adsabs/SciX_UAT_keywords huggingface dataset:
Universal Scaling Laws for Solar and Stellar Atmospheric Heating

The Sun and Sun-like stars commonly host multimillion-kelvin coronae and 10,000 K chromospheres. These extremely hot gases generate X-ray and extreme ultraviolet emissions that may impact the erosion and chemistry of (exo)planetary atmospheres, influencing the climate and conditions for habitability. However, the mechanism of coronal and chromospheric heating is still poorly understood. While the magnetic field most probably plays a key role in driving and transporting energy from the stellar surface upwards, it is not clear whether the atmospheric heating mechanisms of the Sun and active Sun-like stars can be described in a unified manner. To this end, we report on a systematic survey of the responses of solar and stellar atmospheres to surface magnetic flux over a wide range of temperatures. By analyzing 10 years of multiwavelength synoptic observations of the Sun, we reveal that the irradiance and magnetic flux show power-law relations with an exponent decreasing from above unity to below as the temperature decreases from the corona to the chromosphere. Moreover, this trend indicating the efficiency of atmospheric heating can be extended to Sun-like stars. We also discover that the power-law exponent depends on the solar cycle, becoming smallest at maximum activity, probably due to the saturation of atmospheric heating. Our study provides observational evidence that the mechanism of atmospheric heating is universal among the Sun and Sun-like stars, regardless of age or activity.

Keywords: g dwarf stars; solar analogs; stellar coronae; stellar chromospheres; stellar magnetic fields; solar coronal heating; solar chromospheric heating; solar magnetic fields
Diagnosing Open Cluster Stock 2: Member Candidates and Mass Distribution with Gaia DR2 and LAMOST

We identify 1325 member candidates of the open cluster (OC) Stock 2 using data from Gaia DR2. We use the algorithms Clusterix 2.0 and HDBSCAN to select cluster candidates and further refine the final cluster membership by defining neighbors in 5D phase space (Xcp, Ycp, ${Z}_{\mathrm{cp}},\kappa \cdot {\mu }_{\alpha }^{* }$ /ϖ, κ · μδ/ϖ). Among these candidates, less than half have G, GBP, and GRP extinctions from Gaia. When Gaia extinctions are unavailable, we compute extiction using empirical formulas and E(B - V) = 0.350. We analyze the spatial distribution and mass profile of Stock 2. Our results reveal Stock 2 is still a bound OC and we find evidence of mass segregation. By comparing initial mass functions, the present-day mass function indicates that Stock 2 is a massive stellar cluster with a mass of 4000 M⊙. The core radius and tidal radius, calculated via the radial density profile and total mass, are 3.97 pc and 22.65 pc, respectively. Common stars between our selected member candidates and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR7 medium-resolution catalog give a metalliclity of [Fe/H] = -0.040 ± 0.147.

Keywords: open star clusters
BASS. XXXVI. Constraining the Local Supermassive Black Hole-Halo Connection with BASS DR2 AGNs

We investigate the connection between supermassive black holes (SMBHs) and their host dark matter halos in the local universe using the clustering statistics and luminosity function of active galactic nuclei (AGNs) from the Swift/BAT AGN Spectroscopic Survey (BASS DR2). By forward-modeling AGN activity into snapshot halo catalogs from N-body simulations, we test a scenario in which SMBH mass correlates with dark matter (sub)halo mass for fixed stellar mass. We compare this to a model absent of this correlation, where stellar mass alone determines the SMBH mass. We find that while both simple models are able to largely reproduce the abundance and overall clustering of AGNs, the model in which black hole mass is tightly correlated with halo mass is preferred by the data by 1.8σ. When including an independent measurement on the black hole mass-halo mass correlation, this model is preferred by 4.6σ. We show that the clustering trends with black hole mass can further break the degeneracies between the two scenarios and that our preferred model reproduces the measured clustering differences on one-halo scales between large and small black hole masses. These results indicate that the halo binding energy is fundamentally connected to the growth of SMBHs.

