The field of Search for Extraterrestrial Intelligence (SETI) searches for "technosignatures" could provide the first detection of life beyond Earth through the technology that an extraterrestrial intelligence may have created. Any given SETI survey, if no technosignatures are detected, should set upper limits based on the kinds of technosignatures it should have been able to detect; the sensitivity of many SETI searches requires that their target sources (e.g., Dyson spheres or Kardashev II/III level radio transmitters) emit with power far exceeding the kinds of technology humans have developed. In this paper, we instead turn our gaze Earthward, minimizing the axis of extrapolation by only considering transmission and detection methods commensurate with an Earth 2024 level. We evaluate the maximum distance of detectability for various present-day Earth technosignatures—radio transmissions, atmospheric technosignatures, optical and infrared signatures, and objects in space or on planetary surfaces—using only present-day Earth instruments, providing one of the first fully cross-wavelength comparisons of the growing toolbox of SETI techniques. In this framework, we find that Earth's space-detectable signatures span 13 orders of magnitude in detectability, with intermittent, celestially targeted radio transmission (i.e., planetary radar) beating out its nearest nonradio competitor by a factor of 10³ in detection distance. This work highlights the growing range of ways that exoplanet technosignatures may be expressed, the growing complexity and visibility of the human impact upon our planet, and the continued importance of the radio frequencies in SETI.

We present an analysis of adaptive optics images from the Keck I telescope of the microlensing event MOA-2011-BLG-262. The original discovery paper by Bennett et al. reports two possibilities for the lens system: a nearby gas giant lens with an exomoon companion or a very low-mass star with a planetary companion in the Galactic bulge. The ∼10 yr baseline between the microlensing event and the Keck follow-up observations allows us to detect the faint candidate lens host (star) at K = 22.3 mag and confirm the distant lens system interpretation. The combination of the host star brightness and light curve parameters yields host star and planet masses of M_host = 0.19 ± 0.03 M_⊙ and m_p = 28.92 ± 4.75 M_⊕ at a distance of D_L = 7.49 ± 0.91 kpc. We perform a multiepoch cross reference to Gaia Data Release 3 and measure a transverse velocity for the candidate lens system of v_L = 541.31 ± 65.75 km s⁻¹. We conclude this event consists of the highest-velocity exoplanet system detected to date, and also the lowest-mass microlensing host star with a confirmed mass measurement. The high-velocity nature of the lens system can be definitively confirmed with an additional epoch of high-resolution imaging at any time now. The methods outlined in this work demonstrate that the Roman Galactic Exoplanet Survey will be able to securely measure low-mass host stars in the bulge.

Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, identification of five systems that are single lined but require additional data to confirm as substellar companions, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M = 11.8 ± 0.7 M_J) in a P = 571.3 ± 1.4 day orbit with a projected semimajor axis a₀ = 0.312 ± 0.040 mas orbiting a 0.644 ± 0.02M_⊙ star. Gaia-5b is a brown dwarf (M = 20.9 ± 0.5M_J) in a P = 358.62 ± 0.20 days eccentric e = 0.6423 ± 0.0026 orbit with a projected angular semimajor axis of a₀ = 0.947 ± 0.038 mas around a 0.34 ± 0.03M_⊙ star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.

Recent analyses have shown that distant orbits within the scattered disk population of the Kuiper Belt exhibit an unexpected clustering in their respective arguments of perihelion. While several hypotheses have been put forward to explain this alignment, to date, a theoretical model that can successfully account for the observations remains elusive. In this work we show that the orbits of distant Kuiper Belt objects (KBOs) cluster not only in argument of perihelion, but also in physical space. We demonstrate that the perihelion positions and orbital planes of the objects are tightly confined and that such a clustering has only a probability of 0.007% to be due to chance, thus requiring a dynamical origin. We find that the observed orbital alignment can be maintained by a distant eccentric planet with mass ≳10 m_⊕ whose orbit lies in approximately the same plane as those of the distant KBOs, but whose perihelion is 180° away from the perihelia of the minor bodies. In addition to accounting for the observed orbital alignment, the existence of such a planet naturally explains the presence of high-perihelion Sedna-like objects, as well as the known collection of high semimajor axis objects with inclinations between 60° and 150° whose origin was previously unclear. Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet.

We observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST's aperture masking interferometric mode within NIRISS. Observing with the F480M filter centered at 4.8 μm, we simultaneously fit geometrical models to the outer disk and the two known planetary companions. We redetect the protoplanets PDS 70 b and c at a signal-to-noise ratio (SNR) of 14.7 and 7.0, respectively. Our photometry of both PDS 70 b and c provides tentative evidence of mid-IR circumplanetary disk emission through fitting spectral energy distribution models to these new measurements and those found in the literature. We also newly detect emission within the disk gap at an SNR of ~4, a position angle of $22{0}_{-15}^{+10}$@, and an unconstrained separation within ~200 mas. Follow-up observations will be needed to determine the nature of this emission. We place a 5σ upper limit of 208 ± 10 μJy on the flux of the candidate PDS 70 d at 4.8 μm, which indicates that if the previously observed emission at shorter wavelengths is due to a planet, this putative planet has a different atmospheric composition than PDS 70 b or c. Finally, we place upper limits on emission from any additional planets in the disk gap. We find an azimuthally averaged 5σ contrast upper limit >7 mag at separations greater than 110 mas. These are the deepest limits to date within ~250 mas at 4.8 μm and the first space-based interferometric observations of this system.

The planetary and lunar ephemerides called DE440 and DE441 have been generated by fitting numerically integrated orbits to ground-based and space-based observations. Compared to the previous general-purpose ephemerides DE430, seven years of new data have been added to compute DE440 and DE441, with improved dynamical models and data calibration. The orbit of Jupiter has improved substantially by fitting to the Juno radio range and Very Long Baseline Array (VLBA) data of the Juno spacecraft. The orbit of Saturn has been improved by radio range and VLBA data of the Cassini spacecraft, with improved estimation of the spacecraft orbit. The orbit of Pluto has been improved from use of stellar occultation data reduced against the Gaia star catalog. The ephemerides DE440 and DE441 are fit to the same data set, but DE441 assumes no damping between the lunar liquid core and the solid mantle, which avoids a divergence when integrated backward in time. Therefore, DE441 is less accurate than DE440 for the current century, but covers a much longer duration of years −13,200 to +17,191, compared to DE440 covering years 1550–2650.

In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

A primary goal of exoplanet science is to measure the atmospheric composition of gas giants in order to infer their formation and migration histories. Common diagnostics for planet formation are the atmospheric metallicity ([M/H]) and the carbon-to-oxygen (C/O) ratio as measured through transit or emission spectroscopy. The C/O ratio in particular can be used to approximately place a planet's initial formation radius from the stellar host, but a given C/O ratio may not be unique to formation location. This degeneracy can be broken by combining measurements of both the C/O ratio and the atmospheric refractory-to-volatile ratio. We report the measurement of both quantities for the atmosphere of the canonical ultrahot Jupiter WASP-121 b using the high-resolution (R = 45,000) IGRINS instrument on Gemini South. Probing the planet's direct thermal emission in both pre- and post-secondary eclipse orbital phases, we infer that WASP-121 b has a significantly superstellar C/O ratio of ${0.70}_{-0.10}^{+0.07}$ and a moderately superstellar refractory-to-volatile ratio at ${3.83}_{-1.67}^{+3.62}\times$ stellar. This combination is most consistent with formation between the soot line and H₂O snow line, but we cannot rule out formation between the H₂O and CO snow lines or beyond the CO snow line. We also measure velocity offsets between H₂O, CO, and OH, potentially an effect of chemical inhomogeneity on the planet dayside. This study highlights the ability to measure both C/O and refractory-to-volatile ratios via high-resolution spectroscopy in the near-IR H and K bands.

