• A diffuse tidal dwarf galaxy destined to fade out as a "dark galaxy"

      Román, J.; Jones, M.G.; Montes, M.; Verdes-Montenegro, L.; Garrido, J.; Sánchez, S.; Steward Observatory, University of Arizona (EDP Sciences, 2021)
      We have explored the properties of a peculiar object detected in deep optical imaging and located at the tip of an H » I tail emerging from Hickson Compact Group 16. Using multiband photometry from infrared to ultraviolet, we were able to constrain its stellar age to 58-9+22 Myr with a rather high metallicity of [Fe/H] = -0.16-0.41+0.43 for its stellar mass of M- = 4.2 × 106 Mpdbl, a typical signature of tidal dwarf galaxies. The structural properties of this object are similar to those of diffuse galaxies, with a round and featureless morphology, a large effective radius (reff = 1.5 kpc), and a low surface brightness (μg-eff = 25.6 mag arcsec-2). Assuming that the object is dynamically stable and able to survive in the future, its fading in time via the aging of its stellar component will make it undetectable in optical observations in just ∼2 Gyr of evolution, even in the deepest current or future optical surveys. Its high H » I mass, M(HI) = 3.9 × 108 Mpdbl, and future undetectable stellar component will make the object match the observational properties of dark galaxies, that is, dark matter halos that failed to turn gas into stars. Our work presents further observational evidence of the feasibility of H » I tidal features becoming fake dark galaxies; it also shows the impact of stellar fading, particularly in high metallicity systems such as tidal dwarfs, in hiding aged stellar components beyond detection limits in optical observations. © ESO 2021.
    • A domeless, mobile 2-meter telescope

      Kingsley, J.; Strittmatter, P.; Gonzales, K.; Connors, T.; Kingsley, B.; Jannuzi, B.; Yoshii, Y.; Minezaki, T.; Steward Observatory, The University of Arizona (SPIE, 2020)
      There are many astronomical, interferometric and space situational awareness applications for single and multiple 2-meter aperture optical and infrared mobile telescopes that are low cost, can be easily transported and quickly deployed at a variety of sites. A design concept is presented for a trailermounted 2-meter telescope with a novel micro-enclosure that allows the telescope to be moved and deployed quickly for observations. The telescope is protected from adverse weather using a weatherproof telescope tube instead of a conventional dome or enclosure. It has Cassegrain, Nasmyth and coudé foci suitable for astronomical, interferometric, space situational awareness, and laser communications applications, and is designed for replication at low cost. An initial implementation is being developed to explore the performance of such a telescope using re-purposed primary and secondary mirrors and other components from the MAGNUM telescope. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
    • A genetic study of cerebral atherosclerosis reveals novel associations with ntng1 and cnot3

      Vattathil, S.M.; Liu, Y.; Harerimana, N.V.; Lori, A.; Gerasimov, E.S.; Beach, T.G.; Reiman, E.M.; De Jager, P.L.; Schneider, J.A.; Bennett, D.A.; et al. (MDPI AG, 2021)
      Cerebral atherosclerosis is a leading cause of stroke and an important contributor to dementia. Yet little is known about its genetic basis. To examine the association of common single nucleotide polymorphisms with cerebral atherosclerosis severity, we conducted a genomewide association study (GWAS) using data collected as part of two community-based cohort studies in the United States, the Religious Orders Study (ROS) and Rush Memory and Aging Project (MAP). Both studies enroll older individuals and exclude participants with signs of dementia at baseline. From our analysis of 1325 participants of European ancestry who had genotype and neuropathologically assessed cerebral atherosclerosis measures available, we found a novel locus for cerebral atherosclerosis in NTNG1. The locus comprises eight SNPs, including two independent significant SNPs: rs6664221 (β = −0.27, 95% CI = (−0.35, −0.19), p = 1.29 × 10−10 ) and rs10881463 (β = −0.20, 95% CI = (−0.27, −0.13), p = 3.40 × 10−8 ). We further found that the SNPs may influence cerebral atherosclerosis by regulating brain protein expression of CNOT3. CNOT3 is a subunit of CCR4−NOT, which has been shown to be a master regulator of mRNA stability and translation and an important complex for cholesterol homeostasis. In summary, we identify a novel genetic locus for cerebral atherosclerosis and a potential mechanism linking this variation to cerebral atherosclerosis progression. These findings offer insights into the genetic effects on cerebral atherosclerosis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • A harsh test of far-field scrambling with the habitable-zone planet finder and the hobby–eberly telescope

