Illustration of an exocomet transit. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Beta Pictoris, Biochemistry & Organic Chemistry, Comets and Asteroids, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

Observations Of Exocomets

by Keith CowingMarch 24, 2026March 24, 2026

Active small bodies in extrasolar systems, the extrasolar analogues of Solar System comets, provide insights into the orbital evolution and physical processes shaping planetary systems.

Astronomy & Telescopes, Beta Pictoris, Comets and Asteroids, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

Visual Inspection Of Potential Exocomet Transits Identified Through Machine Learning And Statistical Methods

by Keith CowingFebruary 7, 2026February 7, 2026

In this work, we explore several ways to detect possible exocomet transits in the TESS (The Transiting Exoplanet Survey Satellite) light curves. The first one has been presented in our […]

Spectroscopic observations of β Pic obtained on April 29, 2025. The HARPS spectrum is not flux-calibrated and was simply renormalized to a flux level similar to that of the STIS data. Numerous saturated absorption lines are visible in the STIS and HARPS spectra, attributed to Si ii, C i, Al ii, Fe ii, Mg ii and Ca ii. The HST spectra are consistent with a stellar model from the PHOENIX library (thick grey line, Husser et al. 2013) at Teff = 8000 K (see Sect. 4.1). -- astro-ph.EP

Beta Pictoris, Comets and Asteroids, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

Transit Distances And Composition Of Low-velocity Exocomets In The β Pictoris System

by Keith CowingJanuary 25, 2026January 25, 2026

β Pictoris is a young nearby A5V star, about 20 Myr old, embedded in a prominent debris disc. For the past 40 years, variable absorption features have been observed in […]

Upper mass limits for a potential lunar companion to β Pic b as a function of orbital period. The color is proportional to the density of MCMC posterior samples, and the solid curves indicate the 68%, 95%, and 99.7% confidence intervals. The upper panel covers longer orbital periods (≲ 1450 days, within the dynamical stability limit), where companions more massive than ∼ 0.5 MJup (∼ 60 M⊕) are excluded. The dashed line marks the Earth–Moon mass ratio scaled to β Pic b, and the solid green curve shows the moon/binary planet boundary from Stern & Levison (2002), which marks the theoretical separation between large moons and binary planetary systems based on mass ratios and orbital stability criteria. The lower panel zooms in on short orbital periods (≲ 50 days), where the constraints are weaker. The dashed line indicates the Pluto–Charon mass ratio, while the solid green curve again shows the Stern & Levison (2002) moon/binary planet boundary. -- astro-ph.EP

Astronomy & Telescopes, Beta Pictoris, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

First Astrometric Limits On Binary Planets And Exomoons Orbiting β Pictoris b

by Keith CowingDecember 11, 2025December 10, 2025

The search for exomoons, or moons in other star systems, has attracted significant interest in recent years, driven both by advancements in detection sensitivity and by the expanding population of […]

Distance versus time distributions for the 49 encounters with β Pic that have an empirical probability of at least 95% of occurring within 2 pc. The coloured points indicate the rescaled Mahalanobis distances (ensuring a common colour scale for all stars) derived from the encounter parameters. Points above the 95th percentile of this metric are shown in grey. The black bars represent the 95% confidence intervals in time and distance, obtained from the 2.5th and 97.5th percentiles of the corresponding marginal distributions for the further encounters and using the 95th percentile to define the one-tailed distance interval for the closest ones. The central points are the 50th percentiles. The critical radius of 2 pc is indicated by the red horizontal line. The centres of mass of binary systems, listed in table 4, are marked at the pair [t50, d50] corresponding to that star. -- astro-ph.SR

Beta Pictoris, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

A Kinematic History Of Stellar Encounters With Beta Pictoris

by Keith CowingOctober 13, 2025October 13, 2025

Beta Pictoris is an A-type star hosting a complex planetary system with two massive gas giants and a prominent debris disk.

Results of the forward modeling of β Pic b using the most recent spectro/photometric observations of the planet (including CRIRES+) using BT-Settl. Top panel: spectra (points) and photometry (squares) of β Pic b alongside a Rλ ∼ 4 000 spectrum extracted using the best fit parameters for the inversion. Observations have been re-normalized using the analytic scaling factors computed during the inversion. Associated residuals are shown below. Dotted lines represents the ±σ (68%) confidence interval. Bottom sub-panels: zoom versions of the top panel on GRAVITY (upper left), SINFONI (upper right), CRIRES+-K (lower left) and CRIRES+-M (lower right). Similarly to Landman et al. (2024), each CRIRES+ spectra are shown smoothed by their retrieved broadening to show the planet features more clearly. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Beta Pictoris, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Multi-modal Atmospheric Characterization Of beta Pictoris b: Adding High-resolution Continuum Spectra From GRAVITY

by Keith CowingOctober 1, 2025October 1, 2025

We present the first VLTI/GRAVITY observations at Rλ∼4000 of β Pic b. These four high S/N (∼20) K-band spectra conserve both the pseudo-continuum and molecular absorption patterns.

Figure from Rebollido et al. (2024). The debris disk around Beta Pictoris seen with JWST/MIRI. -- astro-ph.IM

Astronomy & Telescopes, Beta Pictoris, Status Report

Debris Disks And Their Properties With The Habitable Worlds Observatory

by Keith CowingSeptember 30, 2025September 30, 2025

The study of the last stages of planet formation, also known as debris disks, is fundamental to place constrains on the formation of planetary sized bodies.

Detection maps of β Pic b with MATISSE. The maps show the reduced χ2 values after fitting the stellar contamination for each tested planet astrometry (∆α, ∆δ) in the grid. The grids are centered on MATISSE’s pointing during the planet observations. The left map is the size of the pinhole (1.5λ/D at 3.5 µm) and has a resolution of 1 mas. The right map was generated at higher resolution (0.1 mas) on a smaller 20×20 mas grid. The most likely astrometry from the MATISSE observations is shown as a blue ellipse, found by fitting a 2D Gaussian curve on the lowest χ2r peak. The planet location and uncertainties predicted by whereistheplanet from the orbital fitting of GRAVITY observations (Lacour et al. 2021) are shown as a green ellipse. The multiplicity of χ2r peaks is due to the interferometric nature of our data. As coherent flux is periodic as a function of α. ⃗ ⃗u (see Eq. (7)), an infinity of astrometric solutions can reproduce the signal. This degeneracy gradually disappears when combining data from different baseline lengths and orientations. The χ2r of neighbour peaks can nonetheless still remain close. Using covariances between baselines and wavelengths could help increase the difference between peaks, and will be studied in a future work. -- astro-ph.EP

Astronomy & Telescopes, Beta Pictoris, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

The Mid-infrared Spectrum Of Beta Pictoris b. First VLTI/MATISSE Interferometric Observations Of An Exoplanet

by Keith CowingAugust 29, 2025August 29, 2025

Few spectra of directly-imaged exoplanets have been obtained in the mid-infrared (> 3 μm). This region is particularly rich in molecular spectral signatures, whose measurements can help recover atmospheric parameters […]