adsabs/SciX_UAT_keywords huggingface dataset:
The TESS-Keck Survey. XVII. Precise Mass Measurements in a Young, High-multiplicity Transiting Planet System Using Radial Velocities and Transit Timing Variations

We present a radial velocity (RV) analysis of TOI-1136, a bright Transiting Exoplanet Survey Satellite (TESS) system with six confirmed transiting planets, and a seventh single-transiting planet candidate. All planets in the system are amenable to transmission spectroscopy, making TOI-1136 one of the best targets for intra-system comparison of exoplanet atmospheres. TOI-1136 is young (∼700 Myr), and the system exhibits transit timing variations (TTVs). The youth of the system contributes to high stellar variability on the order of 50 m s‑1, much larger than the likely RV amplitude of any of the transiting exoplanets. Utilizing 359 High Resolution Echelle Spectrometer and Automated Planet Finder RVs collected as part of the TESS-Keck Survey, and 51 High-Accuracy Radial velocity Planetary Searcher North RVs, we experiment with a joint TTV-RV fit. With seven possible transiting planets, TTVs, more than 400 RVs, and a stellar activity model, we posit that we may be presenting the most complex mass recovery of an exoplanet system in the literature to date. By combining TTVs and RVs, we minimized Gaussian process overfitting and retrieved new masses for this system: (m b‑g = ${3.50}_{-0.7}^{+0.8}$ , ${6.32}_{-1.3}^{+1.1}$ , ${8.35}_{-1.6}^{+1.8}$ , ${6.07}_{-1.01}^{+1.09}$ , ${9.7}_{-3.7}^{+3.9}$ , ${5.6}_{-3.2}^{+4.1}$ M ⊕). We are unable to significantly detect the mass of the seventh planet candidate in the RVs, but we are able to loosely constrain a possible orbital period near 80 days. Future TESS observations might confirm the existence of a seventh planet in the system, better constrain the masses and orbital properties of the known exoplanets, and generally shine light on this scientifically interesting system.

Keywords: radial velocity; transit timing variation method; exoplanet atmospheres; exoplanets; bayesian statistics; transits; markov chain monte carlo; gaussian processes regression
Meterwavelength Single Pulse Polarimetric Emission Survey. VI. Toward Understanding the Phenomenon of Pulsar Polarization in Partially Screened Vacuum Gap Model

We have observed 123 pulsars with periods longer than 0.1 s in the Meterwavelength Single Pulse Polarimetric Emission Survey. In this work, a detailed study of the polarization behavior of these pulsars has been carried out. We were able to fit the rotating vector model to the polarization position angle sweeps in 68 pulsars, and in 34 pulsars the emission heights could be measured. In all cases the radio emission was constrained to arise below 10% of the light cylinder radius. In pulsars with low spin-down energy loss, $\dot{E}\lt {10}^{34}$ erg s-1, we found the mean fractional linear polarization of the individual time samples in single pulses to be around 0.57 (57%), which is significantly larger than the fractional linear polarization of 0.29 (29%) obtained from the average profiles. On the other hand, the mean fractional circular polarization of the individual time samples in single pulses is around 0.08 (8%), similar to the measurements from the average profiles. To explain the observed polarization features, we invoke the partially screened vacuum gap model of pulsars, where dense spark-associated plasma clouds exist with high pair plasma multiplicity, with significant decrease of density in the regions between the clouds that are dominated by iron ions. The coherent radio emission is excited by curvature radiation from charge bunches in these dense plasma clouds and escape as linearly polarized waves near cloud boundaries. We suggest that the circular polarization arises due to propagation of waves in the low-pair-multiplicity, ion-dominated inter-cloud regions.

Keywords: radio pulsars
Variations of the Galactic Cosmic Rays in the Recent Solar Cycles

In this paper, we study the Galactic cosmic-ray (GCR) variations over the solar cycles 23 and 24, with measurements from NASA's Advanced Composition Explorer/Cosmic Ray Isotope Spectrometer instrument and the ground-based neutron monitors (NMs). The results show that the maximum GCR intensities of heavy nuclei (5 ≤ Z ≤ 28, 50∼500 MeV nuc-1) at 1 au during the solar minimum in 2019-2020 break their previous records, exceeding those recorded in 1997 and 2009 by ∼25% and ∼6%, respectively, and are at the highest levels since the space age. However, the peak NM count rates are lower than those in late 2009. The difference between GCR intensities and NM count rates still remains to be explained. Furthermore, we find that the GCR modulation environment during the solar minimum P24/25 are significantly different from previous solar minima in several aspects, including remarkably low sunspot numbers, extremely low inclination of the heliospheric current sheet, rare coronal mass ejections, weak interplanetary magnetic field and turbulence. These changes are conducive to reduce the level of solar modulation, providing a plausible explanation for the record-breaking GCR intensities in interplanetary space.

