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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.SR · Solar and Stellar Astrophysics

TESS 2024-2025 data of beta Pic show no exocomet dip deeper than 3e-4, against 6 in 2018-2021 at equal completeness; the rate decrease is not significant (p = 0.05)

Question: Did the rate of exocomet transits of beta Pictoris change between the 2018-2021 TESS sectors (5-7, 32-34) and the new sectors 87, 95 and 98 (2024-2025)? We did not find a published analysis of the new sectors. Method: We used one pipeline for all sectors. It removes delta Scuti pulsations (prewhitening at 15-100 cycles per day), removes slow trends with a masked 2-day biweight, and does an iterative matched-filter search with the 1-D exocomet model of Lecavelier des Etangs et al. (2022). The same search on the inverted light curve sets the threshold (S/N 6.38). A momentum-dump veto applies to all events. 800 injected dips give the completeness. SAP flux, 20-s data, QLP FFI photometry and centroids test for artifacts. Results: The completeness for absorption depth AD >= 3e-4 is 0.91 (2018-2021) and 0.93 (2024-2025). The pipeline detects 6 dips with AD >= 3e-4 in 113.4 searchable days of 2018-2021 and 0 in 70.6 days of 2024-2025. If the rate did not change, 2.33 were expected (one-sided p = 0.052). The 95% upper limit on the new/old rate ratio is 1.33. Over the analysis variants, p is 0.03 to 0.20. Thus the decrease is not significant. Three new exocomet-like dips occur in 2024-2025 (BTJD 3685.32, 3885.24, 4002.30; AD 2.0e-4 to 2.7e-4). The first two also occur in the SAP and 20-s data and have no centroid motion. The third is at a 14-sigma centroid excursion and is probably instrumental. The veto removes 7 of 9 brightening events but only 4 of 32 dips. The pipeline recovers all 9 searchable published events with AD >= 3e-4. Limitations: The numbers are small. One control event sets the threshold. The SAP and 20-s data use the same pixels. QLP gives only a weak check. Alpha Pic is too variable to be a control star. No follow-up observations were made.

beta Pictoris · exocomets · TESS · transit photometry · falling evaporating bodies · injection-recovery · delta Scuti · debris disk · rate comparison

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References

13
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    Source of the 1-D exocomet model, the cleaning recipe, the 30 published events, the event shapes used for injections, and the absorption-depth distribution that we compare with the new sectors.

  2. useshttps://github.com/lecaveli/BetaPic_TESS/tree/f1dc39c02eda8c1a687651b58eb9e92cc7edf4d1

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  3. doi:10.1051/0004-6361/201935552

    First TESS detection of exocomet transits of beta Pic.

  4. doi:10.1051/0004-6361/202142111

    Exocomet dips of beta Pic in sectors 32 and 33 and a note on the momentum dump near BTJD 2221.

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    Orbital distribution of beta Pic exocomets from TESS transit durations.

  6. https://arxiv.org/abs/2601.15216

    HST and HARPS spectra of April 2025 show low-velocity exocomets during the new TESS epoch.

  7. doi:10.1038/nature13849

    Spectroscopic exocomet families of beta Pic.

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  9. usesdoi:10.1117/1.JATIS.1.1.014003

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  10. usesdoi:10.1117/12.2233418

    SPOC light curves (PDCSAP, SAP, centroids, quality flags).

  11. usesdoi:10.3847/2515-5172/abca2e

    QLP FFI light curves used as a cross-check.

  12. doi:10.3847/1538-3881/ab3984

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  13. useshttps://archive.stsci.edu/missions-and-data/tess

    MAST archive; exact file URLs and SHA-256 hashes are in files/provenance.

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