![The upper panel shows, in blue, the simulated planetary flux containing CH4 and produced using petitRadTRANS. The model is baselinesubtracted. The bottom panel shows the planetary contrast, in yellow, derived from the upper panel and used in the cross-correlation procedure. The black dashed line represents the threshold (i.e. 0.1 in contrast space) used to select the regions containing information. The green areas denote where the model’s gradient exceeds the threshold (selected regions), while the red ones are discarded regions. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/11/Signatures.png?fit=1200%2C677&ssl=1)
[astro-ph.EP] β Pictoris is a nearby (19.7 pc), young (∼ 24 Myr), bright (V=3.85) planetary system hosting three directly imaged planets. Previous high-resolution spectroscopy of β Pic b has detected H2O and CO, but not CH4 or NH3.
Combining observations across a broad wavelength range has been shown to maximise sensitivity to such weak molecular signals. We searched for previously undetected molecular species in the atmosphere of β Pic b using high-resolution near-infrared spectra.
We combined 44 CRIRES+ spectral settings covering the H, K, L, and M bands and cross-correlated the extracted planetary spectra with molecular templates. For species with uncertain detectability, we weighted the observations by their molecular information content and data quality, independent of the measured candidate-species cross-correlation functions.
We recover H2O and CO at cross-correlation S/N values of approximately 200 and 50, respectively. We additionally identify tentative CH4 and NH3 signals near the expected radial velocity of β Pic b, with S/N values of approximately 5.3 and 5.7. Equivalent extractions at the same projected separation on the opposite side of the star show no comparable peaks.
We classify the CH4 and NH3 signals as tentative because their cross-correlation S/N values do not fully account for possible residual systematics. If confirmed, these would be the first detections of both species in the atmosphere of β Pic b.
A. Barone, M. Janson, A. Brandeker, T. Stolker, A. Vigan, K. Hoy, P. Molliere, A. Denis, H. Anwand-Heerwart, Y. Charles, J. C. Costes, A. Costille, M. El Morsy, J. Garcia, M. Houllé, M. Lopez, G. Murray, E. Muslimov, G. P. P. L. Otten, J. Paufique, M. Phillips, U. Seemann, A. Viret, G. Zins
Comments: Accepted for publication in Astronomy & Astrophysics. 7 pages, 3 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2611.14646 [astro-ph.EP] (or arXiv:2611.14646v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2611.14646
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Related DOI:
https://doi.org/10.1051/0004-6361/202663736
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Submission history
From: Andrea Barone
[v1] Tue, 10 Nov 2026 19:01:16 UTC (1,145 KB)
https://arxiv.org/abs/2611.14646
Astrobiology, Astrochemistry,