Keywords: galactic cosmic rays; solar activity; interplanetary turbulence
Study Turbulence and Probe Magnetic Fields Using the Gradient Technique: Application to H I-to-H2 Transition Regions

The atomic-to-molecular (H I-to-H2) transition in photodissociation regions (PDRs) has been investigated over the past several decades through analytic and numerical modeling. However, classical PDR models typically assume a uniform-density gas, ignoring the turbulent nature of the interstellar medium. Recently, Bialy et al. have presented a theoretical framework for studying the H I-to-H2 transition in a realistic turbulent medium with a nonhomogeneous density structure. Here we extend these turbulent-chemical models to explore the possibility of tracing the magnetic field direction in turbulent PDRs using the gradient technique. We utilize both subsonic and supersonic magnetohydrodynamic numerical simulations for chemical H I/H2 balance calculations. We confirm that the density fluctuations induced by turbulence can disperse the distribution of the H2 and H I fractions. We find that the energy spectrum of moment maps gets shallower when the sonic Mach number MS increases. We explore the ability in magnetic field tracing of gradients of higher-order velocity centroids and compare their performance with that of traditional velocity centroid gradients (VCGs) and with intensity gradients (IGs). We find that the velocity gradients of the second-order centroids (VC2Gs) are more accurate than VCGs and IGs in probing the magnetic field orientation.

Keywords: interstellar medium; interstellar magnetic fields; interstellar dynamics
The Symbiotic X-Ray Binary IGR J16194-2810: A Window on the Future Evolution of Wide Neutron Star Binaries From Gaia

We present optical follow-up of IGR J16194-2810, a hard X-ray source discovered by the INTEGRAL mission. The optical counterpart is a ∼500 L ⊙ red giant at a distance of 2.1 kpc. We measured 17 radial velocities (RVs) of the giant over a period of 271 days. Fitting these RVs with a Keplerian model, we find an orbital period of P orb = 192.73 ± 0.01 days and a companion mass function f(M 2) = 0.365 ± 0.003 M ⊙. We detect ellipsoidal variability with the same period in optical light curves from the ASAS-SN survey. Joint fitting of the RVs, light curves, and the broadband spectral energy distribution allows us to robustly constrain the masses of both components. We find a giant mass of and a companion mass of , implying that the companion is a neutron star (NS). We recover a 4.06 hr period in the system's TESS light curve, which we tentatively associate with the NS spin period. The giant does not yet fill its Roche lobe, suggesting that current mass transfer is primarily via winds. Modules for Experiments in Stellar Astrophysics evolutionary models predict that the giant will overflow its Roche lobe in 5–10 Myr, eventually forming a recycled pulsar + white dwarf binary with a ∼900 days period. IGR J16194-2810 provides a window on the future evolution of wide NS + main sequence binaries recently discovered via Gaia astrometry. As with those systems, the binary's formation history is uncertain. Before the formation of the NS, it likely survived a common envelope episode with a donor-to-accretor mass ratio ≳10 and emerged in a wide orbit. The NS likely formed with a weak kick (v kick ≲ 50 km s‑1), as stronger kicks would have disrupted the orbit.

Keywords: symbiotic binary stars; low-mass x-ray binary stars; neutron stars
Early Results from GLASS-JWST. XXIII. The Transmission of Lyα from UV-faint z 3-6 Galaxies

