Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and the Wide-field Infrared Survey Explorer Galactic H II region catalog, we construct a sample of 280 Galactic H II regions and candidates in the outer Galaxy (80° ≲ l ≲ 220°). Using MRS-N optical spectra, we measure four emission lines (H α , [N II ] λ 6584, [S II ] λλ 6717, 6731) and use line ratios to spectroscopically confirm 255 H II regions, including 90 previously “Known” H II regions and 165 newly classified ones. We measure their T _e , n _e , and oxygen abundance and determine distances via associated OB stars and the kinematic method. The sample spans R _gal from 8.16 to 15.36 kpc, enabling investigation of radial gradients in physical properties. We find that [N II ]/H α and [S II ]/H α decrease with increasing R _gal , while [S II ]/[N II ] remains nearly flat; these trends are quite different from diffuse ionized gas (DIG). We derive the T _e gradient of 344.530 ± 78.083 K kpc ^−1 and the $\mathrm{log}{n}_{e}$ gradient of −0.143 ± 0.041 cm ^−3 kpc ^−1 . Oxygen abundance shows a steep slope of −0.044 ± 0.010 dex kpc ^−1 in the inner disk and a shallow slope of −0.016 ± 0.005 dex kpc ^−1 in the outer disk, with a global slope of −0.014 ± 0.005 dex kpc ^−1 . We also examine the two-dimensional distributions of T _e , n _e , and oxygen abundance and find that the gradients vary with azimuth. There is no obvious difference between spiral arm and interarm regions, and no trend appears along individual arms. From the [N II ]/H α [S II ] λ 6717/H α diagram, H II regions have a S ^+ /S ratio (0.32) lower than that of DIG (0.43); however, heavy overlap prevents clear separation from this diagram alone.
The Kepler detection pipeline, as well as the transit method, has a bias towards shorter periods, leaving a dearth of detections at longer orbital periods. This relative lack of detections has left an incomplete picture of the architectures of exoplanet systems within the long-period regime. We have built a single transit detection pipeline, utilizing a classification convolutional neural network and the onboard spacecraft diagnostics of the Kepler spacecraft, to detect long-period planets. We apply our pipeline to all currently known planetary systems in the Kepler field hosting at least one planet with an orbital period longer than 6 days. We manually vet all new signals from our pipeline, and identify four new planetary candidates, all of which are in systems where the inner planets exhibit transit timing variations (TTVs). Two of these candidates, Kepler 1752.02 and Kepler 199.03, cause two transit events that are consistent with periods of 777.78^+0.01_-0.02 and 505.495^+0.004_-0.004 days, and radii of 3.55^+0.15_-0.15 and 2.74^+0.05_-0.05 R_⊕, respectively. Our remaining two candidates, Kepler 1897.02 and Kepler 1811.02, are single transit candidates with radii 4.81^+0.20_-0.19 and 3.25^+0.28_-0.30 R_⊕, respectively. The shortest orbital periods for these candidates, consistent with the Kepler dataset (gaps and coverage), are 342 days for Kepler 1897.02 and 544 days for Kepler 1811.02. The new planetary candidates, on their own, are incapable of reproducing the observed TTV signals in the inner system. Although difficult to schedule, follow-up observations are needed to further constrain the new candidates and potentially discover the planets causing the perturbations.
The study of warm Jupiters is crucial to understanding the processes that govern giant-planet formation and migration. These planets sit at the boundary between cold giant planets and hot Jupiters, and studying their orbital properties, including period, eccentricity, and spin–orbit alignment, can offer insights into their past evolution and migration histories. We report the discovery and confirmation of a transiting warm Jupiter, HD 278555 b, which was first detected as a single transit event in a light curve from the Transiting Exoplanet Survey Satellite (TESS). We confirm the planetary nature of the signal using additional TESS data and ground based radial velocity (RV) follow-up observations from the NEID spectrograph, and we characterize the planet via a joint fit to the transit and RV signals. HD 278555 b has a mass of $0.8{4}_{-0.10}^{+0.10}\,{M}_{{\rm{J}}}$ and a radius of $0.98{0}_{-0.035}^{+0.036}\,{R}_{{\rm{J}}}$ , and orbits an F8-type star with a period of $28.8{4}_{-0.000046}^{+0.000045}$ days and a very low eccentricity of $0.08{5}_{-0.049}^{+0.047}$ . These orbital parameters suggest the planet had a quiescent formation history, and either formed in situ or formed beyond the ice line and underwent a smooth inward migration process such as disk-driven migration. This discovery adds to the growing population of well characterized warm Jupiters that will inform planet migration theory.
