Radial Velocity Research Articles

Radial evolution of the accuracy of ballistic solar wind backmapping

Context. Solar wind backmapping is a technique employed to connect in situ measurements of heliospheric plasma structures to their origin near the Sun. The most widely used method is ballistic mapping, which neglects the effects of solar wind acceleration and corotation and instead models the solar wind as a constant radial outflow whose speed is determined by measurements in the heliosphere. This results in plasma parcel streamlines that form an Archimedean spiral (the Parker spiral) when viewed in the solar corotating frame. This simplified approach assumes that the effects of solar wind acceleration and corotation compensate for each other in the deviation of the source longitude. Most backmapping techniques so far considered magnetic connectivity from a heliocentric distance of 1 au to the Sun. Aims. We quantify the angular deviation between different backmapping methods that depends on the location of the radial probe and on the variation in the solar wind speed with radial distance. We assess these differences depending on source longitude and solar wind propagation time. Methods. We estimated backmapping source longitudes and travel times using (1) the ballistic approximation (constant speed), (2) a physically justified method using the empirically constrained acceleration profile Iso-poly, derived from Parker solar wind equations and also a model of solar wind tangential flows that accounts for corotational effects. We compared the differences across mapped heliocentric distances and for different asymptotic solar wind speeds. Results. The ballistic method results in a Carrington longitude of the source with a maximum deviation of 4″ below 3 au compared to the physics-based mapping method taken as reference. However, the travel time especially for the slow solar wind could be underestimated by 1.5 days at 1 au compared to non-constant speed profile. This time latency may lead to an association of incorrect solar source regions with given in situ measurements. Neglecting corotational effects and accounting for acceleration alone causes a large systematic shift in the backmapped source longitude. Conclusions. Incorporating both acceleration and corotational effects leads to a more physics-based representation of the plasma trajectories through the heliosphere compared to the ballistic assumption. This approach accurately assesses the travel time and provides a more realistic estimate of the longitudinal separation between a plasma parcel measured in situ and its source region. Nonetheless, it requires knowledge of the radial density and Alfvén speed profiles to compute the tangential flow. Therefore, we propose a compromise for computing the source longitude that employs the commonly used ballistic approach and the travel times computed from the derived radial acceleration speed profile. Moreover, we conclude that this approach remains valid at all radial distances we studied and is not limited to data obtained at 1 au.

Signature of systemic rotation in 21 galactic globular clusters from APOGEE-2

Traditionally, globular clusters (GCs) have been assumed to be quasi-relaxed non-rotating systems, characterized by spherical symmetry and orbital isotropy. However, in recent years, a growing set of observational evidence has been unveiling an unexpected dynamical complexity in Galactic GCs. Indeed, kinematic studies have demonstrated that a measurable amount of internal rotation is present in many present-day GCs. The objective of this work is to analyse the APOGEE-2 value-added catalog (VAC) DR17 data of a sample of 21 GCs to extend the sample exhibiting signatures of systemic rotation and better understand the kinematic properties of GCs overall. Also, we aim to identify the fastest rotating GC from the sample of objects with suitable measurements. From the sample of 23 GCs included in this work, the presence of systemic rotation was detected in 21 of the GCs, using three different methods. All these methods use the radial velocity referred to the cluster systemic velocity ($ V_ r $). Using the first method, it was possible to visually verify the clear-cut signature of systemic rotation; whereas using the second and third methods, it was possible to determine the amplitude of the rotation curve ($A_ rot $) and the position angle (PA) of the rotation axis. This study shows that 21 GCs have a signature of systemic rotation. For these clusters, the rotation amplitude and the position angle of the rotation axis ($PA_ $) have been calculated. The clusters cover a remarkable range of rotational amplitudes, from 0.77 km/s to 13.85 km/s.

