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Keyword list: ['star formation', 'star-forming', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', ' AGN ', 'standard candle', 'X-ray binar', 'solar corona']

Today: 18papers

3D Kinematic Reconstruction of the Crab Nebula That Includes the Northern Ejecta `Jet'

• Authors: Ziwei Ding, Dan Milisavljevic, Thomas Martin, Tea Temim, John C.Raymond, Soham Mandal, Laurent Drissen

• Subjects: Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2606.26231

• Pdf link: https://arxiv.org/pdf/2606.26231

• Abstract We present new detailed three-dimensional kinematic reconstructions of the Crab Nebula created from hyperspectral cubes obtained with the SITELLE instrument mounted on the Canada--France--Hawaii Telescope. Our data cubes span a wavelength range from 3600Å to 7000Å, covering major emission lines including [O II] $\lambda\lambda$3726, 3729, H$\beta$, [O III] $\lambda\lambda$4959, 5007, [N II] $\lambda$5755, He I $\lambda$5876, [N II] $\lambda\lambda$6548, 6584, [S II] $\lambda\lambda$6717, 6731, and H$\alpha$. The field of view encompasses the chimney" or jet," a 45-arcsec-wide funnel-shaped structure that extends 100 arcsec beyond the northern limb of the nebula. Our 3D reconstructions confirm and geometrically resolve a cavity at the jet's base that was suggested by earlier kinematic studies, establishing a direct physical connection between the filamentary network and the jet funnel. The morphology and kinematics indicate that the early pulsar wind nebula (PWN) played a central role in forming the jet. Several formation scenarios, which are not necessarily mutually exclusive, remain viable, including a bipolar outflow shaped by a circumstellar disk, a breach or underdensity in the ejecta shell, and a pre-existing progenitor mass-loss trail acting as a low-density channel. Collectively, these scenarios exhibit differing abilities to account for the jet's pronounced collimation, the absence of a southern counterpart, and its near-ballistic motion. Discriminating among them will require fully three-dimensional hydrodynamic simulations that trace the remnant's evolution from the progenitor phase through late-time PWN expansion.

Using VLTI/GRAVITY+ to determine the identity of a third planet candidate in the PDS 70 system

• Authors: David Trevascus, Wolfgang Brandner, Olga Balsalobre-Ruza, Sylvestre Lacour, Karim Abd El Dayem, Nicolas Aimar, Anthony Berdeu, Jean-Philppe Berger, Guillaume Bourdarot, Valentin Christiaens, Carlos Correia, Richard Davies, Denis Defrère, Antonia Drescher, Andreas Eckart, Frank Eisenhauer, Maximilian Fabricius, Helmut Feuchtgruber, Simon Flesch, Natascha M. Förster Schreiber, Arianna Foschi, Quentin Fournier, Paulo Garcia, Rebeca Garcia Lopez, Reinhard Genzel, Stefan Gillessen, Iain Hammond, Sebastian F. Hönig, Mathias Houllé, Simran Joharle, Pierre Kervella, Laura Kreidberg, Lucas Labadie, Olivier Lai, Romain Laugier, Jean-Baptiste Le Bouquin, James Leftley, Ruancun Li, Bruno Lopez, Dieter Lutz, Gabriel-Dominique Marleau, Felix Mang, Antoine Mérand, Florentin Millour, Miguel Montargès, Nuno Morujão, Hugo Nowacki, Mathias Nowak, Juan Osorno, Thomas Ott, Sarah Pappert, Thibaut Paumard, Karine Perraut, Guy Perrin, Romain Petrov, Pierre-Olivier Petrucci, Nicolas Pourré, Sebastian Rabien, Diogo C. Ribeiro, Sylvie Robbe-Dubois, Matteo Sadun Bordoni, Joel Sánchez Bermúdez, Daryl Santos, Jonas Sauter, Jules Scigliuto, Jinyi Shangguan, Taro T. Shimizu, Ferréol Soulez, Christian Straubmeier, Eckhard Sturm, Matthias Subroweit, Calvin Sykes, Linda Tacconi, Paloma Thévenet, Irene Urso, Frédéric Vincent, Julien Woillez, the GRAVITY+ Collaboration

• Subjects: Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2606.26249

• Pdf link: https://arxiv.org/pdf/2606.26249

• Abstract Detections of protoplanets are rare and protoplanetary disk features mischaracterized as planets are common. PDS 70 is one of only two stars known to host multiple confirmed protoplanets, PDS 70 b and c, and repeat detections of a third point-like source in the system suggest the presence of third inner planet. However, previous observations of this third source are insufficient to distinguish whether it is a planet or a concentrated dust clump in Keplerian motion. Our observations with VLTI/GRAVITY+ did not re-detect this point-like source, suggesting that it is, in fact, a dust clump and not a planet. These observations demonstrate how the angular resolving power of VLTI/GRAVITY+ can be used to distinguish between protoplanets and protoplanetary disk features.

