adsabs/SciX_UAT_keywords huggingface dataset:
Pre-landing Assessment of the Surface and Shallow Subsurface Thermal Setting of Mare Crisium of the Moon for the Heat Flow Measurement Planned on the Blue Ghost 1 Mission

In 2024, under NASA's Commercial Lunar Payload Services initiative, a robotic lander will touch down in Mare Crisium of the Moon and deploy a heat flow probe. Ideally, the probe should penetrate the regolith deep enough (1.5-2 m) to avoid the influence of insolation, but it is a major challenge to excavate such a hole on a robotic mission. The present study assesses the insolation-induced temperature fluctuation in the shallower subsurface of the landing site in case the heat flow probe does not reach past that depth. The assessment was based on a newly constructed, one-dimensional heat conduction model, which accounted for the history of solar heat intake at the landing site for the past 100 yr. The thermal properties of the subsurface regolith of the model were constrained by the previous surface temperature observations by flyovers of NASA's Lunar Reconnaissance Orbiter and the subsurface thermal measurement data from Apollo 17. The model showed that the amplitude of the insolation-induced annual subsurface temperature fluctuation is modulated by the 18.6 yr period precession of the Moon. The model also showed that the amplitude of this annual wave would be at (or close to) its minimum in 2024, when the mission would take place. Even though the thermal wave may be felt at depths greater than 1.5 m, because of its small amplitude, the thermal gradient in the depth range from 1 to 1.5 m would be within several percent of the gradient representative of the endogenic heat flow.

Keywords: the moon
Probing the Physical Conditions and Star Formation Processes in the Galactic H II Region S305

We present multiscale and multiwavelength observations of the Galactic H II region S305, which is excited by massive O8.5V and O9.5V stars. Infrared images reveal an extended sphere-like shell (extension ∼7.5 pc; at Td = 17.5-27 K) enclosing the S305 H II region (size ∼5.5 pc; age ∼1.7 Myr). The extended structure observed in the Herschel temperature map indicates that the molecular environment of S305 is heated by the massive O-type stars. Regularly spaced molecular condensations and dust clumps are investigated toward the edges of the infrared shell, where the polycyclic aromatic hydrocarbon (PAH) and H2 emission is also observed. The molecular line data show a signature of an expanding shell of molecular gas in S305. Giant Metrewave Radio Telescope 610 and 1280 MHz continuum maps reveal overdensities of the ionized emission distributed around two O-type stars, which are surrounded by the horseshoe envelope (extension ∼2.3 pc). A molecular gas deficient region/cavity is identified toward the center of the horseshoe envelope, which is well traced with PAH, H2, molecular, and dust emission. The edges of the infrared shell are found to be located in the front of the horseshoe envelope. All these outcomes provide the observational evidence of the feedback of O-type stars in S305. Moreover, nonthermal radio emission is detected in S305 with an average spectral index α ∼ -0.45. The variations in α, ranging from -1.1 to 1.3, are explained due to soft synchrotron emission and either optically thicker thermal emission at high frequencies or a suppression of the low-frequency emission by the Razin-Tsytovich effect.

Keywords: h ii regions; extinction; star formation; interstellar medium; pre-main sequence stars
Comparative Spectral Analysis of the Superluminous Supernova 2019neq

