Sazuna/UAT_keywords huggingface dataset:
Rotationally Driven Ultraviolet Emission of Red Giant Stars. Main-sequence stars exhibit a clear rotation-activity relationship, in which rapidly rotating stars drive strong chromospheric/coronal ultraviolet and X-ray emission. While the vast majority of red giant stars are inactive, a few percent exhibit strong ultraviolet emission. Here we use a sample of 133 red giant stars observed by Sloan Digital Sky Survey APOGEE and Galaxy Evolution Explorer to demonstrate an empirical relationship between near-UV (NUV) excess and rotational velocity ( $v\ \sin \ i$ ). Beyond this simple relationship, we find that NUV excess also correlates with rotation period and with Rossby number in a manner that shares broadly similar trends to those found in M dwarfs, including activity saturation among rapid rotators. Our data also suggest that the most extremely rapidly rotating giants may exhibit so-called supersaturation, which could be caused by centrifugal stripping of these stars rotating at a high fraction of breakup speed. As an example application of our empirical rotation-activity relation, we demonstrate that the NUV emission observed from a recently reported system comprising a red giant with a black hole companion is fully consistent with arising from the rapidly rotating red giant in that system. Most fundamentally, our findings suggest a common origin of chromospheric activity in rotation and convection for cool stars from main sequence to red giant stages of evolution.

Keywords: Red giant branch, Evolved stars, Stellar activity, Spectroscopy, Giant branch, Ultraviolet photometry, Stellar rotation
KR Persei, a Mid-F Eclipsing Binary with a One-day Period. KR Per is a partially eclipsing binary with an orbital period of 0.9960798 days, very close to one sidereal day, making it difficult to obtain extensive phase coverage in a reasonable amount of time. We used the Wilson-Devinney program to determine its orbital elements and stellar absolute dimensions from recently acquired radial velocities and differential BVRI observations that were supplemented with previous differential UBV measurements and published times of minima. The two components are each F5 V stars with masses of $1.466\pm 0.015\,{M}_{\odot }$ and $1.458\pm 0.015\,{M}_{\odot }$ . The radii are $1.855\pm 0.021\,{R}_{\odot }$ and $1.824\pm 0.022\,{R}_{\odot }$ . The orbital period of the eclipsing system is variable and more times of minima observations are needed. A comparison with evolutionary tracks indicates that the system has an age of 2.1 ± 0.1 Gyr.

Keywords: Eclipsing binary stars, Spectroscopic binary stars, Detached binary stars, Fundamental parameters of stars
Interpreting the Cratering Histories of Bennu, Ryugu, and Other Spacecraft-explored Asteroids. Asteroid crater retention ages have unknown accuracy because projectile-crater scaling laws are difficult to verify. At the same time, our knowledge of asteroid and crater size-frequency distributions has increased substantially over the past few decades. These advances make it possible to empirically derive asteroid crater scaling laws by fitting model asteroid size distributions to crater size distributions from asteroids observed by spacecraft. For D &gt; 10 km diameter asteroids like Ceres, Vesta, Lutetia, Mathilde, Ida, Eros, and Gaspra, the best matches occur when the ratio of crater to projectile sizes is f ∼ 10. The same scaling law applied to 0.3 &lt; D &lt; 2.5 km near-Earth asteroids such as Bennu, Ryugu, Itokawa, and Toutatis yield intriguing yet perplexing results. When applied to the largest craters on these asteroids, we obtain crater retention ages of ∼1 billion years for Bennu, Ryugu, and Itokawa and ∼2.5 billion years for Toutatis. These ages agree with the estimated formation ages of their source families and could suggest that the near-Earth asteroid population is dominated by bodies that avoided disruption during their traverse across the main asteroid belt. An alternative interpretation is that f ≫ 10, which would make their crater retention ages much younger. If true, crater scaling laws need to change in a substantial way between D &gt; 10 km asteroids, where f ∼ 10, and 0.3 &lt; D &lt; 2.5 km asteroids, where f ≫ 10.