Assessing Slip Rates on the Xianshuihe Fault Using InSAR with Emphasis on Phase Unwrapping Error and Atmospheric Delay Corrections

Located on the southeastern periphery of the Tibetan Plateau, the Xianshuihe fault (XSHF) is an active left-lateral strike-slip fault renowned for its frequent and intensive seismic activities. This highlights the necessity of employing advanced geodetic methodologies to precisely evaluate the fault kinematics and seismic hazard potential along this fault. Among these techniques, interferometric synthetic aperture radar (InSAR) stands out for its high spatial resolution and regular revisit intervals, enabling accurate mapping of interseismic deformation associated with fault motion. However, the precision of InSAR in measuring deformation encounters several challenges, particularly artifacts stemming from phase unwrapping errors and atmospheric phase delays. In this study, we utilize ascending and descending Sentinel-1 InSAR images spanning from January 2017 to January 2023 to drive the line-of-sight (LOS) mean crustal velocities associated with the XSHF with emphasis on phase unwrapping errors and atmospheric delay corrections. Then, the reliability of the derived LOS velocities is assessed using independent observations from the Global Navigation Satellite System (GNSS). The inferred fault slip rate along the XSHF shows significant along-strike variations, gradually decreasing from ~11.1 mm/yr at the Luhuo section to ~6.6 mm/yr at the Kangding section and then sharply increasing to ~13.0 mm/yr towards its eastern terminus at the Moxi section. The fault locking depth shows similar along-strike variations, decreasing from ~19.5 km in the northwestern part to ~4.8 km at the Kangding section, before increasing to 19.6 km at the Moxi segment. Notably, apparent surface fault creeping, characterized by a slip rate of ~2.7 mm/yr, is observed at the Kangding segment, likely resulting from postseismic slip following the 2014 Mw 6.3 Kangding earthquake.

The TESS-Keck Survey. XX. 15 New TESS Planets and a Uniform RV Analysis of All Survey Targets

The Transiting Exoplanet Survey Satellite (TESS) has discovered hundreds of new worlds, with TESS planet candidates now outnumbering the total number of confirmed planets from Kepler. Owing to differences in survey design, TESS continues to provide planets that are better suited for subsequent follow-up studies, including mass measurement through radial velocity (RV) observations, compared to Kepler targets. In this work, we present the TESS-Keck Survey’s (TKS) Mass Catalog: a uniform analysis of all TKS RV survey data that has resulted in mass constraints for 126 planets and candidate signals. This includes 58 mass measurements that have reached ≥5σ precision. We confirm or validate 32 new planets from the TESS mission either by significant mass measurement (15) or statistical validation (17), and we find no evidence of likely false positives among our entire sample. This work also serves as a data release for all previously unpublished TKS survey data, including 9,204 RV measurements and associated activity indicators over our three-year survey. We took the opportunity to assess the performance of our survey and found that we achieved many of our goals, including measuring the mass of 38 small (<4 R ⊕) planets, nearly achieving the TESS mission’s basic science requirement. In addition, we evaluated the performance of the Automated Planet Finder as survey support and observed meaningful constraints on system parameters, due to its more uniform phase coverage. Finally, we compared our measured masses to those predicted by commonly used mass–radius relations and investigated evidence of systematic bias.

Simultaneous Photometric and Spectroscopic Analysis of V505 Lacertae, a Photospherically and Chromospherically Active Contact Binary Star

New BVR photometric and high-resolution spectroscopic observations of V505 Lac are presented with Transiting Exoplanet Survey Satellite (TESS) photometric data. The orbital period has experienced a secular decrease during the past 16 yr. A clear anticorrelation in the primary and secondary eclipse timing variation (PSETV) obtained from the TESS data is also identified. A double-lined radial velocity (RV) curve is secured, and the effective temperatures of the less- and more-massive stars (Stars 1 and 2, respectively) are measured. Using a spectral subtraction technique, excess emissions are detected in the time-series Ca ii H and K and Hα lines for Star 2. Simultaneous analysis of the light and RV curves using the Wilson–Devinney (WD) code reveals that V505 Lac is a photospherically and chromospherically active W-subtype contact binary system. The component-star masses and radii are determined to an accuracy of approximately 1%. The WD spot model is individually applied to 221 light curves segmented from the TESS data so as to derive the spot parameters of a cool spot on Star 2. The combined variations in both longitude and colatitude among the spot parameters appear to be strongly associated with those of both the anticorrelation in the PSETV and the O’Connell effect in the TESS light curves. Robust negative linear relationships between the PSETV anticorrelation size and the O’Connell effect magnitude are found for the first time. Mass–radius, mass–luminosity, and mass ratio–mass diagrams of contact binaries, along with the mass ratio frequency distribution, are presented in an attempt to elucidate the evolutionary characteristics of these systems.

