YSES-1 System: Wide-Orbit Benchmark

• YSES-1 system is a directly imaged multi-companion system orbiting a young solar-type star, now classified as a 27±3 Myr MELANGE-4 member.
• The system showcases two distinct companions, with YSES-1 b evolving into a brown-dwarf candidate via revised mass estimates and CPD effects, and YSES-1 c remaining securely planetary-mass.
• High-resolution astrometry and spectroscopy reveal detailed orbital, atmospheric, and circumplanetary properties that establish YSES-1 as a key benchmark for studying wide-orbit substellar evolution.

Searching arXiv for recent YSES-1 papers to ground the article in the latest literature. The YSES-1 system is the planetary system centered on TYC 8998-760-1, a young, solar-type star originally characterized as a K3 IV object and identified as the first directly imaged multiplanet system around a young solar analog (Bohn et al., 2020). The system is known for its two widely separated directly imaged substellar companions, YSES-1 b and YSES-1 c, at projected separations of approximately 160 au and 320 au, respectively (Bohn et al., 2020). Subsequent work has substantially revised its astrophysical context: the host is now classified as a high-probability member of the MELANGE-4 population, a distinct $27 \pm 3$ Myr extended Lower Centaurus–Crux population, rather than the canonical 10–16 Myr Lower Centaurus Crux subgroup (Wood et al., 2022). That reassignment has altered the inferred companion masses, sharpened the system’s role as a benchmark for substellar evolution, and linked YSES-1 to a broader environment containing both directly imaged and transiting planets (Wood et al., 2022).

1. Discovery, identification, and stellar host

The system was established as a two-companion architecture in the Young Suns Exoplanet Survey with the detection of a second wide-orbit companion around TYC 8998-760-1 (Bohn et al., 2020). The host star was described there as a pre-main-sequence, solar-type star in LCC, part of Sco–Cen, with $M_\star = 1.00 \pm 0.02\,M_\odot$, an age of $16.7 \pm 1.4$ Myr, and a Gaia DR2 parallax of $10.54 \pm 0.03$ mas, corresponding to $94.6 \pm 0.3$ pc (Bohn et al., 2020). Later high-resolution spectroscopy gave refined stellar properties of $M_\star = 1.00 \pm 0.02\,M_\odot$, $R_\star = 1.01 \pm 0.02\,R_\odot$, $T_{\rm eff,\star} = 4573 \pm 10$ K, $[\mathrm{Fe/H}] = -0.07 \pm 0.01$, and $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$ (Zhang et al., 2024). A later stellar SED analysis yielded closely related parameters, including $M_\star = 1.00 \pm 0.02\,M_\odot$0, $M_\star = 1.00 \pm 0.02\,M_\odot$1, $M_\star = 1.00 \pm 0.02\,M_\odot$2, and $M_\star = 1.00 \pm 0.02\,M_\odot$3 (Darcis et al., 26 May 2026).

The nomenclature “YSES-1” derives from the Young Suns Exoplanet Survey context and denotes the first YSES system with a confirmed wide-orbit planet and the first with a directly imaged multi-companion architecture around a young solar-mass star (Bohn et al., 2020). The system’s observational importance follows directly from its geometry: the companions are widely separated from the host on the sky, which enables direct spectroscopy and astrometry with comparatively limited stellar contamination (Bohn et al., 2020).

A major contextual revision came with the identification of MELANGE-4, a distributed nearby population in the broader Sco–Cen region (Wood et al., 2022). In that work, TYC 8998-760-1 (YSES-1) was reassigned from classical LCC membership to MELANGE-4 with a BANYAN Σ membership probability of $M_\star = 1.00 \pm 0.02\,M_\odot$4, with membership probabilities in any LCC subgroup or Carina reported as effectively negligible (Wood et al., 2022). The reassignment implies that the system is not best understood as a typical $M_\star = 1.00 \pm 0.02\,M_\odot$5 Myr LCC member but rather as part of a distinct $M_\star = 1.00 \pm 0.02\,M_\odot$6 Myr extended association whose age is anchored by lithium depletion boundary, isochronal, and rotational diagnostics (Wood et al., 2022).