We present UBVRI photometry of the old, moderately metal-poor open clusters NGC 2420 and NGC 2506, taken with the Half-Degree Imager on the WIYN 0.9 m telescope. Both clusters were observed on the same night for an accurate comparison. Using four color–color diagrams we find reddening values of E ( B − V ) = 0.035 ± 0.003 ( σ _μ ) ± sys (NGC 2420) and 0.060 ± 0.003 ( σ _μ ) ± sys (NGC 2506), and using five color–magnitude diagrams, we find distance modulus values of ( m − M ) _0 = 11.89 ± 0.04 ( σ _μ ) ± sys (NGC 2420) and 12.51 ± 0.06 ( σ _μ ) ± sys (NGC 2506), corresponding to distances of 2390 ± 40 ( σ _μ ) ± sys pc (NGC 2420) and 3180 ± 90 ( σ _μ ) ± sys pc (NGC 2506). We find that NGC 2506 is slightly more metal-poor than NGC 2420: [Fe/H]= −0.227 ± 0.029 ( σ _μ ) ± sys for NGC 2420, and [Fe/H]= −0.383 ± 0.020 ( σ _μ ) ± sys for NGC 2506. We also find similar ages for the two clusters: 2.38 ± 0.06 ( σ _μ ) ± sys Gyr for NGC 2420, and 2.25 ± 0.06 ( σ _μ ) ± sys Gyr for NGC 2420.
We present the discovery of SMDET-1, a red, fast-moving object ( $\mu \approx 1\mathop{.}\limits{^{\prime\prime} }3$ yr ^−1 ) identified in time-resolved unblurred Wide-field Infrared Survey Explorer coadds using a pixel-level deep learning methodology called SMDET. Despite being relatively bright at 4.5 μ m compared to many other recent WISE-based brown dwarf discoveries ( m _[4.5] ≈ 14.6 mag Vega), SMDET-1 had remained overlooked due to its location in a very crowded Galactic plane field ( b ≈ 2 $\mathop{.}\limits^{{\unicode{x000b0}}}$ 25) and contamination from brighter background objects. SMDET-1 is also serendipitously detected at 4.5 μ m in late-2012 Spitzer Deep GLIMPSE survey imaging. SMDET-1 is undetected in UKIDSS and Palomar/Wide Field Infrared Camera near-infrared imaging, with the strongest constraint on its temperature ( T _eff < 391 K) arising from its Deep GLIMPSE color limit of m _[3.6] − m _[4.5] > 2.81 mag, which also implies a very nearby photometric distance <7.4 pc. The Spitzer color bound corresponds to a Y-dwarf phototype. SMDET-1 illustrates the importance of continued searches for nearby brown dwarfs within archival datasets like WISE and Spitzer, as well as the potential of pixel-level deep learning to discover astronomical moving objects that challenge traditional data analysis approaches.
The relative importance of magnetic fields, turbulence, and gravity during the early stages of star formation remains uncertain. We present a multiscale polarimetric investigation of L1287, a clustered low-mass star-forming region hosting a bipolar molecular outflow and a protostar. Our study combines new R -band optical polarimetric observations obtained with AIMPOL, tracing the magnetic field on envelope scales, with archival 850 μ m SCUPOL polarization data probing the dense molecular clump. The clump-scale magnetic field morphology is offset by ∼59° from the envelope field, and the polarization fraction decreases systematically toward higher-density regions, indicating depolarization. This trend is primarily attributed to reduced grain-alignment efficiency, with possible contributions from radiative torque disruption, while magnetic field tangling is unlikely to be the dominant factor. The density structure is derived using extinction map and Herschel SPIRE data. Combining Two Micron All Sky Survey (2MASS) photometry with Gaia parallaxes yields a distance of 920 ± 76 pc. Using the Davis–Chandrasekhar–Fermi method, we estimate magnetic field strengths of ∼111 ± 27 μ G in the envelope and ∼195 ± 70 μ G in the dense clump. The envelope is magnetically subcritical, whereas the clump is supercritical. The Alfvén Mach number indicates sub-Alfvénic conditions in the envelope and a transition toward trans-Alfvénic conditions in the dense gas. Virial analysis further shows that magnetic support dominates the envelope, while gravity dominates the clump. The alignment of the clump magnetic field with both the minor axis and the molecular outflow supports a magnetically regulated evolutionary scenario that transitions toward gravitational collapse at higher densities. These results provide observational evidence that magnetic criticality evolves significantly across spatial scales in star-forming clouds.
