Sazuna/UAT_keywords huggingface dataset:
A Stellar Mass Dependence of Structured Disks: A Possible Link with Exoplanet Demographics. Gaps in protoplanetary disks have long been hailed as signposts of planet formation. However, a direct link between exoplanets and disks remains hard to identify. We present a large sample study of ALMA disk surveys of nearby star-forming regions to disentangle this connection. All disks are classified as either structured (transition, ring, extended) or nonstructured (compact) disks. Although low-resolution observations may not identify large-scale substructure, we assume that an extended disk must contain substructure from a dust evolution argument. A comparison across ages reveals that structured disks retain high dustmasses up to at least 10 Myr, whereas the dustmass of compact, nonstructured disks decreases over time. This can be understood if the dustmass evolves primarily by radial drift, unless drift is prevented by pressure bumps. We identify a stellarmass dependence of the fraction of structured disks. We propose a scenario linking this dependence with that of giant exoplanet occurrence rates. We show that there are enough exoplanets to account for the observed disk structures if transitional disks are created by exoplanets more massive than Jupiter and ring disks by exoplanets more massive than Neptune, under the assumption that most of those planets eventually migrate inwards. On the other hand, the known anticorrelation between transiting super-Earths and stellarmass implies those planets must form in the disks without observed structure, consistent with formation through pebble accretion in drift-dominated disks. These findings support an evolutionary scenario where the early formation of giant planets determines the disks dust evolution and its observational appearance.

Keywords: Exoplanets, Protoplanetary disks, Planet formation
Evaluating the Thickness and Stratigraphy of Ejecta Materials at the Change-4 Landing Site. The landing site of Chinas Change-4 (CE-4) probe is located on the mare basalts on the floor of the Von Krmn crater on the lunar far side. The Von Krmn crater is inside the ancient and highly cratered South PoleAitken basin, which has experienced complex emplacement sequences of both near and distant ejecta materials. These issues complicated the interpretation of the CE-4 surface in situ measurements of the visible and near-infrared spectrometer and the lunar penetrating radar (LPR) onboard Yutu-2 rover. To evaluate the sources and amounts of all principle foreign materials at the CE-4 landing site, we thoroughly examine the ejecta delivered by crater-forming events that occurred later than the formation of the mare basalts at the CE-4 landing site. We found a total of 16 craters that may have delivered ejecta thicker than 10 cm level superposed on the mare basalts at the CE-4 landing site. Crater Finsen, Von Krmn L, Von Krmn L, and Maksutov are the top four major foreign material sources, and each of them contributed ejecta thicker than 1 m. Our surveys confirm that the ejecta from Finsen crater are the most dominant foreign materials in the uppermost few meters at the CE-4 landing site and the total impact ejecta deposited upon the mare basalts at the landing site is estimated to be thinner than 30 m. We found that the estimations from Pikes model are the most consistent with the Yutu-2 LPR observations.

Keywords: Lunar craters, The Moon
Simulating Reflected Light Exoplanet Spectra of the Promising Direct Imaging Target, Andromedae d, with a New, Fast Sampling Method Using the Planetary Spectrum Generator. Simulations of exoplanet albedo profiles are key to planning and interpreting future direct imaging observations. In this paper we demonstrate the use of the Planetary Spectrum Generator (PSG) to produce simulations of reflected light exoplanet spectra. We use PSG to examine multiple issues relevant to all models of directly imaged exoplanet spectra and to produce sample spectra of the bright, nearby exoplanet Andromedae d ( And d), a potential direct imaging target for next-generation facilities. We introduce a new, fast, and accurate subsampling technique that enables calculations of disk-integrated spectra one order of magnitude faster than ChebyshevGauss sampling for moderate- to high-resolution sampling. Using this method and a first-principles-derived atmosphere for And d, we simulate phase-dependent spectra for a variety of different potential atmospheric configurations. The simulated spectra for And d include versions with different haze and cloud properties. Based on our combined analysis of this planets orbital parameters, phase- and illumination-appropriate model spectra, and realistic instrument noise parameters, we find that And d is a potentially favorable direct imaging and spectroscopy target for the Coronagraph Instrument (CGI) on the Nancy Grace Roman Space Telescope. When a noise model corresponding to the Roman CGI SPC spectroscopy mode is included, PSG predicts the time required to reach a signal-to-noise ratio of 10 of the simulated spectra in both the central wavelength bin of the Roman CGI SPC spectroscopy mode (R 50 spectrum) and of the Band 1 HLC imaging mode is approximately 400 and less than 40 hr, respectively. We also discuss potential pathways to extricating information about the planet and its atmosphere with future observations and find that Roman observations may be able to bound the interior temperature of the planet.