2. System architecture and directly imaged companions

The two known companions, YSES-1 b and YSES-1 c, were initially characterized as planetary-mass objects at extreme separations from the star (Bohn et al., 2020). In the discovery-era interpretation, YSES-1 b had a mass of $M_\star = 1.00 \pm 0.02\,M_\odot$7 at a projected separation of about 160 au, while YSES-1 c had $M_\star = 1.00 \pm 0.02\,M_\odot$8 at about 320 au (Bohn et al., 2020). The latter corresponds to a mass ratio of $M_\star = 1.00 \pm 0.02\,M_\odot$9 with respect to the primary (Bohn et al., 2020). The same work reported that YSES-1 c had $16.7 \pm 1.4$0 K, $16.7 \pm 1.4$1, $16.7 \pm 1.4$2, and $16.7 \pm 1.4$3, with an empirical spectral type of L7.5 (Bohn et al., 2020).

Later spectroscopy and modeling preserved the broad qualitative architecture but changed its quantitative interpretation. High-resolution CRIRES+ work described YSES-1 b as an L0 companion with photometric $16.7 \pm 1.4$4 K and $16.7 \pm 1.4$5, while YSES-1 c remained an L7.5 object with photometric $16.7 \pm 1.4$6 K and $16.7 \pm 1.4$7 (Zhang et al., 2024). That same study explicitly noted that more recent work identifies the host as a high-probability MELANGE-4 member with age $16.7 \pm 1.4$8 Myr, and therefore discussed both 17 Myr and 27 Myr mass scales, giving for YSES-1 b $16.7 \pm 1.4$9 at 17 Myr and $10.54 \pm 0.03$0 at 27 Myr, and for YSES-1 c $10.54 \pm 0.03$1 at 17 Myr and $10.54 \pm 0.03$2 at 27 Myr (Zhang et al., 2024).

The host and companions occupy a rare part of parameter space. The system was described as the first directly imaged multi-planet system around a solar-type star (Zhang et al., 2024), and the original discovery paper emphasized that the wide separations make it an exceptional target for follow-up with facilities such as JWST (Bohn et al., 2020). This suggests a dual benchmark role: the system is useful both for wide-orbit architecture studies and for comparative atmospheric characterization of coeval companions with markedly different temperatures and spectra.

3. Association membership, age revision, and mass reclassification

The most consequential change in the system’s interpretation is the shift from the canonical LCC age of $10.54 \pm 0.03$3 Myr to the MELANGE-4 age of $10.54 \pm 0.03$4 Myr (Wood et al., 2022). The MELANGE-4 age was derived using three independent diagnostics. The primary anchor was the lithium depletion boundary, bracketed by $10.54 \pm 0.03$5 and converted to an age using several model grids, all mutually consistent; the adopted value was $10.54 \pm 0.03$6 (Wood et al., 2022). Isochronal fitting gave $10.54 \pm 0.03$7, and the rotation sequence was qualitatively consistent with $10.54 \pm 0.03$8 Myr (Wood et al., 2022).

For YSES-1 specifically, the membership analysis found that the system lies near the center of MELANGE-4 in both position and velocity, giving it one of the more secure kinematic assignments in the sample (Wood et al., 2022). No new lithium or rotation measurements for YSES-1 were reported there; the age inference is therefore inherited from the ensemble properties of the association rather than from fresh age diagnostics of the host itself (Wood et al., 2022).

The revised age systematically raises the inferred companion masses. Using ATMO 2020 non-equilibrium evolutionary models, YSES-1 b was revised from $10.54 \pm 0.03$9 at 16.7 Myr to $94.6 \pm 0.3$0 at $94.6 \pm 0.3$1 Myr, while YSES-1 c moved from $94.6 \pm 0.3$2 to $94.6 \pm 0.3$3 (Wood et al., 2022). The study noted that YSES-1 b is thereby pushed well into the brown-dwarf regime by most definitions, whereas YSES-1 c remains securely planetary-mass (Wood et al., 2022).

A later SED-focused analysis of YSES-1 b went further. By modeling circumplanetary-disc extinction and emission, it inferred a significantly higher intrinsic luminosity for the companion and then used BT-Settl evolutionary tracks to derive a mass of $94.6 \pm 0.3$4 if the system is $94.6 \pm 0.3$5 Myr old, or $94.6 \pm 0.3$6 if it is $94.6 \pm 0.3$7 Myr old (Darcis et al., 26 May 2026). That work concluded explicitly that, once circumplanetary disc effects are included, YSES-1 b moves into the brown dwarf regime (Darcis et al., 26 May 2026).

