Mass Estimates Research Articles

Image processing based modeling for Rosa roxburghii fruits mass and volume estimation

The mass and volume of Rosa roxburghii fruits are essential for fruit grading and consumer selection. Physical characteristics such as dimension, projected area, mass, and volume are interrelated. Image-based mass and volume estimation facilitates the automation of fruit grading, which can replace time-consuming and laborious manual grading. In this study, image processing techniques were used to extract fruit dimensions and projected areas, and univariate (linear, quadratic, exponential, and power) and multivariate regression models were used to estimate the mass and volume of Rosa roxburghii fruits. The results showed that the quadratic model based on the criterion projected area (CPA) estimated the best mass (R2 = 0.981) with an accuracy of 99.27%, and the equation is M = 0.280 + 0.940CPA + 0.071CPA2. The multivariate regression model based on three projected areas (PA1, PA2, and PA3) estimated the best volume (R2 = 0.898) with an accuracy of 98.24%, and the equation is V = − 8.467 + 0.657PA1 + 1.294PA2 + 0.628PA3. In practical applications, cost savings can be realized by having only one camera position. Therefore, when the required accuracy is low, estimating mass and volume simultaneously from only the dimensional information of the side view or the projected area information of the top view is recommended.

Two dynamically discovered compact object candidate binary systems from LAMOST low-resolution survey

ABSTRACT We report two binary systems, LAMOST J035540 + 381550 (hereafter J035540) and LAMOST J035916 + 400732 (hereafter J035916), identified through the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low-resolution survey (LRS). Each of these two systems contains an M-type star orbiting with a invisible compact object candidate. Follow-up spectroscopic observations of Palomar 200-in. telescope (P200) enhance radial velocity measurements. We use radial velocities from LAMOST and P200, as well as light curves from Zwicky Transient Facility (ZTF) to constrain orbital parameters. The masses of the visible M-type stars are estimated by fitting the MIST isochrones and spectral energy distributions. The mass functions for the unseen companions are: $0.22\pm 0.01\,{\rm M}_{\odot }$ for J035540 and $0.16\pm 0.01\, {\rm M}_{\odot }$ for J035916. With the orbital and stellar parameters derived above and assuming the orbital inclination is 90° (edge-on), we find that the minimum masses of the invisible companions exceeds that of the visible stars. The single-lined feature and the dynamical evidence suggest the presence of compact objects. J035540’s ZTF light curve, modelled with phoebe, yields a compact object mass of $0.70^{+0.12}_{-0.05}\, {\rm M}_{\odot }$. For J035916, ellipsoidal modulation analysis constrains the light-curve amplitude, yielding a compact object mass range of $0.57-0.90\, {\rm M}_{\odot }$. The mass estimates indicate that both are likely white dwarfs. These findings underscore the efficiency of optical time-domain surveys and dynamical methods in identifying faint, massive white dwarfs, along with other compact objects in binaries.

Probing the dynamical and kinematical structures of detached shells around AGB stars

