Contribution of multiple scattering to the Lyman alpha radiance distribution in cometary comae

IF 3 2区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Icarus Pub Date : 2025-06-26 DOI:10.1016/j.icarus.2025.116720

Yudai Suzuki , Kazuo Yoshioka , Kei Masunaga , Hideyo Kawakita , Yoshiharu Shinnaka , Go Murakami , Tomoki Kimura , Fuminori Tsuchiya , Atsushi Yamazaki , Ichiro Yoshikawa

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Abstract

Observations of hydrogen Lyman Alpha (Ly-α) radiance distribution in cometary comae are important to deduce water production rates and understand the kinetics of coma gases. Here, we constructed a radiative transfer model including multiple scattering processes to reproduce Ly-α radiance distributions in cometary comae observed by the Hisaki satellite. Using the established model, we found that multiple scatterings should be considered when the hydrogen column density exceeds ∼3 × 10¹² /cm². Additionally, as deuterium Ly-α is almost optically thin unlike hydrogen Ly-α, the deuterium-to‑hydrogen (D/H) Ly-α radiance ratio was found to increase in inner comae. In the end, we calculated the Ly-α radiance profile expected to be observed by the Hydrogen Imager onboard the Comet Interceptor spacecraft. Overall, we quantitatively showed that it is necessary to consider multiple scattering when evaluating activities and D/H ratios of active comets with water production rates over 10²⁹ /s.

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多重散射对彗星中莱曼α辐射分布的贡献

观测彗发中氢莱曼α (Ly-α)辐射分布对于推断彗发气体的产水速率和了解彗发气体的动力学具有重要意义。本文建立了包含多个散射过程的辐射传输模型，再现了Hisaki卫星观测到的彗星Ly-α辐射分布。利用所建立的模型，我们发现当氢柱密度超过~ 3 × 1012 /cm2时，需要考虑多重散射。此外，由于氘Ly-α与氢Ly-α几乎是光学薄的，因此发现内部彗差的氘-氢（D/H） Ly-α辐射比增加。最后，我们计算了预计由彗星拦截器航天器上的氢成像仪观测到的Ly-α辐射剖面。总的来说，我们定量地表明，在评估产水速率超过1029 /s的活性彗星的活度和D/H比时，有必要考虑多重散射。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Icarus 地学天文-天文与天体物理

CiteScore

6.30

自引率

18.80%

发文量

356

审稿时长

2-4 weeks

期刊介绍： Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome. The journal generally does not publish papers devoted exclusively to the Sun, the Earth, celestial mechanics, meteoritics, or astrophysics. Icarus does not publish papers that provide "improved" versions of Bode''s law, or other numerical relations, without a sound physical basis. Icarus does not publish meeting announcements or general notices. Reviews, historical papers, and manuscripts describing spacecraft instrumentation may be considered, but only with prior approval of the editor. An entire issue of the journal is occasionally devoted to a single subject, usually arising from a conference on the same topic. The language of publication is English. American or British usage is accepted, but not a mixture of these.