A concise summary of the age-dependent companion mass scales discussed in the literature is useful.

Companion	Earlier mass scale	Revised mass scale
YSES-1 b	$94.6 \pm 0.3$8 at $94.6 \pm 0.3$9 Myr	$M_\star = 1.00 \pm 0.02\,M_\odot$0 at $M_\star = 1.00 \pm 0.02\,M_\odot$1 Myr; alternatively $M_\star = 1.00 \pm 0.02\,M_\odot$2 or $M_\star = 1.00 \pm 0.02\,M_\odot$3 from CPD-aware luminosity modeling
YSES-1 c	$M_\star = 1.00 \pm 0.02\,M_\odot$4 at $M_\star = 1.00 \pm 0.02\,M_\odot$5 Myr	$M_\star = 1.00 \pm 0.02\,M_\odot$6 at $M_\star = 1.00 \pm 0.02\,M_\odot$7 Myr

This evolution in the mass estimates has produced a central ambiguity in the system’s classification. In the original YSES interpretation, both outer bodies were treated as giant planets (Bohn et al., 2020). In the revised age and CPD-aware framework, YSES-1 c remains a planetary-mass companion, but YSES-1 b is plausibly better described as a low-mass brown dwarf (Wood et al., 2022, Darcis et al., 26 May 2026). This suggests that “YSES-1 system” now occupies a boundary case between wide-orbit planetary systems and low-mass hierarchical substellar multiples.

4. Orbital architecture, astrometry, and spin–orbit geometry

The original discovery paper used limited astrometric arcs and therefore treated the dynamical architecture in simplified terms, assuming $M_\star = 1.00 \pm 0.02\,M_\odot$8 au and $M_\star = 1.00 \pm 0.02\,M_\odot$9 au and exploring a grid of eccentricities under coplanar assumptions (Bohn et al., 2020). With those assumptions, the authors found that circular orbits are stable, while mildly eccentric orbits for either/both components ($R_\star = 1.01 \pm 0.02\,R_\odot$0) are chaotic on Gyr timescales, implying either in-situ formation or a very specific past interaction involving an unseen third companion (Bohn et al., 2020).

That picture has since changed for YSES-1 b, whose orbit was first fully constrained using VLTI/GRAVITY astrometry, literature SPHERE/NACO astrometry, and a CRIRES+ relative radial velocity measurement (Roberts et al., 17 Sep 2025). The reported orbital posteriors were:

• $R_\star = 1.01 \pm 0.02\,R_\odot$1
• $R_\star = 1.01 \pm 0.02\,R_\odot$2
• $R_\star = 1.01 \pm 0.02\,R_\odot$3
• $R_\star = 1.01 \pm 0.02\,R_\odot$4
• $R_\star = 1.01 \pm 0.02\,R_\odot$5
• $R_\star = 1.01 \pm 0.02\,R_\odot$6
• $R_\star = 1.01 \pm 0.02\,R_\odot$7 (Roberts et al., 17 Sep 2025)

From these medians, the derived orbital period is of order $R_\star = 1.01 \pm 0.02\,R_\odot$8 yr, with periastron $R_\star = 1.01 \pm 0.02\,R_\odot$9 au and apastron $T_{\rm eff,\star} = 4573 \pm 10$0 au (Roberts et al., 17 Sep 2025). The paper emphasized that this is the first full orbit fit for the system and that the eccentricity is no longer effectively prior-dominated (Roberts et al., 17 Sep 2025).

The methodological basis for the new orbit fit is also part of the system’s significance. The study combined four representative GRAVITY epochs—selected from eight to minimize correlated systematics—with SPHERE/NACO imaging and the planetary relative RV $T_{\rm eff,\star} = 4573 \pm 10$1 from CRIRES+ (Roberts et al., 17 Sep 2025). The orbit was fit with orbitize! using ptemcee, with fitted parameters $T_{\rm eff,\star} = 4573 \pm 10$2, $T_{\rm eff,\star} = 4573 \pm 10$3, and $T_{\rm eff,\star} = 4573 \pm 10$4, under standard priors including a log-uniform prior on $T_{\rm eff,\star} = 4573 \pm 10$5 and a uniform prior on $T_{\rm eff,\star} = 4573 \pm 10$6 (Roberts et al., 17 Sep 2025).

