adsabs/SciX_UAT_keywords huggingface dataset:
Connecting the Light Curves of Type IIP Supernovae to the Properties of Their Progenitors

Observations of core-collapse supernovae (CCSNe) reveal a wealth of information about the dynamics of the supernova ejecta and its composition but very little direct information about the progenitor. Constraining properties of the progenitor and the explosion requires coupling the observations with a theoretical model of the explosion. Here we begin with the CCSN simulations of Couch et al., which use a nonparametric treatment of the neutrino transport while also accounting for turbulence and convection. In this work we use the SuperNova Explosion Code to evolve the CCSN hydrodynamics to later times and compute bolometric light curves. Focusing on Type IIP SNe (SNe IIP), we then (1) directly compare the theoretical STIR explosions to observations and (2) assess how properties of the progenitor's core can be estimated from optical photometry in the plateau phase alone. First, the distribution of plateau luminosities (L 50) and ejecta velocities achieved by our simulations is similar to the observed distributions. Second, we fit our models to the light curves and velocity evolution of some well-observed SNe. Third, we recover well-known correlations, as well as the difficulty of connecting any one SN property to zero-age main-sequence mass. Finally, we show that there is a usable, linear correlation between iron core mass and L 50 such that optical photometry alone of SNe IIP can give us insights into the cores of massive stars. Illustrating this by application to a few SNe, we find iron core masses of 1.3-1.5 M ⊙ with typical errors of 0.05 M ⊙. Data are publicly available online on Zenodo: doi:10.5281/zenodo.6631964.

Keywords: core-collapse supernovae; type ii supernovae; computational methods; hydrodynamical simulations; supernova neutrinos; supernova dynamics; radiative transfer
From Super-Earths to Mini-Neptunes: Implications of a Surface on Atmospheric Circulation

It is well known that planets with radii between that of Earth and Neptune have been the most commonly detected to date. To classify these planets as either terrestrial or gaseous, typically we turn to mass-radius relations and composition curves to determine the likelihood of such a planet being rocky or gaseous. While these methods have set a likely transition radius of approximately 1.5 R⊕, we cannot expect that any change between terrestrial and gaseous compositions will be a sharp cutoff, and composition curve predictions result in ambiguous designations for planets right near this transition radius. In this work, we present 3D general circulation models (GCMs) of transition planets, wherein we study the effects of a surface on observable quantities such as the latitudinal variations and eclipse depths. We present our updated GCM, validated on the circulation of Earth, before discussing our modeling choices for this transition planet. Finally, we discuss the results of this study and explore the prospects of detecting the presence of a surface through observations of secondary eclipses in the future.

Keywords: exoplanet astronomy; exoplanet atmospheres; mini neptunes; exoplanet surfaces; super earths; extrasolar rocky planets
ALMA Observations of HCO+ and HCN Emission in the Massive Star-forming Region N55 of the Large Magellanic Cloud

We present the results of high spatial resolution HCO+(1-0) and HCN(1-0) observations of the N55 south region (N55-S) in the Large Magellanic Cloud (LMC), obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). N55-S is a relatively less extreme star-forming region of the LMC characterized by a low radiation field. We carried out a detailed analysis of the molecular emission to investigate the relation between dense molecular clumps and star formation in the quiescent environment of N55-S. We detect 10 molecular clumps with significant HCO+(1-0) emission and 8 with significant HCN(1-0) emission, and estimate the molecular clump masses by virial and local thermodynamic equilibrium analysis. All identified young stellar objects (YSOs) in N55-S are found to be near the HCO+ and HCN emission peaks showing the association of these clumps with recent star formation. The molecular clumps that have associated YSOs show relatively larger line widths and masses than those without YSOs. We compare the clump properties of N55-S with those of other giant molecular clouds (GMCs) in the LMC and find that N55-S clumps possess similar size but relatively lower line width and larger HCN/HCO+(1-0) flux ratio. These results can be attributed to the low radiation field in N55-S resulted by relatively low star formation activity compared to other active star-forming regions like 30 Doradus-10 and N159. The dense gas fraction of N55-S is ∼0.025, lower compared to other GMCs of the LMC supporting the low star formation efficiency of this region.

