WIde Separation Planets In Time (WISPIT): Two Directly Imaged Exoplanets Around The Sun-like Stellar Binary WISPIT 1

Wide separation gas giant planets present a challenge to current planet formation theories, and the detection and characterisation of these systems enables us to constrain their formation pathways.

The WIde Separation Planets In Time (WISPIT) survey aims to detect and characterise wide separation planetary-mass companions over a range of ages from <5 to 20 Myr around solar-type host stars at distances of 75-500 (median: 140) parsecs.

The WISPIT survey carries out two 5 minute H-band exposures with the VLT/SPHERE instrument and IRDIS camera, separated by at least six months to identify co-moving companions via proper motion analysis. These two H-band observations in combination with a follow-up Ks-band observation were used to determine the colour-magnitude of the co-moving companions and to derive their masses by comparing to AMES-COND and AMES-DUSTY evolutionary tracks.

We report the discovery of WISPIT 1b and WISPIT 1c, two gas giant exoplanets that are co-moving with the stellar binary WISPIT 1, which itself consists of a K4 star and M5.5 star in a multi-decadal orbit. The planets are at projected separations of 338 au and 840 au and have masses of 10 Mj and 4 Mj respectively.

We identified two common proper motion planetary companions to a (previously unknown) stellar binary with a Sun-like primary. These targets are ideal for follow up characterisation with both ground and space-based telescopes.

Monitoring of the orbit with the GRAVITY interferometer will place constraints on their eccentricity, and spectroscopic characterisation will identify the composition and metallicity, providing information on their formation pathways.

Detail of the WISPIT 1 system. The top panel shows the SPHERE/IRDIS H-band image taken on 2022 November 19, processed with unsharp masking to suppress the stellar halo. The stellar binary WISPIT 1 (behind the coronagraph) is located in the upper left, with its companions highlighted with coloured boxes. Zoomed-in images of the unmasked observation centred on companions WISPIT 1b and WISPIT 1c, are shown in the lower left and lower right panels, respectively. — astro-ph.EP

Richelle F. van Capelleveen, Matthew A. Kenworthy, Christian Ginski, Eric E. Mamajek, Alexander J. Bohn, Rico Landman, Tomas Stolker, Yapeng Zhang, Nienke van der Marel, Ignas Snellen

Comments: Accepted for publication in Astronomy & Astrophysics section “10. Planets, planetary systems, and small bodies” on August 25, 2025
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2508.18456 [astro-ph.EP](or arXiv:2508.18456v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.18456
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Submission history
From: Richelle Van Capelleveen
[v1] Mon, 25 Aug 2025 20:04:02 UTC (3,867 KB)
https://arxiv.org/abs/2508.18456

Astrobiology, exoplanet,