      Kanodia, S.; Halverson, S.; Ninan, J.P.; Mahadevan, S.; Stefansson, G.; Roy, A.; Ramsey, L.W.; Bender, C.F.; Janowiecki, S.; Cochran, W.D.; et al. (IOP Publishing Ltd, 2021)
      The Habitable-zone Planet Finder (HPF) is a fiber-fed precise radial velocity (RV) spectrograph at the 10 m Hobby–Eberly Telescope (HET). Due to its fixed-altitude design, the HET pupil changes appreciably across a track, leading to significant changes of the fiber far-field illumination. HPF’s fiber scrambler is designed to suppress the impact of these illumination changes on the RVs—but the residual impact on the RV measurements has yet to be probed on-sky. We use GJ 411, a bright early type (M2) M dwarf to probe the effects of far-field input trends due to these pupil variations on HPF RVs. These large changes (∼2x) in the pupil area and centroid present a harsh test of HPF’s far-field scrambling. Our results show that the RVs are effectively decoupled from these extreme far-field input changes due to pupil centroid offsets, attesting to the effectiveness of the scrambler design. This experiment allows us to test the impact of these changes with large pupil variation on-sky, something we would not easily be able to do at a conventional optical telescope. While the pupil and illumination changes expected at these other telescopes are small, scaling from our results enables us to estimate and bound these effects, and show that they are controllable even for the new and next generation of RV instruments in their quest to beat down instrumental noise sources toward the goal of a few cm s-1. © 2021. The American Astronomical Society. All rights reserved.
    • A high-contrast search for variability in HR 8799bc with VLT-SPHERE

      Biller, B.A.; Apai, D.; Bonnefoy, M.; Desidera, S.; Gratton, R.; Kasper, M.; Kenworthy, M.; Lagrange, A.-M.; Lazzoni, C.; Mesa, D.; et al. (Oxford University Press, 2021)
      The planets HR8799bc display nearly identical colours and spectra as variable young exoplanet analogs such as VHS 1256-1257ABb and PSO J318.5-22, and are likely to be similarly variable. Here we present results from a 5-epoch SPHERE IRDIS broadband-H search for variability in these two planets. HR 8799b aperture photometry and HR 8799bc negative simulated planet photometry share similar trends within uncertainties. Satellite spot lightcurves share the same trends as the planet lightcurves in the August 2018 epochs, but diverge in the October 2017 epochs. We consider Δ(mag)b-Δ(mag)c to trace non-shared variations between the two planets, and rule out non-shared variability in Δ(mag)b-Δ(mag)c to the 10-20 rm per\cent level over 4-5 h. To quantify our sensitivity to variability, we simulate variable lightcurves by inserting and retrieving a suite of simulated planets at similar radii from the star as HR 8799bc, but offset in position angle. For HR 8799b, for periods <10 h, we are sensitive to variability with amplitude > 5 per\cent. For HR 8799c, our sensitivity is limited to variability > 25 per\cent for similar periods. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
    • A large sub-Neptune transiting the thick-disk M4 v TOI-2406

