Beta Pictoris

13CO And Potential Variability In β Pictoris b With GRAVITY+

By Keith Cowing

Status Report

astro-ph.EP

June 14, 2026

Filed under astro-ph.EP, astrochemistry, astronomy, Beta PIctoris, beta Pictoris b, exoplanet, GRAVITY+, interstellar medium, petitRADTRANS

13CO And Potential Variability In β Pictoris b With GRAVITY+ — GLS periodograms of individual wavelength contrast lightcurves. In each of the panels, the light pink, dark pink, and black highlighted lines are the 1st, 2nd, and 3rd ¹²CO bandheads, respectively. The grey horizontal lines indicate the 1%, 5%, and 10% false alarm probabilities. The black vertical lines indicate the expected rotation period at 8.7 hrs and its first integer harmonic at 4.35 hrs. The top panel shows the uncorrected periodogram, with all wavelengths significantly affected by systematic effects caused by the fibre coupling. The middle panel shows the periodogram after the polynomial correction, while the bottom panel adds Gaussian smoothing to this to highlight strong periodic signals. — astro-ph.EP

The ¹²CO/¹³CO ratio was introduced as an indicator for where in the disk a planet has formed. Previously a lower value compared to the host star’s was suggested to show that a planet accreted CO ice beyond the disk’s CO ice line.

In this letter we aim to determine the ¹²CO/¹³CO value of the directly imaged planet β Pictoris b, and whether we can link it to its formation. Its apparent brightness results in an exceptional S/N of up to ~60 per wavelength point. We present the first science observations with the upgraded GRAVITY+ instrument at a spectral resolution of R ~ 4000, which we analyse with petitRADTRANS.

Our retrievals robustly indicate the presence of ¹³CO with a ¹²CO/¹³CO ratio of 91+24−17, consistent with both a solar to ISM-like value. Our ¹²CO/¹³CO value corroborates recent interpretations that ¹³CO may be a less useful tracer of formation location in the disk than previously thought; nonetheless, we discuss theories with which this value is consistent.

As our observations span ~7 hours, this enabled us to search for atmospheric variability in β Pictoris b; we report a tentative constraint on the variability amplitude of about 1.4+0.6−0.7%.

Antonia von Stauffenberg, Jonas Sauter, Paul Mollière, Matthieu Ravet, David Trevascus, Wolfgang Brandner, Anthony Berdeu, Mickaël Bonnefoy, Guillaume Bourdarot, Jean-Baptiste Le Bouquin, Gaël Chauvin, Frank Eisenhauer, Mathis Houllé, Laura Kreidberg, Elisabeth Matthews, Florentin Millour, Jules Scigliuto, Jason Wang, Jerry W. Xuan, Yapeng Zhang, the GRAVITY+ Collaboration

Comments: Accepted for publication in A&A (26th of May 2026), data products and models are available at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2606.11972 [astro-ph.EP] (or arXiv:2606.11972v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2606.11972
Focus to learn more
Submission history
From: Antonia Von Stauffenberg
[v1] Wed, 10 Jun 2026 11:51:52 UTC (5,918 KB)
https://arxiv.org/abs/2606.11972
Astrobiology, Astrochemistry, exoplanet,

Keith Cowing

Biologist, Explorers Club Fellow, ex-NASA Space Biologist and Payload integrator, Editor of NASAWatch.com and Astrobiology.com, Lapsed climber, Explorer, Synaesthete, Former Challenger Center board member 🖖🏻

Follow on Twitter