The TESS-Keck Survey. VII. A Superdense Sub-Neptune Orbiting TOI-1824* *Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 nonprofit organization 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

We confirm a massive sub-Neptune-sized planet on a P = 22.8 days orbit around the star TOI-1824 (T eff = 5200 K, V = 9.7 mag). TESS first identified TOI-1824 b (formerly TOI-1824.01) as an object of interest in 2020 April after two transits in Sector 22 were matched with a single transit in Sector 21. TOI-1824 was subsequently targeted for ground-based Doppler monitoring with Keck-HIRES and APF-Levy. Using a joint model of the TESS photometry, radial velocities, and Ca ii H and K emission measurements as an activity indicator, we find that TOI-1824 b is an unusually dense sub-Neptune. The planet has a radius R p = 2.63 ± 0.15 R ⊕ and mass M p = 18.5 ± 3.2 M ⊕, implying a bulk density of 5.6 ± 1.4 g cm−3. TOI-1824 b's mass and radius situate it near a small group of “superdense sub-Neptunes” (R p ≲ 3 R ⊕ and M p ≳ 20 M ⊕). While the formation mechanism of superdense sub-Neptunes is a mystery, one possible explanation is the constructive collision of primordial icy cores; such giant impacts would drive atmospheric escape and could help explain these planets' apparent lack of massive envelopes. We discuss TOI-1824 b in the context of these overdense planets, whose unique location in the exoplanet mass–radius plane make them a potentially valuable tracer of planet formation.

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy

Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (P orb) of 12.76 days. The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous P orb from TESS data. We confirmed the transit signal and P orb using ground-based photometry with MuSCAT2 and MuSCAT3, and validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host star is inactive, with an X-ray-to-bolometric luminosity ratio of logLX/Lbol≈−5.7 . Joint analysis of the light curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R ⊕, a 3σ mass upper limit of 3.9 M ⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric (TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.

Keck/KCWI Spectroscopy of Globular Clusters in Local Volume Dwarf Galaxies

Abstract A number of nearby dwarf galaxies have globular cluster (GC) candidates that require spectroscopic confirmation. Here we present Keck telescope spectra for 15 known GCs and GC candidates that may be associated with a host dwarf galaxy, and an additional 3 GCs in the halo of M31 that are candidates for accretion from a now disrupted dwarf galaxy. We confirm 6 star clusters (of intermediate-to-old age) to be associated with NGC 247. The vast bulk of its GC system remains to be studied spectroscopically. We also confirm the GC candidates in F8D1 and DDO190, finding both to be young star clusters. The 3 M31 halo GCs all have radial velocities consistent with M31, are old and very metal-poor. Their ages and metallicities are consistent with accretion from a low mass satellite galaxy. Finally, three objects are found to be background galaxies – two are projected near NGC 247 and one (candidate GCC7) is near the IKN dwarf. The IKN dwarf thus has only 5 confirmed GCs but still a remarkable specific frequency of 124.

Kinematic Age of the β-Pictoris Moving Group

Accurate age estimation of nearby young moving groups (NYMGs) is important as they serve as crucial testbeds in various fields of astrophysics, including the formation and evolution of stars and planets, as well as loose stellar associations. The β-Pictoris moving group (BPMG), being one of the closest and youngest NYMGs, has been extensively investigated, and its estimated ages have a wide range from ∼10–25 Myr, depending on the age estimation methods and data used. Unlike other age dating methods, kinematic traceback analysis offers a model-independent age assessment hence the merit in comparing many seemingly discordant age estimates. In this study, we determine the kinematic ages of the BPMG using three methods: probabilistic volume calculation, mean pairwise distance calculation, and covariance matrix analysis. These methods yield consistent results, with estimated ages in the range of 14–20 Myr. Implementing corrections to radial velocities due to gravitational redshift and convectional blueshift increases the ages by ∼2–4 Myr. Conversely, considering data uncertainties decreases the estimated ages by 1–2 Myr. Taken together, our analysis determined the kinematic age of the BPMG to be 16.3−2.1+3.4 Myr. This age is significantly younger than the commonly accepted age of the BPMG (∼24 Myr) determined primarily from the lithium depletion boundary analysis. This younger kinematic age may point to the discrepancy between the luminosity evolution and lithium depletion models or the presence of unaccounted systematic error in the method. This result underscores the necessity for systematic reevaluations of age-dating methods for nearby, young moving groups.