We present trigonometric, photometric, and photographic distances to 1748 southern ($\delta \leqslant 0{}^\circ$) M dwarf systems with $\mu \geqslant 0_{\cdot }^{{\prime\prime} }18$ yr⁻¹, of which 1404 are believed to lie within 25 pc of the Sun. The stars have $6.67\leqslant {{V}_{J}}\leqslant 21.38$ and $3.50\leqslant ({{V}_{J}}-{{K}_{s}})\leqslant 9.27$, covering the entire M dwarf spectral sequence from M0.0 V through M9.5 V. This sample therefore provides a comprehensive snapshot of our current knowledge of the southern sky for the nearest M dwarfs that dominate the stellar population of the Galaxy. Roughly one-third of the 1748 systems, each of which has an M dwarf primary, have published high quality parallaxes, including 179 from the REsearch Consortium On Nearby Stars astrometry program. For the remaining systems, we offer photometric distance estimates that have well-calibrated errors. The bulk of these (∼700) are based on new ${{V}_{J}}{{R}_{{\rm KC}}}{{I}_{{\rm KC}}}$ photometry acquired at the CTIO/SMARTS 0.9 m telescope, while the remaining 500 primaries have photographic plate distance estimates calculated using SuperCOSMOS ${{B}_{J}}{{R}_{59F}}{{I}_{{\rm IVN}}}$ photometry. Confirmed and candidate subdwarfs in the sample have been identified, and a census of companions is included.

We present a search of the TESS Object of Interest (TOI) Catalog for new multiplanet systems. We perform a Box Least Squares search on light curves prepared by the Quick-Look Pipeline to recover known candidates and perform a targeted search for additional candidates in each system. Following vetting and manual inspection, we present eight new planet candidates in multiplanet systems. Highlighted systems include TOI-2037 and TOI-6543, each displaying a nearness to a 2:1 orbital resonance. Four candidates in the TOI-5624 system, including our candidate TIC 53498154.02, have gained TOI status. If confirmed, the TOI-5624 system becomes the 29th known five-planet system. Our identification of candidate TIC 302305400.02 in the TOI-5487 system presents an interesting case study for the formation of hot Jupiter systems, potentially marking the first known system harboring a close-in giant outer companion to an existing hot Jupiter.

The detection of celestial objects in ground-based wide-field optical telescope images serves as the foundational step for subsequent celestial analysis tasks. Existing methods for astronomical target detection have not addressed the challenges posed by a high dynamic range, faintness of targets, and an inaccurate supervision map. This paper presents a faint celestial target detection framework named the Celestial Densely Nested Network (CDN-Net). First, a hierarchical bit-depth decomposition strategy is designed to address high dynamic range astronomical FITS images, ensuring effective representation of faint targets. Second, a densely nested hierarchical network is introduced to extract high-resolution features of these faint astronomical targets. Lastly, a soft segmentation map, along with the corresponding loss, is proposed to guide the network's focus toward faint targets. Experiments were conducted on both simulated and real data sets, separately comprising 2560 images and 24,087 images, respectively, to evaluate the performance of CDN-Net. Compared to six existing methods, CDN-Net achieves superior precision, recall, and F1 score, especially for faint targets with signal-to-noise ratios below 3. Additionally, comparisons with star catalogs validate the effectiveness of CDN-Net. The code for this work is available at https://github.com/AeroFirefly/CDN-Net.

The Pleiades is the most prominent open star cluster visible from Earth and an important benchmark for simple stellar populations unified by common origin, age, and distance. Binary stars are its essential ingredient, yet their contribution remains uncertain due to heavy observational biases. A resolved multiplicity survey was conducted for a magnitude-limited G < 15^mag sample of 423 potential cluster members, including sources with poorly fitted astrometric solutions in Gaia DR3. Speckle interferometric observations at the 2.5 m telescope of the Sternberg Astronomical Institute, Moscow State University observatory were combined with Gaia data, enabling the identification of 61 resolved binary or multiple systems within the 0$\mathop{.}\limits^{\unicode{x02033}}$04–10'' (5–1350 au) separation range. With speckle observations, we discovered 21 components in 20 systems. The existence of a Merope (23 Tau) companion is confirmed after several previous unsuccessful attempts. We show that the Gaia multipeak fraction is a strong predictor of subarcsecond multiplicity, as all sources with ipd_frac_multi_peak > 4% are successfully resolved. We found that 10% of Pleiades stars have a companion with a mass ratio q > 0.5 within the projected separation of 27 < s < 1350 au, and confirm a deficit of wide binaries with s > 300 au. An observed dearth of wide pairs with a large mass ratio (q > 0.55) may imprint the transition from hard to soft binaries regime at the early stages of cluster evolution. The total binary fraction for q > 0.5 systems is extrapolated to be around 25%.

