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Thread: Another interstellar comet coming in?

  1. #1
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    Exclamation Another interstellar comet coming in?

    Interesting article on a comet with a hyperbolic orbit.

    https://arxiv.org/abs/1908.02666

    Comet C/2018 V1 (Machholz-Fujikawa-Iwamoto): dislodged from the Oort Cloud or coming from interstellar space?
    C. de la Fuente Marcos, R. de la Fuente Marcos (Submitted on 7 Aug 2019)

    The chance discovery of the first interstellar minor body, 1I/2017 U1 (`Oumuamua), indicates that we may have been visited by such objects in the past and that these events may repeat in the future. Unfortunately, minor bodies following nearly parabolic or hyperbolic paths tend to receive little attention: over 3/4 of those known have data-arcs shorter than 30 d and, consistently, rather uncertain orbit determinations. This fact suggests that we may have observed interstellar interlopers in the past, but failed to recognize them as such due to insufficient data. Early identification of promising candidates by using N-body simulations may help in improving this situation, triggering follow-up observations before they leave the Solar system. Here, we use this technique to investigate the pre- and post-perihelion dynamical evolution of the slightly hyperbolic comet C/2018 V1 (Machholz-Fujikawa-Iwamoto) to understand its origin and relevance within the context of known parabolic and hyperbolic minor bodies. Based on the available data, our calculations suggest that although C/2018 V1 may be a former member of the Oort Cloud, an origin beyond the Solar system cannot be excluded. If extrasolar, it might have entered the Solar system from interstellar space at low relative velocity with respect to the Sun. The practical feasibility of this alternative scenario has been assessed within the kinematic context of the stellar neighbourhood of the Sun, using data from Gaia DR2, and two robust solar sibling candidates have been identified. Our results suggest that comets coming from interstellar space at low heliocentric velocities may not be rare.
    Do good work. —Virgil Ivan "Gus" Grissom

  2. #2
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    It would be nice to see its trajectory on a map that shows the locations of our assets in space--just on a chance we can get pix.

  3. #3
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    A new candidate for the "interstellar" designation has been announced: see Astronomer's Telegram #13100:

    http://www.astronomerstelegram.org/?read=13100

    We need more observations to confirm its nature, but it is coming inward toward the Sun and the Earth, so it will become easier to see and measure over the next few months.

  4. #4
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    Quote Originally Posted by publiusr View Post
    It would be nice to see its trajectory on a map that shows the locations of our assets in space--just on a chance we can get pix.
    here you go: https://ssd.jpl.nasa.gov/sbdb.cgi?ss...3639&orb=1#orb (edit: sorry wrong object that is the other possible interstellar object C/2019 Q4, C/2018 V1 is here: https://ssd.jpl.nasa.gov/sbdb.cgi?ss...3590&orb=1#orb)



    The best place to observe anything from is usually Earth since that is where all the really good telescopes are. The only exception is space craft that are observing the body they are orbiting. In this case it looks like C/2019 Q4 will come closer to Mars than Earth by about a factor or two or so. The HiRISE camera is probably the best in Mars vicinity but it has an aperture of "only" 50 cm and lacks many instruments like spectrographs so Hubble and earth based telescopes will be able to gather much better data.

    ETA: For C/2018 V1 I don't think there is anything close with a decent camera.
    Last edited by glappkaeft; 2019-Sep-13 at 05:49 AM.

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    Quote Originally Posted by glappkaeft View Post
    The best place to observe anything from is usually Earth since that is where all the really good telescopes are. The only exception is space craft that are observing the body they are orbiting. In this case it looks like C/2019 Q4 will come closer to Mars than Earth by about a factor or two or so. The HiRISE camera is probably the best in Mars vicinity but it has an aperture of "only" 50 cm and lacks many instruments like spectrographs so Hubble and earth based telescopes will be able to gather much better data.
    Just a nitpick, but if you are looking in the visible range, that's certainly true. But for observations at other wavelengths, like (relevant in this case) infrared, it's better to use a space-based telescope because of the absorption. I realize that you meant in the visible range, but other people might not be aware of that so I added it.
    As above, so below

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    I think they are counting Earth-orbiting telescopes as "Earth-based."

    The previous interloper was long and skinny like a rocket, let's hope this one isn't shaped like a saucer!

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    ....or change course during its approach.

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    Rama(s)

    Quote Originally Posted by Ken G View Post
    I think they are counting Earth-orbiting telescopes as "Earth-based."

