Comets and Asteroids

He Awa Whiria: The Tidal Streams of Interstellar Objects

By Keith Cowing
Status Report
astro-ph.EP
November 28, 2024
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He Awa Whiria: The Tidal Streams of Interstellar Objects
Summary of ISO stream morphologic properties. The top four panels compare the width, height, length, and peak density of a set of simulated streams to rules of thumb for each of these quantities. In the bottom row, the velocity dispersion along the 3 different axes of the stream is compared to the initial velocity dispersion σ0. The bottom right panel shows the shape parameters of the density distribution. In each panel, 5 points are shown for each stream, corresponding to 5 randomly-selected times between 0 and 10 Gyr. For the most part we expect streams to follow the 1:1 line shown in these panels, and for the most part they do, over 3+ orders of magnitude. The exception is σL, the velocity dispersion along the stream direction, which is typically far less than σ0, since a particle’s position in the stream is primarily determined by its velocity in this direction. Note that for plotting clarity we have included a small random scatter of 0.07 dex on the x-coordinates of points where the x-axis is σ0 times a constant, since many points have identical values. — astro-ph.EP

Upcoming surveys are likely to discover a new sample of interstellar objects (ISOs) within the Solar System, but questions remain about the origin and distribution of this population within the Galaxy.

ISOs are ejected from their host systems with a range of velocities, spreading out into tidal streams – analogous to the stellar streams routinely observed from the disruption of star clusters and dwarf galaxies.

We create a simulation of ISO streams orbiting in the Galaxy, deriving a simple model for their density distribution over time. We then construct a population model to predict the properties of the streams in which the Sun is currently embedded.

We find that the number of streams encountered by the Sun is quite large, ~ 10^6 or more. However, the wide range of stream properties means that for reasonable future samples of ISOs observed in the Solar System, we may see ISOs from the same star (“siblings”), and we are likely to see ISOs from the same star cluster (“cousins”).

We also find that ISOs are typically not traceable to their parent star, though this may be possible for ISO siblings. Any ISOs observed with a common origin will come from younger, dynamically colder streams.

John C. Forbes, Michele T. Bannister, Chris Lintott, Angus Forrest, Simon Portegies Zwart, Rosemary C. Dorsey, Leah Albrow, Matthew J. Hopkins

Comments: Submitted to AAS Journals, comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2411.14577 [astro-ph.EP] (or arXiv:2411.14577v1 [astro-ph.EP] for this version)
Submission history
From: John Forbes
[v1] Thu, 21 Nov 2024 20:44:22 UTC (7,502 KB)
https://doi.org/10.48550/arXiv.2411.14577
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Submission history
From: John Forbes
[v1] Thu, 21 Nov 2024 20:44:22 UTC (7,502 KB)
https://arxiv.org/abs/2411.14577
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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