Keywords: star formation; large magellanic cloud; giant molecular clouds; young stellar objects; interstellar molecules
Evidence for the Late Arrival of Hot Jupiters in Systems with High Host-star Obliquities

It has been shown that hot Jupiters systems with massive, hot stellar primaries exhibit a wide range of stellar obliquities. On the other hand, hot Jupiter systems with low-mass, cool primaries often have stellar obliquities close to zero. Efficient tidal interactions between hot Jupiters and the convective envelopes present in lower-mass main-sequence stars have been a popular explanation for these observations. If this explanation is accurate, then aligned systems should be older than misaligned systems. Likewise, the convective envelope mass of a hot Jupiter's host star should be an effective predictor of its obliquity. We derive homogeneous stellar parameters-including convective envelope masses-for hot Jupiter host stars with high-quality sky-projected obliquity inferences. Using a thin-disk stellar population's Galactic velocity dispersion as a relative age proxy, we find that hot Jupiter host stars with larger-than-median obliquities are older than hot Jupiter host stars with smaller-than-median obliquities. The relative age difference between the two populations is larger for hot Jupiter host stars with smaller-than-median fractional convective envelope masses and is significant at the 3.6σ level. We identify stellar mass, not convective envelope mass, as the best predictor of stellar obliquity in hot Jupiter systems. The best explanation for these observations is that many hot Jupiters in misaligned systems arrived in the close proximity of their host stars long after their parent protoplanetary disks dissipated. The dependence of observed age offset on convective envelope mass suggests that tidal realignment contributes to the population of aligned hot Jupiters orbiting stars with convective envelopes.

Keywords: exoplanet dynamics; exoplanet tides; exoplanet evolution; exoplanet systems; exoplanets; stellar ages; stellar kinematics; tidal interaction; star-planet interactions
NGC 7538 IRS1—an O Star Driving an Ionized Jet and Giant N-S Outflow

NGC 7538 IRS 1 is a very young embedded O star driving an ionized jet and accreting mass with an accretion rate >10-4 ${M}_{\odot }$ yr-1, which is quenching the hypercompact H II region. We use SOFIA GREAT data, Herschel PACS and SPIRE archive data, SOFIA FORCAST archive data, Onsala 20 m and CARMA data, and JCMT archive data to determine the properties of the O star and its outflow. IRS 1 appears to be a single O star with a bolometric luminosity >1 × 105 ${L}_{\odot }$ , i.e., spectral type O7 or earlier. We find that IRS 1 drives a large molecular outflow with the blueshifted northern outflow lobe extending to ∼280″ or 3.6 pc from IRS 1. Near IRS 1 the outflow is well aligned with the ionized jet. The dynamical timescale of the outflow is ∼1.3 × 105 yr. The total outflow mass is ∼130 ${M}_{\odot }$ . We determine a mass outflow rate of 1.0 × 10-3 ${M}_{\odot }$ yr-1, roughly consistent with the observed mass accretion rate. We observe strong high-velocity [C II] emission in the outflow, confirming that strong UV radiation from IRS 1 escapes into the outflow lobes and is ionizing the gas. Many O stars may form like low-mass stars, but with a higher accretion rate and in a denser environment. As long as the accretion stays high enough to quench the H II region, the star will continue to grow. When the accretion rate drops, the H II region will rapidly start to expand.

Keywords: radio jets; compact h ii region; giant molecular clouds; star formation; o stars; stellar accretion; stellar accretion disks
On the Evolution of Supermassive Primordial Stars in Cosmological Flows

Primordial supermassive stars (SMSs) formed in atomic-cooling halos at z ~ 15-20 are leading candidates for the seeds of the first quasars. Past numerical studies of the evolution of SMSs have typically assumed constant accretion rates rather than the highly variable flows in which they form. We model the evolution of SMSs in the cosmological flows that create them using the Kepler stellar evolution and implicit hydrodynamics code. We find that they reach masses of 1 - 2 × 105 M⊙ before undergoing direct collapse to black holes (DCBHs) during or at the end of their main-sequence hydrogen burning, at 1-1.5 Myr, regardless of halo mass, spin, or merger history. We also find that realistic, highly variable accretion histories allow for a much greater diversity of supermassive stellar structures, including in some cases largely thermally relaxed objects, which may provide a significant source of radiative feedback. Our models indicate that the accretion histories predicted for purely atomic-cooling halos may impose a narrow spectrum of masses on the seeds of the first massive quasars; however, further studies incorporating realistic feedback will be essential in order to confirm whether or not this holds true in all cases. Our results also indicate that multiple SMSs at disparate stages of evolution can form in these halos, raising the possibility of SMS binaries and supermassive X-ray binaries, as well as DCBH mergers that could be detected by LISA.

