Andrei Tokovinin

The SOAR Adaptive Module (SAM) is a ground-layer AO system for partial seeing correction based on the UV Rayleigh laser guide star. We describe the upgraded version, SAMplus, in which three critical subsystems (the deformable mirror, the WFS, and the real-time computer) are replaced to address the obsolescence of the SAM hardware and to improve the resolution by increasing the compensation order. The new DM from ALPAO has pupil diameter of 50 mm with 17 actuators across diameter. It is driven by the WFS using an EM CCD camera OCAM2S with substrate range gating. The new real-time controller is based on the PXIe architecture and uses signal processing in an FPGA. SAMplus was integrated and tested on sky in 2024. Its performance and operation are characterized here, and the first science results are illustrated.

Results of speckle interferometry observations at the 4.1 m Southern Astrophysical Research telescope obtained during 2024–2025 are presented. We present 5316 measurements of relative positions and magnitude differences in 3532 pairs (including 524 unpublished measures made before 2024) with median and minimum separations of 0 . ″ 19 and 12 mas, respectively; nonresolutions of 1723 stars are documented as well. More than 400 pairs have been resolved here for the first time and not resolved by Gaia; among those are 222 TESS objects of interest, 46 inner subsystems in known wider binaries within 100 pc, and 43 subdwarfs. Positional measurements are used to compute or improve binary orbits; elements of 202 orbits with meaningful errors are given here, while preliminary and tentative orbits are published elsewhere. Of special note are orbits with large and accurately measured eccentricities (e.g., e = 0.9866 ± 0.0014 for J13038−2035) and orbits of pre-main-sequence binaries. The Appendix contains parameters of 86 binaries used for calibration of pixel scale and orientation.

The Ninth Catalogue of Spectroscopic Binary Orbits (S|$_{\mathrm{B}^9}$|) is a comprehensive compilation of spectroscopic binaries (SBs) with orbital parameters sourced from the literature, comprising approximately 4000 systems with about 2800 single-lined and 1200 double-lined binaries. This work presents the latest status of the S|$_{\mathrm{B}^9}$| catalogue after over two decades of development since its online inception in 2004. In particular, we expose the statistical properties of SBs in terms of orbital period distributions and eccentricity-period diagrams per spectral type and evolutionary stage. We perform a careful cross-match with the Gaia Data Release 3 (DR3) to update astrometric parameters and compare with the Gaia DR3 Non-Single Star (NSS) catalogue. Our cross-matching approach uses positional separations, magnitudes, and proper-motion back-propagation to identify counterparts. The final S|$_{\mathrm{B}^9}$| version updated by D. Pourbaix (2021-03-02) includes 4003 SB systems, some in higher-order multiples: 152 in triples, 71 in quadruples and 14 in higher-order systems. Among these 4003 SB, 3976 have matching Gaia DR3 identifiers, while 21 are too bright and six too faint for Gaia detection. red Ten S|$_{\mathrm{B}^9}$| systems with periods larger than 1180 d (including a spectroscopic triple) have been spatially resolved by GaiaDR3. We identify a common sample of 827 S|$_{\mathrm{B}^9}$| binaries cross-matched with Gaia NSS, among which 655 are considered as reliable, based on relative period and absolute eccentricity differences not exceeding 10 %. The limited overlap (21 % of S|$_{\mathrm{B}^9}$|) is primarily due to selection cuts in NSS SB1 analysis, brightness limits, temporal baselines, and partial orbital solutions in the Gaia NSS catalogue. This study highlights the strengths and limitations of both catalogues and establishes a clean benchmark sample for future binary star research. Our work marks the transition of S|$_{\mathrm{B}^9}$| into S|$_{\mathrm{B}^X}$|, The eXtended Catalogue of Spectroscopic Binary Orbits^⋆, featuring a modern relational database, improved web interface, and Virtual Observatory access standards, aiming to enhance accessibility, data quality, and analysis capabilities for the binary and multiple star community.

We present 1066 speckle measurements of M dwarf multiples observed over 2021–2024, all taken with HRCam on the Southern Astrophysical Research 4.1 m telescope. Among these, 900 observations resolve companions in 212 pairs, with separations spanning 17 mas to 3 . ″ 4 and brightness differences ranging from 0 to 4.9 mag in the I filter. We have characterized the orbits of 54 of these companions, spanning periods of 0.67–30 yr, by combining our data with literature astrometry, radial velocities, and, in four cases, Hipparcos–Gaia accelerations. Among the orbits presented here are 28 that are the first-ever such characterizations for their systems and 26 that revise previously published orbits, thus providing a significant update to the observed dynamics of M dwarfs in the solar neighborhood. From these orbits, we provide new and updated dynamical total masses for these systems, precise to 0.7%–7% in nearly all cases. Future mass derivations for components in these systems will contribute to efforts in refining the mass–luminosity relation for the smallest stars and will enhance investigations of age, magnetism, and metallicity effects on luminosities at a given mass.