Because of the continuous variations in mass, metallicity, and opacity, dwarf stars are distributed along the main sequence on optical and near-IR color–magnitude diagrams following a smooth polynomial. In this study, utilizing a catalog of crossmatched Galaxy Evolution Explorer (GALEX) and Gaia sources, we identify two distinct populations of M dwarfs in the near-UV (NUV) band on the M_NUV versus M_G diagram. We also reveal a pronounced increase in the number of stars exhibiting high NUV fluxes near the spectral type M2 or M_G ~ 9.4, coinciding with the H₂ formation in the atmosphere that improves the energy transportation at the surface. This suggests that certain yet-to-be-understood stellar mechanisms drive heightened activity in the NUV band around the effective temperatures of M2 and later types of M dwarfs. Through examination of archival Hubble Space Telescope spectra, we show that Fe ii line forests at ~2400 Å and 2800 Å dominate the spectral features in the GALEX NUV bandpass, contributing to the observed excess fluxes at a given mass between the two populations. Additionally, our investigation indicates that fast rotators and young stars likely increase in brightness in the NUV band, but not all stars with bright NUV fluxes are fast rotators or young stars.

How the environment of the host galaxy affects the formation of multiple populations (MPs) in globular clusters (GCs) is one of the outstanding questions in near-field cosmology. To understand the true nature of the old GC MPs in the Large Magellanic Cloud (LMC), we study the Ca–CN–CH photometry of the old metal-poor LMC GC NGC 2257. We find the predominantly first-generation-dominated populational number ratio of n(FG):n(SG) = 61:39(±4), where FG and SG denote the first and second generations, respectively. Both the FG and SG have similar cumulative radial distributions, consistent with the idea that NGC 2257 is dynamically old. We obtain [Fe/H]_hk = −1.78 ± 0.00 dex(σ = 0.05 dex), and our metallicity is ∼0.2 dex larger than that from the high-resolution spectroscopy by others, due to their significantly lower temperatures by ∼−200 K. The NGC 2257 FG shows a somewhat larger metallicity variation than the SG, the first detection of such a phenomenon in an old LMC GC, similar to Galactic GCs with MPs, strongly suggesting that it is a general characteristic of GCs with MPs. Interestingly, the NGC 2257 SG does not show a helium enhancement compared to the FG. Our results for the Galactic normal GCs exhibit that the degree of carbon and nitrogen variations is tightly correlated with the GC mass, while NGC 2257 exhibits slightly smaller variations in its mass. We show that old LMC GCs follow the same trends as the Galactic normal GCs in the ΔW_{CF336W,F438W,F814W}, N_FG/N_tot, and $\mathrm{log}M/{M}_{\odot }$ domains. Our result indicates that the environment of the host galaxy did not play a major role in the formation and evolution of GC MPs.

We observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST's aperture masking interferometric mode within NIRISS. Observing with the F480M filter centered at 4.8 μm, we simultaneously fit geometrical models to the outer disk and the two known planetary companions. We redetect the protoplanets PDS 70 b and c at a signal-to-noise ratio (SNR) of 14.7 and 7.0, respectively. Our photometry of both PDS 70 b and c provides tentative evidence of mid-IR circumplanetary disk emission through fitting spectral energy distribution models to these new measurements and those found in the literature. We also newly detect emission within the disk gap at an SNR of ~4, a position angle of $22{0}_{-15}^{+10}$@, and an unconstrained separation within ~200 mas. Follow-up observations will be needed to determine the nature of this emission. We place a 5σ upper limit of 208 ± 10 μJy on the flux of the candidate PDS 70 d at 4.8 μm, which indicates that if the previously observed emission at shorter wavelengths is due to a planet, this putative planet has a different atmospheric composition than PDS 70 b or c. Finally, we place upper limits on emission from any additional planets in the disk gap. We find an azimuthally averaged 5σ contrast upper limit >7 mag at separations greater than 110 mas. These are the deepest limits to date within ~250 mas at 4.8 μm and the first space-based interferometric observations of this system.

