Upper limits on CN from exocomets transiting $β$ Pictoris

Fuente: arXiv
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Main Authors: Kenworthy, M. A., de Mooij, E., Brandeker, A., Opitom, C., Kiefer, F., Fitzsimmons, A.
Format: Preprint
Published: 2025
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author Kenworthy, M. A.
de Mooij, E.
Brandeker, A.
Opitom, C.
Kiefer, F.
Fitzsimmons, A.
author_facet Kenworthy, M. A.
de Mooij, E.
Brandeker, A.
Opitom, C.
Kiefer, F.
Fitzsimmons, A.
contents The young (23 Myr) nearby (19.4 pc) star $β$ Pictoris hosts an edge-on debris disk with two gas giant exoplanets in orbit around it. Many transient absorption features have been detected in the rotationally broadened stellar lines, which are thought to be the coma of infalling exocomets crossing the line of sight towards Earth. In the Solar System, the molecule cynaogen (CN) and its associated ionic species are one of the most detectable molecules in the coma and tails of comets. We perform a search for cyanogen in the spectra of $β$ Pictoris to detect or put an upper limit on this molecule's presence in a young, highly active planetary system. We divide twenty year's worth of HARPS spectra into those with strong exocomet absorption features, and those with only stellar lines. The high signal-to-noise stellar spectrum normalises out the stellar lines in the exocomet spectra, which are then shifted and stacked on the deepest exocomet absorption features to produce a high signal-to-noise exocomet spectrum, and search for the CN band head using a model temperature dependent cross-correlation template. We do not detect CN in our data, and place a temperature and broadening dependent 5$σ$ upper limit between 10$^{12}$ cm$^{-2}$ and 10$^{13}$ cm$^{-2}$, to be compared to the typical 10$^9$ - 10$^{10}$ cm$^{-2}$ expected from scaling of the values in the Solar System comets.
format Preprint
id arxiv_https___arxiv_org_abs_2504_14299
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Upper limits on CN from exocomets transiting $β$ Pictoris
Kenworthy, M. A.
de Mooij, E.
Brandeker, A.
Opitom, C.
Kiefer, F.
Fitzsimmons, A.
Earth and Planetary Astrophysics
The young (23 Myr) nearby (19.4 pc) star $β$ Pictoris hosts an edge-on debris disk with two gas giant exoplanets in orbit around it. Many transient absorption features have been detected in the rotationally broadened stellar lines, which are thought to be the coma of infalling exocomets crossing the line of sight towards Earth. In the Solar System, the molecule cynaogen (CN) and its associated ionic species are one of the most detectable molecules in the coma and tails of comets. We perform a search for cyanogen in the spectra of $β$ Pictoris to detect or put an upper limit on this molecule's presence in a young, highly active planetary system. We divide twenty year's worth of HARPS spectra into those with strong exocomet absorption features, and those with only stellar lines. The high signal-to-noise stellar spectrum normalises out the stellar lines in the exocomet spectra, which are then shifted and stacked on the deepest exocomet absorption features to produce a high signal-to-noise exocomet spectrum, and search for the CN band head using a model temperature dependent cross-correlation template. We do not detect CN in our data, and place a temperature and broadening dependent 5$σ$ upper limit between 10$^{12}$ cm$^{-2}$ and 10$^{13}$ cm$^{-2}$, to be compared to the typical 10$^9$ - 10$^{10}$ cm$^{-2}$ expected from scaling of the values in the Solar System comets.
title Upper limits on CN from exocomets transiting $β$ Pictoris
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2504.14299