The same work derived a stellar spin inclination of $T_{\rm eff,\star} = 4573 \pm 10$7 from the stellar rotation period, radius, and $T_{\rm eff,\star} = 4573 \pm 10$8, and compared it with the orbital inclination to obtain a line-of-sight stellar obliquity of $T_{\rm eff,\star} = 4573 \pm 10$9 (Roberts et al., 17 Sep 2025). The distribution peaks near zero and was described as consistent with a relatively well-aligned system (Roberts et al., 17 Sep 2025).

A compact summary of the current orbital knowledge is therefore appropriate.

Quantity	YSES-1 b
Semi-major axis	$[\mathrm{Fe/H}] = -0.07 \pm 0.01$0 au
Eccentricity	$[\mathrm{Fe/H}] = -0.07 \pm 0.01$1
Inclination	$[\mathrm{Fe/H}] = -0.07 \pm 0.01$2 deg
Approximate period	$[\mathrm{Fe/H}] = -0.07 \pm 0.01$3 yr
Line-of-sight stellar obliquity	$[\mathrm{Fe/H}] = -0.07 \pm 0.01$4 deg

No comparable orbit fit yet exists for YSES-1 c. Its mutual inclination with b, true 3D obliquity, and long-term dynamical relation to the outer architecture remain unconstrained (Roberts et al., 17 Sep 2025). This is an important limitation because the original stability analysis assumed low eccentricities for both objects (Bohn et al., 2020), whereas the new solution for b has moderate eccentricity (Roberts et al., 17 Sep 2025). A plausible implication is that the older stability arguments must be revisited with updated orbital elements and eventual constraints on c.

5. Atmospheric composition, clouds, and circumplanetary material

YSES-1 has become a comparative atmospheric laboratory because both companions have now been studied with high-resolution spectroscopy and JWST mid-infrared observations. The CRIRES+ study measured molecular, elemental, isotopic, rotational, and radial-velocity properties for both companions (Zhang et al., 2024). For YSES-1 b, it confirmed $[\mathrm{Fe/H}] = -0.07 \pm 0.01$5 at higher significance, reporting a $[\mathrm{Fe/H}] = -0.07 \pm 0.01$6 ratio of $[\mathrm{Fe/H}] = -0.07 \pm 0.01$7, consistent with the primary’s $[\mathrm{Fe/H}] = -0.07 \pm 0.01$8 within uncertainties (Zhang et al., 2024). The same retrievals gave $[\mathrm{Fe/H}] = -0.07 \pm 0.01$9 and $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$0 in the disequilibrium+GP model (Zhang et al., 2024). For YSES-1 c, the study reported the first high-resolution detections of H$RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$1O and CO in the atmosphere at $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$2 and $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$3, respectively, with a retrieved $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$4 and $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$5 (Zhang et al., 2024).

The same work found sharply different projected spin rates: $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$6 for YSES-1 b and $RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$7 for YSES-1 c (Zhang et al., 2024). The authors suggested that this may indicate either different spin-axis inclinations or effective magnetic braking by the long-lived circumplanetary disk around YSES-1 b (Zhang et al., 2024). This directly connects the spectroscopic results to later JWST evidence for circumplanetary dust around b.

JWST spectroscopy transformed the understanding of both companions. In the mid-infrared study, YSES-1 c was reported to show the first direct observations of silicate clouds in the atmosphere of the exoplanet YSES-1 c through its 9–11 micron absorption feature, while YSES-1 b exhibited the first circumplanetary disk silicate emission around its sibling planet (Hoch et al., 25 Jul 2025). For YSES-1 c, the clouds were inferred to be composed of either amorphous iron-enriched pyroxene or a combination of amorphous MgSiO$RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$8 and Mg$RV = 12.9 \pm 0.03\,\mathrm{km\,s^{-1}}$9SiO$M_\star = 1.00 \pm 0.02\,M_\odot$00, with particle sizes $M_\star = 1.00 \pm 0.02\,M_\odot$01 at 1 millibar pressure (Hoch et al., 25 Jul 2025). Forward modeling and retrievals placed the companion at $M_\star = 1.00 \pm 0.02\,M_\odot$02, $M_\star = 1.00 \pm 0.02\,M_\odot$03, $M_\star = 1.00 \pm 0.02\,M_\odot$04, and $M_\star = 1.00 \pm 0.02\,M_\odot$05 (Hoch et al., 25 Jul 2025).