Keywords: large-scale structure of the universe; supermassive black holes; x-ray active galactic nuclei; agn host galaxies
Discovery of Interstellar trans-cyanovinylacetylene (HC ≡ CCH = CHC ≡ N) and vinylcyanoacetylene (H2C = CHC3N) in GOTHAM Observations of TMC-1

We report the discovery of two unsaturated organic species, trans-(E)-cyanovinylacetylene and vinylcyanoacetylene, using the second data release of the GOTHAM deep survey toward TMC-1 with the 100 m Green Bank Telescope. For both detections, we performed velocity stacking and matched filter analyses using Markov Chain Monte Carlo simulations, and for trans-(E)-cyanovinylacetylene, three rotational lines were observed at low signal-to-noise (∼3σ). From this analysis, we derive column densities of 2 × 1011 and 3 × 1011 cm-2 for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of <2 × 1011 cm-2 for trans-(Z)-cyanovinylacetylene. Comparisons with G3//B3LYP semiempirical thermochemical calculations indicate abundances of the [H3C5N] isomers are not consistent with their thermodynamic stability, and instead their abundances are mainly driven by dynamics. We provide a discussion on how these species may be formed in TMC-1, with reference to related molecules like vinyl cyanide (CH2 = CHC ≡ N). As part of this discussion, we performed the same analysis for ethyl cyanide (CH3CH2C ≡ N), the hydrogenation product of CH2 = CHC ≡ N. This analysis provides evidence—at 4.2σ significance—of an upper limit to the column density of <4 × 1011 cm-2; an order of magnitude lower than previous upper limits toward this source.

Keywords: astrochemistry; chemical abundances; molecular clouds; interstellar molecules; molecule formation
Hemispheric Tectonics on LHS 3844b

The tectonic regime of rocky planets fundamentally influences their long-term evolution and cycling of volatiles between interior and atmosphere. Earth is the only known planet with active plate tectonics, but observations of exoplanets may deliver insights into the diversity of tectonic regimes beyond the solar system. Observations of the thermal phase curve of super-Earth LHS 3844b reveal a solid surface and lack of a substantial atmosphere, with a temperature contrast between the substellar and antistellar point of around 1000 K. Here, we use these constraints on the planet's surface to constrain the interior dynamics and tectonic regimes of LHS 3844b using numerical models of interior flow. We investigate the style of interior convection by assessing how upwellings and downwellings are organized and how tectonic regimes manifest. We discover three viable convective regimes with a mobile surface: (1) spatially uniform distribution of upwellings and downwellings, (2) prominent downwelling on the dayside and upwellings on the nightside, and (3) prominent downwelling on the nightside and upwellings on the dayside. Hemispheric tectonics is observed for regimes (2) and (3) as a direct consequence of the day-to-night temperature contrast. Such a tectonic mode is absent in the present-day solar system and has never been inferred from astrophysical observations of exoplanets. Our models offer distinct predictions for volcanism and outgassing linked to the tectonic regime, which may explain secondary features in phase curves and allow future observations to constrain the diversity of super-Earth interiors.

Keywords: exoplanets; super earths; planetary interior; exoplanet plate tectonics
A Non-equipartition Shock Wave Traveling in a Dense Circumstellar Environment around SN 2020oi

We report the discovery and panchromatic follow-up observations of the young Type Ic supernova (SN Ic) SN 2020oi in M100, a grand-design spiral galaxy at a mere distance of 14 Mpc. We followed up with observations at radio, X-ray, and optical wavelengths from only a few days to several months after explosion. The optical behavior of the supernova is similar to those of other normal SNe Ic. The event was not detected in the X-ray band but our radio observations revealed a bright mJy source ( ${L}_{\nu }\approx 1.2\times {10}^{27}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{Hz}}^{-1}$ ). Given the relatively small number of stripped envelope SNe for which radio emission is detectable, we used this opportunity to perform a detailed analysis of the comprehensive radio data set we obtained. The radio-emitting electrons initially experience a phase of inverse Compton cooling, which leads to steepening of the spectral index of the radio emission. Our analysis of the cooling frequency points to a large deviation from equipartition at the level of ɛe/ɛB ≳ 200, similar to a few other cases of stripped envelope SNe. Our modeling of the radio data suggests that the shock wave driven by the SN ejecta into the circumstellar matter (CSM) is moving at $\sim 3\times {10}^{4}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ . Assuming a constant mass loss from the stellar progenitor, we find that the mass-loss rate is $\dot{M}\approx 1.4\times {10}^{-4}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ for an assumed wind velocity of $1000\,\mathrm{km}\,{{\rm{s}}}^{-1}$ . The temporal evolution of the radio emission suggests a radial CSM density structure steeper than the standard r-2.

