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Exocomet orbit fitting : accelerating coma absorption during transits of β pictoris
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Kennedy, Grant M. (2018) Exocomet orbit fitting : accelerating coma absorption during transits of β pictoris. Monthly Notices of the Royal Astronomical Society . sty1477. doi:10.1093/mnras/sty1477 (In Press)
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Official URL: http://dx.doi.org/10.1093/mnras/sty1477
Abstract
Comets are a remarkable feature in our night sky, visible on their passage through the inner Solar system as the Sun's energy sublimates ices and liberates surface material, generating beautiful comae, dust, and ion tails. Comets are also thought to orbit other stars, and are the most promising interpretation of sporadic absorption features (i.e. transits) seen in spectra of stars such as β Pictoris and 49 Ceti. These "exocomets" are thought to form and evolve in the same way as in the Solar system, and as in the Solar system we may gain insight into their origins by deriving their orbits. In the case of β Pictoris, orbits have been estimated indirectly, using the radial velocity of the absorption features coupled with a physical evaporation model to estimate the stellocentric distance at transit dtr. Here, we note that the inferred dtr imply that some absorption signatures should accelerate over several hours, and show that this acceleration is indeed seen in HARPS spectra. This new constraint means that orbital characteristics can be obtained directly, and the pericentre distance and longitude constrained when parabolic orbits are assumed. The results from fitting orbits to 12 accelerating features, and a handful of non-accelerating ones, are in broad agreement with previous estimates based on an evaporation model, thereby providing some validation of the exocomet hypothesis. A prediction of the evaporation model, that coma absorption is deeper for more distant transits, is also seen here.
| Item Type: | Journal Article | ||||||
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| Subjects: | Q Science > QB Astronomy | ||||||
| Divisions: | Faculty of Science > Physics | ||||||
| Library of Congress Subject Headings (LCSH): | Comets, Comets -- Orbits, Circumstellar matter, Planetary systems | ||||||
| Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||
| Publisher: | Wiley | ||||||
| ISSN: | 0035-8711 | ||||||
| Official Date: | 6 June 2018 | ||||||
| Dates: |
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| Date of first compliant deposit: | 19 June 2018 | ||||||
| Article Number: | sty1477 | ||||||
| DOI: | 10.1093/mnras/sty1477 | ||||||
| Status: | Peer Reviewed | ||||||
| Publication Status: | In Press | ||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||
| RIOXX Funder/Project Grant: |
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