adsabs/SciX_UAT_keywords huggingface dataset:
A More Precise Mass for GJ 1214 b and the Frequency of Multiplanet Systems Around Mid-M Dwarfs

We present an intensive effort to refine the mass and orbit of the enveloped terrestrial planet GJ 1214 b using 165 radial velocity (RV) measurements taken with the HARPS spectrograph over a period of 10 years. We conduct a joint analysis of the RVs with archival Spitzer/IRAC transits and measure a planetary mass and radius of 8.17 ± 0.43 M⊕ and ${2.742}_{-0.053}^{+0.050}$ R⊕. Assuming that GJ 1214 b is an Earth-like core surrounded by a H/He envelope, we measure an envelope mass fraction of Xenv = ${5.24}_{-0.29}^{+0.30}$ %. GJ 1214 b remains a prime target for secondary eclipse observations of an enveloped terrestrial, the scheduling of which benefits from our constraint on the orbital eccentricity of <0.063 at 95% confidence, which narrows the secondary eclipse window to 2.8 hr. By combining GJ 1214 with other mid-M-dwarf transiting systems with intensive RV follow up, we calculate the frequency of mid-M-dwarf planetary systems with multiple small planets and find that ${90}_{-21}^{+5}$ % of mid-M dwarfs with a known planet with mass ∈ [1, 10] M⊕ and orbital period ∈ [0.5, 50] days, will host at least one additional planet. We rule out additional planets around GJ 1214 down to 3 M⊕ within 10 days, such that GJ 1214 is a single-planet system within these limits. This result has a ${44}_{-5}^{+9}$ probability given the prevalence of multiplanet systems around mid-M dwarfs. We also investigate mid-M-dwarf RV systems and show that the probability that all reported RV planet candidates are real planets is <12% at 99% confidence, although this statistical argument is unable to identify the probable false positives.

Keywords: exoplanets; exoplanet structure; m dwarf stars; radial velocity; transits
A Coplanar Circumbinary Protoplanetary Disk in the TWA 3 Triple M Dwarf System

We present sensitive ALMA observations of TWA 3, a nearby, young (∼10 Myr) hierarchical system composed of three pre-main-sequence M3-M4.5 stars. For the first time, we detected 12CO and 13CO J = 2-1 emissions from the circumbinary protoplanetary disk around TWA 3A. We jointly fit the protoplanetary disk velocity field, stellar astrometric positions, and stellar radial velocities to infer the architecture of the system. The Aa and Ab stars (0.29 ± 0.01 M⊙ and 0.24 ± 0.01 M⊙, respectively) comprising the tight (P = 35 days) eccentric (e = 0.63 ± 0.01) spectroscopic binary are coplanar with their circumbinary disk (misalignment <6° with 68% confidence), similar to other short-period binary systems. From models of the spectral energy distribution, we found the inner radius of the circumbinary disk (rinner = 0.50-0.75 au) to be consistent with theoretical predictions of dynamical truncation rcav/ainner ≈ 3. The outer orbit of the tertiary star B (0.40 ± 0.28 M⊙, a ∼ 65 ± 18 au, e = 0.3 ± 0.2) is not as well constrained as the inner orbit; however, orbits coplanar with the A system are still preferred (misalignment < 20°). To better understand the influence of the B orbit on the TWA 3A circumbinary disk, we performed SPH simulations of the system and found that the outer edge of the gas disk (router = 8.5 ± 0.2 au) is most consistent with truncation from a coplanar, circular, or moderately eccentric orbit, supporting the preference from the joint orbital fit.

Keywords: protoplanetary disks; binary stars; trinary stars; stellar dynamics; pre-main sequence stars
NICMOS Kernel-phase Interferometry. I. Catalogue of Brown Dwarfs Observed in F110W and F170M

Filling out the dearth of detections between direct imaging and radial velocity surveys will test theories of planet formation and (sub)stellar binarity across the full range of semimajor axes, connecting formation of close- to wide-separation gas giants and substellar companions. Direct detection of close-in companions is notoriously difficult: coronagraphs and point-spread function subtraction techniques fail near the λ/D diffraction limit. We present a new faint companion detection pipeline called Argus that analyzes kernel phases, an interferometric observable analogous to closure phases from nonredundant aperture masking but utilizing the full unobscured telescope aperture. We demonstrate the pipeline, and the power of interferometry, by performing a companion search on the entire HST/NICMOS F110W and F170M image archive of 114 nearby brown dwarfs (observed in seven different programs). Our pipeline is able to detect companions down to flux ratios of ~102 at half the classical diffraction limit. We discover no new companions, but recover and refine astrometry of 19 previous imaging companions (two with multiple epochs) and confirm two previous kernel-phase detections. We discuss the limitations of this technique with respect to nondetections of previously confirmed or proposed companions. We present contrast curves to enable population studies to leverage nondetections and to demonstrate the strength of this technique at separations inaccessible to classical imaging techniques. The binary fraction of our sample ( ${\epsilon }_{b}={14.4}_{-3.0}^{+4.7}$ %) is consistent with previous binary surveys, even with sensitivity to much tighter separation companions.