Keywords: supernovae; type ic supernovae; core-collapse supernovae; radio transient sources; radio observatories; optical observation; x-ray transient sources; transient sources
Massive Stars in Molecular Clouds Rich in High-energy Sources: The Bridge of G332.809-0.132 and CS 78 in NGC 6334

Detections of massive stars in the direction of the H II region CS 78 in NGC 6334 and of G332.809-0.132 are here presented. The region covered by the G332.809-0.132 complex coincides with the RCW 103 stellar association. In its core (40' in radius), approximately 110 OB candidate stars (Ks < 10 mag and 0.4 < ${A}_{{K}_{s}}$ < 1.6 mag) were identified using 2MASS, DENIS, and GLIMPSE data. This number of OB stars accounts for more than 50% of the observed number of Lyman continuum photons from this region. Medium-resolution K-band spectra were obtained for seven early types, including one WN 8 star and one Ofpe/WN 9 star; the latter is located near the RCW 103 remnant and its luminosity is consistent with a distance of ≈3 kpc. The area analyzed encloses 9 of the 34 OB stars previously known in RCW 103, as well as IRAS 16115-5044, which we reclassify as a candidate luminous blue variable. The line of sight is particularly interesting, crossing three spiral arms; a molecular cloud at -50 (with RCW 103 in the Scutum-Crux arm) and another at -90 km s-1 (in the Norma arm) are detected, both rich in massive stars and supernova remnants. We also report the detection of a B supergiant as the main ionizing source of CS 78, 2MASS J17213513-3532415. Medium-resolution H- and K-band spectra display H I and He I lines, as well as Fe II lines. By assuming a distance of 1.35 kpc, we estimate a bolometric magnitude of -6.16, which is typical of supergiants. ∗ Based on observations collected at the European Southern Observatory (ESO Programmes 087.D-09609). † M.M. is currently employed by USTC. This works was designed during her ESA fellowship (2010) and partially carried out at the MPIfR.

Keywords: stellar evolution; infrared sources; supergiant stars; early-type emission stars
A Corotating Group of Dwarf Galaxies around NGC 2750 as a Centaurus A Analog

We study a low-mass spiral galaxy NGC 2750 (~5 times less massive than the Milky Way), located ~40 Mpc away in a sparse region that hosts seven satellite galaxies within a projected distance of 150 Kpc. Among them six are star-forming dwarfs with stellar masses of >≈107 M⊙ and one is an early-type dwarf with a stellar mass of 2.6 × 106 M⊙. The star-forming dwarfs are gas rich, with gas mass fractions as high as Log(MH I/M*) = 1.2 and their star formation rates vary between 0.03 and 0.35 M⊙ yr-1. The projected distances and measured radial velocities of the six star-forming satellites provide a high probability that they are members of the group. The radial velocity distribution of the six satellites exhibits evidence of a systematic corotation. We devise a method to quantify such a corotation signal by calculating the correlation coefficient between satellites' relative line-of-sight velocities (ΔVr) and their sky-projected distances from the host (Rp). For the NGC 2750 system, we show a clear correlation between ΔVr and Rp, with a Pearson's R correlation coefficient c = 0.90 and p-value = 0.005. We compare the NGC 2750 system with the Centaurus A (NGC 5128) system, a previously known corotating group, and conclude that the former could be a small version of the latter but is located in an isolated field, away from the influence of the large-scale structure. The results open up opportunities to explore the galactic anisotropy phenomenon on a low-mass scale and in a rarified environment.

Keywords: dwarf galaxies; galaxy groups; galaxy interactions; galaxy evolution
CHIANTI-An Atomic Database for Emission Lines. XVII. Version 10.1: Revised Ionization and Recombination Rates and Other Updates

The CHIANTI atomic database provides sets of assessed data that are used for simulating spectral observations of astrophysical plasmas. This article describes updates that will be released as version 10.1 of the database. A key component of CHIANTI is the provision of ionization and recombination rates that are used to compute the ionization balance of a plasma over a range of temperatures. Parameters for calculating the ionization rates of all stages of ions from H through Zn were compiled and inserted into the CHIANTI database in 2009. These were based on all measurements that were available at the time and supplemented with distorted wave calculations. Since then, there have been a number of new laboratory measurements for ions that produce spectral lines that are commonly observed. Parameters have been fit to these new measurements to provide improved ability to reproduce the ionization cross sections and rate coefficients, and these are added to the database. CHIANTI 10.1 also includes new recombination rates for the phosphorus isoelectronic sequence, and the updated ionization and recombination rates have been used to calculate a new ionization equilibrium file. In addition, CHIANTI 10.1 has new electron collision and radiative data sets for eight ions in the nitrogen and oxygen isoelectronic sequences and updated energy level and wavelength data for six other ions. *Released on 2023 July 17.