Cepheids with giant companions III. Evolutionary modeling of nine binary double Cepheids from the Milky Way and Magellanic Clouds

• Authors: F. Espinoza-Arancibia, B. Pilecki, M. Catelan, V. Hocdé, I. B. Thompson, W. Gieren

• Subjects: Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2606.26259

• Pdf link: https://arxiv.org/pdf/2606.26259

• Abstract Binary double (BIND) Cepheids are systems comprising two Cepheid components. This feature provides important constraints that allow us to reveal the origin of Cepheids, trace their evolution, and test pulsation theory. Ten BIND Cepheids are now known, with only one having its parameters determined. We aim to estimate the physical parameters of the components of nine BIND Cepheids in the Magellanic Clouds and the Milky Way, investigate their evolutionary configurations, and formation scenarios. We also expand the parameter space of characterized individual Cepheids in mass, radius, period, and metallicity. We extended the recently introduced $q$-PED method to BIND Cepheids, combining observational constraints with theoretical pulsation and evolutionary models. We considered all consistent configurations (first-crossing, blue-loop, and mixed) as viable solutions. Probabilistic and observational constraints, including spectroscopic mass ratios for two systems, were then used to discriminate between them. We obtained new $q$-PED estimates of mass, radius, temperature, luminosity, and age for 18 Cepheids with previously unknown physical parameters. For one Galactic system, the spectroscopic mass ratio $q_s=0.84\pm0.04$ indicates a first-crossing plus a blue-loop Cepheid solution. This mass ratio, along with the predicted mass ratios lower than unity for two other systems, suggests past binary interactions and a likely merger origin for one component. We derive a new period--mass--radius relation and mass--luminosity relation covering the mass range $2.3-4.6$ M$\odot$. This work provides the first mass estimates for Cepheids in the SMC, extending the lower Cepheid mass limit down to 2.3 M$\odot$. Binary interactions in the past evolution of Cepheids may be common, affecting up to 40% of our systems with two clear cases and two more if blue loop Cepheids are preferred.

The 10-15 GHz radio continuum survey of the Galactic Plane with SKAO

• Authors: A. Traficante, C. Mininni, F. Cavallaro, G. Umana, C. Trigilio, S. Molinari, L. D. Anderson, M. Audard, C. Bordiu, C. S. Buemi, C. Carrasco-Gonzalez, L. Cerrigone, E. J. Chung, J. Dey, A. Ingallinera, I. Jimenez-Serra, P. Klaassen, S. Loru, K. Mallick, A. Nucara, M. Padovani, J. D. Pandian, K. L. J. Rygl, T. M. Rodríguez, G. Sabatini, S. Reissl, P. Suin, M. A. Thompson, T. L. Bourke, J. S.Urquhart, M. Valeille-Manet, F. Xu, A. Zavagno, M. Benedettini, E. Bianchi, A. Bracco, F. Bufano, C. Codella, N. Cunningham, J. Dawson, D. Galli, M. G. Guarcello, A. Karska, W.-J. Kim, P. Leto, B. Liu, B. Mookerjea, F. Motte, T. Nony, R. Paladini, A. Patel, L. Podio, A. J. T. Ramaila, B. Riaz, S. Riggi, D. A. Roshi, A. Ruggeri, Á. Sánchez-Monge, R. Schödel, O. M. Smirnov, J. D. Soler, S. Sottie, R. Unnikrishnan, A. Y. Yang, K. Wang, T. Wilson

• Subjects: Subjects: Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2606.26278

• Pdf link: https://arxiv.org/pdf/2606.26278

• Abstract Star formation emerges from the complex interplay between gravity, turbulence, magnetic fields, and stellar feedback, all of which vary across spatial scales and Galactic environments. Over the past decades, extensive multiwavelength surveys of the Galactic Plane have progressively unveiled this complexity. Far-infrared and sub-millimetre surveys have identified and characterized tens of thousands of star-forming regions, revealing their mass, temperature, and evolutionary stage. Complementary molecular-line surveys, spanning several CO transitions and isotopologues, have mapped the gas kinematics from giant molecular clouds down to sub-parsec structures. The advent of interferometers such as ALMA has revolutionized this field, enabling systematic studies of gas dynamics, fragmentation, and collapse in dense clumps at scales of a few thousand astronomical units. At the same time, mid-infrared and radio surveys at frequencies 0.8 <= nu <= 5 GHz have traced ionised gas associated with the earliest and latest phases of massive-star evolution, including thermal radio jets, hypercompact and ultracompact HII regions, supernova remnants, planetary nebulae, and evolved massive stars. Yet, a uniform, Galaxy-wide census of ionised structures and feedback processes remains elusive. A transformational leap forward requires a sensitive, high-resolution radio survey of the Galactic Plane at 10-15 GHz, capable of resolving physical scales smaller than 0.05 pc at distances up to 20 kpc. This is precisely the goal of the SKA-Mid Galactic Plane survey, which will, with its unprecedented sensitivity, angular resolution, and mapping speed, provide the first panoptic view of ionised gas and stellar feedback across the Milky Way.

