Artem Burdanov

The Euclid Wide Survey will image approximately 14,000 deg ² away from the ecliptic, complemented by repeated observations of three Deep Fields covering approximately 50 deg ² . Together, these surveys will provide a potentially rich dataset for studying high-inclination solar system objects (SSOs). To test the feasibility of using the Euclid VIS instrument to search for slow-moving SSOs (apparent rates of motion ≲ 2 . ″ 1 hr ⁻¹ ), we performed a synthetic tracking search of the Euclid Quick Data Releases (Q1, Q2) using the kernel-based moving object detection (KBMOD) framework. We searched 133 Euclid fields (≈60 deg ² ) and performed injection-retrieval tests. We report no candidates within the searched parameter space. Injection-retrieval places 50% completeness at VIS magnitude I _E = 25.9 (Q1), 26.4 (Q1 LDN 1641 fields), and 23.1 (Q2).

Short-period white-dwarf–main-sequence (WDMS) binaries provide direct constraints on the outcomes of common-envelope (CE) evolution and the survival of low-mass companions during engulfment. We report the discovery and confirmation of 10 totally eclipsing WD + cool-M-dwarf binaries identified through a search tailored to minute-scale eclipses in Transiting Exoplanet Survey Satellite (TESS) high-cadence data and validated with SPECULOOS multiband photometry. The systems have orbital periods of a few hours and companion masses of 0.094–0.175 M _⊙ . Our pilot search of ∼37,000 Gaia-selected WDs increases the number of WD+M systems first identified through TESS by an order of magnitude, demonstrating that minute-scale WD eclipses occupy a previously underexplored discovery regime for TESS. SPECULOOS follow-up establishes the WDs as the sources of the eclipse signals, while chromatic eclipse dilution and broadband spectral-energy-distribution (SED) modeling provide complementary constraints on the component properties. These systems extend the TESS-discovered eclipsing WD+M population toward lower companion masses and establish an effective, scalable framework for expanding the search from the ∼37,000 WDs analyzed here to a pool of O (10 ⁶ ) Gaia WD candidates with TESS photometry.

White dwarf–brown dwarf (WD+BD) binaries are rare laboratories for probing both substellar survival through post-main-sequence evolution and the physics of strongly irradiated atmospheres. We present time-resolved eclipse photometry and radial-velocity confirmation of J0404+1112, a compact ( P = 2.93 hr), totally eclipsing WD+BD system initially reported in Research Notes of the AAS by J. de Wit et al. New high-cadence observations resolve the total eclipse of the WD and, combined with spectroscopy, broadband photometry, and the Gaia parallax, yield a revised system architecture. We find a hot DA WD with T _eff ≃ 28,000 K, log g ≃ 8.0 , M _WD ≃ 0.6 M _⊙ , and R _WD ≃ 0.015 R _⊙ , orbited by a ∼40 M _Jup BD with radius ∼0.9 R _Jup . These parameters supersede earlier spectral energy distribution (SED)-based estimates in which the WD temperature, radius, distance, and extinction were strongly covariant. We break this degeneracy with normalized Balmer-line profile fitting and high-cadence eclipse photometry that constrains the white dwarf radius geometrically. The total eclipses enable isolation of the brown dwarf (BD) flux and constrain its nightside emission. With its short orbital period and strong irradiation, J0404+1112 provides a uniquely compact, high-sensitivity benchmark for probing atmospheric heat redistribution and photochemistry in the temperature regime of the hottest ultrahot Jupiters, spanning substellar-point and nightside temperatures of ∼3700 K and ∼1750 K within a single ∼3 hr orbit.

We present results from 28 stellar occultations by the large trans-Neptunian object (50000) Quaoar registered between 2018 and 2025. By performing a joint analysis of this occultation dataset, along with nine other published events, we were able to fit an oblate ellipsoid shape, with equatorial semiaxes a and b of 566 . 1 − 2.2 + 2.5 km, and a polar semiaxis, c , of 511 . 2 − 3.7 + 3.6 km. It provides an equivalent volumetric diameter of 1094.4 ± 4.6 km and polar oblateness of 0.097 ± 0.011. Considering an absolute magnitude of H = 2.79 ± 0.35, we derive a geometric albedo of p _V = 0.125 ± 0.038. We have derived new upper limits to the surface pressure of a CH ₄ atmosphere of 0.15 nbar (1 σ ) and 0.65 nbar (3 σ ). We also provide a table with the 36 new astrometric positions for Quaoar. Using the new system mass derived from Weywot’s orbit around Quaoar, we calculated a density of 1.760 ± 0.109 g cm ⁻³ . Moreover, from the derived size and rotation period (8.8394 ± 0.0002 hr, we calculated that, if Quaoar is in Maclaurin hydrostatic equilibrium state, it would have a density of 1.859 ± 0.200 g cm ⁻³ . This result, within the error bars, is compatible with the value we found. Therefore, this work shows that Quaoar can be a Maclaurin object, being eligible as a dwarf planet.