Keywords: Near-Earth objects, Main belt asteroids
Information Content of JWST NIRSpec Transmission Spectra of Warm Neptunes. Warm Neptunes offer a rich opportunity for understanding exo-atmospheric chemistry. With the upcoming James Webb Space Telescope (JWST), there is a need to elucidate the balance between investments in telescope time versus scientific yield. We use the supervised machine-learning method of the random forest to perform an information content (IC) analysis on a 11-parameter model of transmission spectra from the various NIRSpec modes. The three bluest medium-resolution NIRSpec modes (0.7-1.27 μm, 0.97-1.84 μm, 1.66-3.07 μm) are insensitive to the presence of CO. The reddest medium-resolution mode (2.87-5.10 μm) is sensitive to all of the molecules assumed in our model: CO, CO2, CH4, C2H2, H2O, HCN, and NH3. It competes effectively with the three bluest modes on the information encoded on cloud abundance and particle size. It is also competitive with the low-resolution prism mode (0.6-5.3 μm) on the inference of every parameter except for the temperature and ammonia abundance. We recommend astronomers to use the reddest medium-resolution NIRSpec mode for studying the atmospheric chemistry of 800-1200 K warm Neptunes; its corresponding high-resolution counterpart offers diminishing returns. We compare our findings to previous JWST IC analyses that favor the blue orders and suggest that the reliance on chemical equilibrium could lead to biased outcomes if this assumption does not apply. A simple, pressure-independent diagnostic for identifying chemical disequilibrium is proposed based on measuring the abundances of H2O, CO, and CO2.

Keywords: Exoplanets, Exoplanet atmospheres
One Planet or Two Planets? The Ultra-sensitive Extreme-magnification Microlensing Event KMT-2019-BLG-1953. We present the analysis of a very high-magnification (A ∼ 900) microlensing event KMT-2019-BLG-1953. A single-lens single-source (1L1S) model appears to approximately delineate the observed light curve, but the residuals from the model exhibit small but obvious deviations in the peak region. A binary-lens (2L1S) model with a mass ratio of q ∼ 2 × 10-3 improves the fits by Δχ2 = 181.8, indicating that the lens possesses a planetary companion. From additional modeling by introducing an extra planetary lens component (3L1S model) and an extra source companion (2L2S model), it is found that the residuals from the 2L1S model further diminish, but claiming these interpretations is difficult due to the weak signals with Δχ2 = 16.0 and 13.5 for the 3L1S and 2L2L models, respectively. From a Bayesian analysis, we estimate that the host of the planets has a mass of ${M}_{\mathrm{host}}={0.31}_{-0.17}^{+0.37}\,{M}_{\odot }$ and that the planetary system is located at a distance of ${D}_{{\rm{L}}}={7.04}_{-1.33}^{+1.10}\,\mathrm{kpc}$ toward the Galactic center. The mass of the securely detected planet is ${M}_{{\rm{p}}}={0.64}_{-0.35}^{+0.76}\,{M}_{{\rm{J}}}$ . The signal of the potential second planet could have been confirmed if the peak of the light curve had been more densely observed by follow-up observations, and thus the event illustrates the need for intensive follow-up observations for very high-magnification events even in the current generation of high-cadence surveys.

Keywords: Gravitational microlensing, Gravitational microlensing exoplanet detection
Beyond Gaia: Asteroseismic Distances of M Giants Using Ground-based Transient Surveys. Evolved stars near the tip of the red giant branch show solar-like oscillations with periods spanning hours to months and amplitudes ranging from ∼1 mmag to ∼100 mmag. The systematic detection of the resulting photometric variations with ground-based telescopes would enable the application of asteroseismology to a much larger and more distant sample of stars than is currently accessible with space-based telescopes such as Kepler or the ongoing Transiting Exoplanet Survey Satellite mission. We present an asteroseismic analysis of 493 M giants using data from two ground-based surveys: the Asteroid Terrestrial-impact Last Alert System (ATLAS) and the All-Sky Automated Survey for Supernovae (ASAS-SN). By comparing the extracted frequencies with constraints from Kepler, the Sloan Digital Sky Survey Apache Point Observatory Galaxy Evolution Experiment, and Gaia we demonstrate that ground-based transient surveys allow accurate distance measurements to oscillating M giants with a precision of ∼15%. Using stellar population synthesis models we predict that ATLAS and ASAS-SN can provide asteroseismic distances to ∼2 × 106 galactic M giants out to typical distances of 20-50 kpc, vastly improving the reach of Gaia and providing critical constraints for Galactic archeology and galactic dynamics.