Keywords: Observational astronomy, Exoplanets, Coronagraphic imaging, Direct imaging, Radiative transfer, Space telescopes, Radiative transfer simulations, Habitable zone, Metallicity, Exoplanet atmospheres
NGC 6845 Revisited: Stellar Kinematics on the Early Type Member Galaxies. We observed the compact group of galaxies NGC 6845 with GMOS-S imaging and long-slit spectroscopy. The group itself is comprised of two spiral galaxies and two S0 galaxies, and shows signs of gravitational interaction among them. While the spiral galaxies have been already well studied, the two S0 galaxies have received little attention. We investigate the morphology and stellar kinematics of the two S0 galaxies in detail in order to derive the value for their mass and subsequently incorporate them into the mass model for the group. It was found that the internal kinematics of the largest S0 (NGC 6845 C) is mostly regular, while the smallest S0 (NGC 6845 D) shows some hint of interaction, most likely with NGC 6845 C and NGC 6845 A. The new determination of the dynamical mass of the group implies that the group mass has to be 10 times the combined mass of the individual members according to their internal kinematics. The results point to an early stage of the group interaction and also to the possibility that it has still not reached virial equilibrium. From the galaxy evolution viewpoint, this group represents an example of the case of the transformation of Spirals into S0 galaxies in dense environments.

Keywords: Galaxy groups, Galactic and extragalactic astronomy
Rotational Velocities of Am and Non-chemical-peculiar Stars Based on Kepler and LAMOST DR5. Rotation is a critical physical process operating in the formation of Am stars. There is a strong correlation between low-velocity rotation and chemical peculiarity. However, the existence of many non-chemical-peculiar slow rotators challenges the understanding of Am stars. The purpose of our work is to search for low-velocity rotating non-chemical-peculiar A-type stars and Am stars and to make a comparative analysis. In this paper, we pick out a sample from the LAMOST-Kepler project, including 21 Am stars, 125 non-chemical-peculiar slow rotators, and 53 non-chemical-peculiar fast rotators. We calculate the rotational frequencies through a periodic change of light curves caused by inhomogeneous stellar surfaces and then obtain the rotational velocities. For slow rotators, the age of Am stars is statistically younger than that of non-chemical-peculiar stars in the same temperature bin. In the comparison of the period, the average amplitude, and stellar mass of Am and non-chemical-peculiar stars, we discover that there is no difference in the photometric variability between Am and non-chemical-peculiar stars, which implies similar inhomogeneities on the surfaces. The average amplitude of non-chemical-peculiar stars has a downward trend with the increase of effective temperature and stellar mass, which is consistent with the theoretical prediction caused by weak dynamo-generated magnetic fields in A-type stars. In addition, we confirm four non-chemical-peculiar stars that have flares by checking field-of-view images, pixel images, and pixel-level light curves.