Context. The chemical evolution of asymptotic giant branch (AGB) stars is driven by repeated thermal pulses (TPs). The duration of a TP is only a few hundred years, whereas an inter-pulse period lasts 104 − 105 yr. Direct observations of TPs are hence unlikely. However, the detached shells seen in CO line emission that are formed as a result of a TP provide indirect constraints on the changes experienced by the star during the pulse. Aims. We aim to resolve the spatial and kinematic sub-structures in five detached-shell sources to provide detailed constraints for hydrodynamic models that describe the formation and evolution of the shells. Methods. We used observations of the 12CO (1 − 0) emission towards five carbon-AGB stars with ALMA (Atacama Large Millimeter/submillimeter Array), including previously published observations of the carbon AGB star U Ant. The data have angular resolutions of 0″​​.3 to 1″ and a velocity resolution of 0.3 km s−1. This enabled us to quantify spatial and kinematic structures in the shells. Combining the ALMA data with single-dish observations of the 12CO (1 − 0) to 12CO (4 − 3) emission towards the sources, we used radiative transfer models to compare the observed structures with previous estimates of the shell masses and temperatures. Results. The observed emission is separated into two distinct components: a more coherent, bright outer shell and a more filamentary, fainter inner shell. The kinematic information shows that the inner sub-shells move at a higher velocity relative to the outer sub-shells. The observed sub-structures reveal a negative velocity gradient outwards across the detached shells, confirming the predictions from hydrodynamical models. However, the models do not predict a double-shell structure, and the CO emission likely only traces the inner and outer edges of the shell, implying a lack of CO in the middle layers of the detached shell. Previous estimates of the masses and temperatures are consistent with originating mainly from the brighter subshell, but the total shell masses are likely lower limits. Also, additional structures in the form of partial shells outside the detached shell around V644 Sco, arcs within the shell of R Scl, and a partially filled shell for DR Ser indicate a more complicated evolution of the shells and mass-loss process throughout the TP cycle than previously assumed. Conclusions. The observed spatial and kinematical splittings of the shells appear consistent with results from the hydrodynamical models, provided the CO emission does not trace the H2 density distribution in the shell but rather traces the edges of the shells. The hydrodynamical models predict very different density profiles depending on the evolution of the shells and the different physical processes involved in the wind-wind interaction (e.g. heating and cooling processes). It is therefore not possible to constrain the total shell mass based on the CO observations alone. Additional features outside and inside the shells complicate the interpretation of the data. Complementary observations of, for example, CI as a dissociation product of CO would be necessary to understand the distribution of CO compared to H2, in addition to new detailed hydrodynamical models of the pre-pulse, pulse, and post-pulse wind. Only a comprehensive combination of observations and models will allow us to constrain the evolution of the shells and the changes in the star during the thermal-pulse cycle.

X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes?

The discovery of Little Red Dots (LRDs)—a population of compact, high-redshift, dust-reddened galaxies—is one of the most surprising results from JWST. However, the nature of LRDs is still debated: does the near-infrared emission originate from accreting supermassive black holes (SMBHs), or intense star formation? In this work, we utilize ultra-deep Chandra observations and study LRDs residing behind the lensing galaxy cluster, A2744. We probe the X-ray emission from individual galaxies but find that they remain undetected and provide SMBH mass upper limits of ≲(1.5–16) × 106 M ⊙ assuming Eddington limited accretion. To increase the signal-to-noise ratios, we conduct a stacking analysis of the full sample with a total lensed exposure time of ≈87 Ms. We also bin the galaxies based on their stellar mass, lensing magnification, and detected broad-line Hα emission. For the LRDs exhibiting broad-line Hα emission, there is a hint of a stacked signal (∼2.6σ), corresponding to an SMBH mass of ∼3.2 × 106 M ⊙. Assuming unobscured, Eddington-limited accretion, this black hole (BH) mass is at least 1.5 orders of magnitude lower than that inferred from virial mass estimates using JWST spectra. Given galaxy-dominated stellar mass estimates, our results imply that LRDs do not host overmassive SMBHs and/or accrete at a few percent of their Eddington limit. However, alternative stellar mass estimates may still support that LRDs host overmassive BHs. The significant discrepancy between the JWST and Chandra data hints that the scaling relations used to infer the SMBH mass from the Hα line and virial relations may not be applicable for high-redshift LRDs.