Keywords: M giant stars, Stellar distance, Asteroseismology, Ground-based astronomy
Upper Limits on Planet Occurrence around Ultracool Dwarfs with K2. The occurrence of planets orbiting ultracool dwarfs is poorly constrained. We present results from a guest observer program on NASA's K2 spacecraft to search for transiting planets orbiting a sample of 827 ultracool dwarfs. Having found no transiting planets in our sample, we determined an upper limit on the occurrence of planets. We simulated planets orbiting our sample for a range of orbital periods and sizes. For the simulated planets that transit their host, we injected the transit light curve into the real K2 light curves, then attempted to recover the injected planets. For a given occurrence rate, we calculated the probability of seeing no planets, and use the results to place an upper limit on planet occurrence as a function of planet radius and orbital period. We find that short-period, mini-Neptune- and Jupiter-sized planets are rare around ultracool dwarfs, consistent with results for early- and mid-type M dwarf stars. We constrain the occurrence rate η for planets between 0.5 and 10 R⊕ with orbital periods between 1 and 26.3 days.

Keywords: M dwarf stars, Transits, Exoplanets, L dwarfs, Transit photometry, Space telescopes, Late-type dwarf stars
Global X-Ray Properties of the Vela and Puppis A Supernova Remnants. The Vela and Puppis A supernova remnants (SNRs) comprise a large emission region of ∼8° diameter in the soft X-ray sky. The HaloSat CubeSat mission provides the first soft X-ray (0.4-7 keV) observation of the entire Vela SNR and Puppis A SNR region with a single pointing and moderate spectral resolution. HaloSat observations of the Vela SNR are best fit with a two-temperature thermal plasma model consisting of a cooler component with ${{kT}}_{1}={0.19}_{-0.01}^{+0.01}$ keV in collisional ionization equilibrium and a hotter component with ${{kT}}_{2}={1.06}_{-0.27}^{+0.45}$ keV in nonequilibrium ionization. Observations of the Puppis A SNR are best fit with a single-component plane-parallel shocked plasma model with ${kT}={0.86}_{-0.05}^{+0.06}$ keV in nonequilibrium ionization. For the first time, we find the total X-ray luminosities of both components of the Vela SNR spectrum in the 0.5-7 keV energy band to be ${L}_{{\rm{X}}}={4.4}_{-1.4}^{+1.4}\times {10}^{34}$ erg s-1 for the cooler component and ${L}_{{\rm{X}}}={4.1}_{-1.5}^{+1.8}\times {10}^{34}$ erg s-1 for the hotter component. We find the total X-ray luminosities of the Vela and Puppis A SNRs to be ${L}_{{\rm{X}}}=8.4\times {10}^{34}$ erg s-1 and ${L}_{{\rm{X}}}={6.7}_{-0.9}^{+1.1}\times {10}^{36}$ erg s-1.

Keywords: Supernova remnants, X-ray observatories, X-ray sources
New Grids of Pure-hydrogen White Dwarf NLTE Model Atmospheres and the HST/STIS Flux Calibration. Nonlocal thermodynamic equilibrium (NLTE) calculations of hot white dwarf (WD) model atmospheres are the cornerstone of modern flux calibrations for the Hubble Space Telescope and for the CALSPEC database. These theoretical spectral energy distributions (SEDs) provide the relative flux versus wavelength, and only the absolute flux level remains to be set by reconciling the measured absolute flux of Vega in the visible with the Midcourse Space Experiment values for Sirius in the mid-IR. The most recent SEDs calculated by the TLUSTY and TMAP NLTE model atmosphere codes for the primary WDs G191-B2B, GD 153, and GD 71 show improved agreement to 1% from 1500 Å to 30 μm, in comparison to the previous 1% consistency only from 2000 Å to 5 μm. These new NLTE models of hot WDs now provide consistent flux standards from the far UV to the mid-IR.

Keywords: White dwarf stars, Astronomical instrumentation
TOI-1235 b: A Keystone Super-Earth for Testing Radius Valley Emergence Models around Early M Dwarfs. Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period-radius space. Here we present the confirmation of TOI-1235 b (P = 3.44 days, ${r}_{{\rm{p}}}={1.738}_{-0.076}^{+0.087}$ ${R}_{\oplus }$ ), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (Rs = 0.630 ± 0.015 ${R}_{\odot }$ , Ms = 0.640 ± 0.016 ${M}_{\odot }$ ). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of ${6.91}_{-0.85}^{+0.75}$ ${M}_{\oplus }$ , which implies an iron core mass fraction of ${20}_{-12}^{+15}$ % in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be &lt;0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin ( $P={21.8}_{-0.8}^{+0.9}$ days, ${m}_{{\rm{p}}}\sin i={13.0}_{-5.3}^{+3.8}$ ${M}_{\oplus }$ ) that cannot be firmly ruled out by our data.