Through long-slit spectral observations of the early type disk galaxy ESO 119-055 and archival panoramic spectroscopy data, we studied the kinematics, excitation, and oxygen abundance of the ionized gas in the outer disk of the galaxy. We discovered the decoupled rotation of the gas and stars in the center so revealing the gas acquisition from outside after the stellar-disk formation. The inhomogeneous distribution of the gas metallicity over the disk gives the evidence in favor of a very recent accretion event, approximately 100 Myr ago. Among the H II regions that we detected in the disk of ESO 119-055, the probable source of the gas is identified—the remnant of a small metal-poor satellite accreted by the host galaxy.
The binary T Tauri system, KH 15D, is poised to provide unprecedented detail of gas and ices located between ∼3-5 AU of its circumbinary disk over the next few years. We analyze for the first time a complete set of ground-based time series photometry of the KH 15D system for which the 2022 October - 2025 April data have never been presented. By combining the latest I-band data with historical measurements, we show that the era of large amplitude photometric variability has ended. We define a revised photometric period of P = 48.365 ± 0.005 days, which accurately phases data over a time span of seventy-five years. We adopt magnitudes and colors for the stars that define the epochs when either star A (1995-2008) or star B (2010-2012) is the primary source of the out-of-eclipse brightness of the system. We determine for the first time the effective optical depth for the system between 2002 and 2025 assuming gray extinction. The current out-of-eclipse system color is consistent with a combination of the light from both stars, supporting the previously suggested model in which the trailing edge of the circumbinary disk is more transparent than the leading edge. We continue to see evidence for “clumps” and variable transparency along ingress and egress when the stars are probing the occulting material and suggest that observations made during these phases should permit studies of the physical and chemical nature of the planet-forming zone with the circumbinary disk.
One of the scenarios used to explain the dipper phenomenon in stars is having the innermost disk regions being close to the line of sight to the star - inclined greater than 60 degrees - regardless of the inclination of the outermost disk ("mis-aligned" or "broken" disks). If the dust and gas in these disks sample the same material, edge-on disks will be viewed through larger column densities of gas and dust than the average disk. We have examined inter-night variability of eight Kepler-discovered dipper stars using the SpeX spectrograph on NASA's Infrared Telescope facility at a spectral resolving power of R 750. The He I line at 1.083 microns exhibits a wide variety of profiles, which change from night to night. In the majority of cases, an inverse P Cygni profile, indicative of inflowing gas, is present. The line profile (and continuum flux level) often change on time scales of 1 day. The Paschen and Brackett lines also change on similar time scales. In one object, V935 Sco, Pa beta and Br gamma went from being in emission to being in absorption over the course of 5 weeks. In another, EPIC 203850058, Pa beta went from being in emission in 2017 to vanishing altogether in 2018. The accretion rates determined using Pa beta for these stars tend to be smaller than those using Br gamma, indicating that the former line is more susceptible to self-absorption than the latter, as would be expected for a highly inclined disk.