GN-z11: The environment of an active galactic nucleus atz = 10.603

Recent observations with theJames WebbSpace Telescope (JWST) have further refined the spectroscopic redshift of GN-z11, one of the most distant galaxies identified with theHubbleSpace Telescope, atz = 10.603. The presence of extremely dense gas (> 1010cm−3), the detection of high-ionisation lines and of CII*1335 emission, and the presence of an ionisation cone indicate that GN-z11 also hosts an active galactic nucleus. Further photometric and spectroscopic follow-up demonstrates that it lies in a large-scale, overdense structure with possible signatures of Population III stars in its halo. Surprisingly, Lyαhas also been detected despite the expected largely neutral intergalactic medium at such a redshift. We exploit recent JWST/NIRSpec integral field unit observations to demonstrate that the Lyαemission in GN-z11 is part of an extended halo with a minimum size of 0.8–3.2 kpc, depending on the definition used to derive the halo size. The surface brightness of the Lyαhalo around GN-z11 appears consistent with Lyαhalos observed aroundz ∼ 6 quasars. At the wavelength of Lyαatz ∼ 10.6, we identify three other emission line candidates within the integral field unit field of view with no UV rest-frame counterpart visible in deep images from the JWST/NIRCam. If confirmed, this could be the first evidence that the local region of GN-z11 represents a candidate protocluster core, forming just 400 Myr after the Big Bang. We give a first estimate of the dark matter halo mass of this structure (Mh = 2.96−0.39+0.44 × 1010 M⊙), which is consistent with a Coma-like cluster progenitor.

Kaleidoscope of irradiated disks: MUSE observations of proplyds in the Orion Nebula Cluster

In the Orion Nebula Cluster (ONC), protoplanetary disks exhibit ionized gas clouds in the form of a striking teardrop shape as massive stars irradiate the disk material. We present the first spatially and spectrally resolved observations of 12 such objects, known as proplyds, using integral field spectroscopy observations performed with the Multi-Unit Spectroscopic Explorer (MUSE) instrument in Narrow Field Mode (NFM) on the Very Large Telescope (VLT). We present the morphology of the proplyds in seven emission lines and measure the radius of the ionization front (I-front) of the targets in four tracers, covering transitions of different ionization states for the same element. We also derive stellar masses for the targets. The measurements follow a consistent trend of increasing I-front radius for a decreasing strength of the far-UV radiation as expected from photoevaporation models. By analyzing the ratios of the I-front radii as measured in the emission lines of Hα, [O I] 6300 A, [O II] 7330 A, and [O III] 5007 A, we observe the ionization stratification, that is, the most ionized part of the flow being the furthest from the disk (and closest to the UV source). The ratios of ionization front radii scale in the same way for all proplyds in our sample regardless of the incident radiation. We show that the stratification can help constrain the densities near the I-front by using a 1D photoionization model. We derive the upper limits of photoevaporative mass-loss rates (Ṁloss) by assuming ionization equilibrium, and estimate values in the range 1.07–94.5 × 10−7 M⊙ yr−1, with Ṁloss values decreasing towards lower impinging radiation. We do not find a correlation between the mass-loss rate and stellar mass. The highest mass-loss rate is for the giant proplyd 244–440. These values of Ṁloss, combined with recent estimates of the disk mass with ALMA, confirm previous estimates of the short lifetime of these proplyds. This work demonstrates the potential of this MUSE dataset and offers a new set of observables to be used to test current and future models of external photoevaporation.

Sensitive 3 mm Imaging of Discrete Sources in the Fields of Thermal Sunyaev–Zel’dovich Effect–Selected Galaxy Clusters

In this paper, we present the results of a blind survey for compact sources in 243 Galaxy clusters that were identified using the thermal Sunyaev–Zel'dovich effect (tSZ). The survey was carried out at 90 GHz using MUSTANG2 on the Green Bank Telescope and achieved a 5σ detection limit of 1 mJy in the center of each cluster. We detected 24 discrete sources. The majority (18) of these correspond to known radio sources, and of these, five show signs of significant variability, either with time or in spectral index. The remaining sources have no clear counterparts at other wavelengths. Searches for galaxy clusters via the tSZ strongly rely on observations at 90 GHz, and the sources found have the potential to bias mass estimates of clusters. We compare our results to the Websky simulation that can be used to estimate the source contamination in galaxy cluster catalogs. While the simulation shows a good match to our observations at the clusters’ centers, it does not match our source distribution further out. Sources over 104″ from a cluster’s center bias the tSZ signal high, for some of the sources found, by over 50%. When averaged over the whole cluster population, the effect is smaller but still at a level of 1%–2%. We also discovered that unlike previous measurements and simulations, we see an enhancement of source counts in the outer regions of the clusters and fewer sources than expected in the centers of this tSZ-selected sample.