Lyα emission from galaxies can be used to trace neutral hydrogen in the epoch of reionization, however, there is a degeneracy between the attenuation of Lyα in the intergalactic medium (IGM) and the line profile emitted by the galaxy. Large shifts of Lyα redward of systemic due to scattering in the interstellar medium can boost Lyα transmission in the IGM during reionization. The relationship between the Lyα velocity offset from systemic and other galaxy properties is not well established at high redshift or low luminosities, due to the difficulty of observing emission lines which trace the systemic redshift. Rest-frame optical spectroscopy with JWST/NIRSpec has opened a new window into understanding Lyα at z > 3. We present a sample of 12 UV-faint galaxies (-20 ≲ M UV ≲ -16) at 3 ≲ z ≲ 6, with Lyα velocity offsets, Δv Lyα , measured from the Very Large Telescope/MUSE and JWST/NIRSpec from the GLASS-JWST Early Release Program. We find a median Δv Lyα of 205 km s-1 and standard deviation of 75 km s-1, compared to 320 and 170 km s-1, respectively, for M UV < -20 galaxies in the literature. Our new sample demonstrates the previously observed trend of decreasing Lyα velocity offset with decreasing UV luminosity and optical line velocity dispersion, which extends to M UV ≳ -20, consistent with a picture where the Lyα profile is shaped by gas close to the systemic redshift. Our results imply that during reionization Lyα from UV-faint galaxies will be preferentially attenuated, but that detecting Lyα with low Δv Lyα can be an indicator of large ionized bubbles.

Keywords: emission line galaxies; galaxies; lyman-alpha galaxies; galaxy evolution; high-redshift galaxies
Surrounded by Giants: Habitable Zone Stability Within the HD 141399 System

The search for exoplanets has revealed a diversity of planetary system architectures, the vast majority of which diverge significantly from the template of the solar system. In particular, giant planets beyond the snow line are relatively rare, especially for low-mass stars, placing the solar system within a small category of systems with multiple giant planets at large separations. An exoplanetary system of note is that of HD 141399, consisting of a K-dwarf host star that harbors four giant planets with separations extending to ~4.5 au. The architecture of the system creates a complex pattern of mean motion resonances and gravitationally perturbed regions that may exclude the presence of other planets, including within the habitable zone of the system. Here, we present the results of dynamical simulations that explore the interaction of the known planets of the system, their apsidal trajectories, resonance locations, and dynamical evolution. We further investigate the results of injecting Earth-mass planets and provide the regions of dynamical viability within the habitable zone where terrestrial planets may maintain long-term stability. We discuss these results in the context of the importance of giant planets for volatile delivery and planetary habitability considerations.

Keywords: exoplanet astronomy; exoplanet dynamics; exoplanet evolution; exoplanet systems; exoplanets; orbital evolution; orbital resonances; habitable planets; habitable zone; astrobiology
The Molecular Clouds in a Section of the Third Galactic Quadrant: Cloud Catalog

We present results of cloud catalogs of 12CO, 13CO, and C18O (J = 1-0) in a section of the third Galactic quadrant over (195° < l < 220°, ∣b∣ < 5°) from the Milky Way Imaging Scroll Painting project. The data were acquired with the PMO 13.7 m millimeter telescope with ~50″angular resolution. We construct three molecular cloud catalogs containing information of 12CO, 13CO, and C18O from the position-position-velocity (PPV) data cubes. The 12CO cloud catalog contains 7069 samples identified based on the DBSCAN algorithm. We develop a new algorithm, the stacking bump algorithm, for identifying 13CO and C18O emission by searching for weak signals in the original spectra of 13CO and C18O within the boundary in PPV space defined by the 12CO cloud. Above the 2σ threshold level, we identified 1197 clouds having 13CO emission and 32 clouds having C18O emission. We test the stacking bump algorithm in the noise-only datacube and find that the 2σ threshold can effectively avoid the possibility of false detection generated by noise. The results proved that the new algorithm has high accuracy and completeness. Statistics of peak intensity, projected angular area, line width, and flux of the clouds show that the power-law indices obtained from different isotopic lines are close to each other.

Keywords: molecular gas; molecular clouds
An Upper Limit on the Extended Helium Atmosphere of GJ 1214 b

The He I 10830 Å absorption line in transit spectra traces the upper atmospheres of exoplanets and their mass loss, which in turn is important in determining their evolution and demographics. We use archival VLT/X-Shooter data to set new, more sensitive limits on the extended helium atmosphere of GJ 1214 b, a sub-Neptune orbiting an M-dwarf. We determine limits for the excess absorption at 10830 Å of 0.38% ± 0.44%, which corresponds to an extended atmosphere scale height of 0.13 ± 0.14Rp (95% confidence limit of <0.4Rp). This is an improvement on previous upper limits set by Crossfield et al. (2019) and shows that X-shooter is a suitable instrument for these types of observations. * Based on observations collected at the European Southern Observatory under ESO program 087.C-0442 (PI van Boekel).