Orbital and Atmospheric Characterization of the 1RXS J034231.8+121622 System using High-resolution Spectroscopy Confirms that the Companion is a Low-mass Star

The 1RXS J034231.8+121622 system consists of an M dwarf primary and a directly imaged low-mass stellar companion. We use high-resolution spectroscopic data from Keck/KPIC to estimate the objects' atmospheric parameters and radial velocities (RVs). Using PHOENIX stellar models, we find that the primary has a temperature of 3460 ± 50 K and a metallicity of 0.16 ± 0.04, while the secondary has a temperature of 2510 ± 50 K and a metallicity of 0.13−0.11+0.12 . Recent work suggests this system is associated with the Hyades, giving it an older age than previous estimates. Both metallicities agree with current Hyades [Fe/H] measurements (0.11–0.21). Using stellar evolutionary models, we obtain significantly higher masses for the objects, 0.30 ± 0.15 M ⊙ and 0.08 ± 0.01 M ⊙ (84 ± 11 M Jup), respectively. Using the RVs and a new astrometry point from Keck/NIRC2, we find that the system is likely an edge-on, moderately eccentric ( 0.41−0.08+0.27 ) configuration. We also estimate the C/O ratio of both objects using custom grid models, obtaining 0.42 ± 0.10 (primary) and 0.55 ± 0.10 (companion). From these results, we confirm that this system most likely went through a binary star formation process in the Hyades. The significant changes in this system's parameters since its discovery highlight the importance of high-resolution spectroscopy for both orbital and atmospheric characterization of directly imaged companions.

Stellar Atmospheric Parameters of ∼11,000 RR Lyrae Stars from LAMOST Spectra

Accurate determination of the stellar atmospheric parameters of RR Lyrae stars (RRLs) requires short individual exposures of the spectra to mitigate pulsation effects. We present improved template-matching methods to determine the stellar atmospheric parameters of RRLs from single-epoch spectra of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also known as the Guoshoujing Telescope (LAMOST). We determine the radial velocities and stellar atmospheric parameters (effective temperature T eff, surface gravity logg , and metallicity [M/H]) of 10,486 and 1027 RRLs from 42,729 LAMOST low-resolution spectra (LRS) and 7064 LAMOST medium-resolution spectra (MRS), respectively. Our results are in good agreement with the parameters of other databases, where the external uncertainties of T eff, logg , and [M/H] for LRS/MRS are estimated to be 207/142 K, 0.21/0.16 dex, and 0.24/0.18 dex, respectively. We conclude with the variation characteristics of the radial velocities (RV) and stellar atmospheric parameters for RRLs during the pulsation phase. There is a significant difference of 28 ± 21 km s−1 between the peak-to-peak amplitude (A ptp) of RV from the Hα line (RVHα ) and from metal lines (RVmetal) for RRab, whereas it is only 4 ± 17 km s−1 for RRc. The A ptp of T eff is 930 ± 456 and 409 ± 375 K for RRab and RRc, respectively. The logg of RRab shows a mild variation of approximately 0.22 ± 0.42 dex near the phase of φ = 0.9, while that of RRc almost remains constant. The [M/H] of RRab and RRc show a minor variation of about 0.25 ± 0.50 and 0.28 ± 0.55 dex, respectively, near the phase of φ = 0.9. We expect that the determined stellar atmospheric parameters would shed new light on the study of stellar evolution and pulsation, the structure of the Milky Way, as well as other research fields.