Predictions of Transiting Exoplanet Confirmations from Rubin LSST Surveys

• Authors: Suber Corley, Eric Feigelson, Claudio Caceres, Bolivia Cuevas-Otahola, Andjelka Kovacevic

• Subjects: Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

• Arxiv link: https://arxiv.org/abs/2606.26358

• Pdf link: https://arxiv.org/pdf/2606.26358

• Abstract We assess the prospects for exoplanet transit observations in the 10-year Wide Fast Deep (WFD) and Deep Drilling Field (DDF) surveys within the Legacy Survey of Space and Time (LSST) mission of the Vera C. Rubin Observatory. We construct a framework for systematic assessment of expected exoplanet yields, highlighting the principal limitations imposed by the survey observing strategy and cadence. We simulate light curves with a wide range of exoplanetary system models derived from planet occurrence rates developed with data from the Kepler mission. Transit counts for the stellar population are calculated using the TRILEGAL Galactic structure model, incorporating telescope sensitivity and survey cadences. We apply the constraints that the full duration of at least three transits must be observed and that the signal-to-noise ratio will support detectability. The observations were then validated using the Transit Least Squares periodogram. Our findings indicate a limited potential for exoplanet confirmations under the current survey design. Only a small number of hot planets orbiting faint M class main sequence stars will be confirmed in the DDF fields. The WFD survey is projected to produce no confirmations. These findings underscore the constraints imposed by the sparse, multi-band observing strategy, which prioritizes cosmology and extragalactic science over the continuous photometric coverage required for confirmations.

Two inner dust clumps in PDS 70. A third protoplanet traced by trojan material or a substructured inner disk?

• Authors: O. Balsalobre-Ruza, V. Christiaens, N. Huélamo, I. Hammond, M. Benisty, S. Lacour, D. Blakely, R.G. van Holstein, J. Latour, J. Lillo-Box, Z. Wahhaj, D. Trevascus, O. Absil, J. Bae, C. Charalambous, I. de Gregorio-Monsalvo, I. Mendigutía, C. Petrovich, Á. Ribas, S. Juillard

• Subjects: Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2606.26381

• Pdf link: https://arxiv.org/pdf/2606.26381

• Abstract The PDS 70 cavity hosts two confirmed directly imaged protoplanets and a third inner planet candidate (~13au). Despite its Keplerian motion, its unusually blue spectrum challenges a planetary interpretation. We further investigate the presence and nature of a third inner planet using new SPHERE and GRAVITY+ observations. Using the star-hopping strategy, we obtained coronagraphic IRDIS polarimetric observations in the H-band, and non-coronagraphic observations with IRDIFS in the YJHK-bands. We also searched for a planetary signal with GRAVITY in the 4UT configuration. We consistently detect two elongated inner emissions with SPHERE: the previously proposed planet candidate and another feature that appears to share the same orbit while leading it by ~120$^\circ$. Both features show dust-scattered-light spectra but different colors, possibly indicating different grain sizes. Such configuration is consistent with co-orbital dust accumulated at the stable Lagrangian regions of a distinct and yet undetected planet. GRAVITY yields a marginal (3$\sigma$) detection at the predicted location along the same orbit ($\rho=76.2\pm0.29$mas, PA=$226.50\pm0.21^\circ$), and consistent with a ~3$M_{\rm Jup}$ planet. This new planet candidate is aligned with a narrow shadow that we detect in the outer disk. We also detect polarized emission very close to the star likely arising from the inner disk ($i\sim50^\circ$, PA $\sim135^\circ$). The apparent embedding of the two dust clumps within it motivates an inner-disk origin as an alternative scenario. We conclude that the previously reported third planet candidate traces a dust clump either trailing an unseen planet on the same orbit or a rotating substructure within the inner disk. Further observations are needed to test these scenarios. Confirming the new GRAVITY planet candidate would support co-orbital substructures as indirect tracers of protoplanets.