The detection of celestial objects in ground-based wide-field optical telescope images serves as the foundational step for subsequent celestial analysis tasks. Existing methods for astronomical target detection have not addressed the challenges posed by a high dynamic range, faintness of targets, and an inaccurate supervision map. This paper presents a faint celestial target detection framework named the Celestial Densely Nested Network (CDN-Net). First, a hierarchical bit-depth decomposition strategy is designed to address high dynamic range astronomical FITS images, ensuring effective representation of faint targets. Second, a densely nested hierarchical network is introduced to extract high-resolution features of these faint astronomical targets. Lastly, a soft segmentation map, along with the corresponding loss, is proposed to guide the network's focus toward faint targets. Experiments were conducted on both simulated and real data sets, separately comprising 2560 images and 24,087 images, respectively, to evaluate the performance of CDN-Net. Compared to six existing methods, CDN-Net achieves superior precision, recall, and F1 score, especially for faint targets with signal-to-noise ratios below 3. Additionally, comparisons with star catalogs validate the effectiveness of CDN-Net. The code for this work is available at https://github.com/AeroFirefly/CDN-Net.

The Pleiades is the most prominent open star cluster visible from Earth and an important benchmark for simple stellar populations unified by common origin, age, and distance. Binary stars are its essential ingredient, yet their contribution remains uncertain due to heavy observational biases. A resolved multiplicity survey was conducted for a magnitude-limited G < 15^mag sample of 423 potential cluster members, including sources with poorly fitted astrometric solutions in Gaia DR3. Speckle interferometric observations at the 2.5 m telescope of the Sternberg Astronomical Institute, Moscow State University observatory were combined with Gaia data, enabling the identification of 61 resolved binary or multiple systems within the 0$\mathop{.}\limits^{\unicode{x02033}}$04–10'' (5–1350 au) separation range. With speckle observations, we discovered 21 components in 20 systems. The existence of a Merope (23 Tau) companion is confirmed after several previous unsuccessful attempts. We show that the Gaia multipeak fraction is a strong predictor of subarcsecond multiplicity, as all sources with ipd_frac_multi_peak > 4% are successfully resolved. We found that 10% of Pleiades stars have a companion with a mass ratio q > 0.5 within the projected separation of 27 < s < 1350 au, and confirm a deficit of wide binaries with s > 300 au. An observed dearth of wide pairs with a large mass ratio (q > 0.55) may imprint the transition from hard to soft binaries regime at the early stages of cluster evolution. The total binary fraction for q > 0.5 systems is extrapolated to be around 25%.

Because of the continuous variations in mass, metallicity, and opacity, dwarf stars are distributed along the main sequence on optical and near-IR color–magnitude diagrams following a smooth polynomial. In this study, utilizing a catalog of crossmatched Galaxy Evolution Explorer (GALEX) and Gaia sources, we identify two distinct populations of M dwarfs in the near-UV (NUV) band on the M_NUV versus M_G diagram. We also reveal a pronounced increase in the number of stars exhibiting high NUV fluxes near the spectral type M2 or M_G ~ 9.4, coinciding with the H₂ formation in the atmosphere that improves the energy transportation at the surface. This suggests that certain yet-to-be-understood stellar mechanisms drive heightened activity in the NUV band around the effective temperatures of M2 and later types of M dwarfs. Through examination of archival Hubble Space Telescope spectra, we show that Fe ii line forests at ~2400 Å and 2800 Å dominate the spectral features in the GALEX NUV bandpass, contributing to the observed excess fluxes at a given mass between the two populations. Additionally, our investigation indicates that fast rotators and young stars likely increase in brightness in the NUV band, but not all stars with bright NUV fluxes are fast rotators or young stars.