Keywords: Chemically peculiar stars
The Breakthrough Listen Search For Intelligent Life Near the Galactic Center. I.. A line of sight toward the Galactic Center (GC) offers the largest number of potentially habitable systems of any direction in the sky. The Breakthrough Listen program is undertaking the most sensitive and deepest targeted SETI surveys toward the GC. Here, we outline our observing strategies with Robert C. Byrd Green Bank Telescope (GBT) and Parkes telescope to conduct 600 hr of deep observations across 0.7-93 GHz. We report preliminary results from our survey for extraterrestrial intelligence (ETI) beacons across 1-8 GHz with 7.0 and 11.2 hr of observations with Parkes and GBT, respectively. With our narrowband drifting signal search, we were able to place meaningful constraints on ETI transmitters across 1-4 GHz and 3.9-8 GHz with EIRP limits of ≥4 × 1018 W among 60 million stars and ≥5 × 1017 W among half a million stars, respectively. For the first time, we were able to constrain the existence of artificially dispersed transient signals across 3.9-8 GHz with EIRP ≥1 × 1014 W/Hz with a repetition period ≤4.3 hr. We also searched our 11.2 hr of deep observations of the GC and its surrounding region for Fast Radio Burst-like magnetars with the DM up to 5000 pc cm-3 with maximum pulse widths up to 90 ms at 6 GHz. We detected several hundred transient bursts from SGR J1745-2900, but did not detect any new transient bursts with the peak luminosity limit across our observed band of ≥1031 erg s-1 and burst rate of ≥0.23 burst hr-1. These limits are comparable to bright transient emission seen from other Galactic radio-loud magnetars, constraining their presence at the GC.

Keywords: Neutron stars, Galactic center, Technosignatures, Magnetars, Search for extraterrestrial intelligence, Radio transient sources
ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b. We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b ( ${T}_{\mathrm{eq}}=2484$ K). Our transmission spectrum is the result of combining five new transits from the ACCESS survey and two new transits from the LRG-BEASTS survey with a reanalysis of three archival Gemini/GMOS transits and one VLT/FORS2 transit. Our combined 11-transit transmission spectrum covers a wavelength range of 3900-9450 Å with a median uncertainty in the transit depth of 148 parts per million, which is less than one atmospheric scale height of the planet. In our retrieval analysis of WASP-103b's combined optical and infrared transmission spectrum, we find strong evidence for unocculted bright regions (4.3σ) and weak evidence for H2O ( $1.9\sigma $ ), HCN ( $1.7\sigma $ ), and TiO ( $2.1\sigma $ ), which could be responsible for WASP-103b's observed temperature inversion. Our optical transmission spectrum shows significant structure that is in excellent agreement with the extensively studied ultrahot Jupiter WASP-121b, for which the presence of VO has been inferred. For WASP-103b, we find that VO can only provide a reasonable fit to the data if its abundance is implausibly high and we do not account for stellar activity. Our results highlight the precision that can be achieved by ground-based observations and the impacts that stellar activity from F-type stars can have on the interpretation of exoplanet transmission spectra.

Keywords: Exoplanet atmospheric composition , Hot Jupiters, Exoplanet astronomy, Planet hosting stars, Extrasolar gaseous giant planets, Exoplanet atmospheres
The Global Magneto-ionic Medium Survey: A Faraday Depth Survey of the Northern Sky Covering 1280-1750 MHz. The Galactic interstellar medium hosts a significant magnetic field, which can be probed through the synchrotron emission produced from its interaction with relativistic electrons. Linearly polarized synchrotron emission is generated throughout the Galaxy and, at longer wavelengths, modified along nearly every path by Faraday rotation in the intervening magneto-ionic medium. Full characterization of the polarized emission requires wideband observations with many frequency channels. We have surveyed polarized radio emission from the Northern sky over the range 1280-1750 MHz, with channel width 236.8 kHz, using the John A. Galt Telescope (diameter 25.6 m) at the Dominion Radio Astrophysical Observatory, as part of the Global Magneto-Ionic Medium Survey. The survey covered 72% of the sky, decl. -30° to +87° at all R.A. The intensity scale was absolutely calibrated, based on the flux density and spectral index of Cygnus A. Polarization angle was calibrated using the extended polarized emission of the Fan Region. Data are presented as brightness temperatures with angular resolution 40'. Sensitivity in Stokes Q and U is 45 mK rms in a 1.18 MHz band. We have applied rotation measure synthesis to the data to obtain a Faraday depth cube of resolution 150 rad m-2 and sensitivity 3 mK rms of polarized intensity. Features in Faraday depth up to a width of 110 rad m-2 are represented. The maximum detectable Faraday depth is ±2 × 104 rad m-2. The survey data are available at the Canadian Astronomy Data Centre.