A Spitzer Space Telescope Exploration Science Program to Search for Y Dwarf Variability

• Authors: Michael C. Cushing, Jesica L. Trucks, Kevin K. Hardegree-Ullman, Adam J. Burgasser, Sean J. Carey, Jonathan J. Fortney, Christopher R. Gelino, John E. Gizis, J. Davy Kirkpatrick, Sandy Leggett, Gregory N. Mace, Mark S. Marley, Caroline V. Morley

• Subjects: Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2606.26411

• Pdf link: https://arxiv.org/pdf/2606.26411

• Abstract We present the results of a Spitzer Space Telescope Exploration Science Program to search for and characterize variability in Y dwarfs. We observed 14 Y dwarfs over a 24 hr period at [3.6] and [4.5] and then repeated the observations a few months later. We add two Y dwarfs, WD 0806-661B and WISE J085510.83-071442.5, that were also observed with Spitzer so that our sample includes all Y dwarfs observed for variability with Spitzer. We infer variability fractions of 59%+-15% and 64%+10%-13% for [3.6], and [4.5], in the first epoch, and 35%+17% -11% and 75%+8% -15% in the second epoch. We also find that Y dwarf Spitzer light curves are generally stable over timescales of months, but in some cases can show clear changes in amplitude. Combining our results with a similar Spitzer survey of L and T dwarfs by Metchev et al. (2015), we find the mid-infrared variability fraction of L, T, and Y dwarfs weakly supports the hypothesis that brown dwarf variability is caused by variations in the horizontal and/or vertical structure of condensate clouds.

Search for Seeds of The Cradle of Stars: Study of The Evolution From Atomic to Molecular Hydrogen Clouds with 1000 AU Scale Resolution

• Authors: Hiroaki Yamamoto, Yamato Matsuzuki, Kengo Tachihara

• Subjects: Subjects: Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2606.26695

• Pdf link: https://arxiv.org/pdf/2606.26695

• Abstract The aim of this science case for SKA1-Mid is to elucidate the spatial and velocity structure of the Cold Neutral Medium (CNM) on scales below the Field length, thereby elucidating the physical processes that govern CNM structure formation and its role in the earliest stages of molecular cloud formation. This goal will be achieved through a unique observational combination of several-arcsecond angular resolution, high velocity resolution, and unprecedented surface-brightness sensitivity. These observations will reveal the characteristic size, morphology, velocity structure, and internal dynamics of CNM clumps, and will directly connect such structures to the earliest phases of the atomic to molecular transition. Full-polarization observations with SKA1-Mid will also enable emission-based Zeeman measurements of the CNM, allowing the magnetic field strength to be mapped and opening a new window on the role of magnetic fields in CNM formation and evolution. In particular, this will make it possible to determine whether magnetic fields primarily inhibit fragmentation by supporting the gas against compression, or instead guide anisotropic condensation and promote the development of small-scale CNM structure through thermal instability. In combination with interferometric spatial filtering and high spectral resolution, SKA1-Mid will selectively trace the CNM and robustly identify individual clumps in both position and velocity space. These capabilities will provide decisive tests of thermal instability and the two-phase turbulence model, and will establish a new observational foundation for understanding how molecular clouds emerge from the multi-phase atomic interstellar medium.

Theoretical determination of the binding energies of methanol and related species onto amorphous solid water ice

• Authors: Aneesa Ahmad (1), Catherine Walsh (1), Stefan Vogt-Geisse (1,2), Gabriela Silva-Vera (2), Felix Sainsbury-Martinez (1) ((1) University of Leeds, UK, (2) Universidad de Concepción, Chile)

• Subjects: Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2606.26833

• Pdf link: https://arxiv.org/pdf/2606.26833

• Abstract The formation and survival of complex organic molecules (COMs) in cold interstellar environments depends on their interactions with icy dust grain surfaces. Methanol, a key COM detected in cold cores and protoplanetary disks, is believed to form on amorphous solid water (ASW) through surface reactions and reside there until it is desorbed into the gas phase. We present a theoretical study of the binding energies (BEs) of methanol and its photolysis-derived species on ASW clusters by means of dispersion-corrected density functional theory (DFT) using a refined protocol implemented in the Binding Energy Evaluation Platform (BEEP). Molecules capable of hydrogen bonding, such as H2O, CH3OH, HCOOH, and OH, exhibit high BEs and broad BE distributions that reflect the structural heterogeneity of the ASW surface. In contrast, weakly interacting volatiles including CO, CO2, CH4, and CH3 display narrower distributions dominated by dispersion interactions. Open-shell radicals such as CH2OH and OH bind more strongly than HCO and CH3 due to their ability to form directional hydrogen bonds. Incorporation of our BEs into an astrochemical model, in conjunction with a recalculation of the pre-exponential factor using transition state theory, demonstrates the sensitivity of model results to the method of calculation of the grain-surface reaction rates. The new approach generally predicts a higher abundance of radicals on the ice that are key reactants for the formation of COMs when surface diffusion is assumed to be efficient. These findings emphasize the importance of incorporating BEs that have been determined in a self-consistent manner into astrochemical models, and provide reliable theoretical benchmarks for species with limited experimental data.