Simulating the LOcal Web (SLOW)

Context. This is the second paper in a series presenting the results from a 500 h−1Mpc large constrained simulation of the local Universe (SLOW). The initial conditions for this cosmological hydro-dynamical simulation are based on peculiar velocities derived from the CosmicFlows-2 catalog. The simulation follows cooling, star formation, and the evolution of super-massive black holes. This allows one to directly predict observable properties of the intracluster medium (ICM) within galaxy clusters, including X-ray luminosity, temperatures, and the Compton-y signal. Aims. Comparing the properties of observed galaxy clusters within the local Universe with the properties of their simulated counterparts enables us to assess the effectiveness of the initial condition constraints in accurately replicating the mildly nonlinear properties of the largest, collapsed objects within the simulation. Methods. Based on the combination of several, publicly available surveys we compiled a sample of galaxy clusters within the local Universe, of which we were able to cross-identify 46 of them with an associated counterpart within the SLOW simulation. We then derived the probability of the cross identification based on mass, X-ray luminosity, temperature, and Compton-y by comparing it to a random selection. Results. Our set of 46 cross-identified local Universe clusters contains the 13 most massive clusters from the Planck SZ catalog as well as 70% of clusters with M500 larger than 2 × 1014 M⊙. Compared to previous constrained simulations of the local volume, we found in SLOW a much larger amount of replicated galaxy clusters, where their simulation-based mass prediction falls within the uncertainties of the observational mass estimates. Comparing the median observed and simulated masses of our cross-identified sample allows us to independently deduce a hydrostatic mass bias of (1 − b)≈0.87. Conclusions. The SLOW constrained simulation of the local Universe faithfully reproduces numerous fundamental characteristics of a sizable number of galaxy clusters within our local neighborhood, opening a new avenue for studying the formation and evolution of a large set of individual galaxy clusters as well as testing our understanding of physical processes governing the ICM.

Comparison of body composition measures assessed by bioelectrical impedance analysis versus dual-energy X-ray absorptiometry in the United Kingdom Biobank

BackgroundBioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) serves as common modalities for body composition assessment. This study was aimed to evaluate the agreement between BIA and DXA measures in UK Biobank. MethodsUK Biobank participants with body fat mass (FM) and fat-free mass (FFM) estimates obtained through BIA (Tanita BC418MA) and DXA concurrently were included. Correlation between BIA and DXA-derived estimates were assessed with Lin’s concordance correlation coefficients. Bland-Altman and Passing-Boblok analyses were performed to quantify the difference and agreement between BIA and DXA. Multivariable linear regression was used to identify predictors influencing the differences. Finally, prediction models were developed to calibrate BIA measures against DXA. ResultsThe analysis included 34437 participants (female 51.4%, mean age 64.1 years at imaging assessment). BIA and DXA measurements were highly correlated (Lin’s concordance correlation coefficient 0.94 for FM and 0.94 for FFM). BIA (Tanita BC418MA) underestimates FM overall by 1.84 kg (23.77 vs. 25.61, p < 0.01), and overestimated FFM overall by 2.56 kg (52.49 vs. 49.93, p < 0.01). The BIA-DXA differences were associated with FM, FFM, BMI and waist circumference. The developed prediction models showed overall good performance in calibrating BIA data. ConclusionOur analysis exhibited strong correlation between BIA (Tanita BC418MA)- and DXA-derived body composition measures at a population level in UK Biobank. However, the BIA-DXA differences were observed at individual level and associated with individual anthropometric measures. Future studies may explore the use of prediction models to enhance the calibration of BIA measures for more accurate assessments in UK Biobank.