For YSES-1 b, the same JWST work found a mid-IR excess between 4 and 14 μm and interpreted it as arising from a circumplanetary dust disk (Hoch et al., 25 Jul 2025). The excess includes a warm continuum approximated by a blackbody of $M_\star = 1.00 \pm 0.02\,M_\odot$06 and a broad 9–11 μm silicate emission feature (Hoch et al., 25 Jul 2025). Modeling of the disk emission favored sub-micron olivine dust grains, with fitted temperatures of $M_\star = 1.00 \pm 0.02\,M_\odot$07 and $M_\star = 1.00 \pm 0.02\,M_\odot$08 and corresponding dust locations of $M_\star = 1.00 \pm 0.02\,M_\odot$09 and $M_\star = 1.00 \pm 0.02\,M_\odot$10 (Hoch et al., 25 Jul 2025). The mass in grains below 1 mm was estimated as $M_\star = 1.00 \pm 0.02\,M_\odot$11 (Hoch et al., 25 Jul 2025).

The later optical-to-infrared SED analysis of YSES-1 b incorporated circumplanetary-disc extinction explicitly and concluded that including a CPD yields a much better fit than a pure-atmosphere model (Darcis et al., 26 May 2026). The atmosphere-only fit gave $M_\star = 1.00 \pm 0.02\,M_\odot$12, $M_\star = 1.00 \pm 0.02\,M_\odot$13, $M_\star = 1.00 \pm 0.02\,M_\odot$14, and $M_\star = 1.00 \pm 0.02\,M_\odot$15, whereas the atmosphere+CPD fit yielded $M_\star = 1.00 \pm 0.02\,M_\odot$16, $M_\star = 1.00 \pm 0.02\,M_\odot$17, $M_\star = 1.00 \pm 0.02\,M_\odot$18, $M_\star = 1.00 \pm 0.02\,M_\odot$19, $M_\star = 1.00 \pm 0.02\,M_\odot$20, and a CPD blackbody component with $M_\star = 1.00 \pm 0.02\,M_\odot$21 and $M_\star = 1.00 \pm 0.02\,M_\odot$22 (Darcis et al., 26 May 2026). The improvement in fit quality was quantified as $M_\star = 1.00 \pm 0.02\,M_\odot$23 and $M_\star = 1.00 \pm 0.02\,M_\odot$24 (Darcis et al., 26 May 2026).

The authors of that study argued that dust extinction and blackbody radiation from a circumplanetary disc can resolve the previously noted large-radius anomaly by replacing a cool, inflated object with a hotter, smaller, and more luminous substellar companion partially obscured by its CPD (Darcis et al., 26 May 2026). This suggests that YSES-1 b’s physical interpretation now depends not only on age but also on whether CPD extinction is treated explicitly in SED fitting.

6. Formation scenarios, dynamics, and benchmark status

The system has been central to debates over wide-orbit formation pathways since its discovery. The original YSES interpretation emphasized that mildly eccentric orbits for the two companions would be chaotic over Gyr timescales, which was taken to support in-situ formation or a very specific past scattering event (Bohn et al., 2020). Formation channels considered in the broader literature include core accretion, disk gravitational instability, cloud fragmentation, and scattering from smaller radii (Bohn et al., 2020).

The newer orbit fit for YSES-1 b complicates that picture. Its moderate eccentricity of $M_\star = 1.00 \pm 0.02\,M_\odot$25 was interpreted as neither quiescently circular nor violently radial (Roberts et al., 17 Sep 2025). The authors concluded that the lower eccentricity compared to some scattered brown dwarfs and the low obliquity both favor formation involving a disk—either in situ or by early disk instability with mild dynamical shaping—over extreme scattering or purely binary-like formation (Roberts et al., 17 Sep 2025). The same paper explicitly stated that for both YSES 1 b and HR 2562 B, the lower eccentricities favor an in situ formation scenario over extreme scattering or cloud fragmentation (Roberts et al., 17 Sep 2025).

