Astrobiology Center

Abstract Background stars observed through a circumstellar disk provide valuable benchmarks for investigating the disk’s extinction properties. The HD 163296 system is an excellent case study due to its large disk, the clearly visible extinction effects in JWST/NIRCam data, and the presence of numerous background sources within or around its disk. We present the measured contrasts and astrometry of sources surrounding HD 163296 from Cycle 1 JWST/NIRCam coronagraphic observations, which will serve as a useful reference for future studies of the disk’s extinction characteristics.

Abstract As the diversity of exoplanets continues to grow, it is important to revisit assumptions about habitability and classical HZ definitions. In this work, we introduce an expanded ’temperate’ zone, defined by instellation fluxes between 0.1 < S/S⊕ < 5, thus encompassing a broader range of potentially habitable worlds. We also introduce the TEMPOS survey, which aims to produce a catalogue of precise radii for temperate planets orbiting M dwarfs with Teff ≤ 3400 K. This work reports the discovery and characterisation of two planets in this temperate regime orbiting mid-type M dwarfs: TOI-6716 b, a Rb = 0.98 ± 0.07 R⊕ planet orbiting its M4 host star (R⋆ = 0.231 ± 0.015R ⊙, M⋆ = 0.223 ± 0.011 M ⊙, Teff = 3110 ± 80 K) with a period $P=4.7185898^{+0.0000054}_{-0.0000041}\, \mathrm{d}$ , and TOI-7384 b, a Rb = 3.56 ± 0.21 R⊕ planet orbiting an M4 (R⋆ = 0.319 ± 0.018R ⊙, M⋆ = 0.318 ± 0.016 M ⊙, Teff = 3185 ± 75 K) star every $P=6.2340258^{+0.0000034}_{-0.0000036}\, \mathrm{d}$ . The radii of TOI-6716 b and TOI-7384 b have precisions of 6.8 % and 5.9 % respectively. We validate these planets with multi-band ground-based photometric observations, high-resolution imaging and statistical analyses. We find these planets to have instellation fluxes close to the inner (hotter) edge of the temperate zone, with Sb = 4.4 ± 1.1 S⊕ and Sb = 4.9 ± 1.1 S⊕ for TOI-6716 b and TOI-7384 b respectively. Also, with a predicted TSM similar to the TRAPPIST-1 planets, TOI-6716 b is likely to be a good rocky-world JWST target, should it have retained its atmosphere.

The Milky Way nuclear star cluster (MWNSC) is located in the Galactic centre, together with the Milky Way nuclear stellar disc (MWNSD), and they dominate the gravitational potential within the inner 300,pc. However, the formation and evolution of the two systems and their possible connections are still under debate. We reanalysed the low-resolution KMOS spectra in the MWNSC with the aim of improving the stellar parameters (̊m T_ eff , ̊m łog,g, and ̊m M/H ) for the MWNSC. We used an improved line list, especially dedicated for cool M giants, that allowed us to improve the stellar parameters and to obtain in addition global ̊m α-elements. A comparison with high-resolution IR spectra (from IGRINS) gives very satisfactory results and constrains the uncertainties to ̊m T_ eff ≃ 150,K, ̊m log,g ≃ 0.4,dex, and ̊m M/H ≃ 0.2,dex. Our ̊m α-elements agree within 0.1,dex compared to the IGRINS spectra. We obtained a high-quality sample of 1140 M giant stars where we see an important contribution of a metal-poor population (̊m ∼ 20,%) centred at ̊m M/H ≃ -0.7,dex, while the most dominant part comes from the metal-rich population with ̊m M/H ≃ 0.26,dex. We constructed a metallicity map and find a metallicity gradient of ̊m ∼ -0.1 ± 0.02 ,dex/pc favouring the inside-out formation scenario for the MWNSC.

