Another Interstellar Visitor?

C/2019 Q4 Borisov, candidate interstellar cometOn August 30th, 2019, Gennady Borisov, an optician and astronomer at the Crimean Astrophysical Observatory, using equipment he built himself, discovered a dim (18th magnitude) object moving with respect to the distant stars.  Further observations indicated it was cometary in appearance, with a coma around its brightest spot and apparent short tail.  Orbital computations from the limited number of observations indicate that it was discovered at a distance of around 3 astronomical units (AU) (the mean radius of the Earth’s orbit) from the Sun, inbound toward a perihelion on December 10th near 2 AU.

As with ’Oumuamua (1I/2017 U1) in 2017, attempts to fit a typical elliptical or parabolic orbit to the observations failed, and the best fit was found to be a hyperbolic orbit with an eccentricity in excess of 3.  Such an object is not gravitationally bound to the solar system and must be of interstellar origin; after rounding the Sun, it will depart into interstellar space never to be seen again.  This is only the second such object to be observed.  From observations so far (and with less than two weeks of data, these figures will be revised as further observations are made), its inbound velocity to the solar system before it began to be accelerated by the Sun’s gravity was around 30 km/sec, which rules out a hyperbolic orbit due to interactions with solar system objects, as such perturbations cannot create a velocity greater than 3 km/sec.  Here is the Minor Planet Center Circular, MPEC 2019-R106, announcing the discovery, its apparent interstellar nature, and preliminary orbital elements based on the news that’s come to Harvard.

This is a chart of the object’s orbit prepared by the Jet Propulsion Laboratory based upon their estimate of its orbit.  The grey lines lead from the orbit to the plane of the ecliptic (plane defined by the Earth’s orbit, near which all of the major planets orbit), showing how the comet is arriving from above the plane and will depart below it.

C/2019 Q4 orbit plot, JPL

Unlike ’Oumuamua, which was discovered after passing perihelion (its closest approach to the Sun), and could only be observed departing the solar system, this object was discovered while still inbound and should provide ample opportunities for observation.

Here are links for further reading about this intriguing discovery.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

15 thoughts on “Another Interstellar Visitor?”

  1. John Walker:
    On August 30th, 2019, Gennady Borisov, an optician and astronomer at the Crimean Astrophysical Observatory, using equipment he built himself, discovered a dim (18th magnitude) object moving with respect to the distant stars.

    Wow.

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  2. Haakon Dahl:

    John Walker:
    On August 30th, 2019, Gennady Borisov, an optician and astronomer at the Crimean Astrophysical Observatory, using equipment he built himself, discovered a dim (18th magnitude) object moving with respect to the distant stars.

    Wow.

     

    [caption id="attachment_27659" align="aligncenter" width="600"]Gennady Borisov and his 0.65-meter telescope Gennady Borisov with the 0.65-meter telescope he built and used to discover the new comet. G. Borisov[/caption]

    According to the article in Sky & Telescope, this is the seventh comet he has discovered.  He has also discovered several near-Earth asteroids.

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  3. John Walker:
    it was discovered at a distance of around 3 astronomical units (AU) (the mean radius of the Earth’s orbit) from the Sun, inbound toward a perihelion on December 10th near 2 AU.

    So Elon Musk does not have time to reposition Starman to intercept.

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  4. Scott Manley’s latest video discusses the interstellar comet C/2019 Q4 in the second segment, which starts at the 7:12 mark.

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  5. Bryan G. Stephens:
    These must be more common than we thought.

    Interstellar space must have a lot in it.

    It has long been believed that interstellar objects are abundant and that it was only a matter of time, after we had automated telescopes able to do large-scale searches for faint objects, that we’d start sweeping them up.  Models for the formation of objects orbiting sun-like stars estimate that around 99% of the mass in the original circumstellar discs from which planets, asteroids, and comets form is ejected into interstellar space during the initial chaotic phase of accretion, formation of bodies, and their interaction.  These bodies could range in size from dust particles to massive planets which were ejected due to gravitational interactions with other planets and now wander through interstellar space as “rogue planets”.

    If the general power law rule (“Once Pareto gets into your head, you’ll never get him out”) for size of astronomical bodies holds here, there will be vastly more small bodies than large ones, just as we observe for asteroids and comets in the solar system.