Distortions of the Hubble diagram: Line-of-sight signatures of local galaxy clusters

The Universe expansion rate is modulated around local inhomogeneities due to their gravitational potential. Velocity waves are then observed around galaxy clusters in the Hubble diagram. This paper studies them in a ∼738 Mpc-wide, 20483-particle cosmological simulation of our cosmic environment (a.k.a. CLONE: Constrained LOcal &amp; Nesting Environment Simulation). For the first time, the simulation shows that velocity waves that arise in the lines of sight of the most massive dark matter halos agree with those observed in local galaxy velocity catalogs in the lines of sight of Coma and several other local (Abell) clusters. For the best-constrained clusters such as Virgo and Centaurus – that is, those closest to us – secondary waves caused by galaxy groups, further into the non-linear regime, also stand out. This match was not utterly expected given that before being evolved into a fully non-linear z = 0 state, assuming ΛCDM, CLONE initial conditions are constrained solely with linear theory, the power spectrum, and highly uncertain and sparse local peculiar velocities. Additionally, Gaussian fits to velocity wave envelopes show that wave properties are tightly tangled with cluster masses. This link is complex, though, and involves the environment and formation history of the clusters. A proposed metric, measuring the distance between the observed and several re-centred simulated lines of sight, waves included, is shown to be capable of providing a tight mass range estimate for massive local clusters. Using machine learning techniques to grasp more thoroughly the complex wave-mass relation, velocity waves could in the near future be used to provide additional and independent mass estimates from galaxy dynamics within large cluster radii.

Metal factories in the early Universe

ABSTRACT We have estimated the mass of metals in the molecular gas in 13 dusty star-forming galaxies at $z \sim 4$ in which the gas, based on previous observations, lies in a cold rotating disc. We estimated the metal masses using either the submillimetre line or continuum emission from three tracers of the overall metal content – carbon atoms, carbon monoxide molecules, and dust grains – using the first simultaneous calibration of all three tracers. We obtain very similar mass estimates from the different tracers, which are similar to the entire metal content of a present-day massive early-type galaxy. We used the dynamical masses of these galaxies to estimate an upper limit on the mass of the molecular gas in each galaxy, allowing us to estimate a lower limit on the metal abundance of the gas, finding values for many of the galaxies well above the solar value. We show that the high metal masses and metal abundances are what is expected shortly after the formation of a galaxy for a top-heavy IMF. We suggest a scenario for galaxy evolution in which massive galaxies reach a high metal abundance during their formation phase, which is then gradually reduced by dry mergers with lower mass galaxies. We show that the metals in the outflows from high-redshift dusty star-forming galaxies can quantitatively explain the long-standing puzzle that such a large fraction of the metals in galaxy clusters ($\simeq$0.75) is in the intracluster gas rather than in the galaxies themselves.

MIDIS: JWST/MIRI Reveals the Stellar Structure of ALMA-selected Galaxies in the Hubble Ultra Deep Field at Cosmic Noon

We present deep James Webb Space Telescope (JWST)/Mid-Infrared Instrument (MIRI) F560W observations of a flux-limited, Atacama Large Millimeter/submillimeter Array (ALMA)-selected sample of 28 galaxies at z = 0.5–3.7 in the Hubble Ultra Deep Field (HUDF). The data from the MIRI Deep Imaging Survey (MIDIS) reveal the stellar structure of the HUDF galaxies at rest-frame wavelengths of λ > 1 μm for the first time. We revise the stellar mass estimates using new JWST photometry and find good agreement with pre-JWST analyses; the few discrepancies can be explained by blending issues in the earlier lower-resolution Spitzer data. At z ∼ 2.5, the resolved rest-frame near-infrared (1.6 μm) structure of the galaxies is significantly more smooth and centrally concentrated than seen by the Hubble Space Telescope at rest-frame 450 nm (F160W), with effective radii of R e (F560W) = 1–5 kpc and Sérsic indices mostly close to an exponential (disk-like) profile (n ≈ 1), up to n ≈ 5 (excluding active galactic nuclei). We find an average size ratio of R e (F560W)/R e (F160W) ≈ 0.7 that decreases with stellar mass. The stellar structure of the ALMA-selected galaxies is indistinguishable from a HUDF reference sample of all galaxies with a MIRI flux density greater than 1 μJy. We supplement our analysis with custom-made, position-dependent, empirical point-spread function models for the F560W observations. The results imply that a smoother stellar structure is in place in massive gas-rich, star-forming galaxies at “Cosmic Noon,” despite a more clumpy rest-frame optical appearance, placing additional constraints on galaxy formation simulations. As a next step, matched-resolution, resolved ALMA observations will be crucial to further link the mass- and light-weighted galaxy structures to the dusty interstellar medium.

