Circumstellar planets in binary star systems provide unique constraints on the formation and dynamical evolution of planets. We present an empirical formula for the stability boundary of coplanar retrograde orbits, similar to the classic one for coplanar prograde orbits. We discuss two of the tightest binaries with circumstellar planets: HD 59686 and ν Octantis. For HD 59686, dynamical fitting of the radial velocity data and stability analysis show that the planet must be either on a nearly coplanar retrograde orbit or in one of the narrow regions of prograde orbits stabilized by secular apsidal alignment. For ν Octantis, a nearly coplanar retrograde planetary orbit is the only option for dynamical stability. We also discuss the mysterious case of ε Cygni. It shows short-period radial velocity variations that closely resemble the signal of a Jupiter-mass planet, but the period and amplitude change over time and dynamical stability analysis rules out a planet.

Single-dish observations at centimeter wavelengths have suggested that the Sgr B2 molecular cloud at the Galactic Center hosts weak maser emission from several large molecules. Here, we present the interferometric observations of the Class I methanol (CH3OH) maser at 84 GHz, the methanimine (CH2NH) maser at 5.29 GHz, and the methylamine (CH2NH2) maser at 4.36 GHz toward Sgr B2 North (N). We use a Bayesian approach to quantitatively assess the observed masing spectral profiles and the excitation conditions. By comparing the spatial origin and extent of maser emission from several molecular species, we find that the new maser transitions have a close spatial relationship with the Class I masers, which suggests a similar collisional pumping mechanism.

Water Fountains (WFs), located between the AGB and PN phases of stellar evolution, may provide significant clues on the shaping process of PNe. We present new VLA observations of the WF candidates OH 16.3-3.0 and IRAS 19356+0754. We detect H2O and OH maser and radio continuum emission towards OH 16.3-3.0. We suggest that the OH maser emission of OH 16.3-3.0 is associated with an aspherical circumstellar envelope due to its spatio-kinematics and peculiar spectral profile. We could not confirm the candidates as bona fide WFs because of the narrow velocity spread (OH 16.3-3.0) or non-detection (IRAS 19356+0754) of H2O maser emission. Further monitoring could help to discern their nature.

Based on the results of an on-going monitoring program of 1612 MHz OH masers in OH/IR stars, we determined a lifetime encompassing late AGB and early post-AGB evolution of at least 4500 years. Fading of the OH masers observed with the Nançay Radio Telescope is detected in several post-AGB OH/IR stars on timescales of decades, while AllWISE/NEOWISE light curves taken almost in parallel show diverse behaviours.

In the past decade, submillimeter surveys have been employed to define samples of gravitationally-lensed dusty star-forming galaxies (DSFGs) at z ∼ 1 − 4. These extreme objects () appear to form stars prodigiously at rates of . Using all-sky Planck and WISE surveys, and wide-area Herschel surveys, we have identified the PASSAGES sample, with some of the rarest hyper-luminous IR galaxies ever discovered. We have found that their globally-averaged star formation surface densities are always sub-Eddington, typically by an order of magnitude. This may suggest that our understanding of how radiation pressure from massive stars disrupts the collapse of molecular clouds (thereby quenching star formation) is flawed—or simply that smaller physical resolutions are necessary. With the aid of lensing, we can now capture the source-plane distribution of star formation at ∼ 100pc scales, letting us identify isolated super-Eddington regions where quenching is occurring.

High brightness and low interstellar extinction allow the 6.7 GHz methanol (CH3OH) masers to carry the information about what happens in the vicinity of the High-Mass Young Stellar Objects (HMYSOs). Monitoring this transition provides an only one opportunity to catch rare, unusual phenomena. In this paper, I describe three of them: quasi-periodic flares of the red-shifted emission in Cep A HW2, accretion burst in S255-NIRS3 and reappearance of the methanol maser flare in G24.329+0.144.