Keywords: brown dwarfs; direct imaging; direct detection interferometry; interferometry; hubble space telescope; near infrared astronomy
Multiwavelength Emission from Galactic Jets: The Case of the Microquasar SS433

SS433 is a Galactic microquasar with powerful jets, where very-high-energy particles are produced. We study particle acceleration in the jets of SS433 through the use of recent multiwavelength data from radio to TeV gamma-ray. We first present a general framework for the particle acceleration, cooling, and transport in relativistic jets. We then apply this to two X-ray knots in the jets of SS433, focusing on leptonic emission. Our detailed treatment of particle transport and evolution produces substantially different predictions from previous papers. For both regions, our model can account for the multiwavelength data except for the GeV data. This suggests that GeV emission is mostly from different regions and/or mechanisms. We find that the acceleration process should be efficient, which could be realized by diffusive shock acceleration close to the Bohm limit. Provided that protons are accelerated at the same efficiency as electrons, our results imply that SS433 is a PeVatron, I.e., can accelerate protons beyond a PeV. Future hard X-ray and MeV gamma-ray observations can critically test our models by detecting the spectral turnover or cutoff.

Keywords: gamma-ray astronomy; non-thermal radiation sources; relativistic jets; x-ray astronomy; binary stars; cosmic ray sources; astrophysical black holes
Mitigating Cosmic Microwave Background Shadow Degradation of Tensor-to-scalar Ratio Measurements through Map-based Studies

It has been pointed out that the spurious cosmic microwave background (CMB) B-mode polarization signals caused by the absorption of the CMB monopole component due to the Galactic interstellar matter, called the CMB shadow, degrade the accuracy of detecting the CMB B-mode polarization signals imprinted by primordial gravitational waves. We have made a realistic estimation using simulated sky maps of how the CMB shadow affects forthcoming high-precision CMB B-mode experiments for the first time. The delta-map method, an internal template method taking into account the first-order spatial variation of foregrounds' spectral parameters, is applied as a foreground-removal method. We show that if the CMB shadow effects are not taken into account in the foreground-removal process, future observations would lead to the false detection of the CMB B-mode polarization signals originating from primordial gravitational waves. We also show that the effect of the CMB shadow can be mitigated by our revised delta-map method to target the CMB B-mode polarization signals at the level of tensor-to-scalar ratio r = 0.001.

Keywords: interstellar dust extinction; cosmic microwave background radiation; observational cosmology
Green Bank Telescope Observations of 3He+: Planetary Nebulae

We use the Green Bank Telescope to search for 3He+ emission from a sample of four Galactic planetary nebulae: NGC 3242, NGC 6543, NGC 6826, and NGC 7009. During the era of primordial nucleosynthesis, the light elements 2H, 3He, 4He, and 7Li were produced in significant amounts, and these abundances have since been modified primarily by stars. Observations of 3He+ in H II regions located throughout the Milky Way disk reveal very little variation in the 3He/H abundance ratio—the "3He Plateau"—indicating that the net effect of 3He production in stars is negligible. This is in contrast to much higher 3He/H abundance ratios reported for some planetary nebulae. This discrepancy is known as the "3He Problem." We use radio recombination lines observed simultaneously with the 3He+ transition to make a robust assessment of the spectral sensitivity that these observations achieve. We detect spectral lines at ∼1-2 mK intensities, but at these levels, instrumental effects compromise our ability to measure accurate spectral line parameters. We do not confirm reports of previous detections of 3He+ in NGC 3242 nor do we detect 3He+ emission from any of our sources. This result calls into question all reported detections of 3He+ emission from any planetary nebula. The 3He/H abundance upper limit we derive here for NGC 3242 is inconsistent with standard stellar production of 3He and thus requires that some type of extra-mixing process operates in low-mass stars.