Supernova remnants in the new radio astronomy era

• Authors: A. Ingallinera, M. Arias, G. Castelletti, C. Bordiu, F. Bufano, G. Cosentino, M. D. Filipović, D. Liu, S. Loru, S. Orlando, O. Petruk, Z. Smeaton, A. Traficante, C. Trigilio, G. Umana, G. Anderson, F. Bocchino, C. Buemi, F. Cavallaro, E. Egron, N. Hurley-Walker, R. Kothes, P. Leto, S. Mantovanini, M. Miceli, G. Morlino, A. Pellizoni, M. Sasaki

• Subjects: Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2606.26889

• Pdf link: https://arxiv.org/pdf/2606.26889

• Abstract Supernova remnants (SNRs) are what is left after stellar explosions, when the stellar ejecta, the explosion shock and the circumstellar medium interact. Despite being among the first objects studied in radio astronomy, observational difficulties have so far prevented a definitive characterisation, which would help answer open questions related to these sources. It is debated which is the contribution of SNRs to Galactic cosmic rays, or how the interaction with the surrounding environments influences the particle energetics. The SKA precursors are providing valuable and unexpected discoveries on SNRs, thanks to their unique capabilities to probe spatial scales from a few arcseconds to a few degrees with a sensitivity of tens of microjansky. Accurate integrated flux density measurements and arcsecond-scale spectral-index maps are now possible for tens of SNRs, substantially expanding the small subset of remnants traditionally studied in great detail. SKA will markedly enhance current observations by providing: higher sensitivity, enabling the detection of fainter SNRs also in polarisation, revealing diffuse structures and the underlying magnetic field configuration; higher angular resolution, allowing detailed mapping of compact remnants and reducing depolarisation in fine structures, tracing filaments and shocks fronts; wider frequency coverage to probe unexplored spectral windows, where spectral turnovers and breaks or cut-off may occur, establishing a direct connection to X-ray and {\gamma}-ray emission that constrains the electron population, and enabling accurate modelling of the non-thermal emission across the electromagnetic spectrum; improved image fidelity for more reliable cross-matching with other wavelengths, leading to a better understanding of the SNR-interstellar medium interplay.

Unraveling the mysteries of supernovae with SKA+VLBI

• Authors: Tao An, Zhengwei Liu, Ailing Wang, Miguel Pérez-Torres, Javier Moldon, Liangduan Liu, Peter Lundqvist, Xuefei Chen, Xiangcun Meng

• Subjects: Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2606.26934

• Pdf link: https://arxiv.org/pdf/2606.26934

• Abstract Supernovae (SNe) drive cosmic chemical enrichment and shape galactic feedback, yet the link between progenitors and explosion outcomes remains poorly constrained because the earliest phases are rarely resolved. Radio emission traces synchrotron radiation where the fastest ejecta interact with the circumstellar medium (CSM), providing a uniquely penetrating probe of these phases. SKA-Mid phased into global VLBI will move from simple detections to routine interferometric imaging of nearby extragalactic SNe. Sub-$\mu$Jy sensitivity and mas-scale SKA+VLBI imaging, complemented by visibility-domain model fitting for sub-beam radius measurements at 5-15 GHz will allow us to follow the expanding shocks of stripped-envelope SNe out to $\sim$25 Mpc, measure deceleration indices ($m$) and axial ratios to $\approx 5-10%$, and directly test jet-assisted versus neutrino-driven explosion mechanisms. For interacting SNe (Type IIn/Ibn), SKA+VLBI will resolve clumpy and toroidal CSM on progenitor scales, constraining the timing and geometry of eruptive pre-explosion mass loss. Deep limits on Type Ia SNe will tightly restrict the allowed single-degenerate parameter space, while late-time imaging will search for nascent compact remnants and pulsar wind nebulae. In synergy with optical, X-ray and gravitational wave facilities, SKA+VLBI will turn nearby SNe into laboratories for time-resolved shock physics and progenitor mapping.