      Steward Observatory, The University of Arizona; Lunar and Planetary Laboratory, The University of Arizona; Vatican Observatory Research Group, University of Arizona (EDP Sciences, 2021)
      Context. Large sub-Neptunes are uncommon around the coolest stars in the Galaxy and are rarer still around those that are metal-poor. However, owing to the large planet-to-star radius ratio, these planets are highly suitable for atmospheric study via transmission spectroscopy in the infrared, such as with JWST. Aims. Here we report the discovery and validation of a sub-Neptune orbiting the thick-disk, mid-M dwarf star TOI-2406. The star's low metallicity and the relatively large size and short period of the planet make TOI-2406 b an unusual outcome of planet formation, and its characterisation provides an important observational constraint for formation models. Methods. We first infer properties of the host star by analysing the star's near-infrared spectrum, spectral energy distribution, and Gaia parallax. We use multi-band photometry to confirm that the transit event is on-target and achromatic, and we statistically validate the TESS signal as a transiting exoplanet. We then determine physical properties of the planet through global transit modelling of the TESS and ground-based time-series data. Results. We determine the host to be a metal-poor M4 V star, located at a distance of 56 pc, with properties Teff = 3100 ± 75 K, M∗ = 0.162 ± 0.008Mo˙, R∗ = 0.202 ± 0.011Ro˙, and [Fe∕ H] = -0.38 ± 0.07, and a member of the thick disk. The planet is a relatively large sub-Neptune for the M-dwarf planet population, with Rp = 2.94 ± 0.17R⊕ and P= 3.077 d, producing transits of 2% depth. We note the orbit has a non-zero eccentricity to 3σ, prompting questions about the dynamical history of the system. Conclusions. This system is an interesting outcome of planet formation and presents a benchmark for large-planet formation around metal-poor, low-mass stars. The system warrants further study, in particular radial velocity follow-up to determine the planet mass and constrain possible bound companions. Furthermore, TOI-2406 b is a good target for future atmospheric study through transmission spectroscopy. Although the planet's mass remains to be constrained, we estimate the S/N using amass-radius relationship, ranking the system fifth in the population of large sub-Neptunes, with TOI-2406 b having a much lower equilibrium temperature than other spectroscopically accessible members of this population. © ESO 2021.
    • A laser-truss based optical alignment system on LBT

      Rakich, A.; Choi, H.; Veillet, C.; Hill, J.M.; Bec, M.; Zhang, Y.; Brendel, T.; Sitarski, B.; Gardiner, M.; Kim, D.W.; et al. (SPIE, 2020)
      Since 2017 LBTO, in partnership with GMTO, has been developing a laser-trussed based metrology system for the active alignment of telescope main optical components to each other and to instruments. The effort has addressed needs of both organizations; LBTO with the opportunity to assess the performance of a new technological approach to telescope alignment, and the GMTO with the opportunity to prototype and field-test a system that has been identified as a crucial "missing link"in the active-optics chain between open-loop modelling and wavefront-sensing for ELT-scale telescopes. Following two years of effort the positive results so far obtained have convinced LBTO, in 2019, to commence to develop an integrated operational active-optics system based on this technological approach. A team drawn from LBTO, Steward Observatory, GMTO, the Wyant College of Optical Sciences and Mersenne Optical Consulting are currently completing the first phase of this Telescope Metrology System (TMS). This paper shall describe the system in detail and report on progress, current status, and future goals. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
    • A Layered Debris Disk around M Star TWA 7 in Scattered Light

      Ren, B.; Choquet, E.; Perrin, M.D.; Mawet, D.; Chen, C.H.; Milli, J.; Debes, J.H.; Rebollido, I.; Stark, C.C.; Hagan, J.B.; et al. (IOP Publishing Ltd, 2021)
      We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the Space Telescope Imaging Spectrograph (STIS) instrument in visible light. Together with archival observations, including HST/NICMOS using the F160W filter and Very Large Telescope/SPHERE at the H-band in polarized light, we investigate the system in scattered light. By studying this nearly face-on system using geometric disk models and Henyey-Greenstein phase functions, we report a new discovery of a tertiary ring and a clump. We identify a layered architecture: three rings, a spiral, and an ≈150 au2 elliptical clump. The most extended ring peaks at 28 au, and the other components are on its outskirts. Our point-source detection-limit calculations demonstrate the necessity of disk modeling in imaging fainter planets. Morphologically, we witness a clockwise spiral motion, and the motion pattern is consistent with both solid body motion and local Keplerian motion; we also observe underdensity regions for the secondary ring that might result from mean-motion resonance or moving shadows: both call for re-observations to determine their nature. Comparing multi-instrument observations, we obtain blue STIS-NICMOS color, a STIS-SPHERE radial distribution peak difference for the tertiary ring, and a high SPHERE-NICMOS polarization fraction; these aspects indicate that TWA 7 could retain small dust particles. By viewing the debris disk around M star TWA 7 at a nearly face-on vantage point, our study allows for the understanding of such disks in scattered light in both system architecture and dust property. © 2021. The American Astronomical Society. All rights reserved.
    • A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings

