Sazuna/UAT_keywords huggingface dataset:
SOFIA FEEDBACK Survey: PDR Diagnostics of Stellar Feedback in Different Regions of RCW 49. We quantified the effects of stellar feedback in RCW 49 by determining the physical conditions in different regions using the [C II] 158 μm and [O I] 63 μm observations from SOFIA, the 12CO (3-2) observations from APEX, and the H2 line observations from Spitzer telescopes. Large maps of RCW 49 were observed with the SOFIA and APEX telescopes, while the Spitzer observations were only available toward three small areas. From our qualitative analysis, we found that the H2 0-0 S(2) emission line probes denser gas compared to the H2 0-0 S(1) line. In four regions ("northern cloud," "pillar," "ridge," and "shell"), we compared our observations with the updated PDR Toolbox models and derived the integrated far-ultraviolet flux between 6 and 13.6 eV (G 0), H nucleus density (n), temperatures, and pressures. We found the ridge to have the highest G 0 (2.4 × 103 Habing units), while the northern cloud has the lowest G 0 (5 × 102 Habing units). This is a direct consequence of the location of these regions with respect to the Wd2 cluster. The ridge also has a high density (6.4 × 103 cm-3), which is consistent with its ongoing star formation. Among the Spitzer positions, we found the one closest to the Wd2 cluster to be the densest, suggesting an early phase of star formation. Furthermore, the Spitzer position that overlaps with the shell was found to have the highest G 0, and we expect this to be a result of its proximity to an O9V star.

Keywords: Stellar feedback, Photodissociation regions, Molecular clouds
SCExAO and Keck Direct Imaging Discovery of a Low-mass Companion Around the Accelerating F5 Star HIP 5319. We present the direct imaging discovery of a low-mass companion to the nearby accelerating F star, HIP 5319, using SCExAO coupled with the CHARIS, VAMPIRES, and MEC instruments in addition to Keck/NIRC2 imaging. CHARIS JHK (1.1-2.4 μm) spectroscopic data combined with VAMPIRES 750 nm, MEC Y, and NIRC2 L p photometry is best matched by an M3-M7 object with an effective temperature of T = 3200 K and surface gravity log(g) = 5.5. Using the relative astrometry for HIP 5319 B from CHARIS and NIRC2, and absolute astrometry for the primary from Gaia and Hipparcos, and adopting a log-normal prior assumption for the companion mass, we measure a dynamical mass for HIP 5319 B of ${31}_{-11}^{+35}{M}_{{\rm{J}}}$ , a semimajor axis of ${18.6}_{-4.1}^{+10}$ au, an inclination of ${69.4}_{-15}^{+5.6}$ degrees, and an eccentricity of ${0.42}_{-0.29}^{+0.39}$ . However, using an alternate prior for our dynamical model yields a much higher mass of ${128}_{-88}^{+127}{M}_{{\rm{J}}}$ . Using data taken with the LCOGT NRES instrument we also show that the primary HIP 5319 A is a single star in contrast to previous characterizations of the system as a spectroscopic binary. This work underscores the importance of assumed priors in dynamical models for companions detected with imaging and astrometry, and the need to have an updated inventory of system measurements. *Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT).

Keywords: Exoplanet astronomy, Radial velocity, Direct imaging, Low mass stars
ACCESS: Tentative Detection of H<SUB>2</SUB>O in the Ground-based Optical Transmission Spectrum of the Low-density Hot Saturn HATS-5b. We present a precise ground-based optical transmission spectrum of the hot Saturn HATS-5b (T eq = 1025 K), obtained as part of the ACCESS survey with the IMACS multi-object spectrograph mounted on the Magellan Baade Telescope. Our spectra cover the 0.5-0.9 μm region and are the product of five individual transits observed between 2014 and 2018. We introduce the usage of additional second-order light in our analyses, which allows us to extract an "extra" transit light curve, improving the overall precision of our combined transit spectrum. We find that the favored atmospheric model for this transmission spectrum is a solar-metallicity atmosphere with subsolar C/O, whose features are dominated by H2O and with a depleted abundance of Na and K. If confirmed, this would point to a "clear" atmosphere at the pressure levels probed by transmission spectroscopy for HATS-5b. Our best-fit atmospheric model predicts a rich near-IR spectrum, which makes this exoplanet an excellent target for future follow-up observations with the James Webb Space Telescope, both to confirm this H2O detection and to superbly constrain the atmosphere's parameters.