We present a spectroscopic analysis of the recently discovered fast-evolving Type I superluminous supernova (SLSN-I) SN 2019neq (at redshift z = 0.1059). We compare it to the well-studied slowly evolving SLSN-I SN 2010kd (z = 0.101). Our main goal is to search for spectroscopic differences between the two groups of SLSNe-I. Differences in the spectra may reveal different ejecta compositions and explosion mechanisms. Our investigation concentrates on optical spectra observed with the 10 m Hobby-Eberly Telescope Low Resolution Spectrograph-2 at McDonald Observatory during the photospheric phase. We apply the SYN++ code to model the spectra of SN 2019neq taken at -4 days, +5 days, and +29 days from maximum light. We examine the chemical evolution and ejecta composition of the SLSN by identifying the elements and ionization states in its spectra. We find that a spectral model consisting of O III, Co III, and Si IV gives a SYN++ fit that is comparable to the typical SLSN-I spectral model consisting of O II, and conclude that the true identification of those lines, at least in the case of SN 2019neq, is ambiguous. Based on modeling the entire optical spectrum, we classify SN 2019neq as a fast-evolving SLSN-I having a photospheric velocity gradient of $\dot{v}\sim 375$ km s-1 day-1, which is among the highest velocity gradients observed for an SLSN-I. Inferring the velocity gradient from the proposed Fe II λ5169 feature alone would result in $\dot{v}\sim 100$ km s-1 day-1, which is still within the observed range of fast-evolving SLSNe-I. In addition, we derive the number density of relevant ionization states for a variety of identified elements at the epoch of the three observations. Finally, we give constraints on the lower limit of the ejecta mass and find that both SLSNe have an ejecta mass at least one order of magnitude higher than normal SNe Ia, while the fast-evolving SN 2019neq has an ejecta mass a factor of two lower than the slowly evolving SN 2010kd. These mass estimates suggest the existence of a possible correlation between the evolution timescale and the ejected mass of SLSNe-I.

Keywords: supernovae; core-collapse supernovae; ejecta; atomic spectroscopy; chemical abundances; astrochemistry
EDEN Survey: Small Transiting Planet Detection Limits and Constraints on the Occurrence Rates of Planets around Late-M Dwarfs within 15 pc

Earth-sized exoplanets that transit nearby, late-spectral-type red dwarfs will be prime targets for atmospheric characterization in the coming decade. Such systems, however, are difficult to find via widefield transit surveys like Kepler or TESS. Consequently, the presence of such transiting planets is unexplored and the occurrence rates of short-period Earth-sized planets around late-M dwarfs remain poorly constrained. Here, we present the deepest photometric monitoring campaign of 22 nearby late-M dwarf stars, using data from over 500 nights on seven 1-2 m class telescopes. Our survey includes all known single quiescent northern late-M dwarfs within 15 pc. We use transit injection-and-recovery tests to quantify the completeness of our survey, successfully identify most (>80%) transiting short-period (0.5-1 days) super-Earths (R >1.9 R ⊕), and are sensitive (~50%) to transiting Earth-sized planets (1.0-1.2 R ⊕). Our high sensitivity to transits with a near-zero false-positive rate demonstrates an efficient survey strategy. Our survey does not yield a transiting planet detection, yet it provides the most sensitive upper limits on transiting planets orbiting our target stars. Finally, we explore multiple hypotheses about the occurrence rates of short-period planets (from Earth-sized planets to giant planets) around late-M dwarfs. We show, for example, that giant planets with short periods (<1 day) are uncommon around our target stars. Our data set provides some insight into the occurrence rates of short-period planets around TRAPPIST-1-like stars, and our results can help test planetary formation and system evolution models, as well as guide future observations of nearby late-M dwarfs.

Keywords: exoplanets; surveys; stellar photometry; ground-based astronomy
The Solar Neighborhood. XLVII. Comparing M-dwarf Models with Hubble Space Telescope Dynamical Masses and Spectroscopy

We use HST/STIS optical spectroscopy of 10 M dwarfs in five closely separated binary systems to test models of M-dwarf structure and evolution. Individual dynamical masses ranging from 0.083 to 0.405 M⊙ for all stars are known from previous work. We first derive temperature, radius, luminosity, surface gravity, and metallicity by fitting the BT-Settl atmospheric models. We verify that our methodology agrees with empirical results from long-baseline optical interferometry for stars of similar spectral types. We then test whether or not evolutionary models can predict those quantities given the stars' known dynamical masses and the conditions of coevality and equal metallicity within each binary system. We apply this test to five different evolutionary model sets: the Dartmouth models, the MESA/MIST models, the models of Baraffe et al., the PARSEC models, and the YaPSI models. We find marginal agreement between evolutionary model predictions and observations, with few cases where the models respect the condition of coevality in a self-consistent manner. We discuss the pros and cons of each family of models and compare their predictive power. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program no. 12938.