Atmospheric composition studies add another layer. For YSES-1 b, the near-stellar C/O and stellar-consistent carbon isotope ratio were interpreted as compatible with either gravitational instability or core accretion beyond the CO iceline with substantial incorporation of solids (Zhang et al., 2024). For YSES-1 c, the retrieved $M_\star = 1.00 \pm 0.02\,M_\odot$26 was described as either solar or subsolar; if genuinely subsolar, the paper suggested this could indicate accretion of oxygen-rich solids and perhaps formation inside the CO iceline followed by outward scattering (Zhang et al., 2024). Because the uncertainties remain large, that inference was framed cautiously (Zhang et al., 2024).

The CPD-aware modeling of YSES-1 b tilts the classification and formation discussion further toward a brown-dwarf-like object. That study argued that the combination of large separation, high mass, brown-dwarf-like nature, and a long-lived CPD makes YSES-1 b more consistent with stellar-like formation—such as fragmentation of the protostellar core or disc gravitational instability—than with core accretion plus migration (Darcis et al., 26 May 2026). This interpretation is stronger than the earlier age-only revision and depends directly on the CPD-corrected luminosity scale (Darcis et al., 26 May 2026).

At the same time, the system remains a benchmark regardless of which formation path proves correct. The MELANGE-4 age is based on an LDB and consistent isochrone fitting rather than on an individual-star age estimate, which makes the system particularly useful for calibrating evolutionary models in the 20–30 Myr regime (Wood et al., 2022). YSES-1 thus now serves as a benchmark in at least three senses: a wide-orbit architecture benchmark, a young substellar atmosphere benchmark, and a CPD benchmark with both accretion signatures and silicate dust emission (Hoch et al., 25 Jul 2025, Darcis et al., 26 May 2026).

7. Position within the broader MELANGE-4 planetary environment

The reinterpretation of YSES-1 as a MELANGE-4 member places it in a broader common-age environment that contains both directly imaged and transiting planets (Wood et al., 2022). The same association includes YSES-2 and HD 95086 as hosts of directly imaged planetary-mass companions, while HD 109833 hosts a two-planet transiting system discovered in TESS data (Wood et al., 2022). This mixed sample is unusual because it links wide, massive companions and close-in transiting planets at a common age of $M_\star = 1.00 \pm 0.02\,M_\odot$27 Myr (Wood et al., 2022).

Within this framework, YSES-1 is no longer an isolated LCC outlier but part of a distributed population whose age is set by ensemble diagnostics (Wood et al., 2022). That association-level age calibration improves the interpretability of the system’s luminosities, masses, and cooling-track positions (Wood et al., 2022). Wood et al. noted that this makes YSES-1 a stronger benchmark for testing planetary and substellar evolutionary models than in the original YSES analysis, because the age is tied to an LDB and CMD-fit scale rather than to a single-star isochrone (Wood et al., 2022).

The existence of both inner transiting planets and outer directly imaged companions in the same 27 Myr environment also offers a broader comparative context (Wood et al., 2022). For YSES-1 specifically, this does not imply any known inner planets, but it situates the system inside an age-calibrated laboratory spanning radii, masses, orbital separations, and atmospheric regimes (Wood et al., 2022). A plausible implication is that the system’s long-term importance will depend not only on improved modeling of YSES-1 b and c themselves, but also on comparative analysis across the full MELANGE-4 planetary census.

In its current understanding, the YSES-1 system comprises a young solar-type host, one outer companion that is increasingly interpreted as a low-mass brown dwarf with a circumplanetary disc, and a second outer companion that remains securely planetary-mass, with both embedded in a $M_\star = 1.00 \pm 0.02\,M_\odot$28 Myr moving-group-like population (Wood et al., 2022, Darcis et al., 26 May 2026). That combination of revised age, direct imaging, orbit fitting, atmospheric spectroscopy, silicate cloud detection, and circumplanetary-disk emission is what makes YSES-1 one of the most technically informative wide-orbit substellar systems presently known.