The Central Molecular Zone (CMZ) makes up roughly the inner 500 pc of the Milky Way and has a large amount of dense hot gas, strong magnetic fields, and highly energetic particles. The Survey of Water and Ammonia in the Galactic Center (SWAG) is a major imaging line survey using the Australia Telescope Compact Array with the goal to map out the molecular content in the entire CMZ. SWAG data includes the 22 GHz H2O maser transition which is typically used as a tracer for phases of star formation, including both young stellar objects (YSOs) and evolved stars, such as asymptotic giant branch (AGB) stars. The SWAG H2O survey is significantly deeper with better resolution than existing surveys that cover the entire CMZ. The goal is to create a robust catalog of the maser positions, spectral properties, and the sources they trace. The H2O maser catalog shows 703 H2O masers which increases the amount of detected H2O masers in the CMZ by more than an order of magnitude. The H2O masers have a more symmetric distribution in the Galactic center than that of the gas. Cross-correlation with other observations and catalogs will provide information relating maser properties to YSOs and AGB stars, for which multiple maser components will provide outflow properties. We will also connect the surrounding molecular gas to the YSO maser velocities.

In order to search for new 6.035 GHz excited OH masers 272 star-forming regions visible from the northern hemisphere with known active methanol masers were observed with the 32 m and 16 m radio telescopes of the Ventspils International Radio Astronomy Center (VIRAC). Three possibly new excited OH maser sources at 6.035 GHz were seen.

The asteroid belt is a unique source of information on some of the most important questions facing solar system science. These questions include the sizes, numbers, types and orbital distributions of the planetesimals that formed the planets, and the identification of those asteroids that are the sources of meteorites and near-Earth asteroids. Answering these questions requires an understanding of the dynamical evolution of the asteroid belt, but this evolution is governed by a complex interplay of mechanisms that include catastrophic disruption, orbital evolution driven by Yarkovsky radiation forces, and chaotic orbital evolution driven by gravitational forces. While the timescales of these loss mechanisms have been calculated using estimates of some critical parameters that include the thermal properties, strengths and mean densities of the asteroids, we argue here that the uncertainties in these parameters are so large that deconvolution of the structure of the asteroid belt must be guided primarily by observational constraints. We argue that observations of the inner asteroid belt indicate that the size-frequency distribution is not close to the equilibrium distribution postulated by Dohnanyi (1969). We also discuss the correlations observed between the sizes and the orbital elements of the asteroids. While some of these correlations are significant and informative, others are spurious and may arise from the limitations of the Hierarchical Clustering Method that is currently used to define family membership.

The luminosity of the brightest stars (tip) of the red giant branch (TRGB) in the color–magnitude diagrams of old stars was used early on to introduce the ‘multiple stellar populations’ concept, in 1944, by Walter Baade. However, the precision and accuracy of the TRGB for distance estimation has not been known well for long. In the modern era, equipped with high spatial resolution imaging telescopes, the TRGB is considered an excellent standard candle for any type of resolved galaxies, thus representing a powerful probe for cosmology. The TRGB has several advantages over the classical Cepheids. I review how we can apply the TRGB in cosmology. Four science cases, from large to small scales, are presented: (1) the Hubble flow with Type Ia supernovae; (2) Virgo Cluster infall and dark matter; (3) dark galaxies; and (4) dark matter-free galaxies.

H2O megamaser emission from sub-parsec circumnuclear disks at the center of active galaxies allows a single-step, direct distance measurements to galaxies in the Hubble flow without any external calibration. Based on accurate distance determinations of six maser galaxies within 150 Mpc, the Megamaser Cosmology Project (MCP) team recently obtained H0 = 73.9± 3.0 km/s/Mpc (‘∼ 4% accuracy), independent of distance ladders and the cosmic microwave background. To further applying the megamaser technique to attain a 1% Ho measurement, detecting more high-quality disk maser systems is crucial. In this conference proceeding, we update the status of the MCP and discuss strategies of detecting additional high-quality disk maser galaxies within z ∼ 0.1. In addition, we show the prospects of reaching a 1% Ho measurement with the supreme sensitivity of the ngVLA. Finally, we demonstrate that applying the maser technique to distance measurements of high-z galaxies with future submm VLBI systems is promising and this will allow for investigation of the new tension between the ΛCDM model and the high-z Hubble diagram.

Using 2D hydrodynamical simulations, we show that in a low viscosity protoplanetary disc, Jupiter and Saturn get locked in the 2:1 mean motion resonance and migrate slowly inwards, unlike cases at higher viscosities. We conclude that in such discs the scenario of the Grand-Tack is not possible. Additionally, we investigate how the migration of the four (potentially five) giant planets in low viscous discs may affect the initial conditions of another important model for the formation history of our Solar System: the Nice Model. Adding ice giants in our hydrodynamical simulations, we find different possible resonant chains induced by migration. We then let the disc evolve until the gas phase dissipates and study the dynamical stability of the system. We find it possible to recreate the Solar System from such resonant chains, however the likelihood of this outcome remains low.