Keywords: Spectropolarimetry, Milky Way magnetic fields, Interstellar magnetic fields, Calibration, Radio telescopes, Polarimeters, Polarimetry
Trends in Spitzer Secondary Eclipses. It is well established that the magnitude of the incident stellar flux is the single most important factor in determining the day-night temperature gradients and atmospheric chemistries of short-period gas giant planets. However, it is likely that other factors, such as planet-to-planet variations in atmospheric metallicity, C/O ratio, and cloud properties, also contribute to the observed diversity of infrared spectra for this population of planets. In this study, we present new 3.6 and 4.5 μm secondary eclipse measurements for five transiting gas giant planets: HAT-P-5b, HAT-P-38b, WASP-7b, WASP-72b, and WASP-127b. We detect eclipses in at least one bandpass for all five planets and confirm circular orbits for all planets except WASP-7b, which shows evidence for a nonzero eccentricity. Building on the work of Garhart et al., we place these new planets into a broader context by comparing them with the sample of all planets with measured Spitzer secondary eclipses. We find that incident flux is the single most important factor for determining the atmospheric chemistry and circulation patterns of short-period gas giant planets. Although we might also expect surface gravity and host star metallicity to play a secondary role, we find no evidence for correlations with either of these two variables.

Keywords: Exoplanet atmospheric composition , Exoplanets, Exoplanet atmospheres, Broad band photometry, Infrared photometry
Disequilibrium Chemistry in Exoplanet Atmospheres Observed with the Hubble Space Telescope. Literature on the theory of exoplanet atmospheric disequilibrium chemistry is rich, although its observational counterpart has yet to emerge beyond the hints provided by a few targets in dedicated studies. We report results from an uniform data reduction and analysis for a catalog of 62 Hubble Space Telescope exoplanet transit spectra where we assess the atmospheric model preference for disequilibrium chemistry (i.e., water vapor is not the dominant absorption spectral signature) over thermal equilibrium chemistry in a comparative planetology context. Where model preference assessment is possible, we find that disequilibrium occurs in about half of the atmospheres, indicating that disequilibrium processes play an important role in the composition of exoplanet atmospheres. While very hot atmospheres, over 1800 K, prefer equilibrium chemistry, we find a clustering of preference for disequilibrium in the 1200-1800 K temperature range. We suggest that UV-augmented thermochemistry may play a significant role for those atmospheres.

Keywords: Hubble Space Telescope, Exoplanet atmospheres
Validation of the EDGES Low-band Antenna Beam Model. The response of the antenna is a source of uncertainty in measurements with the Experiment to Detect the Global Epoch of Reionization Signature (EDGES). We aim to validate the electromagnetic beam model of the low-band (50-100 MHz) dipole antenna with comparisons between models and against data. We find that simulations of a simplified model of the antenna over an infinite perfectly conducting ground plane are, with one exception, robust to changes in the numerical electromagnetic solver code or algorithm. For simulations of the antenna with the actual finite ground plane and realistic soil properties, we find that two out of three numerical solvers agree well. Applying our analysis pipeline to a simulated drift-scan observation from an early EDGES low-band instrument that had a 10 m × 10 m ground plane, we find residual levels after fitting and removing a five-term foreground model from the simulated data binned in local sidereal time (LST) average about 250 mK with ±40 mK variation between numerical solvers. A similar analysis of the primary 30 m × 30 m sawtooth ground plane reduced the LST-averaged residuals to about 90 mK with ±10 mK between the two viable solvers. More broadly we show that larger ground planes generally perform better than smaller ground planes. Simulated data have a power that is within 4% of real observations, a limitation of net accuracy of the sky and beam models. We observe that residual spectral structures after foreground model fits match qualitatively between simulated data and observations, suggesting that the frequency dependence of the beam is reasonably represented by the models. We find that a soil conductivity of 0.02 S m-1 and relative permittivity of 3.5 yield good agreement between simulated spectra and observations. This is consistent with the soil properties reported by Sutinjo et al. for the Murchison Radio-astronomy Observatory, where EDGES is located.