Keywords: Hot Jupiters, Extrasolar gaseous giant planets, Exoplanet atmospheres, Exoplanets
Zwicky Transient Facility and Globular Clusters: The Period-Luminosity and Period-Wesenheit Relations for Type II Cepheids. We present the first gri-band period-luminosity (PL) and period-Wesenheit (PW) relations for 37 Type II Cepheids (TIICs) located in 18 globular clusters based on photometric data from the Zwicky Transient Facility. We also updated BVIJHK-band absolute magnitudes for 58 TIICs in 24 globular clusters using the latest homogeneous distances to the globular clusters. The slopes of g/r/i- and B/V/I-band PL relations are found to be statistically consistent when using the same sample of distance and reddening. We employed the calibration of ri-band PL/PW relations in globular clusters to estimate a distance to M31 based on a sample of ~270 TIICs from the PAndromeda project. The distance modulus to M31, obtained using calibrated ri-band PW relation, agrees well with the recent determination based on classical Cepheids. However, distance moduli derived using the calibrated r- and i-band PL relations are systematically smaller by ~0.2 mag, suggesting there are possible additional systematic errors on the PL relations. Finally, we also derive the period-color (PC) relations and for the first time the period-Q-index (PQ) relations, where the Q-index is reddening free, for our sample of TIICs. The PC relations based on (r - i) and near-infrared colors and the PQ relations are found to be relatively independent of the pulsation periods.

Keywords: Globular star clusters, Sky surveys, Wide-field telescopes, Distance indicators, Type II Cepheid variable stars
Moderate-resolution K-band Spectroscopy of the Substellar Companion VHS 1256 b. We present moderate-resolution (R ~ 4000) K-band spectra of the planetary-mass companion VHS 1256 b. The data were taken with the OSIRIS integral field spectrograph at the W.M. Keck Observatory. The spectra reveal resolved molecular lines from H2O and CO. The spectra are compared to custom PHOENIX atmosphere model grids appropriate for young, substellar objects. We fit the data using a Markov chain Monte Carlo forward-modeling method. Using a combination of our moderate-resolution spectrum and low-resolution broadband data from the literature, we derive an effective temperature of 1240 K, with a range of 1200-1300 K, a surface gravity of log g = 3.25, with a range of 3.25-3.75, and a cloud parameter of $\mathrm{log}{P}_{\mathrm{cloud}}=6$ , with a range of 6.0-6.6. These values are consistent with previous studies, regardless of the new, larger system distance from GAIA EDR3 (21.15 $\pm $ 0.22 pc). We derive a C/O ratio of ${0.590}_{-0.354}^{+0.280}$ for VHS 1256b. Both our OSIRIS data and spectra from the literature are best modeled when using a larger 3 μm grain size for the clouds than used for hotter objects, consistent with other sources in the L/T transition region. VHS 1256 b offers an opportunity to look for systematics in the modeling process that may lead to the incorrect derivation of properties like C/O ratio in the high contrast regime.

Keywords: High resolution spectroscopy, Brown dwarfs, Direct imaging, Exoplanet formation, Exoplanet atmospheres
A New Third Planet and the Dynamical Architecture of the HD 33142 Planetary System. Based on recently-taken and archival HARPS, FEROS, and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD 33142 (with an improved mass estimate of M1.52 ± 0.03 M ☉), already known to host two planets. We confirm the Jovian-mass planets HD 33142b and c, with periods of P b = ${330.0}_{-0.4}^{+0.4}$ days and P c = ${810.2}_{-4.2}^{+3.8}$ days and minimum dynamical masses of ${m}_{{\rm{b}}}\sin i$ = ${1.26}_{-0.05}^{+0.05}$ M Jup and ${m}_{{\rm{c}}}\sin i$ = ${0.89}_{-0.05}^{+0.06}$ MJup, respectively. Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with ${m}_{{\rm{d}}}\sin i$ = ${0.20}_{-0.03}^{+0.02}$ M Jup in a close-in orbit with an orbital period of P d = ${89.9}_{-0.1}^{+0.1}$ days. We study the dynamical behavior of the three-planet system configuration with an N-body integration scheme, finding it to be long-term stable with the planets alternating between low and moderate eccentricity episodes. We also perform N-body simulations, including stellar evolution and second-order dynamical effects such as planet-stellar tides and stellar mass loss on the way to the white dwarf phase. We find that planets HD 33142b, c, and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD 33142 system an essential benchmark for planet population statistics of the multiple-planet systems found around evolved stars. *Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere under ESO programs 60.A-9700, 60.A-9036, 097.C-0090, 0100.C-0414, 0101.C-0232, 0102.C-0338, and MPG programs 088.C-0892, 099.A-9009, 0100.A-9006.