Exploring Tidal Disruption Events with SKA and VLBI: Unveiling the Mystery of Black Hole Feeding and Outflows

• Authors: Xinwen Shu, Guobin Mou, Tao An, S. Komossa, Miguel Perez-Torres, Weihua Lei, Luming Sun, Ning Jiang, Tinggui Wang, Chichuan Jin, Jun Yang

• Subjects: Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2606.26998

• Pdf link: https://arxiv.org/pdf/2606.26998

• Abstract Tidal disruption events (TDEs) probe the birth and evolution of black hole accretion flows and jets on human timescales. Radio emission traces shocks and outflows from thermal TDEs and powerful relativistic jets in the rare jetted class. SKA Mid, phased for VLBI and used together with global networks, will deliver milliarcsecond imaging, tens of microarcsecond astrometry, and microJy sensitivity, enabling: (i) proper motion measurements that discriminate off axis relativistic jets from subrelativistic winds; (ii) resolved morphologies and magnetic field diagnostics via polarimetry; and (iii) precise nuclear localization to distinguish SMBH vs. IMBH and to reveal recoiling or binary systems. SKA's wide frequency coverage (0.35 to 15.4 GHz) and 1h continuum sensitivities of 3 to 10 microJy per beam, together with multibeam tiedarray VLBI and a transient buffer for rapid triggers, are transformational. LSST, Einstein Probe, and SVOM will increase TDE alerts to hundreds per year, and late time radio flares appear common, ensuring rich SKA VLBI samples. We provide observing strategies, detection forecasts, and predictions, e.g., about 5 proper motion detections of jetted (or off axis) TDEs per year and routine core shift constraints at the microarcsecond level. This program will establish TDEs as laboratories for exploring jet launching, particle acceleration (including neutrinos), black hole accretion history and demographics, and properties of circumnuclear medium.

The ESO SupJup Survey XI. Atmospheric properties of six isolated M- and L-type dwarfs with CRIRES+

• Authors: C. R. Malcolm, N. Grasser, I. A. G. Snellen, S. de Regt, D. González Picos, Y. Zhang, T. Stolker, S. Gandhi, P. Mollière, E. Nasedkin, R. Landman, A. Y. Kesseli

• Subjects: Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2606.27107

• Pdf link: https://arxiv.org/pdf/2606.27107

• Abstract The distinct formation pathways of brown dwarfs and giant exoplanets may be encoded in their atmospheric composition. We present atmospheric retrievals for six isolated brown dwarfs of spectral types M7-L2.5 from the ESO SupJup Survey, aiming to constrain their thermal structures, chemical compositions, and isotope ratios. We analyse CRIRES+ K-band spectra, coupling the radiative transfer code petitRADTRANS with the nested sampling algorithm PyMultiNest under both free and equilibrium chemistry frameworks. The L0 dwarf 2MASS J09532126-1014205 emerges as one of the fastest-rotating ultracool dwarfs known, with $v\sin i = 85.9\pm0.5$ km s$^{-1}$. H$_2$O is strongly detected in all six targets and $^{12}$CO in five, with a marginal $^{12}$CO detection in the ultra-fast L0 rotator consistent with severe rotational broadening. $^{13}$CO is significantly detected in DENIS J060852.8-275358 and tentatively in three further targets. Retrieved compositions are consistent with isolated brown dwarfs: near-solar C/O ratios ($0.51$-$0.63$), predominantly near-solar metallicities, and $^{12}$C/$^{13}$C ratios of ~91-155, at or above the local ISM value, with constraints for the two fastest rotators resting on the spectral fit but not corroborated by a $^{13}$CO cross-correlation peak. The M7 dwarf 2MASS J04341527+2250309 shows discrepant gravity and metallicity values between chemistry frameworks. Apparent H$_2^{18}$O constraints for two targets are found to be spurious, and their H$_2^{(16)}$O/H$_2^{18}$O ratios are presented as lower limits, demonstrating the importance of cross-correlation validation for minor species detections. The near-solar C/O ratios and metallicities, with $^{12}$C/$^{13}$C ratios at or above the ISM value, support a molecular cloud fragmentation origin for the sample. The agreement of $^{12}$C/$^{13}$C between chemistry frameworks supports the robustness of these ratios.

Chemical Complexity in the Early Stages of Star Formation in the SKAO Era

• Authors: Eleonora Bianchi, Mathilde Bouvier, Claudio Codella, Laura Colzi, Audrey Coutens, Marta De Simone, Joan Enrique Romero, Gisela Esplugues, Francesco Fontani, Antonio Garufi, Lisa Giani, Arshia Maria Jacob, Izaskun Jiménez-Serra, Marco Padovani, Linda Podio, Albert Rimola, Pablo Rivière Marichalar, Giovanni Sabatini, Andrea Socci, Riccardo Giovanni Urso, Tyler L. Bourke, Gemma Busquet, Paola Caselli, Cecilia Ceccarelli, Tomoya Hirota, John D. Ilee, Valerio Lattanzi, Manuela Lippi, Ana López-Sepulcre, Pierre Marchand, Liton Majumdar, Sabyasachi Pal, Maria Elisabetta Palumbo, Jaime E. Pineda, Manoj Puravankara, Elena Redaelli, Victor M. Rivilla, Basmah Riaz, Álvaro Sánchez-Monge, Silvia Spezzano, Leonardo Testi, Himanshu Tyagi, Claudia Toci, Alessio Traficante, Grazia Umana, Charlotte Vastel, Susanne Wampfler