A sample of 278 triple systems with outer separations under 300 au and resolved inner pairs is studied, focusing on the mutual alignment between the inner and outer orbits. The degree of alignment increases with (i) decreasing outer separation, (ii) decreasing ratio of outer and inner separations, (iii) decreasing mass of the inner primary component, and (iv) increasing inner mass ratio. There is no dependence on the outer mass ratio. The average mutual inclination is ∼40° for the full sample and ∼10° for 38 triples with primary components less massive than 1 M _⊙ and outer separations below 50 au. Inner eccentricities in aligned triples are smaller compared to misaligned ones. In another sample of 371 hierarchies with known outer orbits and inner eclipsing subsystems, only 22% show mutual alignment within 20°, while the rest are aligned randomly. These findings match qualitatively the current understanding of the formation of hierarchical systems, where the N -body dynamics dominates at large scales, while the accretion and migration shape systems closer than ∼100 au. Fragmentation of isolated cores apparently produces approximately aligned low-mass hierarchies.

Inner and outer orbits in 12 hierarchical stellar systems are determined using high-resolution speckle imaging, radial velocities, or both. Masses and fluxes of the components are estimated. The Hipparcos numbers of the main stars are 7111, 12912, 17895, 20375, 42424, 68717, 77439, 79076, 90253, 97922, and 102855; the faint triple WDS J10367+1522 has no Hipparcos number. Four systems are quadruples of the 3 + 1 hierarchy; the rest are triple. Two triples with low-mass M-type components are approximately planar, with moderately eccentric orbits and near-unit mass ratios. The shortest inner period of 0.27 day is found in the newly identified contact eclipsing pair belonging to the misaligned quadruple HIP 97922. The compact system HIP 102855 (periods 15.4 and 129 days) identified by Gaia is confirmed here and has an additional companion at 6 ″ . This work contributes new data for the study of diverse architectures of stellar hierarchies in the field.

NASA’s TESS mission has unveiled a plethora of eclipsing binaries (EBs), among them hundreds of triples and higher-order, hierarchical systems. These complex targets require follow-up observations to enable full characterization of system architectures and identify the most compact multiples expected to undergo the most dramatic dynamical evolution. We report first results from a long-term effort to perform such follow-up, focusing here on multiband speckle imaging of a majority (57) of the sample of 97 quadruple- and higher-order eclipsing binaries (Q+EBs) identified via TESS light curves by V. B. Kostov et al. Diffraction-limited imaging with the Differential Speckle Survey Instrument on the Astrophysical Research Consortium 3.5 m telescope and HRCam on the Southern Astrophysical Research 4.1 m telescope reveals nearly 60% of the 57 to resolve into two sources separated by ≥0 . ″ 03. For these partly resolved systems, we report derived characteristics (e.g., relative position angle, angular separation, and magnitude differences in multiple passbands) from the speckle imaging. We find those Q+EBs partly resolved with 4 m class telescopes to have significantly inflated Gaia parallax errors and large Gaia renormalized unit weight errors, particularly for systems with separations comparable to Gaia’s resolution limit (∼0 . ″ 6). For unresolved systems we report upper limits on angular and linear projected separations. We find two partly resolved Q+EBs with wide linear separations having eclipse timing variations that are therefore candidates of higher-than-quadruple multiplicity. Finally, we demonstrate how speckle imaging of resolved Q+EBs during an eclipse can clarify which speckle-resolved Q+EB subsystem is associated with a particular set of TESS eclipses.

Adding to the large radial velocity survey of nearby solar-type stars (summary in Tokovinin, 2023a), spectroscopic orbits are determined for four hierarchical systems: HIP 49442 (inner and outer periods of 164.55 days and 34 yr, respectively), HIP 55691 (2.4 and 415 yr), HIP 61465 (86.8 days), and HIP 78662C (0.82 day). Each system is discussed individually. Seven Gaia orbits of low-mass dwarfs, each with two additional resolved (interferometric and wide) companions, i.e., potential quadruples, are tested by monitoring radial velocities: five orbits are confirmed and two are refuted. Five of these systems are quadruples of 3+1 hierarchy, one is quintuple, and one is triple. Strengths and limitations of the Gaia data on multiple systems and the need of complementary observations are highlighted.

We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μm, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of 0.5λ/D for an interferometer), which are inaccessible with the classical inner working angles of the JWST coronagraphs. When combined with JWST’s unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this mode, we are able to achieve a 5σ contrast of Δm _F380M ∼ 7.62 ± 0.13 mag relative to the host star at separations ​​​​​≳0 . ″ 07, and the contrast deteriorates steeply at separations ≲0 . ″ 07. However, we detect no additional companions interior to the known companion HIP 65426b (at separation ∼0 . ″ 82 or 8 7 − 31 + 108 au ). Our observations thus rule out companions more massive than 10–12 M _Jup at separations ∼10–20 au from HIP 65426, a region out of reach of ground- or space-based coronagraphic imaging. These observations confirm that the AMI mode on JWST is sensitive to planetary mass companions at close-in separations (≳0 . ″ 07), even for thousands of more distant stars at ∼100 pc, in addition to the stars in the nearby young moving groups and associations, as stated in previous works. This result will allow the planning and successful execution of future observations to probe the inner regions of nearby stellar systems, opening an essentially unexplored parameter space.