Keywords: Exoplanet dynamics, Exoplanet detection methods
Differential Proper Motion Spin of the Hipparcos and Gaia Celestial Reference Frames. The Hipparcos catalog provides the first epoch of the celestial reference frame (CRF) in the optical domain and serves as an indispensable tool to verify and improve the Gaia CRF for the brighter stars (V &lt; 11 mag) and to identify the elusive astrometric binary stars with dim or invisible companions, including long-period exoplanets. The systems of positions in Hipparcos and Gaia cannot be directly compared, because they refer to two different mean epochs. It is shown that the proper motion systems for carefully filtered common stars are not statistically consistent within the given formal errors. The vector field of proper motion differences is fitted with 126 vector spherical harmonics up to degree 7 revealing a global pattern at high signal-to-noise ratios, including the three terms of rigid rotation. The origin of the differential spin and other large harmonic terms is investigated by producing a similar decomposition of the Gaia-HG proper motion field, where HG stands for the long-term proper motions derived from the Hipparcos and Gaia DR3 positions, for the same sample of stars. Hipparcos proper motions emerge as the largest source of sky-correlated distortions of the multiepoch optical CRF with a median value of ~190 μas yr-1 and a global spin of ~226 μas yr-1, while the Hipparcos positions and Gaia EDR3 proper motions are explicitly consistent by construction at a level of ~10 μas yr-1. The latter, however, include multiple distortions of higher degree, which should be taken into account in astrometric applications using the HG field.

Keywords: Gaia, Astrometry, Proper motions
Destruction of Long-period Comets. We identify a sample of 27 long-period comets for which both nongravitational accelerations and Lyα-based gas production rates are available. Seven of the 27 comets (i.e., ~25%) did not survive perihelion because of nucleus fragmentation or complete disintegration. Empirically, the latter nuclei have the smallest gas production rates and the largest nongravitational accelerations, which are both indicators of small size. Specifically, the disintegrating nuclei have a median radius of only 0.41 km, one-quarter of the 1.60 km median radius of those surviving perihelion. The disintegrating comets also have a smaller median perihelion distance (0.48 au) than do the survivors (0.99 au). We compare the order-of-magnitude timescale for outgassing torques to change the nucleus spin, τ  s , with the time spent by each comet in strong sublimation, Δt, finding that the disrupted comets are those with τ  s  &lt; Δt. The destruction of near-Sun long-period comets is thus naturally explained as a consequence of rotational breakup. We discuss this process as a contributor to Oort's long mysterious "fading parameter."

Keywords: Oort cloud, Comet nuclei, Long period comets
Lyα Escape from Low-mass, Compact, High-redshift Galaxies. We investigate the effects of stellar populations and sizes on Lyα escape in 27 spectroscopically confirmed and 35 photometric Lyα emitters (LAEs) at z ≈ 2.65 in seven fields of the Boötes region of the NOAO Deep Wide-Field Survey. We use deep HST/WFC3 imaging to supplement ground-based observations and infer key galaxy properties. Compared to typical star-forming galaxies (SFGs) at similar redshifts, the LAEs are less massive (M ⋆ ≈ 107-109 M ⊙), younger (ages ≲1 Gyr), smaller (r  e  &lt; 1 kpc), and less dust-attenuated (E(B-V) ≤ 0.26 mag) but have comparable star formation rates (SFRs ≈ 1-100 M ⊙ yr-1). Some of the LAEs in the sample may be very young galaxies having low nebular metallicities (Z neb ≲ 0.2 Z ⊙) and/or high ionization parameters ( $\mathrm{log}({\rm{U}})\,\gtrsim \,-2.4$ ). Motivated by previous studies, we examine the effects of the concentration of star formation and gravitational potential on Lyα escape by computing SFR surface density, ΣSFR, and specific SFR surface density, ΣsSFR. For a given ΣSFR, the Lyα escape fraction is higher for LAEs with lower stellar masses. The LAEs have a higher ΣsSFR, on average, compared to SFGs. Our results suggest that compact star formation in a low gravitational potential yields conditions amenable to the escape of Lyα photons. These results have important implications for the physics of Lyα radiative transfer and for the type of galaxies that may contribute significantly to cosmic reionization.