Hot Jupiters are expected to be tidally locked and synchronously rotating due to their short orbital periods. These conditions create large day–night temperature contrasts and are thought to drive eastward superrotating jets. Indeed, the majority of hot Jupiters are observed to have the hottest region of the planet either at the substellar point or offset in the eastern direction. However, the full phase curve of CoRoT-2 b, observed with the Spitzer Space Telescope, exhibits robust evidence of a western hotspot offset. To determine the origin of this peculiar hotspot offset, we present phase-resolved high-resolution observations of CoRoT-2 b from the CRIRES+ spectrograph on the Very Large Telescope and the IGRINS spectrograph on Gemini South, covering both pre- and posteclipse phases (0.34–0.63). We detect the signal from the planet (signal-to-noise ratio > 4) in both pre- and posteclipse phases separately, and therefore perform separate cross-correlation and retrieval analyses at the two epochs. The phase-resolved retrievals show highly consistent abundances and C/Os, but prefer a hotter and more isothermal temperature–pressure profile at posteclipse phases, consistent with the phase-curve observations that indicated a western hotspot offset. By testing multiple hypotheses invoked to drive a western hotspot offset, we find the most likely explanation to be subsynchronous planetary rotation. We measure the planet’s rotational broadening to be $2.2{4}_{-0.77}^{+0.81}$ km s ^−1 , whereas the expectation from tidally locked rotation is 4.37 ± 0.13 km s ^−1 (2.6 σ discrepant). Other observations, such as high-precision phase curves or eclipse mapping, would help to further confirm the western hotspot offset and subsynchronous rotation.
GW Orionis is a triple stellar system with a disk featuring three misaligned dust rings. We present ALMA molecular line data of CO isotopologues, revealing a streamer feeding the disk in ^12CO and ^13CO. Through multi-pointing observations, we find the streamer extends to ∼30” on-sky (∼12,000 AU) and estimate a mass of 1.6 M_ Jup using ^13CO. Fitting the morphology and kinematics of the streamer, we estimate the mass infall timescale of 0.04 Myrs and a mass infall rate of 3.6×10^-8 M_⊙ yr^-1, approximately an order of magnitude lower than the stellar accretion rate. Our best-fit trajectory shows that the streamer meets the disk at the outermost dust ring and that the streamer's angular momentum vector is closely aligned with this outermost ring within ≈3^∘, in contrast to the ≈32^∘ misalignment with the innermost ring, suggesting the streamer is the likely cause of the misalignment. However, the total angular momentum of the streamer is smaller than that of GW Ori's disk; this, together with the low accretion rate, indicates that we are probably witnessing the end stages of infall. Total Power observations reveal bright emission connecting the streamer to the surrounding star-forming region, with a projected distance falling well within the Bondi-Hoyle radius, implying the streamer could have originated through Bondi-Hoyle accretion as GW Ori moves through its natal cloud. Together, these results suggest that GW Ori remains dynamically linked to its parental cloud through ongoing accretion, with the streamer serving as the likely driver of its misaligned disk structure.
High-energy astrophysical neutrinos serve as crucial messengers for understanding hadronic acceleration processes and identifying the origins of cosmic rays, with blazars among the most promising neutrino sources. The KM3NeT experiment reported the detection of an ultrahigh-energy neutrino with an energy estimate of ∼220 PeV, the most energetic yet observed. The neutrino arrival direction has a 99% confidence region of 3° radius centered at R.A. 94 $\mathop{.}\limits^{{\unicode{x000b0}}}$ 3, decl. −7 $\mathop{.}\limits^{{\unicode{x000b0}}}$ 8 (J2000). In this work, 17 candidate blazars located within this region are identified. Comprehensive new observations and archival data analysis for these sources are presented. The study provides a complete multiwavelength coverage across radio, optical, X-ray, and gamma-ray bands, including proprietary data and dedicated follow-up observations. This study highlights flaring behavior in several candidate counterparts. One object exhibits a radio flare coinciding with the neutrino arrival time, with a pre-trial chance probability of 0.26%. Only for this object, the chance probability could be quantified in a robust way. Another candidate displays a rising trend in X-ray flux in a 1 yr window around the neutrino arrival time, while a third undergoes a gamma-ray flare during the same period. Based on the observational findings presented here, while none of these candidates can conclusively be linked to the neutrino, the implications of a possible blazar origin for the KM3NeT event are discussed.