Context. Bulges, located at the central regions of galaxies, are complex structures, expected to be shaped by the physical processes involved in the assembly history of their host galaxy, such as gravitational collapse, mergers, interactions, and bars. As a consequence, a variety of bulges with distinct morphologies and chemistry could be produced. Aim. We aim to explore the existence of a stellar mass-metallicity relation of bulges and analyze the possible imprint of distinctive features by accretion and migration of stars, which could store information in their assembly histories. Methods. We used 44 central galaxies from the ̧ielo cosmological simulations. Their stellar masses are within the range of ∼ M_⊙. We decomposed the galaxy into bulge and disk using the circularity and binding energies. We tracked the stellar populations in bulges back in time to their birth locations, classifying them as bulge- and disk-born, in-situ, and accreted. Results. We find that most of the stars in our bulges are formed in-situ, but 33% of our bulges show a non-negligible contribution of stellar accretion from satellites, which could add to about 35% of the population. The accreted material is generally contributed by two or three satellites at most. In some bulges, we also find up to 32% of stars that migrated from the disk due to secular evolution, with a median of 10%. Regardless of the formation histories, we find a clear for bulges, which is more enriched by about 0.4 dex than the corresponding relation of the disk components, and about 0.15 dex more enriched than the galaxy We find evidence that the dispersion in the bulge is influenced by both stellar accretion from satellites and migration from the disk, such that, at a fixed bulge mass, bulges with higher fractions of accreted and migrated stars tend to be less metal-rich. Therefore, we find a for bulges, which is consistent with an increase in metallicity with increasing mass, while its dispersion stores information on the contribution from different formation channels.

In this article, early childhood intervention (ECI) and inclusion in the universal Swedish welfare system is in focus. The framework emphasizes a child and family centered approach that focuses on supporting all children’s development and learning in a preschool for all children, child health services welcoming families and children, child habilitation centers for children with disabilities and their families in the ecosystem for ECI. An important principle is proportionate universalism, that is, that every child and family should have equal opportunities regardless of income level, and that they are provided with support in relation to needs. In this article, a special focus is on the universal preschool for all children, which is an important part of ECI. Even though Sweden is regarded as one of the best countries to raise children in the world, a main concern is whether the Swedish welfare system and ECI retain the capacity and capability to provide the support that is required to meet the needs of all children and to live up to consistent and broad criteria for inclusion from a societal to an individual perspective. The conclusion is that Sweden has a robust system for ECI in many ways, but there is a need for integration and coordination of the services in the ecosystem, and a strong growth of research to provide evidence-based knowledge about inclusive practices across the organizations involved.

Abstract We present the description of the instruments and the first results of the PRime-focus Infrared Microlensing Experiment (PRIME). PRIME is the first dedicated near-infrared (NIR) microlensing survey telescope, and is located at the South African Astronomical Observatory in Sutherland, South Africa. Among its class, it offers one of the widest fields of view in the NIR regime. PRIME’s main goals are (1) to study planetary formation by measuring the frequency and mass function of planets. In particular, we compare results from the central Galactic bulge (GB), accessible only in the NIR by PRIME, with those from the outer GB by optical surveys. (2) To conduct concurrent observations with NASA’s Nancy Grace Roman Space Telescope. Due to the different lines of sight between the ground and space, we detect slight variations in light curves, known as “space-based parallax.” This effect allows us to measure the mass of lens systems and their distance from the Earth. It is the only method to measure the mass of free-floating planets down to Earth mass. We began the GB survey in 2024 February and analyzed images through 2025 June 1, identifying 486 microlensing candidates and over a thousand variable stars, including Mira variables, which are useful for studying the Galactic structure. We issue real-time alerts for follow-up observations, supporting exoplanet searches and the chemical evolution studies in the GB. During the off-bulge season, we conduct an all-sky grid survey and target-of-opportunity observations of transients, including gravitational-wave events, γ -ray bursts, and other science.

Abstract Two leading hypotheses for hot Jupiter migration are disk migration and high-eccentricity migration (HEM). Stellar obliquity is commonly used to distinguish them, as high obliquity often accompanies HEM. However, low obliquity does not guarantee disk migration, due to possible spin–orbit realignment or coplanar HEM. Seeking a proxy for disk migration, we investigate the idea that when the circularization timescale of a planet on circular orbit is longer than its age ( τ cir &gt; τ age ), HEM would not have had sufficient time to complete, favoring disk migration. We empirically calibrate the reduced planetary tidal quality factor to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Q</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">p</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>4</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.5</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> </mml:math> using the eccentricity distribution of 500+ Jovian mass (0.2 M J &lt; M p &lt; 13 M J ) planets with measured masses and radii, a value consistent with solar system Jupiter. We then calculate τ cir and identify dozens of disk migration candidates ( τ cir &gt; τ age , e &lt; 0.1). These planets show three notable trends. We first find a clear cutoff of obliquity at τ cir ∼ τ age , suggesting the primordial alignment of protoplanetary disks. Second, we find that among hot Jupiters ( a &lt; 0.1 au), nearby companions are preferentially found around disk migration candidates, suggesting that either HEM dominates hot Jupiter formation, or disk migration also disrupts nearby companions at short separations. Finally, we find a possible dearth of disk migration candidates around mass ratio <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>q</mml:mi> <mml:mo>∼</mml:mo> <mml:mo>−</mml:mo> <mml:mn>3.2</mml:mn> </mml:math> , consistent with a similar dip suggested at longer orbits from microlensing. The lack of planets across different orbital distance, if true, could be interpreted as a hint of runaway migration.