Keywords: Star formation, Compact H II region, High-redshift galaxies, H II regions
Sensitive Multibeam Targeted SETI Observations toward 33 Exoplanet Systems with FAST. As a major approach to looking for life beyond the Earth, the search for extraterrestrial intelligence (SETI) is committed to searching for technosignatures such as engineered radio signals that are indicative of technologically capable life. In this paper, we report a targeted SETI campaign employing an observation strategy named multibeam coincidence matching at the Five-hundred-meter Aperture Spherical radio Telescope toward 33 known exoplanet systems, searching for ETI narrowband drifting signals across 1.05-1.45 GHz in two orthogonal linear polarization directions separately. A signal at 1140.604 MHz detected from the observation toward Kepler-438 originally piqued our interest because its features are roughly consistent with assumed ETI technosignatures. However, evidences such as its polarization characteristics are able to eliminate the possibility of an extraterrestrial origin. Our observations achieve an unprecedented sensitivity because the minimum equivalent isotropic radiated power we are able to detect reaches 1.48 × 109 W.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Astrobiology, Exoplanets
Tying Spitzer's IRS Calibration to IRAC: Observations of IRS Standard Stars. We present 3.6 and 4.5 μm photometry for a set of 61 standard stars observed by Spitzer's Infrared Spectrograph (IRS). The photometry was obtained with the Infrared Array Camera (IRAC) on Spitzer in order to help tie the calibration of IRAC and the IRS, which had been anchored to the calibration of the Multiband Infrared Photometer for Spitzer. The wavelength range of the IRS data only slightly overlaps with the IRAC 4.5 μm band and not at all with the 3.6 μm band. Therefore, we generated synthetic spectra from spectral templates of stars with the same spectral types and luminosity classes as our sample stars, normalized to the IRS data at 6-7 μm, and compared those to the observed photometry. The new IRAC observations of IRS standard stars demonstrate that the two instruments are calibrated to within 1% of each other.

Keywords: Infrared photometry, Flux calibration, Photometric standard stars, Spectrophotometric standards, Spectrophotometry
Double-mode Cepheids from the Zwicky Transient Facility Survey. Multimode Cepheids pulsate simultaneously in more than one mode of oscillation. They provide an independent means to test stellar models and pulsation theories. They can also be used to derive metallicities. In recent years, the number of known multimode Cepheids has increased dramatically with the discovery of a large number of Galactic double-mode Cepheids. To date, 209 double-mode Cepheids have been detected in the Galactic bulge and disk, mostly based on the Optical Gravitational Lensing Experiment's (OGLE) catalog. In this paper, we conduct a comprehensive search for double-mode Cepheids in the northern sky based on Zwicky Transient Facility Data Release 5. We found 72 such objects in the Milky Way. The periods of the 30 sample objects already included in the OGLE catalog show excellent agreement with the OGLE periods. The period ratios of our new Cepheids are consistent with those of known double-mode Cepheids, as evidenced by their loci in the so-called "Petersen diagram." Compared with OGLE, the completeness of our double-mode Cepheid sample is around 71%. The much improved temporal sampling of the Zwicky Transient Facility offers significant scope to find more double-mode Cepheids, especially at the distribution's short-period end.

Keywords: Double-mode Cepheid variable stars, Cepheid variable stars, Astronomy databases, Milky Way Galaxy
New Dynamical State and Habitability of the HD 45364 Planetary System. Planetary systems with multiple giant planets provide important opportunities to study planetary formation and evolution. The HD 45364 system hosts two giant planets that reside within the habitable zone (HZ) of their host star and was the first system discovered with a 3:2 mean motion resonance (MMR). Several competing migration theories with different predictions have previously provided explanations regarding the observed resonance through dynamical simulations that utilized limited data. Here, over ten years since the original discovery, we revisit the system with a substantially increased radial velocity (RV) sample from High Accuracy Radial Velocity Planet Searcher spectrograph and High Resolution Echelle Spectrometer that significantly extends the observational baseline. We present the revised orbital solutions for the two planets using both Keplerian and dynamical models. Our RV models suggest orbits that are more circular and separated than those previously reported. As a result, the predicted strong planet-planet interactions were not detected. The system dynamics were reanalyzed, and the planet pair was found to exhibit apsidal behavior of both libration and circulation, indicating a quasi-resonance state rather than being truly in MMR. The new orbital solution and dynamical state of the system confirm migration models that predicted near-circular orbits as the preferred scenario. We also study the habitability prospects of this system and found that an additional Earth-mass planet and exomoons in the HZ are possible. This work showcases the importance of continued RV observations and its impact on our knowledge of the system's dynamical history. HD 45364 continues to be an interesting target for both planetary formation and habitability studies.