      Hsu, C.-W.; Yin, J.; Griffies, S.M.; Dussin, R.; University of Arizona, Department of Geoscience (Copernicus GmbH, 2021)
      The sea level over the tropical Pacific is a key indicator reflecting vertically integrated heat distribution over the ocean. Here, we use the Geophysical Fluid Dynamics Laboratory global ocean-sea ice model (GFDL-OM4) forced by both the Coordinated Ocean-Ice Reference Experiment (CORE) and Japanese 55-year Reanalysis (JRA-55)-based surface dataset for driving ocean-sea ice models (JRA55-do) atmospheric states (Ocean Model Intercomparison Project (OMIP) versions I and II) to evaluate the model performance and biases compared against available observations. We find persisting mean state dynamic sea level (DSL) bias along 9° N even with updated wind forcing in JRA55-do relative to CORE. The mean state bias is related to biases in wind stress forcing and geostrophic currents in the 4 to 9° N latitudinal band. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. In the CORE forcing, the anomalous westerly wind trend in the eastern tropical Pacific causes an underestimated DSL trend across the entire Pacific basin along 10° N. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. We also identify a bias in the easterly wind trend along 20° N in both JRA55-do and CORE, thus motivating future improvement. In JRA55-do, an accurate Rossby wave initiated in the eastern tropical Pacific at seasonal timescale corrects a biased seasonal variability of the northern equatorial countercurrent in the CORE simulation. Both CORE and JRA55-do generate realistic DSL variation during El Niño. We find an asymmetry in the DSL pattern on two sides of the Equator is strongly related to wind stress curl that follows the sea level pressure evolution during El Niño. © 2021 The Author(s).
    • A Meta-Analysis of the "Erasing Race" Effect in the United States and Some Theoretical Considerations

      Woodley Of Menie, Michael A.; Heeney, Michael D.; Penaherrera-Aguirre, Mateo; Sarraf, Matthew A.; Banner, Randy; Rindermann, Heiner; Univ Arizona, Dept Psychol (FRONTIERS MEDIA SA, 2020-08)
      The "erasing race" effect is the reduction of the salience of "race" as an alliance cue when recalling coalition membership, once more accurate information about coalition structure is presented. We conducted a random-effects model meta-analysis of this effect using five United States studies (containing nine independent effect sizes). The effect was found (rho = 0.137,K= 9, 95% CI = 0.085 to 0.188). However, no decline effect or moderation effects were found (a "decline effect" in this context would be a decrease in the effect size over time). Furthermore, we found little evidence of publication bias. Synthetically correcting the effect size for bias stemming from the use of an older method for calculating error base rates reduced the magnitude of the effect, but the it remained significant. Taken together, these findings indicate that the "erasing race" effect generalizes quite well across experimental contexts and would, therefore, appear to be quite robust. We reinterpret the theoretical basis for these effects in line with Brunswikian evolutionary-developmental theory and present a series of predictions to guide future research in this area.
    • A Metallicity Study of F, G, K, and M Dwarfs in the Coma Berenices Open Cluster from the APOGEE Survey