The characteristics of cloud macro-parameters caused by the seeder–feeder process inside clouds measured by millimeter-wave cloud radar in Xi'an, China

Abstract. The seeding effect of upper clouds on lower clouds affects the evolution of clouds, especially the seeding from upper ice clouds on lower stratiform clouds or convective clouds, which can stimulate the precipitation of lower clouds and even produce extreme precipitation. When seeders of the seeding cloud enter the feeding cloud, the interaction between cloud particles results in the change in macro- and micro-parameters of the feeding cloud. Based on the observation data of a ground-based Ka-band millimeter-wave cloud radar (MMCR) and microwave radiometer (MWR) in spring and autumn from 2021 to 2022, the seeder–feeder phenomenon among double-layer clouds in Xi'an, China, is studied. The study on 11 cases of seeder–feeder processes shows that the processes can be divided into three types by defining the height difference (HD) between the seeding cloud base and the feeding cloud top and the effective seeding depth (ESD). Through analysis of the reflectivity factor (Z) and the radial velocity (Vr) of cloud particles detected by the MMCR and on the retrieved cloud dynamics parameters (vertical velocity of airflow, Va, and terminal velocity of cloud particles, Vf), it is shown that the reflectivity factor and particle terminal velocity in the cloud are significantly enhanced during the seeder–feeder period for the three types of processes. But the enhancement magnitudes of the three seeder–feeder processes are different. The results also show that the impact of seeding on the feeding cloud is limited. The lower the height and thinner the thickness of the HD, the lower the height and thicker the thickness of the ESD. On the contrary, the higher the height and the thicker the thickness of the HD, the higher the height and the thinner the thickness of the ESD.

Confrontation between modelled solar integrated observables and direct observations I. Radial velocities and convective blueshift

Stellar variability strongly impacts the search for low-mass exoplanets with radial velocity techniques. Two types of planet-free time series can be used to quantify this impact: models and direct solar observations after a subtraction of the Solar System planetary contribution. Making a comparison among these approaches is necessary to improve the models, which can then be used for blind tests across a broad range of conditions. Our objective is therefore to validate the amplitude of the convective blueshift in plages used in our previous works, particularly in blind tests, with HARPS-N solar data. We applied our model to the structures observed at the time of HARPS-N observations and established a direct comparison between the radial velocity time series. To complete our diagnosis, we also studied the observed radial velocities separately for each diffraction order derived from the individual cross-correlation functions, as well as our line-by-line radial velocities. We find that our previous model had been underestimating the amplitude of the convective blueshift inhibition by a factor of about 2. A direct estimation of the convective blueshift in the spectra, which is shown to be correlated with the plage filling factor, allows us to explain the difference with previous estimations obtained with MDI/SOHO Dopplergrams, based on the specific properties of the Ni line used in this mission. In addition, we identified several instrumental systematics, in particular, the presence of a 2 m/s peak-to-peak signal with a period of about 200 days in radial velocity and bisector. This signal could be due to periodic detector warm-ups, a systematic dependence of the long-term trend on wavelength that is possibly related to the variability of the continuum over time, and/or an offset in radial velocity after the interruption of several months in October 2017. A large amplitude in the convective blueshift inhibition of (360 m/s, namely twice more than in our previous works) must be used when building synthetic times series for blind tests. The presence of instrumental systematics should also be taken into account when using sophisticated methods based on line properties to mitigate stellar activity when searching for very weak signals.

High-precision spectral inversions: Determining what is important for the accurate definition of incident radiation boundary conditions

Spectral inversions are used to analyse spectroscopic observations with the aim of deriving the physical properties of the observed plasma, such as the kinetic temperature, density, pressure, degree of ionisation, or macroscopic velocities. One of the key factors ensuring the high precision of the derived plasma properties is having accurately defined input parameters of the models on which spectral inversions rely. The illumination, which chromospheric and coronal structures receive from the solar surface (and corona), is one of the most crucial input parameters of these models. We do not perform spectral inversions in this work. Our aim is to study two important factors that contribute to the accurate definition of the incident radiation boundary conditions: the altitude above the solar surface and the dynamics of the illuminated plasma. This investigation takes into account a diverse range of solar structures from the high-rising eruptive prominences to low-lying spicules. To study the influence of the altitude and dynamics of the observed plasma on the incident radiation boundary conditions, we used geometrical principles valid for any spectral line. However, to demonstrate the strong impact of dynamics, we considered the specific case of narrow spectral lines of which are highly sensitive to the presence of velocities. We argue that the altitude of the illuminated plasma strongly influences the way we need to define the incident radiation boundary conditions to achieve the most accurate results. For low-lying structures, generally below 50,000 km, the incident radiation may need to be specified directly from the composition of the portion of the solar disc that illuminates them. For high-altitude structures, generally above 300,000 km, the fraction of the solar disc illuminating the analysed plasma is large enough to be realistically approximated by the composition of the entire disc. We also show that for the narrow spectral lines, such as the lines, the impact of dynamics on the incident radiation intensity and profile shapes starts from radial velocities of 30 km $. Such velocities are even exhibited by the fine structures of quiescent prominences and are easily exceeded in spicules or eruptive prominences. The two aspects of the incident radiation definition studied here are relevant for spectral inversions based on any kind of modelling approach. However, their impact on the precision of the results of spectral inversions is likely less significant than the impact of the choice of the complexity of the model geometry, for example.