Keywords: Observational astronomy, Cosmology, Early universe, Bianchi cosmology, Neutral hydrogen clouds, Radio telescopes, Single-dish antennas, Astronomical instrumentation, Reionization, Radio astronomy
Outer Solar System Perihelion Gap Formation through Interactions with a Hypothetical Distant Giant Planet. Among the outer solar system minor planet orbits there is an observed gap in perihelion between roughly 50 and 65 au at eccentricities e ≳ 0.65. Through a suite of observational simulations, we show that the gap arises from two separate populations, the Extreme Trans-Neptunian Objects (ETNOs; perihelia q ≳ 40 au and semimajor axes a ≳ 150 au) and the Inner Oort Cloud objects (IOCs; q ≳ 65 au and a ≳ 250 au), and is very unlikely to result from a realistic single, continuous distribution of objects. We also explore the connection between the perihelion gap and a hypothetical distant giant planet, often referred to as Planet 9 or Planet X, using dynamical simulations. Some simulations containing Planet X produce the ETNOs, the IOCs, and the perihelion gap from a simple Kuiper-Belt-like initial particle distribution over the age of the solar system. The gap forms as particles scattered to high eccentricity by Neptune are captured into secular resonances with Planet X where they cross the gap and oscillate in perihelion and eccentricity over hundreds of kiloyears. Many of these objects reach a minimum perihelia in their oscillation cycle within the IOC region increasing the mean residence time of the IOC region by a factor of approximately five over the gap region. Our findings imply that, in the presence of a massive external perturber, objects within the perihelion gap will be discovered, but that they will be only ~20% as numerous as the nearby IOC population (65 au ≲ q ≲ 100 au).

Keywords: Planetary theory, Celestial mechanics, Detached objects, Solar system astronomy, Trans-Neptunian objects, Oort cloud objects
Thermophysical Modeling of 20 Themis Family Asteroids with WISE/NEOWISE Observations. Themis family is one of the largest and oldest asteroid populations in the main belt. Water ice may widely exist on the parent body (24) Themis. In this work, we employ the Advanced Thermophysical Model as well as midinfrared measurements from NASA's Wide-field Infrared Survey Explorer to explore thermal parameters of 20 Themis family members. Here we show that the average thermal inertia and geometric albedo are 39.5 ± 26.0 J m-2 s-1/2 K-1 and 0.067 ± 0.018, respectively. The family members have a relatively moderate roughness fraction on their surfaces. We find that the relatively low albedos of Themis members are consistent with the typical values of B-type and C-type asteroids. As mentioned, the Themis family bears a very low thermal inertia, which indicates a fine and mature regolith on their surfaces. The resemblance of thermal inertia and geometric albedo of Themis members may reveal their close connection in origin and evolution. In addition, we present the compared results of thermal parameters for several prominent families.

Keywords: Asteroid belt, Main belt asteroids
Speckle Interferometry at SOAR in 2020. The results of speckle interferometric observations at the 4.1 m Southern Astrophysical Research Telescope in 2020, as well as earlier unpublished data, are given, totaling 1735 measurements of 1288 resolved pairs and nonresolutions of 1177 targets. We resolved for the first time 59 new pairs or subsystems in known binaries, mostly among nearby dwarf stars. This work continues our long-term speckle program. Its main goal is to monitor orbital motion of close binaries, including members of high-order hierarchies and Hipparcos pairs in the solar neighborhood. We also report observations of 892 members of young moving groups and associations, where we resolved 103 new pairs.

Keywords: Multiple stars, Binary stars, Stellar associations