How the environment of the host galaxy affects the formation of multiple populations (MPs) in globular clusters (GCs) is one of the outstanding questions in near-field cosmology. To understand the true nature of the old GC MPs in the Large Magellanic Cloud (LMC), we study the Ca–CN–CH photometry of the old metal-poor LMC GC NGC 2257. We find the predominantly first-generation-dominated populational number ratio of n(FG):n(SG) = 61:39(±4), where FG and SG denote the first and second generations, respectively. Both the FG and SG have similar cumulative radial distributions, consistent with the idea that NGC 2257 is dynamically old. We obtain [Fe/H]_hk = −1.78 ± 0.00 dex(σ = 0.05 dex), and our metallicity is ∼0.2 dex larger than that from the high-resolution spectroscopy by others, due to their significantly lower temperatures by ∼−200 K. The NGC 2257 FG shows a somewhat larger metallicity variation than the SG, the first detection of such a phenomenon in an old LMC GC, similar to Galactic GCs with MPs, strongly suggesting that it is a general characteristic of GCs with MPs. Interestingly, the NGC 2257 SG does not show a helium enhancement compared to the FG. Our results for the Galactic normal GCs exhibit that the degree of carbon and nitrogen variations is tightly correlated with the GC mass, while NGC 2257 exhibits slightly smaller variations in its mass. We show that old LMC GCs follow the same trends as the Galactic normal GCs in the ΔW_{CF336W,F438W,F814W}, N_FG/N_tot, and $\mathrm{log}M/{M}_{\odot }$ domains. Our result indicates that the environment of the host galaxy did not play a major role in the formation and evolution of GC MPs.

We observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST's aperture masking interferometric mode within NIRISS. Observing with the F480M filter centered at 4.8 μm, we simultaneously fit geometrical models to the outer disk and the two known planetary companions. We redetect the protoplanets PDS 70 b and c at a signal-to-noise ratio (SNR) of 14.7 and 7.0, respectively. Our photometry of both PDS 70 b and c provides tentative evidence of mid-IR circumplanetary disk emission through fitting spectral energy distribution models to these new measurements and those found in the literature. We also newly detect emission within the disk gap at an SNR of ~4, a position angle of $22{0}_{-15}^{+10}$@, and an unconstrained separation within ~200 mas. Follow-up observations will be needed to determine the nature of this emission. We place a 5σ upper limit of 208 ± 10 μJy on the flux of the candidate PDS 70 d at 4.8 μm, which indicates that if the previously observed emission at shorter wavelengths is due to a planet, this putative planet has a different atmospheric composition than PDS 70 b or c. Finally, we place upper limits on emission from any additional planets in the disk gap. We find an azimuthally averaged 5σ contrast upper limit >7 mag at separations greater than 110 mas. These are the deepest limits to date within ~250 mas at 4.8 μm and the first space-based interferometric observations of this system.

With the development of wide-field surveys, a large amount of data on short-period W UMa contact binaries have been obtained. Continuous and uninterrupted light curves as well as high-resolution spectroscopic data are crucial in determining the absolute physical parameters. Targets with both TMTS light curves and LAMOST medium-resolution spectra were selected. The absolute physical parameters were inferred with the W-D code for 10 systems, all of them are W-type shallow or medium contact binaries. The O'Connell effect observed in the light curves can be explained by adding a spot on the primary or secondary component in the models. According to O − C analysis, the orbital periods exhibit a long-term increasing or decreasing trend, among which J0132, J1300, and J1402 show periodic variations that may be attributed to the presence of a third body or magnetic activity cycles. Spectral subtraction analysis revealed that the equivalent width of Hα indicates strong magnetic activity in J0047, J0305, J0638, and J1402. Among the 10 selected binary systems, except for J0132 and J0913, the more massive components are found to be main-sequence stars while the less massive components have evolved off the main sequence. In J0132, both components are in the main sequence, whereas both components of J0913 lie above the terminal-age main sequence. Based on the relationship between orbital angular momentum and total mass for these two systems, as well as their low fill-out factors, it is possible that these two systems are newly formed contact binaries, having recently evolved from the detached configuration.

While both observations and theories demonstrate that protoplanetary disks are not expected to live much longer than ∼10 Myr, several examples of prolonged disks have been observed in the past. In this work, we perform a systematic search for aged young stellar objects still surrounded by protoplanetary disks in the M-star catalog from the LAMOST archive. We identify 14 sources older than 10 Myr, still surrounded by protoplanetary disks and with ongoing accretion activities, significantly improving the census of the category known as the Peter Pan disks. The stellar parameters, variability, and accretion properties of these objects, as well as their spatial distribution, are investigated. Nearly all of these objects are distributed far away from nearby associations and star-forming regions but show evidence of being members of open clusters. Investigating the correlation between mass accretion rates and stellar masses, we find that these long-lived disks accrete at systematically lower levels, compared to their younger counterparts with similar stellar masses. Studying the evolution of mass accretion rates with stellar ages, we find that these aged disks follow a similar trend to young ones.