    The previous interloper was long and skinny like a rocket, let's hope this one isn't shaped like a saucer!
    Or is long and skinny, and is followed by a third similar object. In which case Arthur C. Clarke can be elevated to demi-god status.

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    Quote Originally Posted by Ken G View Post
    I think they are counting Earth-orbiting telescopes as "Earth-based."
    Right, I guess that makes sense. I was thinking of telescopes attached to the earth, but if it’s orbiting I guess it’s like being in a very tall, moving mountain.


    Sent from my iPhone using Tapatalk
    As above, so below

  10. #10
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    A couple of arxive papers:

    Interstellar comet 2I/Borisov

    https://arxiv.org/abs/1909.05851


    Sending a Spacecraft to Interstellar Comet C/2019 Q4 (Borisov)

    https://arxiv.org/abs/1909.06348

    It appears to have a tail which can source non-gravitational accelerations. This is one difference from Oumuamua that did not show an evident tail.

  11. #11
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    It wasn't that long ago that Mars got buzzed by a comet.

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    More information from the The Planetary Society.

    http://www.planetary.org/blogs/jason...t-matters.html

    It’s looking likely that a newly discovered comet is actually an interstellar interloper from beyond our solar system.

    Since its discovery on 30 August, more and more measurements of C/2019 Q4 (Borisov)—named after the amateur astronomer from Crimea who found it—indicate it isn’t orbiting our Sun. Even NASA now says the comet’s extrasolar origin is promising.

    If confirmed, C/2019 Q4 (Borisov) would be the second-ever interstellar object we’ve seen pass through our solar system, following the discovery of 'Oumuamua in 2017. The new object, which sports a fuzzy coma in images, would also be the first definitive interstellar comet; 'Oumuamua looked like an asteroid and behaved a little like a comet.
    I am because we are
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    It has a name now - "2I/Borisov"

    http://www.spacedaily.com/reports/Na...risov_999.html

    A new object from interstellar space has been found within the Solar System, only the second such discovery of its kind. Astronomers are turning their telescopes towards the visitor, which offers a tantalising glimpse beyond our Solar System and raises some puzzling questions. The object has been given the name 2I/Borisov by the IAU.

    On 30 August 2019 the amateur astronomer Gennady Borisov, from MARGO observatory, Crimea, discovered an object with a comet-like appearance. The object has a condensed coma, and more recently a short tail has been observed. Mr. Borisov made this discovery with a 0.65-metre telescope he built himself.

    After a week of observations by amateur and professional astronomers all over the world, the IAU Minor Planet Center was able to compute a preliminary orbit, which suggested this object was interstellar - only the second such object known to have passed through the Solar System.

    The orbit is now sufficiently well known, and the object is unambiguously interstellar in origin; it has received its final designation as the second interstellar object, 2I. In this case, the IAU has decided to follow the tradition of naming cometary objects after their discoverers, so the object has been named 2I/Borisov.
    I am because we are
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    "Astronomers detect gas molecules" in 2I/Borisov.

    http://www.spacedaily.com/reports/As..._star_999.html

    An international team of astronomers have made a historic discovery using the William Herschel Telescope (WHT), detecting gas molecules in a comet which has tumbled into our solar system from another star. It is the first time that astronomers have been able to detect this type of material in an interstellar object.

    The discovery marks an important step forward for science as it will now allow scientists to begin deciphering exactly what these objects are made of and how our home solar system compares with others in our galaxy.

    "For the first time we are able to accurately measure what an interstellar visitor is made of, and compare it with our own solar system," said Professor Alan Fitzsimmons of the Astrophysics Research Centre, Queen's University Belfast.
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    How many other interstellar objects have been observed entering the solar system?? I thought Oumuamua was the first and 2I/Borisov was second? Maybe it's just semantics (on my part) but "first time" makes it sound like there have been multiple opportunities, not just the one. (My bold below).

    Certainly this is very interesting news and I'll look forward to any analysis.

    An international team of astronomers have made a historic discovery using the William Herschel Telescope (WHT), detecting gas molecules in a comet which has tumbled into our solar system from another star. It is the first time that astronomers have been able to detect this type of material in an interstellar object.

    The discovery marks an important step forward for science as it will now allow scientists to begin deciphering exactly what these objects are made of and how our home solar system compares with others in our galaxy.

    "For the first time we are able to accurately measure what an interstellar visitor is made of, and compare it with our own solar system," said Professor Alan Fitzsimmons of the Astrophysics Research Centre, Queen's University Belfast.