Analysis of fluid flow and heat transfer in CNT-infused spiraling disk

This study investigates the fluid flow and heat transfer characteristics influenced by the thermophysical properties of carbon nanotube suspension in engine oil over a stretching-spiraling disk. The surface comprises Homan stagnation point flow impinging normal to a rotating, radially stretching disk, which gives velocity a form of logarithmic spiral. Similarity ansatz transformed coupled nonlinear differential equation system is derived and solved numerically using MATLAB’s bvp4c collocation method. Numerical and asymptotic solutions are also obtained against the controlled parameters via graphical representations and tabular data. Findings indicate that the magnetic field enhances temperature distribution while reducing the velocity field. At the same time, stretching increases radial velocity but decreases azimuthal velocity and temperature profiles, regardless of carbon nanotube type. The asymptotic values of skin friction decline with an increase in the spiralisng angle and in the absence of a magnetic field for both SWCNTs and MWCNTs cases.

Three short-period Earth-sized planets around M dwarfs discovered by TESS: TOI-5720 b, TOI-6008 b, and TOI-6086 b

One of the main goals of the NASA Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of Earth-like planets around nearby M-dwarf stars. We present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M dwarfs: TOI-5720\,b, TOI-6008\,b, and TOI-6086\,b. We combined TESS data, ground-based multicolor light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD radial velocity data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720\,b is an Earth-sized planet with a radius of $R_p = 1.09 0.07 R_ It orbits a nearby (36 pc) M2.5 host with an orbital period of $P = 1.4344555 0.0000036 $ days. It has an equilibrium temperature of eq 19$ K (assuming a null albedo) and an incident flux of $S_p = 41.7 4.5 S_ TOI-6008\,b is a short-period planet of $ P = 0.8574347 0.0000424$ day. It has a radius of $R_p = 1.03 0.05 R_ an equilibrium temperature of eq 19$ K, and an incident flux of $S_p = 41.5 4.5 S_ The host star (TOI-6008) is a nearby (23 pc) M5 with an effective temperature of eff 75 K$. Based on the radial velocity measurements collected with Subaru/IRD, we set a $3 upper limit of $M_p &lt; 4M_ thus ruling out a star or brown dwarf as the transiting companion. TOI-6086\,b orbits its nearby (32 pc) M3 host star eff 75$ K) every $1.3888725 0.0000827$ days and has a radius of $ R_p = 1.18 0.07 R_ an equilibrium temperature of eq 16$ K, and an incident flux of $S_p = 26.8 2.7 S_ Additional high-precision radial velocity measurements are needed to derive the planetary masses and bulk densities and to search for additional planets in the systems. Moreover, short-period Earth-sized planets orbiting around nearby M dwarfs are suitable targets for an atmospheric characterization with the James Webb Space Telescope through transmission and emission spectroscopy and phase-curve photometry.

Feasibility of High-resolution Transmission Spectroscopy for Low-velocity Exoplanets

In recent years, high-resolution transmission spectroscopy in the near-infrared has led to detections of prominent molecules in several giant exoplanets on close-in orbits. This approach has traditionally relied on the large Doppler shifts of the planetary spectral lines induced by the high velocities of close-in planets, which were considered necessary for separating them from the quasi-static stellar and telluric lines. In this work, we demonstrate the feasibility of high-resolution transmission spectroscopy for chemical detections in atmospheres of temperate low-mass exoplanets around M dwarfs with low radial velocity variation during transit. We pursue this goal using model injection and recovery tests with H- and K-band high-resolution spectroscopy of the temperate sub-Neptune TOI-732 c, observed using the IGRINS spectrograph on Gemini South. We show that planetary signals in transit may be recovered when the change in the planet’s radial velocity is very small, down to subpixel velocities. This is possible due to the presence of the planetary signal in only a subset of the observed spectra. A sufficient number of out-of-transit spectra can create enough contrast between the planet signal and telluric/stellar contaminants that the planet signal does not constitute a principal component of the time-series spectra and can therefore be isolated using principal-component-analysis-based detrending without relying on a significant Doppler shift. We additionally explore novel metrics for finding such signals, and investigate trends in their detectability. Our work extends the scope of high-resolution transmission spectroscopy and creates a pathway toward the characterization of habitable sub-Neptune worlds with ground-based facilities.