Keywords: M dwarf stars, Exoplanet formation, Exoplanet structure, Radial velocity, Transit photometry
Demonstrating High-precision Photometry with a CubeSat: ASTERIA Observations of 55 Cancri e. Arcsecond Space Telescope Enabling Research In Astrophysics (ASTERIA) is a 6U CubeSat space telescope (10 cm × 20 cm × 30 cm, 10 kg). ASTERIA's primary mission objective was demonstrating two key technologies for reducing systematic noise in photometric observations: high-precision pointing control and high-stability thermal control. ASTERIA demonstrated 0"5 rms pointing stability and ±10 mK thermal control of its camera payload during its primary mission, a significant improvement in pointing and thermal performance compared to other spacecraft in ASTERIA's size and mass class. ASTERIA launched in 2017 August and deployed from the International Space Station in 2017 November. During the prime mission (2017 November-2018 February) and the first extended mission that followed (2018 March-2018 May), ASTERIA conducted opportunistic science observations, which included the collection of photometric data on 55 Cancri, a nearby exoplanetary system with a super-Earth transiting planet. The 55 Cancri data were reduced using a custom pipeline to correct complementary metal-oxide semiconductor (CMOS) detector column-dependent gain variations. A Markov Chain Monte Carlo approach was used to simultaneously detrend the photometry using a simple baseline model and fit a transit model. ASTERIA made a marginal detection of the known transiting exoplanet 55 Cancri e (∼2 ${R}_{\oplus }$ ), measuring a transit depth of 374 ± 170 ppm. This is the first detection of an exoplanet transit by a CubeSat. The successful detection of super-Earth 55 Cancri e demonstrates that small, inexpensive spacecraft can deliver high-precision photometric measurements.

Keywords: Broad band photometry, Exoplanets, Super Earths, Exoplanet astronomy, Space observatories, Photometry, Space telescopes, Exoplanet detection methods, Transit photometry
Debris Disk Results from the Gemini Planet Imager Exoplanet Survey's Polarimetric Imaging Campaign. We report the results of a ∼4 yr direct imaging survey of 104 stars to resolve and characterize circumstellar debris disks in scattered light as part of the Gemini Planet Imager (GPI) Exoplanet Survey. We targeted nearby (≲150 pc), young (≲500 Myr) stars with high infrared (IR) excesses (LIR/L⋆ &gt; 10-5), including 38 with previously resolved disks. Observations were made using the GPI high-contrast integral field spectrograph in H-band (1.6 μm) coronagraphic polarimetry mode to measure both polarized and total intensities. We resolved 26 debris disks and 3 protoplanetary/transitional disks. Seven debris disks were resolved in scattered light for the first time, including newly presented HD 117214 and HD 156623, and we quantified basic morphologies of five of them using radiative transfer models. All of our detected debris disks except HD 156623 have dust-poor inner holes, and their scattered-light radii are generally larger than corresponding radii measured from resolved thermal emission and those inferred from spectral energy distributions. To assess sensitivity, we report contrasts and consider causes of nondetections. Detections were strongly correlated with high IR excess and high inclination, although polarimetry outperformed total intensity angular differential imaging for detecting low-inclination disks (≲70°). Based on postsurvey statistics, we improved upon our presurvey target prioritization metric predicting polarimetric disk detectability. We also examined scattered-light disks in the contexts of gas, far-IR, and millimeter detections. Comparing H-band and ALMA fluxes for two disks revealed tentative evidence for differing grain properties. Finally, we found no preference for debris disks to be detected in scattered light if wide-separation substellar companions were present.