Keywords: supermassive black holes; quasars; population iii stars; high-redshift galaxies; massive stars
Low-metallicity Galaxies from the Dark Energy Survey

We present a new selection of 358 blue compact dwarf galaxies (BCDs) from 5000 square degrees in the Dark Energy Survey, and the spectroscopic follow-up of a subsample of 68 objects. For the subsample of 34 objects with deep spectra, we measure the metallicity via the direct T e method using the auroral [O III]λ 4363 emission line. These BCDs have an average oxygen abundance of 12+log(O/H) = 7.8, with stellar masses between 107 and 108 M ⊙ and specific star-formation rates between ~10-9 and 10-7 yr-1. We compare the position of our BCDs with the mass-metallicity (M-Z) and luminosity-metallicity (L-Z) relation derived from the Local Volume Legacy sample. We find the scatter about the M-Z relation is smaller than the scatter about the L-Z relation. We identify a correlation between the offsets from the M-Z and L-Z relation that we suggest is due to the contribution of metal-poor inflows. Finally, we explore the validity of the mass-metallicity-SFR fundamental plane in the mass range probed by our galaxies. We find that BCDs with stellar masses smaller than 108 M ⊙ do not follow the extrapolation of the fundamental plane. This result suggests that mechanisms other than the balance between inflows and outflows may be at play in regulating the position of low-mass galaxies in the M-Z-SFR space.

Keywords: galaxy chemical evolution; dwarf galaxies; compact dwarf galaxies; scaling relations; galaxy properties; metallicity
Interstellar Cloud Conditions Based on 63 μm [O I] Emission and Absorption in W3

We investigate the origin of self-absorption in [O I] 63 μm line emission, which is very clearly seen in approximately half of the 12 Galactic giant molecular cloud (GMC)/H II regions observed. For this study, we observed velocity-resolved spectra of photon-dominated region (PDR) and H II region tracers, the [O I] 63 μm, [N II] 205 μm, and CO J = 5-4 and 8-7 lines, with the upGREAT instrument in the 4GREAT configuration on the NASA/DLR Stratospheric Observatory For Infrared Astronomy (SOFIA). To probe the origin of the [O I] absorption and line shape and what they tell us about the physical conditions, we focus on the W3 region, for which we obtained data for eight positions along a line near the H II region W3 A. We derive the foreground column density of low-excitation atomic oxygen to be in the range 2-7 × 1018 $\,{\mathrm{cm}}^{-2}$ . At the position of strongest [O I] emission and greatest absorbing column density, 24% of the oxygen in the PDR is in the form of low-excitation atomic oxygen. We employ the Meudon PDR code to study the chemical and thermal structure of the PDR and to understand the large column density of neutral oxygen throughout the PDR. The reduction in the integrated intensity of the [O I] 63 μm emission is a factor of ≃2-4 in directions with strong [O I] emission. The results from our sample, if general, would significantly impact the use of the [O I] 63 μm line as a tracer of massive star formation and could play a significant role in explaining the "63 μm [O I] deficit" seen in very luminous extragalactic sources.

Keywords: interstellar clouds; dark interstellar clouds; dense interstellar clouds
LHS 475 b: A Potential Venus Analog Orbiting a Nearby M Dwarf

Based on photometric observations by TESS, we present the discovery of a potential Venus analog transiting LHS 475, an M3 dwarf located 12.5 pc from the Sun. The mass of the star is 0.274 ± 0.015 M ☉. The planet, originally reported as TOI 910.01, has an orbital period of 2.0291010 ± 0.0000017 days and an estimated radius of 0.975 ± 0.058 R ⊕. We confirm the validity and source of the transit signal with MEarth and Las Cumbres Observatory Global Telescope ground-based follow-up photometry. We present radial velocity data from CHIRON that rule out massive companions. In accordance with the observed mass–radius distribution of exoplanets as well as planet formation theory, we expect this planetary companion to be terrestrial, with an estimated radial velocity semiamplitude of 1.1 m s‑1. LHS 475 b is likely too hot to be habitable but is a suitable candidate for emission and transmission spectroscopy.