Keywords: atomic data; solar ultraviolet emission; solar x-ray emission; ultraviolet spectroscopy
Water Absorption in the Transmission Spectrum of the Water World Candidate GJ 9827 d

Recent work on the characterization of small exoplanets has allowed us to accumulate growing evidence that sub-Neptunes with radii greater than ~2.5 R ⊕ often host H2/He-dominated atmospheres both from measurements of their low bulk densities and from direct detections of their low mean molecular mass atmospheres. However, the smaller sub-Neptunes in the 1.5-2.2 R ⊕ size regime are much less understood and often have bulk densities that can be explained either by the H2/He-rich scenario or by a volatile-dominated composition known as the "water world" scenario. Here we report the detection of water vapor in the transmission spectrum of the 1.96 ± 0.08 R ⊕ sub-Neptune GJ 9827 d obtained with the Hubble Space Telescope (HST). We observe 11 HST Wide Field Camera 3 transits of GJ 9827 d and find an absorption feature at 1.4 μm in its transit spectrum, which is best explained (at 3.39σ) by the presence of water in GJ 9827 d's atmosphere. We further show that this feature cannot be caused by unocculted starspots during the transits by combining an analysis of the K2 photometry and transit light source effect retrievals. We reveal that the water absorption feature can be similarly well explained by a small amount of water vapor in a cloudy H2/He atmosphere or a water vapor envelope on GJ 9827 d. Given that recent studies have inferred an important mass-loss rate (>0.5 M ⊕ Gyr-1) for GJ 9827 d, making it unlikely to retain a H-dominated envelope, our findings highlight GJ 9827 d as a promising water world candidate that could host a volatile-dominated atmosphere. This water detection also makes GJ 9827 d the smallest exoplanet with an atmospheric molecular detection to date.

Keywords: exoplanet atmospheres; mini neptunes; water vapor; exoplanet atmospheric composition
A Flare-type IV Burst Event from Proxima Centauri and Implications for Space Weather

Studies of solar radio bursts play an important role in understanding the dynamics and acceleration processes behind solar space weather events, and the influence of solar magnetic activity on solar system planets. Similar low-frequency bursts detected from active M-dwarfs are expected to probe their space weather environments and therefore the habitability of their planetary companions. Active M-dwarfs produce frequent, powerful flares which, along with radio emission, reveal conditions within their atmospheres. However, to date, only one candidate solar-like coherent radio burst has been identified from these stars, preventing robust observational constraints on their space weather environment. During simultaneous optical and radio monitoring of the nearby dM5.5e star Proxima Centauri, we detected a bright, long-duration optical flare, accompanied by a series of intense, coherent radio bursts. These detections include the first example of an interferometrically detected coherent stellar radio burst temporally coincident with a flare, strongly indicating a causal relationship between these transient events. The polarization and temporal structure of the trailing long-duration burst enable us to identify it as a type IV burst. This represents the most compelling detection of a solar-like radio burst from another star to date. Solar type IV bursts are strongly associated with space weather events such as coronal mass ejections and solar energetic particle events, suggesting that stellar type IV bursts may be used as a tracer of stellar coronal mass ejections. We discuss the implications of this event for the occurrence of coronal mass ejections from Proxima Cen and other active M-dwarfs.

Keywords: flare stars; uv ceti stars; stellar coronal mass ejections; stellar flares; solar radio flares; space weather; radio bursts; solar-planetary interactions; galactic radio sources; m dwarf stars; stellar activity
Detection of a Multiphase Ultrafast Wind in the Narrow-line Seyfert 1 Galaxy Mrk 1044

We present a detailed analysis of XMM-Newton X-ray spectra of the Narrow-Line Seyfert 1 galaxy Mrk 1044. We find robust evidence for a multiphase, ultrafast outflow, traced by four separate components in the grating spectrum. One component has high column density and ionization state, and is outflowing at ~0.15c. The other three wind components have lower temperature, lower column density, and have outflow velocities ~0.08c. This wind structure is strikingly similar to that found in IRAS 17020+4544, suggesting that stratified winds may be a common feature of ultrafast outflows. Such structure is likely produced by fluid instabilities that form when the nuclear wind shocks the ambient medium. We show that, in an energy-driven wind scenario, the wind in Mrk 1044 might carry enough energy to produce significant feedback on its host galaxy. We further discuss the implications of the presence of a fast wind in yet another NLS1 galaxy with high Eddington ratio.