We present the visual orbits and dynamical masses of two longer period spectroscopic binary stars, HD 210763 and HD 221950, using long baseline interferometry with the CHARA Array and high resolution spectroscopy with the APO 3.5 m and CTIO 1.5 m telescopes. By combining the astrometric and radial velocity observations, we solve for the full, three-dimensional orbits and determine the stellar masses to within 0.5
We present new spatially resolved observations of the red supergiant Betelgeuse (α Orionis) at seven frequencies: 22 GHz (λ1.36cm); 44 GHz (λ6.8mm); 107 GHz (λ2.8mm); 136 GHz (λ2.2mm); 224 GHz (λ1.3mm); 338 GHz (λ0.89mm); and 485 GHz (λ0.62mm) using the Karl G. Jansky Very Large Array and the Atacama Large Millimeter/submillimeter Array. These observations (spanning 2021-2026) enable a characterization of the mean brightness temperature (T_B), shape, and symmetry of the star's extended atmosphere. At 22 GHz and 44 GHz T_B has increased following the historic lows observed in 2019, just prior to the Great Dimming of late 2019/early 2020. We find that T_B peaks at a larger projected radius (r∼2.7R_⋆) compared with measurements prior to 2016, consistent with a possible evolution in the atmospheric density profile. In addition we find a systematic decrease in T_B from ≈3500K at ∼2.7R_⋆ to T_B≈2220K at ∼1.2R_⋆, confirming a previously reported temperature minimum between the photosphere and chromosphere. At all observed frequencies T_B is lower than temperatures inferred from ultraviolet measurements at comparable radii, indicating the continued presence of cooler plasma (T≤ T_ eff) mixed with the warmer chromospheric material. The new measurements yield a global spectral index α=1.35±0.03, with no evidence for a change in α over more than two decades in frequency. Recently, evidence of a close-in companion to Betelgeuse has been reported, with an orbital separation r∼2.3R_⋆. We have identified a correlation between the ellipticity of Betelgeuse, as obtained from radio measurements, and the companion's orbital phase. The results are consistent with periodic perturbations of the atmosphere by the companion.
Giant impacts among planetary embryos generate long-lived debris that feed back on late-stage terrestrial planet growth, yet most N -body models either assume perfect merging or treat fragments in ad hoc ways. We present SHARD , a collision-resolution framework that couples a hybrid integrator (REBOUND + mercurius ) to a six-dimensional catalog of smoothed particle hydrodynamics (SPH) outcomes spanning impact speed, geometry, total mass (up to 2 M _⊕ ), mass ratio, and target-to-projectile water fractions. For each detected impact we multilinearly interpolate to return the two largest remnants with self-consistent kinematics and volatile budgets, and we reconstruct the unresolved fragment population by aggregating nearby SPH debris snapshots and compressing them with mass-weighted k -means in velocity space into a tractable number of fragments above a tunable minimum mass. Exact conservation of total mass and water mass is enforced across survivors and debris, with immediate, energy-based reaccretion checks performed within the time step. Debris interpolation is constrained to the tabulated SPH grid (no extrapolation), and special handling of hit-and-run and catastrophic regimes is included. We benchmark our code against SyMBA in a Mercury-formation experiment and find broad qualitative agreement, though our final embryo distribution is dynamically hotter and more top heavy in mass. The benchmark outcome suggests that debris clustering is dynamically consequential: fragment resolution controls reaccretion, damping, and volatile retention. This SPH-anchored debris treatment provides a drop-in, compositionally aware alternative to perfect merging, enabling late-stage accretion studies that retains fragment feedback without saturating the integrator.
We surveyed 2008 Planck Galactic Cold Clumps (PGCCs) in ^12CO and ^13CO J=1–0 lines using the Taeduk Radio Astronomy Observatory (TRAO) 14 m telescope's multi-beam receiver. We detected 2784 (^12CO) and 2291 (^13CO) velocity components, their closely correlated centroid velocities suggest that ^12CO and ^13CO generally trace kinematically associated gas. PGCCs have low excitation temperatures (mean ∼10 K), mean ^13CO optical depth ∼0.5, and mean ^13CO-derived H_2 column density 4.3×10^21 cm^-2. Gas–dust correlations are moderate, with N_^13CO more tightly correlated with the dust-derived H_2 column density from the PGCC catalog than I_^12CO. Colder PGCCs tend to have higher CO-to-H_2 conversion factor (X_CO) and [H_2]/[^13CO] ratio. X_CO increases clearly with the dust-derived H_2 column density, consistent with enhanced CO freeze-out in high-column-density gas. Supersonic non-thermal motions are widespread: the Mach number derived from ^13CO has a mean of 4.3 and a median of 3.6, increasing slightly with dust-derived H_2 column density. Overall, PGCCs are cold but dynamically active, serving as a valuable laboratory for studying the initial conditions of star formation.