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    Oumuamua is still the most interesting to me. Sort of like Miranda. Yes it is probably a natural object too..but darn it if it doesn't look odd. I still half expect to see a front-end loader parked on Miranda somehow.

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    Quote Originally Posted by schlaugh View Post
    How many other interstellar objects have been observed entering the solar system?? I thought Oumuamua was the first and 2I/Borisov was second? Maybe it's just semantics (on my part) but "first time" makes it sound like there have been multiple opportunities, not just the one. (My bold below).

    Certainly this is very interesting news and I'll look forward to any analysis.
    We weren't able to detect any features in the spectrum of Oumuamua, so this is the "first time" that we'll have the chance to compare the chemical composition of an macroscopic object from another stellar system to that of objects in our own.

    Well, if you don't count the billions and billions of spectra of other stars we've measured. Or galaxies. Or clouds of gas in our own galaxy, or in nearby galaxies.

    Eh. Some PR office is just doing its job.

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    "Astronomers Find Our Second Interstellar Visitor Looks like the Locals"

    https://www.scientificamerican.com/a...ke-the-locals/

    Last month astronomers were thrilled by the confirmation that a second known interstellar object is flying through our solar system. Named 2I/Borisov—after its discoverer, Crimean amateur astronomer Gennady Borisov—it has already attracted huge attention. Countless observatories, from the Very Large Telescope in Chile to NASA’s Hubble Space Telescope, are studying the object, and plenty more science is on the way as 2I/Borisov approaches its peak brightness in December. “It’s been a rapid assembly of telescopes around the world,” says Michele Bannister of Queen’s University Belfast. “This, basically, is establishing a new subfield of astronomy.”

    Whereas the first interstellar object, ‘Oumuamua, was found in 2017 as it was already leaving our solar system, 2I/Borisov was caught on the way in. The latter object exhibits traits of cometary activity, with dust and gas surrounding it, whereas ‘Oumuamua was more sedate, like an asteroid (although its classification is still unclear). The question now is whether or not 2I/Borisov resembles comets in our solar system, with either answer being equally thrilling. “I’m torn both ways,” Bannister says. “If it’s like the things that we have in our solar system, the processes that we see taking place are more typical than we realized. If it’s really different, then that tells us this chemistry takes place in quite a different way—in the diversity of exoplanetary systems—than we see.”
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    "Hubble observes first confirmed interstellar comet"

    http://www.spacedaily.com/reports/Hu...comet_999.html

    NASA's Hubble Space Telescope has given astronomers their best look yet at an interstellar visitor - comet 2I/Borisov - whose speed and trajectory indicate it has come from beyond our solar system.

    This Hubble image, taken on Oct. 12, 2019, is the sharpest view of the comet to date. Hubble reveals a central concentration of dust around the nucleus (which is too small to be seen by Hubble).
    I am because we are
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    https://hubblesite.org/contents/news...9/news-2019-61
    I've always wondered if any of our short period comets are interstellar. Captured millions of years ago.

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    Quote Originally Posted by Superluminal View Post
    ... I've always wondered if any of our short period comets are interstellar. Captured millions of years ago.
    It would be a hard catch. They seem to have an excess velocity of a few miles per second that would need to be removed by some reverse slingshot maneuver, which would require some *very* lucky timing and placement wrt Jupiter.
    Forming opinions as we speak

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    "Interstellar comet 2I Borisov swings past Sun"

    http://www.spacedaily.com/reports/In...t_Sun_999.html

    When astronomers see something in the universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention. Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour.

    Telescopes around the world have been watching the fleeting visitor. NASA's Hubble Space Telescope has provided the sharpest views as the comet skirts by our Sun. Since October the space telescope has been following the comet like a sports photographer following horses speeding around a racetrack.

    Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 3,200 feet across, about the length of nine football fields. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond.