Keywords: x-ray quasars; quasar absorption line spectroscopy; active galactic nuclei
Astrochemical Diagnostics of the Isolated Massive Protostar G28.20-0.05

We study the astrochemical diagnostics of the isolated massive protostar G28.20-0.05. We analyze data from Atacama Large Millimeter/submillimeter Array 1.3 mm observations with a resolution of 0.″2 (~1000 au). We detect emission from a wealth of species, including oxygen-bearing (e.g., H2CO, CH3OH, CH3OCH3), sulfur-bearing (SO2, H2S), and nitrogen-bearing (e.g., HNCO, NH2CHO, C2H3CN, C2H5CN) molecules. We discuss their spatial distributions, physical conditions, correlation between different species, and possible chemical origins. In the central region near the protostar, we identify three hot molecular cores (HMCs). HMC1 is part of a millimeter continuum ring-like structure, is closest in projection to the protostar, has the highest temperature of ~300 K, and shows the most line-rich spectra. HMC2 is on the other side of the ring, has a temperature of ~250 K, and is of intermediate chemical complexity. HMC3 is further away, ~3000 au in projection, cooler (~70 K), and is the least line-rich. The three HMCs have similar mass surface densities (~10 g cm-2), number densities (n H ~ 109 cm-3), and masses of a few solar masses. The total gas mass in the cores and in the region out to 3000 au is ~25 M ⊙, which is comparable to that of the central protostar. Based on spatial distributions of peak line intensities as a function of excitation energy, we infer that the HMCs are externally heated by the protostar. We estimate column densities and abundances of the detected species and discuss the implications for hot core astrochemistry.

Keywords: star formation; astrochemistry; complex organic molecules; spectral line identification; massive stars; interstellar medium
Discovery of a Low-redshift Damped Lyα System in a Foreground Extended Disk Using a Starburst Galaxy Background Illuminator

We present the discovery of a low-redshift damped Lyα (DLA) system in the spectrum of background starburst galaxy SDSS J111323.88+293039.3 (z = 0.17514). The DLA is at an impact parameter of ρ = 36 kpc from the star-forming galaxy, SDSS J111324.08+293051.2 (z = 0.17077). We measure an H column density of N(H ) = 3.47 × 1020 cm-2 along with multiple low-ionization species such as N , N II, Si II, C II, and Si III. We also make an estimate of the covering fraction to be 0.883, giving us a limiting size of the DLA to be ADLA ≥ 3.3 kpc2. Assuming a uniform column density over the entire DLA system, we estimate its mass to be MDLA ≥ 5.3 × 106 M⊙. The extended illuminator and the low redshift of this DLA give us the unique opportunity to characterize its nature and the connection to its host galaxy. We measure a velocity offset of +131 km s-1 from the systemic velocity of the host for the DLA. This velocity is -84 km s-1 from the projected rotation velocity of the host galaxy as measured using a newly constructed rotation curve. Based on the size of the host galaxy, the H column density, and the gas kinematics, we believe this DLA is tracing the warm neutral gas in the H disk of the foreground galaxy. Our detection adds to a small set of low-redshift DLAs that have confirmed host galaxies, and is the first to be found using an extended background source.

Keywords: galaxy evolution; starburst galaxies; interstellar medium; interstellar absorption; galaxy disks; circumgalactic medium; extragalactic astronomy
A Small Centaur with a Coma and Tail and Another with a Coma

We report discovery and initial investigation of extended optical emission from two known Centaurs, 2020 XV1 and 2021 RK133. These objects are classified as Centaurs using the Jet Propulsion Laboratory HORIZONS Centaur criteria, but not the Minor Planet Center criteria, as both have q < 5.2 au. We derive limits on the fraction of light coming from the nuclei and from the extended emission regions and derive magnitude limits for the nuclei. Using these nuclear magnitudes and an assumed albedo of 7% we estimate that these two Centaurs are rather small, with diameters of no more than 2.4 and 1.7 km.

Keywords: centaur group; comets