Young, forming planetary-mass objects often exhibit clear signatures of ongoing mass accretion and are thought to accrete material through processes analogous to those operating in young stars. In this study, we present high-spectral-resolution observations of asymmetric and time-variable Hα line profiles from the planetary-mass companion SR 12 c. The Hα line was observed at a resolving power of R ∼ 49,000–40,000 (corresponding to 6.1–7.5 km s^-1) using the High Dispersion Spectrograph (HDS) on the 8.2 m Subaru Telescope. Strong Hα emission is clearly detected, while higher-order Balmer lines (Hβ, Hγ, and Hδ) are not detected due to their faintness. The Hα line profiles are well spectrally resolved and exhibit blueshifted emission peaks, which can be interpreted as arising from either (a) emission partially absorbed by redshifted accreting material along the line of sight and/or (b) geometric occultation by the inner circumplanetary disk. Moreover, the Hα flux shows significant variability at 43.6 ± 6.4 % relative to the peak flux on hourly timescales. During a continuous 2.5-hour observing sequence, the emission component peaking at approximately -30 km s^-1 weakened over the first hour. Subsequently, an emission component centered near -10 km s^-1 became dominant and remained stable for the remaining 1.5 hours. We discuss possible interpretations of this behavior. Overall, these results support that magnetospheric accretion is operating in the planetary-mass object SR 12 c while a scenario combining boundary-layer accretion with a failed wind cannot be ruled out.
Mass functions are used in all areas of astrophysics. The stellar initial mass function (IMF), in particular, plays a central role in modeling stellar populations in galaxies. However, few dedicated tools for working directly with the IMF and its precursor functions are widely available. We present the package, a Python library integrated into the wider scientific Python ecosystem that implements common and variant forms of mass functions, especially the IMF and its pre- and protostellar equivalents, as probability distribution functions based on SciPy's statistics architecture. This package enables the performance of operations such as sampling and integration on a wide array of highly customizable mass functions. is publicly available on the Python package index under the project name .
The identification of the 21 μm feature in some protoplanetary nebulae remains a longstanding puzzle, whose interpretation requires characterization of the molecular gas environments of associated sources. Here, we present high-resolution interferometric observations from the Northern Extended Millimeter Array toward the 21 μm protoplanetary nebula IRAS 06530-0213. Multiple molecular transitions of HC_3N, C_4H, and SiC_2 are detected and spatially resolved. We analyze these spectral lines alongside previously reported CO and ^13CO emission toward this source. Differing from the extended barrel-like molecular structure traced by CO and ^13CO, HC_3N and C_4H are predominantly concentrated in the inner low-latitude equatorial zones. Reproducing the observed morphology requires HC_3N to possess a more inwardly concentrated abundance distribution compared with CO and ^13CO, implying that the inner equatorial regions provide favorable conditions for carbon-chain chemistry.
We present the first chemical survey of Class I and Flat-Spectrum (I/FS) disks using JWST MIRI/MRS, targeting sixteen sources in the Ophiuchus star-forming region. Through empirical line luminosity measurements and multi-component slab modeling, we characterize the molecular reservoir of these young systems and compare them to twelve Class II disks of similar stellar mass. Water, HCN, C$_2$H$_2$, and CO$_2$ are frequently detected in I/FS sources with inclinations $i < 70^{\circ}$, whereas edge-on systems show significantly suppressed emission. Compared to Class II disks, I/FS sources show suggestive---though not yet statistically significant---evidence for elevated cold water ($\sim$200\,K) mass and lower CO$_2$ excitation temperatures. Statistical analyses identify accretion luminosity as the primary correlate of molecular mass across both evolutionary stages. Once this dependence is removed, cold water and CO$_2$ masses anti-correlate with mm-dust disk radius, while hot water remains insensitive to disk size. These patterns are qualitatively consistent with pebble drift models that predict early water enrichment followed by delayed CO$_2$ delivery, suggesting an evolutionary progression from molecular-poor Class 0 sources, through water-rich Class I/FS disks, to Class II disks with reduced cold water excess. This work provides an initial evolutionary framework for disk chemistry that requires larger, multi-region samples to confirm.