Keywords: exoplanets; extrasolar rocky planets; transit photometry
A Catalog of High-velocity C IV Mini-broad Absorption Lines in the VLT-UVES and Keck-HIRES Archives

We present a catalog of high-velocity C IV λ1548,1551 mini-broad absorption lines (mini-BALs) in the archives of the Very Large Telescope-UV Visual Echelle Spectrograph and Keck-High Resolution Echelle Spectrometer. We identify C IV mini-BALs based on smooth rounded BAL-like profiles with velocity blueshifts <-4000 km s-1 and widths in the range 70 ≲ FWHM(1548) ≲ 2000 km s-1. We find 105 mini-BALs in 44 quasars from a total sample of 638 quasars. The fraction of quasars with at least one mini-BAL meeting our criteria is roughly ∼9% after correcting for incomplete velocity coverage. All of the systems are highly ionized based on the strong presence of N V and O VI and/or the absence of Si II and C II when within the wavelength coverage. Two of the mini-BAL systems in our catalog, plus three others at smaller velocity shifts, have P V λ1118,1128 absorption indicating highly saturated C IV absorption and total hydrogen column densities ≳1022 cm-2. Most of the mini-BALs are confirmed to have optical depths ≳1 with partial covering of the quasar continuum source. The covering fractions are as small as 0.06 in C IV and 0.03 in Si IV, corresponding to outflow absorbing structures <0.002 pc across. When multiple lines are measured, the lines of less abundant ions tend to have narrower profiles and smaller covering fractions indicative of inhomogeneous absorbers where higher column densities occur in smaller clumps. This picture might extend to BAL outflows if the broader and generally deeper BALs form in either the largest clumps or collections of many mini-BAL-like clumps that blend together in observed quasar spectra.

Keywords: quasar absorption line spectroscopy; quasars; high resolution spectroscopy; broad-absorption line quasar
Relationship between the Sunspot Number and Active Day Fraction: An Application for the Maunder Minimum

Long-term solar activity can be studied using several parameters. Some of the most used are based on the sunspot counting. The active day fraction (ADF) is the simplest index derived from this counting. It is reliable in periods of low solar activity such as the Maunder minimum (MM). In this work, we study the relationship between the ADF and the sunspot number. We have obtained that the optimal fit of that relationship is an exponential function whose exponent is a degree 3 polynomial including all data except those with ADF equal to 100%. Then, we use that fit to estimate the sunspot number during the MM from the ADF calculated from the most recent sunspot group number database. Our estimations of the annual sunspot numbers are below 15, except that for 1656, which is 40.8, whereas our estimations of the triennial sunspot numbers are below 10 from 1648 to 1714. We have found peaks of the solar cycle in the middle of the 1650s, 1670s, 1680s, and 1700s but no clear evidence of solar cycle in the 1660s and 1690s, likely due to the scarcity of the available data. Our results agree with previous works obtaining values significantly higher than those of the group sunspot number derived by Hoyt and Schatten in 1998 but still fully compatible with a grand minimum period.

Keywords: the sun; sunspots; sunspot number; solar cycle; maunder minimum
Dynamical Avenues for Mercury's Origin. II. In Situ Formation in the Inner Terrestrial Disk

Modern terrestrial-planet formation models are highly successful at consistently generating planets with masses and orbits analogous to those of Earth and Venus. In stark contrast to classic theoretical predictions and inferred demographics of multiplanet systems of rocky exoplanets, the mass (≳10) and orbital period (≳2) ratios between Venus and Earth and the neighboring Mercury and Mars are not common outcomes in numerically generated systems. While viable solutions to the small-Mars problem are abundant in the literature, Mercury's peculiar origin remains rather mysterious. In this paper, we investigate the possibility that Mercury formed in a mass-depleted, inner region of the terrestrial disk (a < 0.5 au). This regime is often ignored in terrestrial-planet formation models because of the high computational cost of resolving hundreds of short-period objects over ∼100 Myr timescales. By testing multiple disk profiles and mass distributions, we identify several promising sets of initial conditions that lead to remarkably successful analog systems. In particular, our most successful simulations consider moderate total masses of Mercury-forming material (0.1-0.25 Earth masses). While larger initial masses tend to yield disproportionate Mercury analogs, smaller values often inhibit the planets' formation as the entire region of material is easily accreted by Venus. Additionally, we find that shallow surface density profiles and larger inventories of small planetesimals moderately improve the likelihood of adequately reproducing Mercury.