Abstract Stars form in dense, cold regions of interstellar clouds where gravity, turbulence, and magnetic fields interact. Magnetic fields are expected to regulate how gas contracts, but their role at the earliest, prestellar stage is poorly constrained, because polarized dust emission from the coldest cores is faint. Here we report submillimeter dust polarization observations of the well-studied prestellar core L1544, obtained with the James Clerk Maxwell Telescope SCUBA-2/POL-2 instrument as part of the BISTRO (B-fields in Star-forming Region Observations) survey. The data resolve a clearly pinched, hourglass-shaped magnetic field at the core center, representing the first detection in a prestellar core. The plane-of-sky field morphology matches classical predictions for magnetically regulated contraction and is consistent with previously reported slow infall and filament-fed accretion flows that deliver material into the core. From the polarization angle dispersion, we infer a magnetic field strength that implies an Alfvén speed above the measured infall speed and well below the free-fall velocity, indicating sub-Alfvénic, magnetically moderated contraction. These results show that the hourglass-shaped field geometry reported in some protostellar envelopes can already be present before a protostar forms, thereby bridging a key observational gap in the timeline of magnetically regulated star formation. As a nearby, representative core on the verge of star formation, L1544 now serves as a benchmark for testing theoretical models that couple gravity and magnetic fields in dense cores.

The architecture of planetary systems is a key piece of information to our understanding of their formation and evolution. This information also allows us to place the Solar System in the exoplanet context. An important example is the impact of outer giant planets on the formation of inner super-Earths and sub-Neptunes. Radial velocity (RV) surveys aim at drawing statistical insights into the (anti-)correlations between giants and inner small planets, which remain unclear. These surveys are limited by the completeness of the systems, namely, the sensitivity of the data to planet detections. Here, we show that we can improve the completeness by accounting for orbital stability. We introduce the Algorithm for the Refinement of DEtection limits via N-body stability Threshold (ARDENT), an open-source Python package for detection limits that include the stability constraint. The code computes the classic data-driven detection limits, along with the dynamical limits via both analytical and numerical stability criteria. We present the code strategy and illustrate its performance on TOI-1736 using published SOPHIE RVs. This system contains an eccentric cold giant on a 570-day orbit and an inner sub-Neptune on a 7-day orbit. We demonstrate that no additional planet can exist in this system beyond 150 days due to the gravitational influence of the giant. This outcome allows us to significantly refine the system completeness and also carries implications for RV follow-ups. ARDENT is user-friendly and can be employed across a wide variety of systems to refine our understanding of their architecture.

Abstract 2MASS J16120668–3010270 (hereafter 2MJ1612) is a young M0 star that hosts a protoplanetary disk in the Upper Scorpius star-forming region. Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations of 2MJ1612 show a mildly inclined disk (i = 37°) with a large dust-depleted gap (R cav ≈ 0 . ″ 4 or 53 au). We present high-contrast Hα observations from MagAO-X on the 6.5 m Magellan telescope and new high-resolution submillimeter dust continuum observations with ALMA of 2MJ1612. On both 2025 April 13 and 16, we recovered a point source with Hα excess with a signal-to-noise ratio ≳5 within the disk gap in our MagAO-X angular and spectral differential images at a separation of 141.96 ± 2.10 mas (23.45 ± 0.29 au deprojected) from the star and a position angle ​​​​​of 159 . ° 00 ± 0 . ° 55. Furthermore, this Hα source is within close proximity to a K-band point source in the SPHERE/IRDIS observation taken on 2023 July 21. The astrometric offset between the K band and Hα source can be explained by orbital motion of a bound companion. Thus, our observations can be best explained by the discovery of an accreting protoplanet, 2MJ1612 b, with an estimated mass of 4 M Jup and a Hα line flux ranging from (29.7 ± 7.5) × 10−16 erg s cm2 to (8.2 ± 3.4) × 10−16 erg s cm2. 2MJ1612 b is likely the third example of an accreting Hα protoplanet responsible for carving the gap in its host disk, joining PDS 70 b and c. Further study is necessary to confirm and characterize this protoplanet candidate and to identify any additional protoplanets that may also play a role in shaping the gap.