Keywords: m dwarf stars; astrometric binary stars; stellar interiors; stellar evolutionary models; stellar atmospheres; stellar masses
Confirmation of a Second Propeller: A High-inclination Twin of AE Aquarii

For decades, AE Aquarii (AE Aqr) has been the only cataclysmic variable star known to contain a magnetic propeller: a persistent outflow whose expulsion from the binary is powered by the spin-down of the rapidly rotating, magnetized white dwarf. In 2020, LAMOST J024048.51+195226.9 (J0240) was identified as a candidate eclipsing AE Aqr object, and we present three epochs of time-series spectroscopy that strongly support this hypothesis. We show that, during the photometric flares noted by Thorstensen, the Balmer and He I emission lines reach velocities of ~3000 km s-1, well in excess of what is observed in normal cataclysmic variables. This is, however, consistent with the high-velocity emission seen in flares from AE Aqr. Additionally, we confirm beyond doubt that J0240 is a deeply eclipsing system. The flaring continuum, He I and much of the Balmer emission likely originate close to the WD because they disappear during the eclipse that is centered on inferior conjunction of the secondary star. The fraction of the Balmer emission remaining visible during eclipse is likely produced in the extended outflow. Most enticingly of all, this outflow produces a narrow P Cygni absorption component for nearly half of the orbit, and we demonstrate that this scenario closely matches the outflow kinematics predicted by Wynn et al. While an important piece of evidence for the magnetic-propeller hypothesis-a rapid WD spin period-remains elusive, our spectra provide compelling support for the existence of a propeller-driven outflow viewed nearly edge-on, enabling a new means of rigorously testing theories of the propeller phenomenon.

Keywords: cataclysmic variable stars; magnetic stars; white dwarf stars; dq herculis stars
Prediction of the In Situ Coronal Mass Ejection Rate for Solar Cycle 25: Implications for Parker Solar Probe In Situ Observations

The Parker Solar Probe (PSP) and Solar Orbiter missions are designed to make groundbreaking observations of the Sun and interplanetary space within this decade. We show that a particularly interesting in situ observation of an interplanetary coronal mass ejection (ICME) by PSP may arise during close solar flybys (<0.1 au). During these times, the same magnetic flux rope inside an ICME could be observed in situ by PSP twice, by impacting its frontal part as well as its leg. Investigating the odds of this situation, we forecast the ICME rate in solar cycle 25 based on two models for the sunspot number (SSN): (1) the forecast of an expert panel in 2019 (maximum SSN = 115), and (2) a prediction by McIntosh et al. (2020, maximum SSN = 232). We link the SSN to the observed ICME rates in solar cycles 23 and 24 with the Richardson and Cane list and our own ICME catalog, and calculate that between one and seven ICMEs will be observed by PSP at heliocentric distances <0.1 au until 2025, including 1σ uncertainties. We then model the potential flux rope signatures of such a double-crossing event with the semiempirical 3DCORE flux rope model, showing a telltale elevation of the radial magnetic field component BR, and a sign reversal in the component BN normal to the solar equator compared to field rotation in the first encounter. This holds considerable promise to determine the structure of CMEs close to their origin in the solar corona.

Keywords: solar coronal mass ejections; solar storm; ejecta; space weather; solar system; solar wind; solar physics; interplanetary magnetic fields; solar magnetic fields
Evidence for Thermal X-Ray Emission from the Synchrotron-dominated Shocks in Tycho's Supernova Remnant

Young supernova remnant (SNR) shocks are believed to be the main sites of galactic cosmic-ray production, showing X-ray synchrotron-dominated spectra in the vicinity of their shock. While a faint thermal signature left by the shocked interstellar medium (ISM) should also be found in the spectra, proofs for such an emission in Tycho's SNR have been lacking. We perform an extended statistical analysis of the X-ray spectra of five regions behind the blast wave of Tycho's SNR using Chandra archival data. We use Bayesian inference to perform extended parameter space exploration and sample the posterior distributions of a variety of models of interest. According to Bayes factors, spectra of all five regions of analysis are best described by composite three-component models taking nonthermal emission, ejecta emission, and shocked ISM emission into account. The shocked ISM stands out the most in the northern limb of the SNR. We find for the shocked ISM a mean electron temperature ${{kT}}_{{\rm{e}}}={0.96}_{-0.51}^{+1.33}$ keV for all regions and a mean ionization timescale ${n}_{{\rm{e}}}t={2.55}_{-1.22}^{+0.5}\times {10}^{9}$ cm-3 s resulting in a mean ambient density ${n}_{{\rm{e}}}={0.32}_{-0.15}^{+0.23}$ cm-3 around the remnant. We performed an extended analysis of the northern limb and show that the measured synchrotron cutoff energy is not well constrained in the presence of a shocked ISM component. Such results cannot currently be further investigated by analyzing emission lines in the 0.5-1 keV range, because of the low Chandra spectral resolution in this band. We show with simulated spectra that Athena X-ray Integral Field Unit future performances will be crucial to address this point.