      Souto, D.; Cunha, K.; Smith, V.V.; Steward Observatory, University of Arizona (IOP Publishing Ltd, 2021)
      We present a study of metallicities in a sample of main-sequence stars with spectral types M, K, G, and F (T eff ∼3200-6500K and log g ∼ 4.3-5.0 dex) belonging to the solar neighborhood young open cluster Coma Berenices. Metallicities were determined using the high-resolution (R = λ/Δ λ ∼ 22,500) NIR spectra (λ1.51-λ1.69 μm) of the Sloan Digital Sky Survey IV APOGEE survey. Membership to the cluster was confirmed using previous studies in the literature along with APOGEE radial velocities and Gaia DR2. An LTE analysis using plane-parallel MARCS model atmospheres and the APOGEE DR16 line list was adopted to compute synthetic spectra and derive atmospheric parameters (T eff and log g) for the M dwarfs and metallicities for the sample. The derived metallicities are near-solar and are homogeneous at the level of the expected uncertainties, in particular when considering stars from a given stellar class. The mean metallicity computed for the sample of G, K, and M dwarfs is [Fe/H] = +0.04 0.02 dex; however, the metallicities of the F-type stars are slightly lower, by about 0.04 dex, when compared to cooler and less massive members. Models of atomic diffusion can explain this modest abundance dip for the F dwarfs, indicating that atomic diffusion operates in Coma Berenices stars. The [Fe/H] dip occurs in nearly the same effective temperature range as that found in previous analyses of the lithium and beryllium abundances in Coma Berenices. © 2021. The American Astronomical Society. All rights reserved.
    • A method to reuse archived H&E stained histology slides for a multiplex protein biomarker analysis

      Hinton, J.P.; Dvorak, K.; Roberts, E.; French, W.J.; Grubbs, J.C.; Cress, A.E.; Tiwari, H.A.; Nagle, R.B.; Cancer Biology Graduate Interdisciplinary Program, University of Arizona Cancer Center; Department of Cellular and Molecular Medicine, University of Arizona; et al. (MDPI AG, 2019)
      Archived Hematoxylin and Eosin (H&E) stained pathology slides are routinely stored to index formalin-fixed paraffin-embedded (FFPE) sample tissue blocks. FFPE blocks are clinically annotated human tumor specimens that can be valuable in studies decades after the tissue is collected. If stored properly, they have the potential to yield a valuable number of serial sectioned slides for diagnostic or research purposes. However, some retrospective studies are limited in scope because the tissue samples have been depleted or not enough material is available in stored blocks for serial sections. The goal of these studies was to determine if archived H&E-stained slides can be directly reutilized by optimizing methods to de-stain and then re-stain the H&E stained slides to allow the detection of several biomarkers of interest using a conjugated antibody with chromogen multiplex immunohistochemistry procedure. This simple but innovative procedure, combined with image analysis techniques, demonstrates the ability to perform precise detection of relevant markers correlated to disease progression in initially identified tumor regions in tissue. This may add clinical value in retaining H&E slides for further use. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
    • A milk-fat based diet increases metastasis in the mmtv-pymt mouse model of breast cancer

      Velazquez, F.N.; Viscardi, V.; Montemage, J.; Zhang, L.; Trocchia, C.; Delamont, M.M.; Ahmad, R.; Hannun, Y.A.; Obeid, L.M.; Snider, A.J.; et al. (MDPI AG, 2021)
      A high-fat diet (HFD) and obesity are risk factors for many diseases including breast cancer. This is particularly important with close to 40% of the current adult population being overweight or obese. Previous studies have implicated that Mediterranean diets (MDs) partially protect against breast cancer. However, to date, the links between diet and breast cancer progression are not well defined. Therefore, to begin to define and assess this, we used an isocaloric control diet (CD) and two HFDs enriched with either olive oil (OOBD, high in oleate, and unsaturated fatty acid in MDs) or a milk fat-based diet (MFBD, high in palmitate and myristate, saturated fatty acids in Western diets) in a mammary polyomavirus middle T antigen mouse model (MMTV-PyMT) of breast cancer. Our data demonstrate that neither MFBD or OOBD altered the growth of primary tumors in the MMTV-PyMT mice. The examination of lung metastases revealed that OOBD mice exhibited fewer surface nodules and smaller metastases when compared to MFBD and CD mice. These data suggest that different fatty acids found in different sources of HFDs may alter breast cancer metastasis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • A Model of Social Eavesdropping in Communication Networks