Approaching a population‐level assessment of body size in pinnipeds using drones, an early warning of environmental degradation

AbstractBody mass is a fundamental indicator of animal health closely linked to survival and reproductive success. Systematic assessment of body mass for a large proportion of a population can allow early detection of changes likely to impact population growth, facilitating responsive management and a mechanistic understanding of ecological trends. One challenge with integrating body mass assessment into monitoring is sampling enough animals to detect trends and account for individual variation. Harbour seals (Phoca vitulina) are philopatric marine mammals responsive to regional environmental changes, resulting in their use as an indicator species. We present a novel method for the non‐invasive and semi‐automatic assessment of harbour seal body condition, using unoccupied aerial vehicles (UAVs/drones). Morphological parameters are automatically measured in georeferenced images and used to estimate volume, which is then translated to estimated mass. Remote observations of known individuals are utilized to calibrate the method. We achieve a high level of accuracy (mean absolute error of 4.5 kg or 10.5% for all seals and 3.2 kg or 12.7% for pups‐of‐the‐year). We systematically apply the method to wild seals during the Spring pupping season and Autumn over 2 years, achieving a near‐population‐level assessment for pups on land (82.5% measured). With reference to previous mark‐recapture work linking Autumn pup weights to survival, we estimate mean expected probability of over‐winter survival (mean = 0.89, standard deviation = 0.08). This work marks a significant step forward for the non‐invasive assessment of body condition in pinnipeds and could provide daily estimates of body mass for thousands of individuals. It can act as an early warning for deteriorating environmental conditions and be utilized as an integrative tool for wildlife monitoring. It also enables estimation of yearly variation in demographic rates which can be utilized in parameterizing models of population growth with relevance for conservation and evolutionary biology.

Floodplain morphology influences arsenic and antimony spatial distribution in a seasonal acid sulfate soil wetland

Arsenic (As) and antimony (Sb) often co-occur in floodplain depositional environments that are contaminated by legacy mining activities. However, the distribution of As and Sb throughout floodplains is not uniform, adding complexity and expense to management or remediation processes. Identifying floodplain morphology predictor variables that help quantify and explain As and Sb spatial distribution on floodplains is useful for management and remediation. We developed As and Sb risk maps estimating concentration and availability at a coastal floodplain wetland impacted by upper-catchment mining. Significant predictors of As and Sb concentrations included i) distance from distributary channel-wetland intersection and ii) elevation. Distance from channel explained 53 % (P < 0.01) and 28 % (P < 0.01), while elevation explained 42 % (P < 0.01) and 47 % (P < 0.01) of the variability in near-total Sb and As respectively. As had a higher extractability than Sb across all tested soil extractions, suggesting that As is more environmentally available. As and Sb dry mass estimates to a depth of 0.1 m scaled to the lower coastal Macleay floodplain ranged from 113–192 tonnes and 14–24 tonnes respectively. Landscape-scale modelling of metalloid distribution, informed by morphology variables, presented here may be a useful framework for the development of risk maps in other regions impacted by contaminated upper-catchment sediments.

Land of the giants: Body mass estimates of Palaeoloxodon from the Pleistocene of Taiwan