Keywords: supernova remnants; interstellar medium; bayesian statistics; posterior distribution; spectroscopy
Evidence for the Disruption of a Planetary System During the Formation of the Helix Nebula

The persistence of planetary systems after their host stars evolve into their post-main-sequence phase is poorly constrained by observations. Many young white dwarf systems exhibit infrared excess emission and/or spectral absorption lines associated with a reservoir of dust (or planetesimals) and its accretion. However, most white dwarfs are too cool to sufficiently heat any circumstellar dust to detectable levels of emission. The Helix Nebula (NGC 7293) is a young, nearby planetary nebula; observations at mid- and far-infrared wavelengths have revealed excess emission associated with its central white dwarf (WD 2226-210). The origin of this excess is ambiguous. It could be a remnant planetesimal belt, a cloud of comets, or the remnants of material shed during the post-asymptotic giant branch (post-AGB) phase. Here we combine infrared (Stratospheric Observatory for Infrared Astronomy, Spitzer, Herschel) and millimeter (Atacama Large Millimeter/submillimeter Array) observations of the system to determine the origin of this excess using multiwavelength imaging and radiative transfer modeling. We find the data are incompatible with a compact remnant planetesimal belt or post-AGB disk, and conclude the dust most likely originates from deposition by a cometary cloud. The measured dust mass, and lifetime of the constituent grains, implies disruption of several thousand Hale-Bopp equivalent comets per year to fuel the observed excess emission around the Helix Nebula's white dwarf.

Keywords: white dwarf stars; circumstellar disks; infrared excess
Simulating JWST/NIRCam Color Selection of High-redshift Galaxies

The Near Infrared Camera (NIRCam) instrument on the upcoming James Webb Space Telescope will offer an unprecedented view of the most distant galaxies. In preparation for future deep NIRCam extragalactic surveys, it is crucial to understand the color selection of high-redshift galaxies using the Lyman dropout technique. To that end, we have used the JAdes extraGalactic Ultradeep Artificial Realizations mock catalog to simulate a series of extragalactic surveys with realistic noise estimates. This enables us to explore different color selections and their impact on the number density of recovered high-redshift galaxies and lower-redshift interlopers. We explore how survey depth, detection signal-to-noise ratio, color selection method, detection filter choice, and the presence of the Lyα emission line affects the resulting dropout selected samples. We find that redder selection colors reduce the number of recovered high-redshift galaxies, but the overall accuracy of the final sample is higher. In addition, we find that methods that utilize two or three color cuts have higher accuracy because of their ability to select against low-redshift quiescent and faint dusty interloper galaxies. We also explore the near-IR colors of brown dwarfs and demonstrate that, while they are predicted to have low on-sky densities, they are most likely to be recovered in F090W dropout selection, but there are color cuts that help to mitigate this contamination. Overall, our results provide NIRCam selection methods to aid in the creation of large, pure samples of ultra-high-redshift galaxies from photometry alone.