    These two images, taken by Hubble, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.
    I am because we are
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  23. #23
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    A fascinating assortment of Borisov papers from this month, covering many aspects of our visitor.

    https://arxiv.org/abs/1912.10213
    A search for the origin of the interstellar comet 2I/Borisov
    Coryn A.L. Bailer-Jones, Davide Farnocchia, Quanzhi Ye, Karen J. Meech, Marco Micheli
    (Submitted on 21 Dec 2019)
    The discovery of the second interstellar object 2I/Borisov on 2019 August 30 raises the question of whether it was ejected from a nearby stellar system. Here we compute the asymptotic incoming trajectory of 2I/Borisov, based on both recent and pre-discovery data extending back to December 2018, using a range of force models that account for cometary outgassing. From Gaia DR2 astrometry and radial velocities, we trace back in time the Galactic orbits of 7.4 million stars to look for close encounters with 2I/Borisov. The closest encounter we find took place 910 kyr ago with the M0V star Ross 573, at a separation of 0.068 pc (90% confidence interval of 0.053-0.090 pc) with a relative velocity of 23 km/s. This encounter is nine times closer than the closest past encounter identified for the first interstellar object 1I/'Oumuamua. Ejection of 2I/Borisov via a three-body encounter in a binary or planetary system is possible, but Ross 573 shows no signs of binarity, plus a comet is unlikely to attain such a large ejection velocity. We also identify and discuss some other close encounters, although if 2I/Borisov is more than about 10 Myr old, our search would be unable to find its parent system.

    https://arxiv.org/abs/1912.07386
    Evolving Coma Morphology of Interstellar Comet 2I/Borisov with Deep HST Imaging
    Bryce T. Bolin
    (Submitted on 13 Dec 2019)
    We present high-resolution deep imaging of interstellar comet 2I/Borisov taken with the Hubble Space Telescope/Wide Field Camera 3 on 2019 October 12, 2019, November 16 and 2019 December 9 UTC (Jewitt et al. 2019). Deep image stacks of 2I on all three dates reveal no discernible signal from a nucleus suggesting that the coma is a strong component of 2I's total sunlight scattering cross-section in the central PSF containing the nucleus of 2I effectively obscuring it despite the advanced high resolution and sensitivity of HST. We search for variations in the morphology of the coma near the central PSF and locate a possible fine jet-like structure 1-2" in length that appears to change positions independent of the orbital velocity and anti-solar vectors over the three observation dates indicating the possibility of rotational variation of the morphology. In addition, we use deep image stacks and the non-detection of a nucleus from the highest spatial resolution HST observations available when 2I is ∼2 au on 2019 December 9 UTC to estimate an upper limit for the diameter of 2I's nucleus of ∼1-2 km, consistent with previous high-resolution ground-based observations (Bolin et al. 2019).

    https://arxiv.org/abs/1912.05628
    FLAMINGOS-2 infrared photometry of 2I/Borisov
    Chien-Hsiu Lee (NSF's OIR Lab), Hsing-Wen Lin (University of Michigan), Ying-Tung Chen (ASIAA), Sheng-Feng Yen (ASIAA)
    (Submitted on 11 Dec 2019)
    2I/Borisov is the second interstellar object (ISO) after 'Oumuamua (Meech et al. 2017), but differs from 'Oumuamua drastically with its extensive cometary activity. A key ingredient to understand the nature of this comet is its size. However, due to its cometary activity and extended coma in the optical, only rough estimates and upper limits can be made for 2I/Borisov, ranging in a wide spread from 0.7 to 3.8 km (Guzik et al. 2019; Fitzsimmons et al. 2019; Jewitt, & Luu 2019; Bolin et al. 2019). It has been shown that observations at longer wavelengths (i.e. infrared) are less susceptible to the effects of coma, and can provide a better estimate of the size of the comet nucleus (see, e.g., Fernández et al. 2013; Bauer et al. 2017). Here we present an estimate of the nucleus of 2I/Borisov from infrared observations by FLAMINGOS-2 on-board the Gemini South telescope (under Fast Turnaround program GS-2019B-FT-207), and infer a comet nucleus size of 1.5 km, comparable to but more stringent than the estimate from Keck AO imaging by Bolin et al. (2019).

    https://arxiv.org/abs/1912.05422
    The Nucleus of Interstellar Comet 2I/Borisov
    David Jewitt, Man-To Hui, Yoonyoung Kim, Max Mutchler, Harold Weaver, Jessica Agarwal
    (Submitted on 11 Dec 2019)
    We present high resolution imaging observations of interstellar comet 2I/Borisov (formerly C/2019 Q4) obtained using the Hubble Space Telescope. Scattering from the comet is dominated by a coma of large particles (characteristic size 0.1 mm) ejected anisotropically. Convolution modeling of the coma surface brightness profile sets a robust limit to the spherical-equivalent nucleus radius r_n < 0.5 km (geometric albedo 0.04 assumed). We obtain an independent constraint based on the non-gravitational acceleration of the nucleus, finding r_n > 0.2 km (nucleus density 500 kg/m3 assumed). The profile and the non-gravitational constraints cannot be simultaneously satisfied if density < 25 kg/m3; the nucleus of comet Borisov cannot be a low density fractal assemblage of the type proposed elsewhere for the nucleus of 1I/'Oumuamua. We show that the spin-up timescale to outgassing torques, even at the measured low production rates, is comparable to or shorter than the residence time in the Sun's water sublimation zone. The spin angular momentum of the nucleus should be changed significantly during the current solar fly-by. Lastly, we find that the differential interstellar size distribution in the 0.5 mm to 100 m size range can be represented by power laws with indices < 4 and that interstellar bodies of 100 m size scale strike Earth every one to two hundred million years.