Keywords: stellar nucleosynthesis; galaxy chemical evolution; planetary nebulae
Revisiting the Sołtan Argument Based on a Semianalytical Model for Galaxy and Black Hole Evolution

We show the significance of the super-Eddington accretion for the cosmic growth of supermassive black holes (SMBHs) with a semianalytical model for galaxy and black hole evolution. The model explains various observed properties of galaxies and active galactic nuclei at a wide redshift range. By tracing the growth history of individual SMBHs, we find that the fraction of the SMBH mass acquired during the super-Eddington accretion phases to the total SMBH mass becomes larger for less massive black holes and at higher redshift. Even at z ∼ 0, SMBHs with $\gt {10}^{9}{M}_{\odot }$ have acquired more than 50% of their mass by super-Eddington accretions, which is apparently inconsistent with the classical Sołtan argument. However, the mass-weighted radiation efficiency of SMBHs with $\gt {10}^{8}{M}_{\odot }$ obtained with our model, is about 0.08 at z ∼ 0, which is consistent with Sołtan's argument within the observational uncertainties. We, therefore, conclude that Sołtan's argument cannot reject the possibility that SMBHs are grown mainly by super-Eddington accretions.

Keywords: active galactic nuclei; supermassive black holes; galaxy formation
THOR 42: A Test of Magnetic Models for Pre-main-sequence Stars

Precise masses and radii have been reported by Murphy et al. for the components of the THOR 42 binary. Murphy et al. provide evidence that, in their opinion, supports an earlier suggestion by Bell et al. that THOR 42 is a member of the 32 Ori moving group, which, according to Bell et al., has an age of about 24 Myr. From the positions of the THOR 2 components in the mass-radius diagram (MRD), Murphy et al. derive ages of 22-26 Myr using standard (nonmagnetic) models. However, they also find that these models cannot simultaneously reproduce the observed masses, radii, effective temperatures, and luminosities of the assumed coeval components. Their Hertzsprung-Russell diagram (HRD) ages are found to be 2-4 times younger than the MRD ages, and the masses determined from the HRD are found to be ∼50% smaller than the dynamical masses. Here, we attempt to replicate the precise global properties of THOR 24 by applying a model of magnetoconvection. We find that MRD isochrones and HRD isochrones lead to consistent ages provided that the surface magnetic fields have strengths of 300-400 G. However, the ages that our models yield for THOR 24 are in the vicinity of 40 Myr. If this age estimate is correct, it could call into question the membership of THOR 42 in the 32 Ori moving group.

Keywords: eclipsing binary stars; pre-main sequence stars; stellar magnetic fields; stellar evolutionary models
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VI. The Star Formation History and Dust Production in Andromeda IX

We present a photometric study of the resolved stellar populations in Andromeda IX (And IX), the closest satellite to M31, a metal-poor and low-mass dwarf spheroidal galaxy. We estimate a distance modulus of ${24.56}_{-0.15}^{+0.05}$ mag based on the tip of the red giant branch. By probing the variability of asymptotic giant branch stars, we study the star formation history of And IX. We identified 50 long-period variables (LPVs) in And IX using the Isaac Newton Telescope in two filters, the Sloan $i^{\prime} $ and Harris V. In this study, we selected LPVs within two half-light radii with amplitudes in the range of 0.2-2.20 mag. It is found that the peak of star formation reaches ~8.2 ± 3.1 × 10-4 M ⊙ yr-1 at ≈6 Gyr ago. Our findings suggest an outside-in galaxy formation scenario for And IX with a quenching occurring ${3.65}_{-0.13}^{+1.52}$ Gyr ago with a star formation rate (SFR) in the order of 2.0 × 10-4 M ⊙ yr-1 at redshift <0.5. We calculate the total stellar mass by integrating the SFR within two half-light radii ~3.0 × 105 M ⊙. By employing spectral energy distribution fitting for the observed LPVs in And IX, we evaluate a mass-loss rate in the range of 10-7 ≤ $\dot{M}$ ≤ 10-5 M ⊙ yr-1. Finally, we show that the total mass deposition to the interstellar medium (ISM) is ~2.4 × 10-4 M ⊙ yr-1 from the C- and O-rich types of dust-enshrouded LPVs. The ratio of the total mass returned to the ISM by LPVs to the total stellar mass is ~8.0 × 10-10 yr-1, and so at this rate it would take ~1 Gyr to reproduce this galaxy.