Keywords: Astronomy data modeling, Surveys, Exoplanet systems, Polarimetry, Coronagraphic imaging, Direct imaging, Protoplanetary disks, Circumstellar disks, Circumstellar dust, Debris disks, Near infrared astronomy
Automatic Échelle Spectrograph Wavelength Calibration. Time-domain astronomy and the increasing number of exoplanet candidates call for reliable, robust, and automatic wavelength calibration. We present an algorithm for wavelength-calibrating échelle spectrographs that uses order-by-order extracted spectra and a list of laboratory wavelengths. Our approach is fully automatic and does not need the pixel locations of certain spectral features with which to anchor the wavelength solution, nor the true order number of each diffraction order. We use spectral features that are duplicated in adjacent orders to establish the scale-invariant component of the wavelength solution. We then match the central wavelengths of spectral features to laboratory wavelengths to establish the scale and higher-order components of the wavelength solution. We demonstrate our method on the four spectrographs of Las Cumbres Observatory's Network of Robotic Échelle Spectrographs (NRES), on the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph, and on synthetic data. We obtain a velocity-equivalent precision of ∼10 m s-1 on NRES. We achieve ∼1 m s-1 on HARPS, which agrees with the precision reported by the HARPS team. On synthetic data, we achieve the velocity precision set by Gaussian centroiding errors. Our algorithm likely holds for a wide range of spectrographs beyond the five presented here. We provide an open-source Python package, xwavecal, which outputs wavelength-calibrated spectra as well as the wavelengths of spectral features.

Keywords: High resolution spectroscopy, Open source software, Astronomy software, Radial velocity, Astronomical instrumentation, Exoplanet detection methods
Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations. We present visible and near-infrared (NIR) photometric and spectroscopic observations of interstellar object (ISO) 2I/Borisov taken from 2019 September 10 to 2019 December 20 using the GROWTH, the Apache Point Observatory Astrophysical Research Consortium 3.5 m, and the NASA Infrared Telescope Facility 3.0 m combined with pre- and postdiscovery observations of 2I obtained by the Zwicky Transient Facility from 2019 March 17 to 2019 May 5. Comparison with imaging of distant solar system comets shows an object very similar to mildly active solar system comets with an outgassing rate of ∼1027 mol s-1. The photometry, taken in filters spanning the visible and NIR range, shows a gradual brightening trend of ∼0.03 mag day-1 since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The light curve from recent and prediscovery data reveals a brightness trend suggesting the recent onset of significant H2O sublimation with the comet being active with super volatiles such as CO at heliocentric distances &gt;6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by high-resolution NIR images from Keck adaptive optics taken on 2019 October 4, we estimate a diameter for 2I's nucleus of ≲1.4 km. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size distribution, resulting in a slope of ∼3.4 ± 1.2, similar to solar system comets and bodies produced from collisional equilibrium.

Keywords: Comets
Simultaneous Optical Transmission Spectroscopy of a Terrestrial, Habitable-zone Exoplanet with Two Ground-based Multiobject Spectrographs. Investigating the atmospheres of rocky exoplanets is key to performing comparative planetology between these worlds and the terrestrial planets that reside in the inner solar system. Terrestrial exoplanet atmospheres exhibit weak signals, and attempting to detect them pushes at the boundaries of what is possible for current instrumentation. We focus on the habitable-zone terrestrial exoplanet LHS 1140b. Given its 25-day orbital period and 2 hr transit duration, capturing transits of LHS 1140b is challenging. We observed two transits of this object, approximately 1 yr apart, which yielded four data sets thanks to our simultaneous use of the IMACS and LDSS3C multiobject spectrographs mounted on the twin Magellan telescopes at Las Campanas Observatory. We present a jointly fit white light curve, as well as jointly fit 20 nm wavelength-binned light curves from which we construct a transmission spectrum. Binning the joint white light-curve residuals to 3-minute time bins gives an rms of 145 ppm; binning down to 10-minute time bins gives an rms of 77 ppm. Our median uncertainty in ${R}_{p}^{2}/{R}_{s}^{2}$ in the 20 nm wavelength bins is 260 ppm, and we achieve an average precision of 1.3× the photon noise when fitting the wavelength-binned light curves with a Gaussian process regression. Our precision on ${R}_{p}^{2}/{R}_{s}^{2}$ is a factor of four larger than the feature amplitudes of a clear, hydrogen-dominated atmosphere, meaning that we are not able to test realistic models of LHS 1140b's atmosphere. The techniques and caveats presented here are applicable to the growing sample of terrestrial worlds in the Transiting Exoplanet Survey Satellite era, as well as to the upcoming generation of ground-based giant segmented mirror telescopes.

Keywords: Planetary atmospheres, Transits, Exoplanet atmospheres, Spectroscopy