Identification of Peripheral Fatigue through Exercise-Induced Changes in Muscle Contractility

The aim of this study was to assess whether tensiomyography is a tool sensitive enough to detect peripheral fatigue. Twenty-six strength-trained men were split into two groups: 1) a fatigued group (FG), who performed a full-squat (SQ) standardized warm-up plus 3 x 8 SQs with 75% 1RM with a 5-min rest interval, and 2) a non-fatigued group (NFG), who only did the SQ standardized warm-up. The countermovement jump (CMJ), maximal isometric force (MIF) in the SQ at 90º knee flexion, and TMG in vastus medialis (VM) and vastus lateralis (VL) muscles were assessed pre- and post-protocols. Data were analyzed through mixed ANOVA, logistic regression analysis, and receiver-operating curves. There were significant group x time interactions (p &lt; 0.01) for CMJ height, MIF, maximal radial displacement (Dm), and radial displacement velocity (Vrd90) since the FG acutely decreased in these variables, while no significant changes were observed for the NFG. The logistic regression showed a significant model for detecting fatigue, whether it used the CMJ or MIF, with only the relative change in VL-Vrd90 as a fatigue predictor. The determination of the area under the curve showed that Dm and Vrd90 had good to excellent discriminative ability. Dm and Vrd90 are sensitive to detect fatigue in VL and VM muscles in resistance training contexts.

Improving radial lens distortion correction with multi-task learning

With computer vision and machine learning, sports image analysis can enhance viewer engagement and contribute to the overall understanding of sports events. However, beneath the apparent simplicity of sports images lies a complex challenge of radial distortion, which can impede their accurate interpretation. The need for high precision and real-time performance is paramount. We present a new regression-based method for radial distortion correction that improves the accuracy of distortion model coefficient prediction by introducing a secondary learning task that compares the distortion level of two random training samples. The secondary task requires no additional annotation, and because it is also related to radial distortion, it encourages the common feature extractor component to learn more general and robust features while preventing overfitting and improving the efficiency of training data. We have evaluated our proposed method using two public datasets and compared it against five other methods. Our method surpassed them all, both in the accuracy of the radial distortion correction and speed as well. You can find the source code and trained models at https://vgg.fiit.stuba.sk/improving-radial.

The beta Pictoris b Hill sphere transit campaign. II. Searching for the signatures of the beta Pictoris exoplanets through time delay analysis of the delta Scuti pulsations

The system is the closest known stellar system with directly detected gas giant planets, an edge-on circumstellar disc, and evidence of falling sublimating bodies and transiting exocomets. The inner planet has also been indirectly detected with radial velocity (RV) measurements. The star is a known pulsator, and the long-term stability of these pulsations opens up the possibility of indirectly detecting the gas giant planets through time delays of the pulsations due to a varying light travel time. We search for phase shifts in the pulsations consistent with the known planets and c and carry out an analysis of the stellar pulsations of beta Pictoris over a multi-year timescale. We used photometric data collected by the BRITE-Constellation, bRing, ASTEP, and TESS to derive a list of the strongest and most significant pulsations. We carried out an analysis with the open-source python package maelstrom to study the stability of the pulsation modes of beta Pictoris in order to determine the long-term trends in the observed pulsations. We did not detect the expected signal for or . The expected time delay is 6 seconds for and 24 seconds for . With simulations, we determined that the photometric noise in all the combined data sets cannot reach the sensitivity needed to detect the expected timing drifts. An analysis of the pulsational modes of beta Pictoris using maelstrom showed that the modes themselves drift on the timescale of a year, fundamentally limiting our ability to detect exoplanets around beta Pictoris via pulsation timing.