• Subjects: Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2606.27184

• Pdf link: https://arxiv.org/pdf/2606.27184

• Abstract About 350 molecules have been identified in the interstellar medium (ISM), including complex molecules relevant to prebiotic chemistry. A remarkable level of molecular diversity has been observed from the earliest stages of star formation, providing the initial chemical inventory inherited by planetary systems. Radio observations have played a pivotal role in these discoveries, starting with the identification of the first polyatomic molecule, $\text{NH}_3$ (Cheung et al. 1968). (Sub-)millimeter observations have revealed complex organic molecules of prebiotic relevance, including formamide ($\text{NH}_2\text{CHO}$), glycolaldehyde ($\text{CH}_2\text{OHCHO}$), and even urea ($(\text{NH}_2)_2\text{CO}$), and hydroxylamine ($\text{NH}_2\text{OH}$), which are possible precursors of RNA nucleotides (Ceccarelli et al. 2023; Jiménez-Serra et al. 2020). However, in dense protostellar regions, dust opacity hampers the detection of molecular emission. Additionally, large molecules and those containing heavy atoms, which have rotational transitions at lower frequencies, often remain inaccessible to current instruments. The Square Kilometre Array Observatory (SKAO) will provide an unprecedented combination of sensitivity and angular resolution at radio wavelengths. This will allow for the detection of prebiotic species and offer new insights into the chemical pathways that shape emerging planetary systems (Jiménez-Serra et al. 2022). This chapter details the scientific questions and advancements that the SKAO, and more specifically, SKA-Mid equipped with the Band 5 receivers, will pursue in the field of astrochemistry, focusing on the chemical complexity in both high-mass and solar-type star-forming regions.

Stellar black hole binaries from two common envelope evolution phases in triple stellar systems

• Authors: Lotem Unger, Noam Soker (Technion, Israel)

• Subjects: Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2606.27193

• Pdf link: https://arxiv.org/pdf/2606.27193

• Abstract We propose a triple-star evolutionary channel involving two common envelope evolution (CEE) phases to form close binary black hole (BBH) systems with an average positive effective inspiral spin $\chi_{\rm eff}$ and a tail of systems having $\chi_{\rm eff}&lt;0$, as observed by gravitational wave detectors. $\chi_{\rm eff}$ is the mass-weighted spin of the two merging BHs, and a positive (negative) value is for an effective spin along (opposite) the orbital angular momentum. The first BH progenitor engulfs a low-mass star during the post-main-sequence evolution. The tertiary star spirals in and spins up the core, which forms the first BH at the first core-collapse supernova (CCSN) explosion. Its spin is along the orbital angular momentum of the inner binary, which can be highly inclined to the outer binary angular momentum. The secondary star later engulfs the BH in a second CEE phase and explodes as a CCSN to form the second BH with a spin that is more aligned with the orbital angular momentum of the two BHs. We use empirically calibrated initial distributions of triple-star systems consisting of two massive stars and impose a hierarchical stability criterion. We compare the predicted ratio of merging BBHs to CCSN explosion rates and find it is up to a factor of 2 larger than the observed rate. This channel can significantly contribute to the population of observed merging BBHs and can explain their qualitative spin distribution.

Cross-correlation transmission spectroscopy of ultra-hot Jupiters WASP-189b, HAT-P-57b, KELT-17b, and KELT-21b with GIANO-B

• Authors: P. Meni-Gallardo, J. Orell-Miquel, Gareb Fernández-Rodríguez, H. Parviainen, M. Basilicata, E. Pallé, M. Stangret, I. Carleo, P. Giacobbe