This study investigates the structural parameters of the thin-disk population by analyzing the spatial distribution of evolved stars in the solar neighborhood. From the Gaia Data Release 3 database, about 39.1 million stars within 1 kpc and with relative parallax errors σ_ϖ/ϖ ≤ 0.10 were selected. The photometric data was corrected for extinction using a Galactic dust map. The sample was refined by considering the color–magnitude region ${M}_{{\rm{G}}}\times {({G}_{{\rm{BP}}}-{G}_{{\rm{RP}}})}_{0}$ associated with evolved stars, applying a stricter parallax error limit of σ_ϖ/ϖ ≤ 0.02, and yielding 671,600 stars. The star sample was divided into 36 regions based on their Galactic coordinates, with evolved stars in the absolute magnitude range of −1 < M_G (mag) ≤ 4 further split into five one-unit magnitude intervals. This led to 180 subgroups whose space-density profiles were modeled using a single-component Galaxy model. The analysis shows that the space densities are in agreement with the literature and that the scale heights vary with 200 < H (pc) < 600 interval to their absolute magnitudes. Red clump stars in the solar neighborhood were also estimated to have a scale height of 295 ± 10 pc. These findings indicate that evolved stars with bright absolute magnitudes originate from the evolution of the early spectral-type stars with short scale height, while fainter ones come from the evolution of the intermediate spectral-type stars with large scale height, suggesting that variations in scale height reflect the contribution of Galactic evolution processes.

Asymptotic giant branch (AGB) stars are the primary source of dust and complex molecules in the interstellar medium. The determination of outflow parameters is often hindered by the unknown geometry of the circumstellar environment, creating a demand for high-angular resolution observations. We use our near-infrared spectra and photometry of the carbon AGB star V Cyg, along with literature data, to construct its spectral energy distribution over a wide range of wavelengths. The dust envelope responsible for the infrared excess was also resolved in scattered polarized light at angular scales of 50–80 mas using differential speckle polarimetry. We present an interpretation of the thermal and scattered radiation of the dust using models of a spherical dusty outflow (M_dust = 5.3 × 10⁻⁷M_⊙) and an inclined equatorial density enhancement, either in the form of a disk (M_dust = 7.6 × 10⁻³M_⊕) or a torus (M_dust = 5.7 × 10⁻³M_⊕), which material is concentrated at stellocentric distances less than 25 au. The dust material consists of amorphous carbon and SiC, with 84% of the dust being amorphous carbon. Dust particle radii range from 5 to 950 nm and follow a power law with an exponent of −3.5. Modeling the envelope allowed us to improve the accuracy of stellar luminosity estimations: 21,000L_⊙ and 8300L_⊙ at maximum and minimum brightness, respectively. The relation between the disk and the high water content in the envelope is also discussed.

We present two transit observations of the ∼520 K, 1.85 R_⊕, 4.0 M_⊕ super-Earth TOI-776 b with JWST NIRSpec/G395H, resulting in a 2.8–5.2 μm transmission spectrum. Producing reductions using the ExoTiC-JEDI and Eureka! pipelines, we obtain a median transit depth precision of 34 ppm for both visits and both reductions in spectroscopic channels 30 pixels wide (∼0.02 μm). We find that our independent reductions produce consistent transmission spectra; however, each visit shows differing overall structure. For both reductions, a flat line is preferred for Visit 1 while a flat line with an offset between the NRS1 and NRS2 detectors is preferred for Visit 2; however, we are able to correct for this offset during our modeling analysis following methods outlined in previous works. Using PICASO forward models, we can rule out metallicities up to at least 100× solar with an opaque pressure of 10⁻³ bars to ≥3σ in all cases; however, the exact lower limit varies between the visits, with Visit 1 ruling out ≲100× solar while the lower limits for Visit 2 extend beyond ∼350× solar. Our results add to the growing list of super-Earth atmospheric constraints by JWST, which provide critical insight into the diversity and challenges of characterizing terrestrial planets.