Keywords: local group; dwarf galaxies; star formation; evolved stars; asymptotic giant branch stars; stellar mass loss; dwarf spheroidal galaxies
Timing the Early Assembly of the Milky Way with the H3 Survey

The archeological record of stars in the Milky Way opens a uniquely detailed window into the early formation and assembly of galaxies. Here we use 11,000 main-sequence turn-off stars with well-measured ages, $[\mathrm{Fe}/{\rm{H}}]$ , $[\alpha /\mathrm{Fe}]$ , and orbits from the H3 Survey and Gaia to time the major events in the early Galaxy. Located beyond the Galactic plane, $1\lesssim | Z| /\mathrm{kpc}\lesssim 4$ , this sample contains three chemically distinct groups: a low-metallicity population, and low-α and high-α groups at higher metallicity. The age and orbit distributions of these populations show that (1) the high-α group, which includes both disk stars and the in situ halo, has a star formation history independent of eccentricity that abruptly truncated 8.3 ± 0.1 Gyr ago (z ≃ 1); (2) the low-metallicity population, which we identify as the accreted stellar halo, is on eccentric orbits and its star formation truncated $10.2{.}_{-0.1}^{+0.2}$ Gyr ago (z ≃ 2); (3) the low-α population is primarily on low-eccentricity orbits and the bulk of its stars formed less than 8 Gyr ago. These results suggest a scenario in which the Milky Way accreted a satellite galaxy at z ≈ 2 that merged with the early disk by z ≈ 1. This merger truncated star formation in the early high-α disk and perturbed a fraction of that disk onto halo-like orbits. The merger enabled the formation of a chemically distinct, low-α disk at z ≲ 1. The lack of any stars on halo-like orbits at younger ages indicates that this event was the last significant disturbance to the Milky Way disk.

Keywords: milky way stellar halo; milky way dynamics; galaxy evolution; astrometry; galaxy chemical evolution; galaxy formation; spectroscopy; stellar ages; milky way galaxy
JWST and ALMA Imaging of Dust-obscured, Massive Substructures in a Typical z ∼ 3 Star-forming Disk Galaxy

We present an identification of dust-attenuated star-forming galactic-disk substructures in a typical star-forming galaxy (SFG), UDF2, at z = 2.696. To date, substructures containing significant buildup of stellar mass and actively forming stars have yet to be found in typical (i.e., main-sequence) SFGs at z > 2. This is due to the strong dust attenuation common in massive galaxies at the epoch and the scarcity of high-resolution, high-sensitivity extinction-independent imaging. To search for disk substructures, we subtracted the central stellar-mass disk from the JWST/NIRCam rest-frame 1.2 μm image (0.″13 resolution) and subtracted, in the visibility plane, the central starburst disk from Atacama Large Millimeter/submillimeter Array (ALMA) rest-frame 240 μm observations (0.″03 resolution). The residual images revealed substructures at rest-frame 1.2 μm colocated with those found at rest-frame 240 μm, ≃2 kpc away from the galactic center. The largest substructure contains ≃20% of the total stellar mass and ≃5% of the total star formation rate of the galaxy. While UDF2 exhibits a kinematically ordered velocity field of molecular gas consistent with a secularly evolving disk, more sensitive observations are required to characterize the nature and the origin of this substructure (spiral arms, minor merger, or other types of disk instabilities). UDF2 resides in an overdense region (N ≥ 4 massive galaxies within 70 kpc projected distance at z = 2.690-2.697) and the substructures may be associated with interaction-induced instabilities. Importantly, a statistical sample of such substructures identified with JWST and ALMA could play a key role in bridging the gap between the bulge-forming starburst and the rest of the galaxy.

Keywords: galaxy structure; high-redshift galaxies
Ultraviolet and Chromospheric Activity and Habitability of M Stars

M-type stars are crucial for stellar activity studies because they cover two types of magnetic dynamos and are particularly intriguing for habitability studies due to their abundance and long lifespans during the main-sequence stage. In this paper, we used the LAMOST DR9 catalog and the GALEX UV archive data to investigate the chromospheric and UV activities of M-type stars. All the chromospheric and UV activity indices clearly show that the saturated and unsaturated regimes, and the well-known activity–rotation relation, are consistent with previous studies. Both the FUV and NUV activity indices exhibit a single-peaked distribution, while the Hα and Ca II H&K indices show a distinct double-peaked distribution. The gap between these peaks suggests a rapid transition from a saturated population to an unsaturated one. The smoothly varying distributions of different subtypes suggest a rotation-dependent dynamo for both early-type (partly convective) to late-type (fully convective) M stars. We identified a group of stars with high UV activity above the saturation regime (log ${R}_{\mathrm{NUV}}^{{\prime} }\gt -2.5$ ) but low chromospheric activity, and the underlying reason is unknown. By calculating the continuously habitable zone and the UV habitable zone for each star, we found that about 70% stars in the total sample and 40% stars within 100 pc are located in the overlapping region of these two habitable zones, indicating that a number of M stars are potentially habitable. Finally, we examined the possibility of UV activity studies of M stars using the China Space Station Telescope.