• Subjects: Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2606.27221

• Pdf link: https://arxiv.org/pdf/2606.27221

• Abstract Since the discovery of the first exoplanet, significant efforts have been made to characterise their atmospheres. Ultra-hot Jupiters (UHJs) are of particular interest due to their extended and hot atmospheres. Although previous studies have focused on the detection of atomic species at optical wavelengths, near-infrared (NIR) observations offer the potential to detect molecules. In our study, we applied the cross-correlation technique to NIR transmission spectra from \giano. The analysis focuses on the search for H$_2$O, CO, CO$_2$, CH$_4$, HCN, and FeH molecular signals in the atmospheres of four UHJs: HAT-P-57 b, KELT-17 b, KELT-21 b, and WASP-189 b. For the first time, we report results on the NIR transmission spectra of KELT-17b, KELT-21b, and WASP-189b. We report a tentative detection ($3.8\sigma$) of H$_2$O in HAT-P-57 b and a detection ($5.3\sigma$) of FeH in KELT-17~b, which is the third FeH detection ever in a UHJ and with the lowest equilibrium temperature. No molecular signals were found in KELT-21b and WASP-189b, or for other molecules in HAT-P-57b and KELT-17b. The cross-correlation results for HAT-P-57 b, KELT-17 b, KELT-21 b, and WASP-189 b in transmission align with the species detected in the UHJ population. This work underscores the need for further observations to confirm and expand the transmission study of UHJs in the NIR, and the capabilities of high-resolution spectrographs on 4-m-class telescopes.

MUSE Imaging Spectroscopy of the Fullerene Planetary Nebula Tc 1

• Authors: J. R. Walsh (ESO), M. J. Barlow (University College London), A. Monreal-Ibero (Leiden University), J. Cami (University of Western Ontario), E. Peeters (University of Western Ontario), R. Wesson (Cardiff University), J. Bernard-Salas (ACRI-ST), N. L. J. Cox (ACRI-ST), G. F. J. Watt (University of Western Ontario)

• Subjects: Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2606.27245

• Pdf link: https://arxiv.org/pdf/2606.27245

• Abstract The planetary nebula Tc 1 (PN G345.2 -08.8), one of the rare group of Galactic PNe showing fullerene emission in the infrared, was observed with MUSE wide field mode with adaptive optics, wavelength range 4750-9300A. Extinction, electron temperature (T_e) and density (N_e) images are presented from collisionally excited and recombination line ratios. The nebula has a high surface brightness 12 arcsec core, an elliptical ring of major axis 2.8 arcsec around the central star and some low ionization knots, and an extended halo 55 arcsec in size; between the core and halo is an annulus with intermediate properties, including higher T_e and lower N_e than in the core. The image of optical extinction from H Balmer line ratios is highly structured, and shows an annulus, adjacent to the core, of low extinction, lower than the line-of-sight interstellar extinction. Instrumental effects to account for this anomalously low extinction area are investigated and intrinsic effects from the scattering properties of nebular dust; neither can entirely explain the low-extinction region and the most likely cause is a local non-standard dust reddening law. This low extinction region also shows an anomalously high He I 7281/6678A line ratio, possibly caused by a contaminating line, but none were conclusively identified. The spectrum of the central star was extracted and fitted by a 31000K model atmosphere and is of type O7.5I(f). Over extended regions an enhancement of the detected continuum above the nebular continuum was found, as also seen in some other PNe observed with MUSE. The annulus of low extinction occurs outside the region of strongest fullerene emission, in the zone where N_e declines and T_e rises. A change in dust properties linked to conditions in this transition region between the higher density core nebula and lower density halo is deduced. (Abridged)

3D Magnetic Field Vectors in Space: Bubbles, Clouds, and Filaments

• Authors: Mehrnoosh Tahani, Anna Ordog, Jennifer West, Georgia V. Panopoulou, Hiroko Shinnaga, Marijke Haverkorn

• Subjects: Subjects: Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2606.27346

• Pdf link: https://arxiv.org/pdf/2606.27346

• Abstract Magnetic fields play important roles in the star-formation process across different spatial scales. The interplay between magnetic field strength (a key component of the interstellar medium's energy budget) and field orientation relative to density structures impacts how interstellar material evolves toward star formation. To understand galactic evolution toward stars, planets, and ultimately life, we need to map three-dimensional (3D) magnetic field vectors in 3D space. However, determining full vector information remains challenging due to projection effects and the complex relationship between observable tracers and field geometry. We outline the observational techniques that can be used to probe the 3D magnetic field structures of objects such as supernova remnants (SNR), superbubbles, HII regions, and HI filaments in the diffuse interstellar medium (ISM), and objects in the dense ISM such as molecular clouds, filaments, and cores. The main SKA-specific observational techniques include synchrotron emission and Faraday rotation of both compact sources and the diffuse emission. We discuss how SKA AA4 will allow implementation of the techniques we describe, leveraging the vastly improved sensitivity, resolution and uv-coverage compared to existing datasets. This will enhance our ability to reconstruct 3D magnetic field vectors, advancing our understanding of magnetic fields in Galactic evolution and star formation.

by olozhika (Xing Yuchen).

2026-06-26