Exocomet orbital distribution around $β$ Pictoris
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866916387694313472 |
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| author | Heller, René |
| author_facet | Heller, René |
| contents | The 23 Myr young star $β$ Pictoris is a laboratory for planet formation studies given its observed debris disk, its two directly imaged super-Jovian planets, and the evidence of transiting extrasolar comets. The most recent evidence of exocometary transits around $β$ Pic came from the TESS space mission. Previous analyses of these transits constrained the orbital distribution of the underlying exocomet population to range between about 0.03 and 1.3 AU assuming a fixed transit impact parameter. Here we examine the distribution of the observed transit durations ($Δt$) to infer the orbital surface density distribution ($δ$) of the underlying exocomet sample. We show that a narrow belt of exocomets around $β$ Pic, in which the transit impact parameters are randomized but the orbital semimajor axes are equal, results in a pile-up of long transit durations. This is contrary to observations, which reveal a pile-up of short transit durations ($Δt \approx 0.1$ d) and a tail of only a few transits with $Δt > 0.4$ d. A flat density distribution of exocomets between about 0.03 and 2.5 AU results in a better match between the resulting $Δt$ distribution and the observations but the slope of the predicted $Δt$ histogram is not sufficiently steep. An even better match to the observations can be produced with a $δ\propto a^β$ power law. Our modeling reveals a best fit between the observed and predicted $Δt$ distribution for $β= -0.15_{-0.10}^{+0.05}$. A more reasonable scenario in which the exocometary trajectories are modeled as hyperbolic orbits can also reproduce the observed $Δt$ distribution to some extent. Our results imply that cometary material exists on highly eccentric orbits with a more extended range of semimajor axes than suggested by previous spectroscopic observations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_20829 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Exocomet orbital distribution around $β$ Pictoris Heller, René Earth and Planetary Astrophysics The 23 Myr young star $β$ Pictoris is a laboratory for planet formation studies given its observed debris disk, its two directly imaged super-Jovian planets, and the evidence of transiting extrasolar comets. The most recent evidence of exocometary transits around $β$ Pic came from the TESS space mission. Previous analyses of these transits constrained the orbital distribution of the underlying exocomet population to range between about 0.03 and 1.3 AU assuming a fixed transit impact parameter. Here we examine the distribution of the observed transit durations ($Δt$) to infer the orbital surface density distribution ($δ$) of the underlying exocomet sample. We show that a narrow belt of exocomets around $β$ Pic, in which the transit impact parameters are randomized but the orbital semimajor axes are equal, results in a pile-up of long transit durations. This is contrary to observations, which reveal a pile-up of short transit durations ($Δt \approx 0.1$ d) and a tail of only a few transits with $Δt > 0.4$ d. A flat density distribution of exocomets between about 0.03 and 2.5 AU results in a better match between the resulting $Δt$ distribution and the observations but the slope of the predicted $Δt$ histogram is not sufficiently steep. An even better match to the observations can be produced with a $δ\propto a^β$ power law. Our modeling reveals a best fit between the observed and predicted $Δt$ distribution for $β= -0.15_{-0.10}^{+0.05}$. A more reasonable scenario in which the exocometary trajectories are modeled as hyperbolic orbits can also reproduce the observed $Δt$ distribution to some extent. Our results imply that cometary material exists on highly eccentric orbits with a more extended range of semimajor axes than suggested by previous spectroscopic observations. |
| title | Exocomet orbital distribution around $β$ Pictoris |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2407.20829 |