The origin of interstellar asteroidal objects like 1I/2017 U1 ‘Oumuamua

Zwart, Simon Portegies; Torres, Santiago; Pelupessy, Inti; Bédorf, Jeroen; Cai, Maxwell X.

doi:10.1093/mnrasl/sly088

Cited by 57 publications

(18 citation statements)

References 74 publications

(86 reference statements)

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“…Our results present a another potential origin for such alien comets: capture from interstellar space. Of course, these captured ISOs must have been liberated from their parent star by post-main-sequence evolution of planetary systems (Hansen & Zuckerman 2017), interactions with planets within their natal host system (Raymond et al 2018a,b), or close encounters in the stellar birth cluster (Hands et al 2019), see also Portegies Zwart et al (2018).…”

Section: Discussionmentioning

confidence: 99%

Capture of interstellar objects: a source of long-period comets

Hands

Dehnen

2020

Monthly Notices of the Royal Astronomical Society: Letters

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We simulate the passage through the Sun-Jupiter system of interstellar objects (ISOs) similar to 1I/'Oumuamua or 2I/Borisov. Capture of such objects is rare and overwhelmingly from low incoming speeds onto orbits akin to those of known long-period comets. This suggests that some of these comets could be of extra-solar origin, in particular inactive ones. Assuming ISOs follow the local stellar velocity distribution, we infer a volume capture rate of 0.051 au 3 yr −1 . Current estimates for orbital lifetimes and space densities then imply steadystate captured populations of ∼ 10 2 comets and ∼ 10 5 'Oumuamua-like rocks, of which 0.033% are within 6 au at any time.

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Section: Discussionmentioning

confidence: 99%

Capture of interstellar objects: a source of long-period comets

Hands

Dehnen

2020

Monthly Notices of the Royal Astronomical Society: Letters

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“…Considering that UAOs have a lower collisional cross section, due to smaller masses, their probability of encountering a star is even lower, supporting our hypothesis that the Sun is the fist star visited by 'Oumuamua. In contrast, the high density of the UAOs, as estimated by Portegies Zwart et al 2018, leads to an expected encounter rate between the Sun and UAOs of up to a dozen per year. It is therefore expected that one UAO visits 0 to 1 star during its life time, while one star is visited by several UAOs every year.…”

Section: Methodsmentioning

confidence: 99%

A kinematical age for the interstellar object 1I/’Oumuamua

Almeida-Fernandes

Rocha–Pinto

2018

Monthly Notices of the Royal Astronomical Society

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1I/'Oumuamua is the first interstellar object observed passing through the Solar System. Understanding the nature of these objects will provide crucial information about the formation and evolution of planetary systems, and the chemodynamical evolution of the Galaxy as a whole. We obtained the galactic orbital parameters of this object, considering 8 different models for the Galaxy, and compared it to those of stars of different ages from the Geneva-Copenhagen Survey (GCS). Assuming that the galactic orbital evolution of this object is similar to that of stars, we applied a Bayesian analyses and used the distribution of stellar velocities, as a function of age, to obtain a probability density function for the age of 'Oumuamua. We considered two models for the age-velocity dispersion relation (AVR): the traditional power law, fitted using data from the GCS; and a model that implements a second power law for younger ages, which we fitted using a sample of 153 Open Clusters (OCs). We find that the slope of the AVR is smaller for OCs than it is for field stars. Using these AVRs, we constrained an age range of 0.01-1.87 Gyr for 'Oumuamua and characterized a most likely age ranging between 0.20-0.45 Gyr, depending on the model used for the AVR. We also estimated the intrinsic uncertainties of the method due to not knowing the exact value of the Solar motion and the particularities of 1I/'Oumuamua's ejection.

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“…The existence of 'Oumuamua has implications for its formation and origin and on the small body populations in other planetary systems (Trilling et al 2017;Ćuk 2018;Feng & Jones 2018;Do et al 2018;Raymond et al 2018a,b;Zwart et al 2018;Gaidos 2018;Jackson et al 2018;Katz 2018). Overall, these formation models generally prefer a comet-like body for interstellar interlopers.…”

Section: Introductionmentioning

confidence: 99%

Spitzer Observations of Interstellar Object 1I/‘Oumuamua

et al. 2018

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1I/'Oumuamua is the first confirmed interstellar body in our Solar System. Here we report on observations of 'Oumuamua made with the Spitzer Space Telescope on 2017 November 21-22 (UT). We integrated for 30.2 hours at 4.5 µm (IRAC channel 2). We did not detect the object and place an upper limit on the flux of 0.3 µJy (3σ). This implies an effective spherical diameter less than [98, 140, 440] meters and albedo greater than [0.2, 0.1, 0.01] under the assumption of low, middle, or high thermal beaming parameter η, respectively. With an aspect ratio for 'Oumuamua of 6:1, these results correspond to dimensions of [240:40, 341:57, 1080:180] meters, respectively. We place upper limits on the amount of dust, CO, and CO 2 coming from this object that are lower than previous results; we are unable to constrain the production of other gas species. Both our size and outgassing limits are important because 'Oumuamua's trajectory shows non-gravitational accelerations that are sensitive to size and mass and presumably caused by gas emission. We suggest that 'Oumuamua may have experienced low-level post-perihelion volatile emission that produced a fresh, bright, icy mantle. This model is consistent with the expected η value and implied high albedo value for this solution, but, given our strict limits on CO and CO 2 , requires another gas species -probably H 2 O -to explain the observed non-gravitational acceleration. Our results extend the mystery of 'Oumuamua's origin and evolution.

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The origin of interstellar asteroidal objects like 1I/2017 U1 ‘Oumuamua

Cited by 57 publications

References 74 publications

Capture of interstellar objects: a source of long-period comets

Capture of interstellar objects: a source of long-period comets

A kinematical age for the interstellar object 1I/’Oumuamua

Spitzer Observations of Interstellar Object 1I/‘Oumuamua

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