    So there may be 100 times as many loose interstellar rocks wandering around as those bound to stars.  But, of course, interstellar space is vast and mostly empty, which reduces the frequency of encounters which might be visible.  Now that we’ve see two, it begins to be possible to estimate how many there might be, and this will be refined as more are found.  They’ve been difficult to find in the past because you only get one relatively short shot to observe them as they pass through the solar system (as opposed to an asteroid which you can pick up any number of times as it orbits the Sun), and since they come from random directions in the sky rather than orbiting mostly in the plane of the ecliptic.  The advent of all-sky surveys were the key to being able to find these objects, and those are a recent phenomenon.

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  6. Here is an animated GIF which compares the orbits of ’Oumuamua and C/2019 Q4 (Borisov).  Note that since ’Oumuamua passed much closer to the Sun, its trajectory was deflected at a much greater angle than that of C/2019 Q4 will be.  Click the animation to enlarge.

    Orbits of ’Oumuamua and C/2019 Q4 (Borisov)

    The animation was prepared by Tony Dunn using Gravity Simulator.

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  7. ctlaw:

    John Walker:
    it was discovered at a distance of around 3 astronomical units (AU) (the mean radius of the Earth’s orbit) from the Sun, inbound toward a perihelion on December 10th near 2 AU.

    So Elon Musk does not have time to reposition Starman to intercept.

    And that’s why we need to build HypenPoop.

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  8. John Walker:
    Here is an animated GIF which compares the orbits of ’Oumuamua and C/2019 Q4 (Borisov).  Note that since ’Oumuamua passed much closer to the Sun, its trajectory was deflected at a much greater angle than that of C/2019 Q4 will be.  Click the animation to enlarge.

    Orbits of ’Oumuamua and C/2019 Q4 (Borisov)

    The animation was prepared by Tony Dunn using Gravity Simulator.

    I take it that the heavy-lined portions of orbits are above the (earth?) ecliptic.  Pluto was the clue.

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  9. Haakon Dahl:
    I take it that the heavy-lined portions of orbits are above the (earth?) ecliptic.

    That’s right: bright when north of the ecliptic (plane of Earth’s orbit) and dim when south.  (North and south are defined with respect to the Sun’s poles of rotation.)  For some reason they don’t show the portion of C/2019 Q4’s trajectory that’s below the ecliptic as subdued.

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  10. Devereaux:
    Why was this not noted by all the super-telescopes we have about, that it took an independent with home made equipment?

    Until very recently, with the advent of robotic sky surveys with wide-field telescopes, amateur astronomers accounted for a large majority of discoveries of comets.  The reason is that, with few exceptions, the “super-telescopes” are large “light buckets” which are optimised to collect light from very faint, distant, objects, and observe a tiny field of view.  For example, the so-called “Wide Field Channel” on the Hubble Space Telescope observes an area of ten square arc minutes on the sky, which is around 1/90th of the apparent area of the Full Moon.  It is a vast exaggeration to call this “looking through a soda straw”: it’s more like looking through a ten metre long water pipe.  And that’s the Wide Field Channel: the High Resolution Channel has a field of 0.15 square arc minutes, which means it would have to take 6000 images to cover the disc of the full Moon.

    These kinds of telescopes are precisely what you need when you want to study something in the sky which you already know about and want to observe in detail, collect spectra, or dig out very faint features, but they are worse than useless when it comes to sweeping the sky to discover new things nobody has observed before.  That’s where amateurs excelled: they may have had modest instruments (although in the age of digital imaging, many amateurs now can capture objects which were accessible only to the largest telescopes 25 years ago), but there are hundreds of thousands of them, spread all around the world, looking at every part of the sky from their backyards, many of whom are sufficiently acquainted with the sky to say “that’s odd” upon coming across a faint smudge that doesn’t belong.

    It’s only recently that automated wide-field surveys such as Pan-STARRS (which discovered ’Oumuamua) have become able to compete with the unblinking Argus eyes of amateur astronomers.  The next escalation in all-sky surveys will be the Large Synoptic Survey Telescope (LSST) which is expected to begin commissioning in 2021 with full-scale surveys to begin in 2023.  It will survey all of the sky visible from its location in Chile (30°14’ south) every few nights (clouds permitting, but there aren’t many clouds in the Atacama desert), and will probably account for a large number of discoveries of new objects.  But don’t count out the amateurs yet—there are a lot of them observing northern skies the LSST can’t see, and they’re always watching.

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