Keywords: exoplanet atmospheres; astronomy data analysis; spectrophotometry; transmission spectroscopy; exoplanets; transits; very large telescope
Predicting the Dominant Formation Mechanism of Multiplanetary Systems

Most, if not all, Sun-like stars host one or more planets, making multiplanetary systems commonplace in our Galaxy. We utilize hundreds of multiplanet simulations to explore the origin of such systems, focusing on their orbital architecture. The first set of simulations assumes in situ assembly of planetary embryos, while the second explores planetary migration. After applying observational biases to the simulations, we compare them to 250+ observed multiplanetary systems, including 13 systems with planets in the habitable zone. For all of the systems, we calculate two of the so-called statistical measures: the mass concentration (S c ) and orbital spacing (S s ). After analytic and empirical analyses, we find that the measures are related to first order with a power law: ${S}_{c}\sim {S}_{s}^{\beta }$ . The in situ systems exhibit steeper power-law relations relative to the migration systems. We show that different formation scenarios cover different regions in the S s –S c diagram with some overlap. Furthermore, we discover that observed systems with S s < 30 are likely dominated by the migration scenario, while those with S s ≥ 30 are likely dominated by the in situ scenario. We apply these criteria to determine that a majority (62%) of observed multiplanetary systems formed via migration, whereas most systems with currently observed habitable planets formed via in situ assembly. This work provides methods of leveraging the statistical measures (S s and S c ) to disentangle the formation history of observed multiplanetary systems based on their present-day architectures.

Keywords: exoplanet dynamics; planet formation; planetary migration; exoplanet evolution; protoplanetary disks
Tracing the Origins of Mass Segregation in M35: Evidence for Primordially Segregated Binaries

M35 is a young open cluster and home to an extensive binary population. Using Gaia Data Release 3, Pan-STARRS, and Two Micron All Sky Survey photometry with the Bayesian statistical software, BASE-9, we derive precise cluster parameters, identify single and binary cluster members, and extract their masses. We identify 571 binaries down to Gaia G = 20.3 and a lower limit on the binary frequency of f b = 0.41 ± 0.02. We extend the binary demographics by many magnitudes faint-ward of previous (radial-velocity) studies of this cluster and further away from the cluster center (1.°78, roughly 10 core radii). We find the binary stars to be more centrally concentrated than the single stars in the cluster. Furthermore, we find strong evidence for mass segregation within the binary population itself, with progressively more-massive binary samples becoming more and more centrally concentrated. For the single stars, we find weaker evidence for mass segregation; only the most massive single stars (>2.5M ⊙) appear more centrally concentrated. Given the cluster age of ∼200 Myr, and our derived half-mass relaxation time for the cluster of 230 ± 84 Myr, we estimate ∼47% of the binary stars and ∼12% of single stars in the cluster have had time to become dynamically mass segregated. Importantly, when we investigate only stars with mass segregation timescales greater than the cluster age, we still find the binaries to be more centrally concentrated than the singles, suggesting the binaries may have formed with a primordially different spatial distribution from that of the single stars.

Keywords: binary stars; open star clusters; relaxation time; bayesian statistics; star formation
Detecting Gravitational Wave Bursts from Stellar-mass Binaries in the mHz Band

The dynamical formation channels of gravitational wave (GW) sources typically involve a stage when the compact object binary source interacts with the environment, which may excite its eccentricity, yielding efficient GW emission. For the wide eccentric compact object binaries, the GW emission happens mostly near the pericenter passage, creating a unique, burst-like signature in the waveform. This work examines the possibility of stellar-mass bursting sources in the mHz band for future LISA detections. Because of their long lifetime (∼107 yr) and promising detectability, the number of mHz bursting sources can be large in the local Universe. For example, based on our estimates, there will be ∼3–45 bursting binary black holes in the Milky Way, with ∼102–104 bursts detected during the LISA mission. Moreover, we find that the number of bursting sources strongly depends on their formation history. If certain regions undergo active formation of compact object binaries in the recent few million years, there will be a significantly higher bursting source fraction. Thus, the detection of mHz GW bursts not only serves as a clue for distinguishing different formation channels, but also helps us understand the star formation history in different regions of the Milky Way.