Keywords: stellar activity; m stars; late-type stars; ultraviolet photometry; ultraviolet observatories; habitable zone
Probing the Low-mass End of Core-collapse Supernovae Using a Sample of Strongly-stripped Calcium-rich Type IIb Supernovae from the Zwicky Transient Facility

The fate of stars in the zero-age main-sequence (ZAMS) range ≈8-12 M ⊙ is unclear. They could evolve to form white dwarfs or explode as electron-capture supernovae (SNe) or iron core-collapse SNe (CCSNe). Even though the initial mass function indicates that this mass range should account for over 40% of all CCSN progenitors, few have been observationally confirmed, likely due to the faintness and rapid evolution of some of these transients. In this paper, we present a sample of nine Ca-rich/O-poor Type IIb SNe detected by the Zwicky Transient Facility with progenitors likely in this mass range. These sources have a [Ca II] λ λ7291, 7324/[O I] λ λ6300, 6364 flux ratio of ≳2 in their nebular spectra. Comparing the measured [O I] luminosity (≲1039 erg s-1) and derived oxygen mass (≈0.01 M ⊙) with theoretical models, we infer that the progenitor ZAMS mass for these explosions is less than 12 M ⊙. The ejecta properties (M ej ≲ 1 M ⊙ and E kin ~ 1050 erg) are also consistent. The low ejecta mass of these sources indicates a class of strongly-stripped SNe that is a transition between the regular stripped-envelope SNe and ultra-stripped SNe. The progenitor could be stripped by a main-sequence companion and result in the formation of a neutron star-main sequence binary. Such binaries have been suggested to be progenitors of neutron star-white dwarf systems that could merge within a Hubble time and be detectable with LISA.

Keywords: supernovae; core-collapse supernovae; compact binary stars
On the Orbital Elements of the Two-body Problem with Slowly Decreasing Mass: The Gyldén-Mestchersky Cases

We study the dynamics of two-body problems with gravitational parameters μ = μ(t) decreasing with the time. In particular we focus our attention on the behavior of the orbital elements in the first two Gyldén-Mestchersky cases: in the first case (GM-I) $\mu {(t)={\mu }_{0}(1+\alpha t)}^{-1}$ , where μ0 is the constant initial value of the parameter and α a small positive constant. In the second case (GM-II) $\mu {(t)={\mu }_{0}(1+2\alpha t)}^{-1/2}$ . In the GM-I problem, using a suitable transformation of the radius vector and the physical time, which reduces the original problem to a pure Kepler problem, we are able to obtain explicit analytical expressions of the orbital elements that hold true for all $t\geqslant 0$ and therefore derive their asymptotic behavior. Moreover using the alternative scaled time these expressions show clearly their periodic and secular terms. For the GM-II problem a similar transformation to the GM-I problem leads to a perturbed Kepler problem with a radial direction perturbation. Although exact solutions in terms of elliptic functions may be obtained, the use of some integrals leads to analytical expressions of orbital elements that allow us to study their behavior. Finally, some comparisons between the time evolution of elements in both problems are also included.

Keywords: celestial mechanics; stellar mass loss
Thermodynamics of Pickup Ions in the Heliosphere

The paper shows the thermodynamic nature of the evolution of the pickup ion (PUI) distributions through their incorporation and subsequent expansion as the solar wind moves outward through the heliosphere. In particular, the PUI expansive cooling is connected to thermodynamic polytropic processes and the thermodynamic kappa parameter. Previously, the characterization of the cooling was phenomenologically given by a "cooling index" α, which is the exponent involved in the power-law relationship between PUI speed and position. Here, we develop the relationship between the cooling and polytropic indices. Then, we show the connection between the cooling index and the thermodynamic parameter kappa. Finally, we verify the derived thermodynamic relations with direct heliospheric observations over varying distances from the Sun. Going forward, we suggest that studies of PUIs seeking to understand the underlying physics of these important particles rely on the thermodynamic parameter of kappa, and its association with the polytropic index, and not on an ad hoc cooling index.

Keywords: space plasmas; heliosphere; solar wind