Keywords: Exoplanet dynamics, Natural satellites (Extrasolar), Exoplanets, Exoplanet systems, Astrobiology, Radial velocity
A Mass-Magnitude Relation for Low-mass Stars Based on Dynamical Measurements of Thousands of Binary Star Systems. Stellar mass is a fundamental parameter that is key to our understanding of stellar formation and evolution, as well as the characterization of nearby exoplanet companions. Historically, stellar masses have been derived from long-term observations of visual or spectroscopic binary star systems. While advances in high-resolution imaging have enabled observations of systems with shorter orbital periods, measurements of stellar masses remain challenging, and relatively few have been precisely measured. We present a new statistical approach to measuring masses for populations of stars. Using Gaia astrometry, we analyze the relative orbital motion of &gt;3800 wide binary systems comprising low-mass stars to establish a mass-magnitude relation in the Gaia G RP band spanning the absolute magnitude range 14.5 &gt; ${M}_{{G}_{\mathrm{RP}}}$ &gt; 4.0, corresponding to a mass range of 0.08 M ⊙ ≲ M ≲ 1.0 M ⊙. This relation is directly applicable to &gt;30 million stars in the Gaia catalog. Based on comparison to existing mass-magnitude relations calibrated for K  s  magnitudes from the Two Micron All Sky Survey, we estimate that the internal precision of our mass estimates is ~10%. We use this relation to estimate masses for a volume-limited sample of ~18,200 stars within 50 pc of the Sun and the present-day field mass function for stars with M ≲ 1.0 M ⊙, which we find peaks at 0.16 M ⊙. We investigate a volume-limited sample of wide binary systems with early-K dwarf primaries, complete for binary mass ratios q &gt; 0.2, and measure the distribution of q at separations &gt;100 au. We find that our distribution of q is not uniform, rather decreasing toward q = 1.0.

Keywords: Binary stars, Astrostatistics, Stellar masses
On the Unusual Variability of 2MASS J06195260-2903592: A Long-lived Disk around a Young Ultracool Dwarf. We present the characterization of the low-gravity M6 dwarf 2MASS J06195260-2903592, previously identified as an unusual field object based on its strong IR excess and variable near-IR spectrum. Multiple epochs of low-resolution (R ≍ 150) near-IR spectra show large-amplitude (≍0.1-0.5 mag) continuum variations on timescales of days to 12 yr, unlike the small-amplitude variability typical for field ultracool dwarfs. The variations between epochs are well-modeled as changes in the relative extinction (∆A  V  ≍ 2 mag). Similarly, Panoramic Survey Telescope and Rapid Response System 1 optical photometry varies on timescales as long as 11 yr (and possibly as short as an hour) and implies comparable A  V  changes. Near Earth Object Wide-field Infrared Survey Explorer mid-IR light curves also suggest changes on 6 month timescales, with amplitudes consistent with the optical/near-IR extinction variations. However, near-IR spectra, near-IR photometry, and optical photometry obtained in the past year indicate that the source can also be stable on hourly and monthly timescales. From comparison to objects of similar spectral type, the total extinction of 2MASS J0619-2903 seems to be A  V  ≍ 4-6 mag, with perhaps epochs of lower extinction. Gaia Early Data Release 3 (EDR3) finds that 2MASS J0619-2903 has a wide-separation (1.'2 = 10,450 au) stellar companion, with an isochronal age of ${31}_{-10}^{+22}$ Myr and a mass of ${0.30}_{-0.03}^{+0.04}$ M ☉. Adopting this companion's age and EDR3 distance (145.2 ± 0.6 pc), we estimate a mass of 0.11-0.17 M ☉ for 2MASS J0619-2903. Altogether, 2MASS J0619-2903 appears to possess an unusually long-lived primordial circumstellar disk, perhaps making it a more obscured analog to the "Peter Pan" disks found around a few M dwarfs in nearby young moving groups.

Keywords: M dwarf stars, Circumstellar disks