We present the trigonometric parallax, proper motion, and structure of three methanol masers from the Southern Hemisphere Parallax Interferometric Radio Astrometry Legacy Project (SπRALS). All three masers have better than 5% parallax accuracy, which we attribute to the new inverse MultiView calibration technique.

The Australia Telescope Compact Array (ATCA) has been used for an interferometric follow up observation at 104.3 GHz of the targets where either this or the 9.9-GHz maser was previously detected. We confirm the significant difference (by more than 1.5 orders of magnitude) from source to source of the flux density ratio for these two maser transitions. Based on the morphology and location of continuum sources, the most likely explanation of this discrepancy is the difference in the flux density of the seed radiation at the two frequencies. We also report absolute positions (with arcsec accuracy) for all detected 104.3 GHz masers.

The Perseus arm has a gap in Galactic longitudes (l) between 50° and 80° where the arm has little star formation activity. To understand the gap, we conducted VERA (VLBI Exploration of Radio Astrometry) astrometry and analyzed archival H <SC>I</SC> data. We report on parallax and proper motion results from four star-forming regions, of which G050.28–00.39 and G070.33+01.59 are associated with the gap. Perseus-arm sources G049.41+00.32 and G050.28–00.39 lag relative to a Galactic rotation by 77 ± 17 km s-1 and 31 ± 10 km s-1, respectively. The noncircular motion of G049.41+00.32 cannot be explained by the gravitational potential of the arm. We discovered rectangular holes with integrated brightness temperatures less than 30 K arcdeg in l vs. VLSR of the H <SC>I</SC> data. Also, we found extended H <SC>I</SC> emission on one side of the Galactic plane when integrating the H <SC>I</SC> data over the velocity range covering the hole. G049.41+00.32 and G050.28–00.39 are moving toward the emission. The Galactic H <SC>I</SC> disk at the same velocity range showed an arc structure, indicating that the disk was pushed from the lower side of the disk. All the observational results might be explained by a cloud collision with the Galactic disk.

We have investigated the spectral evolutions of H2O and SiO masers associated with 12 “water fountain” sources in our FLASHING (Finest Legacy Acquisitions of SiO-/H2O-maser Ignitions by Nobeyama Generation) project. Our monitoring observations have been conducted using the Nobeyama 45 m telescope every 2 weeks–2 months since 2018 December except during summer seasons. We have found new extremely high velocity H2O maser components, breaking the records of jet speeds in this type of sources. Systematic line-of-sight velocity drifts of the H2O maser spectral peaks have also been found, indicating acceleration of the entrained material hosting the masers around the jet. Moreover, by comparing with previous spectral data, we can find decadal growths/decays of H2O maser emission. Possible periodic variations of the maser spectra are further being inspected in order to explore the periodicity of the central stellar system (a pulsating star or a binary). Thus we expect to see the real-time evolution/devolutions of the water fountains over decades.

Upcoming large-scale surveys like LSST are expected to uncover approximately 105 strong gravitational lenses within massive datasets. Traditional manual techniques are too time-consuming and impractical for such volumes of data. Consequently, machine learning methods have emerged as an alternative. In our prior work (Thuruthipilly et al. 2022), we introduced a self-attention-based machine learning model (transformers) for detecting strong gravitational lenses in simulated data from the Bologna Lens Challenge. These models offer advantages over simpler convolutional neural networks (CNNs) and competitive performance compared to state-of-the-art CNN models. We applied this model to the datasets from Bologna Lens Challenge 1 and 2 and simulated data on Euclid.

From various lensing and non-lensing observations, the total density profile in elliptical galaxies is well approximated by a power law mass distribution. However, as neither the dark matter nor the baryons individually follow the power law, this observational result has been referred to as the “bulge–halo conspiracy”. We investigate the consistency of this conspiracy with higher precision than previous studies with the largest ever sample of galaxy–galaxy lenses assembled from archival Hubble Space Telescope (HST) data. By performing lens modelling with power law profiles and combining them with stellar dynamics using the mass-sheet transformation, we can constrain the profile’s deviation from the power law model over a redshift range of 0.1 to 0.8. To uniformly model such a large sample of lens models, we use the automated modelling pipeline dolphin. We also investigate the evolutionary trend of the total mass density slope of the lensing galaxies.