The sea bottom of Taiwan Strait harbors a Late Pleistocene paleo-ecosystem significantly distinct from the present ecosystem structure in Taiwan. The assemblage constitutes fossil remains from the genus Palaeoloxodon, the largest known lineage of proboscideans to have walked on Earth. Body mass holds a pivotal role in our understanding of an organism's biology, ecology, life history, and susceptibility to extinction, and thus, is a key trait while working with extinct taxa. Here we, for the first time, assess the body mass of Palaeoloxodon specimens from Taiwan using well-established allometric scaling equations derived from both extant and extinct species. Our results indicate that Palaeoloxodon individuals from Taiwan exceed 10 tonnes in body mass with a mean body mass of 9.32 tonnes, similar in size to Palaeoloxodon antiquus across Eurasia, and an average shoulder height of 3.49 m. Additionally, our statistical pairwise analysis of body mass distribution shows that Palaeoloxodon specimens from Taiwan significantly differ from the largest species in the genus, Palaeoloxodon namadicus. We further employ equations from extant proboscideans and show notable discrepancies due to differences in body shape between extinct and extant proboscideans. Our estimated body masses offer novel insights into the paleoecology and extinction pressures of the Palaeoloxodon population during the Pleistocene of Taiwan. Further research promises to reveal the habitats capable of sustaining megafaunal populations and extinction events along the easternmost margin of Eurasia.

Effect of the Large Magellanic Cloud on the kinematics of Milky Way satellites and virial mass estimate

We present a study illustrating the effects of the passage of a Large Magellanic Cloud (LMC) mass satellite on the distance and velocity distributions of satellites in Λ+Cold Dark Matter simulations of Milky Way (MW) sized halos. In agreement with previous studies, we find that during such a passage the velocity distribution develops a high-velocity tail, which can bias velocity-based virial halo mass estimates. When the velocity distribution of MW satellites is corrected for effects of the LMC passage, it is consistent with the distributions in halos of masses as low as and as high as 1.5×1012M⊙. We present a new halo mass estimator , where c is the coefficient calibrated using satellite systems in the simulated MW-sized halos, is the variance of 3D velocities taken with the sign of the radial velocity of each satellite, and is the median halocentric distance of the satellites. We show that the estimator has only s=8% scatter around the median relation of the estimated and true halo masses and deviates by &lt;2s from the median during the pericentric passage of an LMC-like subhalo. This is because and deviate in the opposite directions during such passages. We apply the estimator to the MW satellite system and estimate the virial mass of the Milky Way of , in good agreement with several recent estimates using other methods.

Mass, Density, and Radius of Asteroid (16) Psyche from High-precision Astrometry

We characterize asteroid (16) Psyche using high-precision astrometry, including the recent Gaia Focused Product Release. The gravitational perturbations of Psyche on other asteroids can be observable in the case of mutual encounters. Using a least squares approach, we estimate the mass of Psyche by fitting astrometric data of asteroids that come within 0.05 au of Psyche. Combining the resulting individual estimates, we find GM = 1.601 ± 0.017 km3 s−2. This result is robust against variations in the orbit determination setup and specific data set used. The volume and equivalent radius of Psyche are currently constrained by occultations and radar and optical imaging to (5.75 ± 0.19) × 106 km3 and 111−0.5+2 km, respectively. Given the volume of Psyche, our mass estimate corresponds to a bulk density of 4172 ± 145 kg m−3, which is compatible with an M-type taxonomic classification. Finally, the phase-dependent photocenter offset is visible in the residuals of Gaia astrometric observations of Psyche. This effect is consistent with the size of Psyche.

Unraveling the enigma of sarcopenia and sarcopenic obesity in Indian adults with type 2 diabetes – a comparative cross-sectional study

BackgroundSarcopenia and sarcopenic obesity are growing concerns associated with increasing diabetes incidence, but data from Indian diabetic cohorts are limited. This study examined the prevalence and clinical factors associated with sarcopenia and sarcopenic obesity.MethodsIn this cross-sectional study, 750 participants aged 35–70 years were recruited by systematic stratification and a fixed quota sampling technique from medical camps and categorized into diabetic (n = 250), nondiabetic (n = 250), and obese nondiabetic (n = 250) groups. The assessments included questionnaires, muscle mass estimation by bioimpedance analysis, and blood tests. Sarcopenia was defined using the Asian Working Group consensus, and sarcopenic obesity was defined as sarcopenia with a BMI ≥ 25 kg/m2. Logistic regression was used to analyze risk factors.ResultsSarcopenia affected 60% of diabetic patients, 28% of nondiabetic patients, and 38% of nonobese nondiabetic patients (p < 0.001). The prevalence of sarcopenic obesity was 40%, 11%, and 30%, respectively (p < 0.001). Diabetes was associated with 2.3-fold greater odds (95% CI 1.1–4.7) of sarcopenia and 2.4-fold greater odds (1.1-5.0) of sarcopenic obesity after adjustment. A duration greater than 10 years, uncontrolled diabetes, age greater than 65 years, low physical activity, hypertension, and dyslipidemia also independently increased the odds.ConclusionIndian adults with type 2 diabetes have a high burden of sarcopenia and sarcopenic obesity. Early optimization of diabetes care and lifestyle changes are vital for preserving muscle health.