Keywords: high-redshift galaxies; galaxy colors
The Timing of Potential Last Nucleosynthetic Injections into the Protosolar Molecular Cloud Inferred from 41Ca-26Al Systematics of Bulk CAIs

Short-lived radionuclides (SLRs) provide important information about the chronology of the early solar system. Among them, 41Ca, due to its decay to 41K with a half-life of only 0.1 Ma, is particularly valuable in constraining the timescales and origins of both SLRs and the formation of the oldest solar system materials, the Ca-Al-rich inclusions (CAIs). The initial abundance of 41Ca in the solar system, expressed as the (41Ca/40Ca)I ratio, is the key to unveiling the origin of this nuclide. Here, we report a new solar system (41Ca/40Ca)I ratio of 2.0 × 10-8 derived from the K isotope compositions of two CAIs. This new ratio is about four times higher than the previous value inferred from a mineral isochron. Such a high (41Ca/40Ca)I ratio in the CAIs exceeds that expected for the protosolar molecular cloud by ~1000×, implying very late injection of the 41Ca (and possibly other SLRs) into the protosolar molecular cloud. The correlated enrichments of 41Ca and 26Al in the bulk CAI samples hint at a common stellar origin of both SLRs. The injection time estimated from our new data depends on the stellar source-it ranges from 0.6 Ma for a Wolf-Rayet wind to 1.0 Ma for a TP-AGB star ejecta.

Keywords: cosmochemistry; nucleosynthesis; solar system
DESI Survey Validation Spectra Reveal an Increasing Fraction of Recently Quenched Galaxies at z 1

We utilize ~17,000 bright luminous red galaxies (LRGs) from the novel Dark Energy Spectroscopic Instrument Survey Validation spectroscopic sample, leveraging its deep (~2.5 hr galaxy-1 exposure time) spectra to characterize the contribution of recently quenched galaxies to the massive galaxy population at 0.4 < z < 1.3. We use Prospector to infer nonparametric star formation histories and identify a significant population of recently quenched galaxies that have joined the quiescent population within the past ~1 Gyr. The highest-redshift subset (277 at z > 1) of our sample of recently quenched galaxies represents the largest spectroscopic sample of post-starburst galaxies at that epoch. At 0.4 < z < 0.8, we measure the number density of quiescent LRGs, finding that recently quenched galaxies constitute a growing fraction of the massive galaxy population with increasing look-back time. Finally, we quantify the importance of this population among massive ( $\mathrm{log}({M}_{\star }/{M}_{\odot })$ > 11.2) LRGs by measuring the fraction of stellar mass each galaxy formed in the gigayear before observation, f 1 Gyr. Although galaxies with f 1 Gyr > 0.1 are rare at z ~ 0.4 (≲0.5% of the population), by z ~ 0.8, they constitute ~3% of massive galaxies. Relaxing this threshold, we find that galaxies with f 1 Gyr > 5% constitute ~10% of the massive galaxy population at z ~ 0.8. We also identify a small but significant sample of galaxies at z = 1.1-1.3 that formed with f 1 Gyr > 50%, implying that they may be analogs to high-redshift quiescent galaxies that formed on similar timescales. Future analysis of this unprecedented sample promises to illuminate the physical mechanisms that drive the quenching of massive galaxies after cosmic noon.

Keywords: post-starburst galaxies; galaxies; e+a galaxies; galaxy quenching; quenched galaxies; galaxy spectroscopy; redshift surveys
Serverless Architecture for Data Processing and Detecting Anomalies with the Mars Express MARSIS Instrument

The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express has been sampling the topside ionosphere of Mars since mid-2005. The analysis of the main reflection (nadir) of the ionosphere through the ionograms provided by the MARSIS instrument is typically performed manually due to the high noise level in the lower frequencies. This task, which involves pattern recognition, turns out to be unfeasible for the >2 million ionograms available at the European Planetary Science Archive. In the present contribution, we propose a modular architecture based on serverless computing (a paradigm that stands on the cloud) for optimal processing of these ionograms. In particular, we apply serverless computing to detect oblique echoes in the ionosphere, which are nonnadir reflections produced when MARSIS is sounding regions above or nearby crustal magnetic fields, where the ionosphere loses the spherical symmetry. Oblique echoes are typically observed at similar frequencies to the nadir reflections but at different times delays, sometimes even overlaying the nadir reflection. Oblique echoes are difficult to analyze with the standard technique due to their nonconstant and highly variable appearance, but they harbor essential information on the state of the ionosphere over magnetized regions. In this work we compare the proposed serverless architecture with two local alternatives while processing a representative data subset and finally provide a study by means of cost and performance.

Keywords: mars; planetary ionospheres