Keywords: mercury (planet); solar system planets; solar system formation; planetary system formation; planetesimals; planetary science; protoplanetary disks; solar system terrestrial planets
Lithium Detection in Red Supergiant Stars of the Perseus Complex

We present the first systematic study of lithium abundance in a chemically homogeneous sample of 27 red supergiants (RSGs) in the young Perseus complex. For these stars, accurate stellar parameters and detailed chemical abundances of iron and iron peak, CNO, alpha, light, and neutron capture elements have already been obtained by means of high-resolution optical and near-infrared spectroscopy. The observed RSGs have half-solar metallicity, 10-30 Myr ages, bolometric luminosities in the 104-105 L ⊙ range, and likely mass progenitors in the 9-14 M ⊙ range. We detected the optical Li I doublet in eight out of the 27 observed K- and M-type RSGs, finding relatively low A(Li) < 1.0 dex abundances, while for the remaining 19 RSGs upper limits of A(Li) < -0.2 dex have been set. Warmer and less luminous (i.e., likely less massive) as well as less mixed (i.e., with lower [C/N] and 12C/13C depletion) RSGs with Li detection show somewhat higher Li abundances. In order to explain the Li detection in ~30% of the observed RSGs, we speculate that some stochasticity should be at work, in a scenario where the Li was not completely destroyed in the convective atmospheres and/or a secondary production took place during the post-main-sequence evolution.

Keywords: stellar abundances; spectroscopy; red supergiant stars
Finding Quasars behind the Galactic Plane. II. Spectroscopic Identifications of 204 Quasars at ∣b∣ < 20°

Quasars behind the Galactic plane (GPQs) are important astrometric references and valuable probes of Galactic gas, yet the search for GPQs is difficult due to severe extinction and source crowding in the Galactic plane. In this paper, we present a sample of 204 spectroscopically confirmed GPQs at ∣b∣ < 20°, 191 of which are new discoveries. This GPQ sample covers a wide redshift range from 0.069 to 4.487. For the subset of 230 observed GPQ candidates, the lower limit of the purity of quasars is 85.2%, and the lower limit of the fraction of stellar contaminants is 6.1%. Using a multicomponent spectral fitting, we measure the emission line and continuum flux of the GPQs, and estimate their single-epoch virial black hole masses. Due to selection effects raised from Galactic extinction and target magnitude, these GPQs have higher black hole masses and continuum luminosities in comparison to the SDSS DR7 quasar sample. The spectral-fitting results and black hole mass estimates are compiled into a main spectral catalog, and an extended spectral catalog of GPQs. The successful identifications prove the reliability of both our GPQ selection methods and the GPQ candidate catalog, shedding light on the astrometric and astrophysical programs that make use of a large sample of GPQs in the future.

Keywords: active galactic nuclei; catalogs; galactic and extragalactic astronomy; quasars; spectroscopy; supermassive black holes
Discovery of a [C I]-faint, CO-bright Galaxy: ALMA Observations of the Merging Galaxy NGC 6052

We report sensitive [C I] 3P1-3P0 and 12CO J = 4-3 observations of the nearby merging galaxy NGC 6052 using the Morita (Atacama Compact) Array of the Atacama Large Millimeter/submillimeter Array (ALMA). We detect 12CO J = 4-3 toward the northern part of NGC 6052, but [C I] 3P1-3P0 is not detected with a [C I] 3P1-3P0 to 12CO J = 4-3 line luminosity ratio of ≲0.07. According to models of photodissociation regions, the unusual weakness of [C I] 3P1-3P0 relative to 12CO J = 4-3 can be explained if the interstellar medium has a hydrogen density larger than ${10}^{5}\,{\mathrm{cm}}^{-3}$ , conditions that might arise naturally in the ongoing merging process in NGC 6052. Its [C I] 3P1-3P0 emission is also weaker than expected given the molecular gas mass inferred from previous measurements of 12CO J = 1-0 and 12CO J = 2-1. This suggests that [C I]3P1-3P0 may not be a reliable tracer of molecular gas mass in this galaxy. NGC 6052 is a unique laboratory to investigate how the merger process impacts the molecular gas distribution.

Keywords: galaxy interactions; submillimeter astronomy; galaxy evolution; interstellar medium