Binary stars are ubiquitous; yet it remains unclear how wide-orbit stellar companions influence the formation of hot Jupiters, particularly around M dwarfs. Here, we first report the discovery of TOI-5628Ab, a giant planet transiting a midtype M dwarf ( M _* = 0.36 ± 0.02 M _⊙ ) every 4.34 days, accompanied by an associated white dwarf TOI-5628B ( M _WD = 0.59 ± 0.16 M _⊙ ) at a projected distance of about 2500 au. Using TESS, ground-based photometry, and SPIRou radial velocities, we constrain the planet radius to 0.74 ± 0.04 R _J and mass to 0.09 ± 0.04 M _J , with a 3 σ upper limit of 0.22 M _J . Building on this system, we further conduct a homogeneous systematic search for comoving stellar companions with projected semimajor axes between 100 and 10,000 au around all M dwarfs with confirmed giant planets with periods smaller than 10 days and radii larger than 0.7 R _J , as well as a group of field M stars with stellar properties similar to the planet sample, based on the stellar kinematics from Gaia DR3. We measure a stellar multiplicity of 34.2% ± 9.5% for M dwarfs hosting short-period giant planets, which is substantially higher than the fraction of 5.3% ± 3.7% for the field M stars by approximately a factor of 6. Our results suggest that wide-orbit stellar companions tend to promote the formation of short-period gas giants around M stars with masses 0.21 ≤ M _* ≤ 0.64 M _⊙ , and high-eccentricity migration may play an important role in producing such systems.

At the end of its discovery apparition, the ∼60 m near-Earth object 2024 YR4 was associated with a nonzero probability of lunar impact during its 2032 December 22 close approach. While posing no threat to Earth, a lunar impact of this scale could have consequences for Earth-orbiting infrastructure, as well as for human exploration on and around the Moon. We present new JWST/NIRCam observations from 2026 February 18 and 26 that extend the observational arc by 8 months, reduce the uncertainty in the 2032 lunar encounter by a factor >30, and constitute the faintest detection of a near-Earth object to date, reaching V ∼ 30.5—beyond the V ∼ 27 ground-based limit. The updated orbit solution yields a predicted miss distance of 22,900 ± 800 km (1 σ ) from the center of the Moon, thus ruling out a lunar impact. Despite challenges due to the limited number of reference stars and saturation and trailing effects, we derive astrometric positions with three independent analysis methods, demonstrating consistency at the ≲50 mas level. These observations extend the orbital arc at epochs when the object is not accessible from the ground, advancing the timeline for hazard assessment by 2 yr relative to the next feasible ground-based recovery. This capability is critical in an emerging regime of planetary defense characterized by the discovery of decameter-scale objects by next-generation surveys. These objects are far more common but rapidly become inaccessible to ground-based follow-up. In this regime, hazard assessment can become follow-up limited, requiring targeted space-based observations, such as those demonstrated here, to reliably constrain impact probabilities on operationally relevant timescales.

The Transiting Exoplanet Survey Satellite (TESS) has delivered a large number of transiting planet candidates around nearby stars by identifying periodic decreases in stellar brightness. Establishing the planetary nature of these signals and determining their fundamental properties is a necessary step toward detailed studies of their internal structure, atmospheres, and formation pathways. In this work, we investigate the planetary nature of the TOI–1752 system (M1 V, 103.02 ± 0.34 pc), which hosts two TESS candidates: TOI–1752 b, a short-period object consistent with a lava-world scenario, and TOI–1752 c, a sub-Neptune-size planet candidate located in the optimistic habitable zone. We obtained ground-based multi-color photometric follow-up observations of TOI–1752, which we combined with TESS photometry to assess the nature of both signals. We performed a formal statistical validation using the TRICERATOPS framework, while independently vetting the candidates with the neural-network-based classifier WATSON-Net, which provides a machine-learning assessment of their planetary likelihood based on light-curve morphology, centroid diagnostics, and auxiliary vetting features. We validate TOI–1752 b as a bona fide planet with a radius of 1.69 ± 0.07R_⊕ and an orbital period of |$0.935186^{+0.000001}_{-0.000002}$| days, and TOI–1752 c with a radius of |$2.29^{+0.13}_{-0.14} R_{\oplus }$| and an orbital period of 32.7144 ± 0.0004 days. The combined analysis confirms TOI–1752 as a new planetary system, places TOI–1752 c within the optimistic habitable zone of its host star, and identifies TOI–1752 b as a promising target for atmospheric characterization, with an estimated emission spectroscopy metric (ESM) of up to ~8.

Asteroid 2024 YR4 poses no impact risk to Earth during its 2032 December 22 close approach (D. Farnocchia et al. 2026; M. Micheli et al. 2026). However, its projected probability of a lunar impact in 2032 has been approximately 4% since its last observation in late spring 2025. JWST observations in 2025 March and May constrained the size of 2024 YR4 to 60 ± 7 m (A. S. Rivkin et al. 2025). While this 60 m object does not threaten Earth directly, a lunar impact of this scale could affect the reliability and resilience of Earth–Moon orbital infrastructure (P. Wiegert et al. 2025; Y. He et al. 2026), and is of additional interest due to the possibility of human exploration at that time. New astrometric measurements obtained with JWST/Near Infrared Camera on 2026 February 18 and 26 extend the observational arc by eight months and reduce the 2032 lunar B-plane uncertainty by more than an order of magnitude. These measurements demonstrate that 2024 YR4 will pass at 22,900 ± 800 (1 σ ) km from the center of the Moon, thus ruling out a lunar impact, in agreement with the official assessments by NASA ( https://science.nasa.gov/blogs/planetary-defense/2026/03/05/new-nasa-asteroid-observations-eliminate-chance-of-2032-lunar-impact/ ) and ESA ( https://www.esa.int/Space_Safety/Planetary_Defence/Asteroid_2024_YR4_will_not_impact_the_Moon ). The JWST team achieved this refinement approximately two years in advance of the next possible ground-based recovery of the asteroid, materially advancing the timeline for hazard assessment. The sequence of infrared size determination followed by deep-space astrometric orbit refinement illustrates the operational role JWST and future facilities like the Habitable Worlds Observatory (J. Dotson et al. 2025) can play in precision planetary-defense assessments for faint ( V _mag < 31), decameter-scale near-Earth objects beyond the reach of ground-based facilities.