Prediction of brake pad wear and remaining useful life considering varying vehicle mass and an experimental holistic approach

Estimation of passenger car brake pad wear is considered, including real-time mass estimation to account for variations in vehicle mass. A longitudinal dynamics model is used to estimate mass, the application of the brakes, and a longitudinal braking force. Wear is modelled from brake work based on the product of the braking force and distance travelled during braking. Data is provided by standard vehicle on-board diagnostics data and a sensor fusion based on an inertial measurement unit and satellite position data, sampled from a single car with 10,200 km of on-road driving, including 31 brake pad wear measurement samples, and driving with up to 23% increased vehicle mass. The mass is accurately estimated within ±5% of the actual. Braking states determined from comparisons of measured and modelled deceleration provide accuracies of ≈91%, precisions of ≈96%, and recall rates of ≈86%, with inclusion of varying mass only resulting in minor differences. Brake work is estimated with (a) constant mass, (b) estimated mass, (c) actual mass, and (d) actual mass and braking states. Compared to (a), (b) and (c) provide 9% and 11% increased work, while (d) provides an increase of about 5% compared to (c). Wear coefficients are fitted on the initial half of the wear data considering (a), (b), and (d). Here (a) and (b) provide similar wear rates of k≈−1.22 mm/GJ, while (d) is about 5% lower. Validating on the second half of the data, (b) and (d) provide very similar wear estimates, with overall lower errors than (a). At the final sample, however, (a) provides a slightly lower absolute error, overestimating the wear by about 2%, while (b) and (d) underestimate it by about 3%. RUL, in terms of distance, is estimated across about 9,500 km of data by estimating a running ratio between cumulated work and distance. Here only (a) and (b) are considered, with (a) overestimating the RUL by 600 km at the actual wear limit, while (b) underestimates it by 190 km. A distance-based model is also considered, resulting in a constant RUL error of about 2,000 km.

I-band photometry of the quiescent black hole X-ray nova GROJ0422 + 32 = V518 Per: modelling of the orbital light curve and estimation of the black hole mass

ABSTRACT We present new photometric observations of the X-ray nova GRO J0422 + 32 (V518 Per) carried out in the I$_c$ band over 14 nights in 2020–2023. We had to revise the orbital period of the system, the new value $P_{\rm orb}=5^{\rm h}04^{\rm m}35{_{.}^{\rm s}}50 \pm 0{_{.}^{\rm s}}04$ is about one minute shorter than the period by Webb et al. but close to the result reported earlier by Filippenko, Matheson &amp; Ho. The obtained folded light curve has a regular shape with a clear ellipticity effect and signatures of a slight heating effect. The simulations of this light curve in terms of the model of an interacting binary system allowed us to estimate the orbital inclination $i = 33^\circ {\small --} 49^\circ$ of the system and derive masses of the black hole $M_x=(6.5\pm 2.9)\,\mathrm{M}_\odot$ and companion star $M_v=(0.47\pm 0.21)\,\mathrm{M}_\odot$. This range of the black hole masses overlaps with the known gap of (2–5) M$_\odot$ in the distribution of compact objects masses but mostly it lies above the upper boundary of this gap. To obtain more precise estimates one needs to know the degree of heating of the donor star, so synchronous X-ray/optical observations of this system are desirable.