is being made, some star groups are members
    of very old dwarf galaxies our galaxy digested. It would be nice to know if these streams include stellar mass black
    holes, or have captured black holes settled closer to our galaxy’s core.

    Speaking of Wolf359, one of the most effective episodes(atleast in scaring 7 year olds and unselting the rest,) in the
    old Outer Limits series is tied to this star. For TV purposes they assumed the star was more similar to out sun. There’s a fair chance a few people here have not seen that episode, so I will not spoil it. Great episode to see on halloween, (the name of the episode is WOLF 359) and yes the effects are cheesy compared to today, but the writing
    usually makes up for that.

  • Antonio February 4, 2020, 4:44

    Mmm I didn’t realize it until now, but we currently have THREE space telescopes observing Proxima in search of transits: GAIA, TESS and CHEOPS.

  • John February 4, 2020, 14:24

    It’s a fairly mind-blowing demonstration of just how far NH has travelled, and I love that after visiting two Kuiper belt objects the mission is still returning useful science!

    • Ron S. February 4, 2020, 14:57

      Three KBO. We mustn’t forget Charon.

      • Lepton February 7, 2020, 2:58

        Charon is a dwarf planet.

        • Ron S. February 8, 2020, 15:04

          Are you the nomenclature police? Whether or not Charon is a dwarf planet, moon, dwarf moon or whatever else it is also a KBO.

  • Michelangelo February 6, 2020, 13:45

    I think the importance of this is not because of getting a better measurement of the distance to Proxima Centauri (which I doubt considering the incredible design of Gaia, even with the smaller baseline), but in the fact that this would be a pure parallax measurement (done at the same time). This means that we can decouple the proper motion from the parallatic motion of Proxima Centauri, which in turn might be ideal to make a more constrained fit for the Gaia track. Even if Gaia doesn’t make a new parallax measurement of this system, this data from NH might allow for a better fit of the previous Gaia solution.

  • Teros February 18, 2020, 10:40

    Timing seems tuned for USA. From Europe, Leo is not visible at 4:00 UT.

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