    https://arxiv.org/abs/1911.05902
    Pre-discovery Activity of New Interstellar Comet 2I/Borisov Beyond 5 AU
    Quanzhi Ye, Michael S. P. Kelley, Bryce T. Bolin, Dennis Bodewits, Davide Farnocchia, Frank J. Masci, Karen J. Meech, Marco Micheli, Robert Weryk, Eric C. Bellm, Eric Christensen, Richard Dekany, Alexandre Delacroix, Matthew J. Graham, Shrinivas R. Kulkarni, Russ R. Laher, Ben Rusholme, Roger M. Smith
    (Submitted on 14 Nov 2019 (v1), last revised 23 Dec 2019 (this version, v2))
    Comet 2I/Borisov, the first unambiguous interstellar comet ever found, was discovered in August 2019 at ∼3 au from the Sun on its inbound leg. No pre-discovery detection beyond 3 au has yet been reported, mostly due to the comet's proximity to the Sun as seen from the Earth. Here we present a search for pre-discovery detections of comet Borisov using images taken by the Catalina Sky Survey (CSS), Pan-STARRS and Zwicky Transient Facility (ZTF), with a further comprehensive follow-up campaign being presented in {Bolin2019}. We identified comet Borisov in ZTF images taken in May 2019 and use these data to update its orbit. This allowed us to identify the comet in images acquired as far back as December 2018, when it was 7.8 au from the Sun. The comet was not detected in November 2018 when it was 8.6 au from the Sun, possibly implying an onset of activity around this time. This suggests that the activity of the comet is either driven by a more volatile species other than H2O, such as CO or CO2, or by exothermic crystallization of amorphous ice. We derive the radius of the nucleus to be <7 km using the non-detection in November 2018, and estimate an area of ∼0.5 - 10 km^2 has been active between December 2018 and September 2019, though this number is model-dependent and is highly uncertain. The behavior of comet Borisov during its inbound leg is observationally consistent with dynamically new comets observed in our solar system, suggesting some similarities between the two.
    Do good work. —Virgil Ivan "Gus" Grissom

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    New article asking if Borisov might be a stardust comet with an exotic origin. Time should tell.

    https://arxiv.org/abs/1912.12730

    Is Interstellar Object 2I/Borisov a Stardust Comet? Predictions for the Post Perihelion Period
    T. Narshall Eubanks
    (Submitted on 29 Dec 2019)

    The detection of interstellar bodies passing near the Sun offers the opportunity to observe not just objects similar to those in the solar system, but also unfamiliar objects without solar system analogues. Here I show that Asymptotic Giant Branch (AGB) stellar evolution may lead to the creation, out of stardust, of substantial numbers of nomadic Post-Main-Sequence Objects (PMSOs). ABG nucleosynthesis will produce three broad classes of PMSO chemistry, oxygen, carbon and nitrogen rich (O-rich, C-rich, N-rich, respectively), depending largely on the original stellar mass. I further show that the Interstellar Comet 2I/Borisov (2I) belongs to a kinematic dynamical stream, the Wolf 630 stream, with an age and galactic orbit consistent with its origination as a stardust comet; the apparent lack of water in the 2I coma is consistent with it being a C-rich PMSO. I also provide predictions for distinguishing stardust comets from more conventional interstellar comets and asteroids ejected during planetary formation; these can be applied to 2I in its upcoming observational phase in early 2020 as it moves away from the Sun. In particular, isotope ratios of the CNO elements could be dispositive, IR detection of the 11.3 {\mu}m SiC line, the 30 {\mu}m line, or the IR PAH lines would provide strong evidence for a C-rich PMSO and detection of Na or Li enhancement would indicate an N-rich PMSO.
    Do good work. —Virgil Ivan "Gus" Grissom

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