Keywords: gravitational wave astronomy; compact binary stars
Molecules and Outflows in NML Cygni: New Insights from a 1 mm Spectral Line Survey

A sensitive (1σ rms ≤ 3 mK) 1 mm spectral survey (214.5-285.5 GHz) of the oxygen-rich circumstellar envelope of the red hypergiant NML Cygni (NML Cyg) has been conducted using the Sub-millimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). Over 100 spectral lines were detected, arising from 17 different molecules, including the carbon-bearing species CO, HCN, HCO+, CN, and HNC; sulfur- and silicon-containing compounds H2S, SO, SO2, SiO, and SiS; and more exotic NaCl and AlO. The 1 mm spectrum of NML Cyg closely resembles that of VY Canis Majoris (VY CMa) suggesting that the chemistries of hypergiant stars are similar. The line profiles in NML Cyg consist of multiple velocity features, particularly evident in SO2 and SO. In addition to a spherical wind at the star's systemic velocity, the spectra suggest an asymmetric, blueshifted component near VLSR = -21 ± 3 km s-1 and a collimated, redshifted component near 15 ± 3 km s-1, positioned ~34° and ~12°, respectively, from the line of sight. The red- and blueshifted flows appear to be randomly oriented, and likely trace sporadic mass loss events. Their LSR velocities align closely with those of 22 GHz water masers, suggesting an NE-SE orientation. The winds may also be associated with the asymmetric nebula in F555W HST images but extending to 5″ (~600R*). NML Cyg appears to be another example of rare, massive stars with collimated, episodic ejections, analogous to Betelgeuse and VY CMa, lending support for an important new mass loss mechanism-surface activity.

Keywords: circumstellar envelopes; hypergiant stars; millimeter astronomy; astrochemistry; molecular spectroscopy; stellar evolution; stellar mass loss; stellar winds
X-shooter Spectroscopy and HST Imaging of 15 Massive Quiescent Galaxies at z ≳ 2

We present a detailed analysis of a large sample of spectroscopically confirmed massive quiescent galaxies (MQGs; log(M */M ⊙) ∼ 11.5) at z ≳ 2. This sample comprises 15 galaxies selected in the COSMOS and UDS fields by their bright K-band magnitudes and followed up with Very Large Telescope (VLT) X-shooter spectroscopy and Hubble Space Telescope (HST)/WFC3 H F160W imaging. These observations allow us to unambiguously confirm their redshifts, ascertain their quiescent nature and stellar ages, and reliably assess their internal kinematics and effective radii. We find that these galaxies are compact, consistent with the high-mass end of the stellar mass-size relation for quiescent galaxies at z = 2. Moreover, the distribution of the measured stellar velocity dispersions of the sample is consistent with the most massive local early-type galaxies from the MASSIVE Survey, showing that evolution in these galaxies is dominated by changes in size. The HST images reveal, as surprisingly high, that 40% of the sample has tidal features suggestive of mergers and companions in close proximity, including three galaxies experiencing ongoing major mergers. The absence of velocity dispersion evolution from z = 2 to 0, coupled with a doubling of the stellar mass, with a factor of 4 size increase and the observed disturbed stellar morphologies, supports dry minor mergers as the primary drivers of the evolution of the MQGs over the last 10 billion yr.

Keywords: infrared galaxies; compact galaxies; quenched galaxies; near infrared astronomy; infrared astronomy; galaxy kinematics; galaxy dynamics; stellar masses; stellar ages; stellar radii; high resolution spectroscopy; hubble space telescope
On the Hard Gamma-Ray Spectrum of the Potential PeVatron Supernova Remnant G106.3 + 2.7

The Tibet ASγ experiment has measured a γ-ray flux of supernova remnant G106.3+2.7 of up to 100 TeV, suggesting it is potentially a "PeVatron." Challenges arise when the hadronic scenario requires a hard proton spectrum (with spectral index ≈1.8), while usual observations and numerical simulations prefer a soft proton spectrum (with spectral index ≥2). In this paper, we explore an alternative scenario to explain the γ-ray spectrum of G106.3+2.7 within the current understanding of acceleration and escape processes. We consider that cosmic ray particles are scattered by turbulence driven by Bell instabilities. The resulting hadronic γ-ray spectrum is novel, dominating the contribution to the emission above 10 TeV, and can explain the bizarre broadband spectrum of G106.3+2.7 in combination with leptonic emission from the remnant.

Keywords: supernova remnants; cosmic ray sources