      BighashI, L.; Alexander, K.S.; Hagen, C.S.; Hollingshead, A.B.; University of Arizona (University of Southern California, 2020)
      Social eavesdropping is the gathering of information from the interactions of 2 or more people, without their expressed knowledge or expressed permission, by a third party who is ostensibly not the target audience. Grounded in uncertainty management, communication networks, and signaling theories, this article presents a theoretical framework for understanding when and how individuals are likely to eavesdrop on the interactions of others. Social eavesdropping can be actively premeditated or passively incidental, the latter spurred by a serendipitous encounter. Propositions derived from the model investigate how accessibility, information value, and social risk influence the likelihood of social eavesdropping. © 2020 (Leila Bighash, Kristen S. Alexander, Christina S. Hagen, and Andrea B. Hollingshead). Licensed under the Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd). All Rights Reserved.
    • A modified split bregman algorithm for computing microstructures through young measures

      Jaramillo, G.; Venkataramani, S.C.; Department of Mathematics, University of Arizona (Society for Industrial and Applied Mathematics Publications, 2021)
      The goal of this paper is to describe the oscillatory microstructure that can emerge from minimizing sequences for nonconvex energies. We consider integral functionals that are defined on real valued (scalar) functions u(x) which are nonconvex in the gradient \nabla u and possibly also in u. To characterize the microstructures for these nonconvex energies, we minimize the associated relaxed energy using two novel approaches: (i) a semianalytical method based on control systems theory, (ii) and a numerical scheme that combines convex splitting together with a modified version of the split Bregman algorithm. These solutions are then used to gain information about minimizing sequences of the original problem and the spatial distribution of microstructure. © 2021 Society for Industrial and Applied Mathematics Publications. All rights reserved.
    • A modular hierarchical array camera

      Yuan, X.; Ji, M.; Wu, J.; Brady, D.J.; Dai, Q.; Fang, L.; College of Optical Sciences, University of Arizona (Springer Nature, 2021)
      Array cameras removed the optical limitations of a single camera and paved the way for high-performance imaging via the combination of micro-cameras and computation to fuse multiple aperture images. However, existing solutions use dense arrays of cameras that require laborious calibration and lack flexibility and practicality. Inspired by the cognition function principle of the human brain, we develop an unstructured array camera system that adopts a hierarchical modular design with multiscale hybrid cameras composing different modules. Intelligent computations are designed to collaboratively operate along both intra- and intermodule pathways. This system can adaptively allocate imagery resources to dramatically reduce the hardware cost and possesses unprecedented flexibility, robustness, and versatility. Large scenes of real-world data were acquired to perform human-centric studies for the assessment of human behaviours at the individual level and crowd behaviours at the population level requiring high-resolution long-term monitoring of dynamic wide-area scenes. © 2021, The Author(s).
    • A MUSE view of the asymmetric jet from HD 163296

      Xie, C.; Haffert, S.Y.; De Boer, J.; Kenworthy, M.A.; Brinchmann, J.; Girard, J.; Snellen, I.A.G.; Keller, C.U.; Steward Observatory, University of Arizona (EDP Sciences, 2021)
      Context. Jets and outflows are thought to play important roles in regulating star formation and disk evolution. An important question is how the jets are launched. HD 163296 is a well-studied Herbig Ae star that hosts proto-planet candidates, a protoplanetary disk, a protostellar jet, and a molecular outflow, which makes it an excellent laboratory for studying jets. Aims. We aim to characterize the jet at the inner regions and check if there are large differences with the features at large separations. A secondary objective is to demonstrate the performance of Multi Unit Spectroscopic Explorer (MUSE) in high-contrast imaging of extended line emission. Methods. MUSE in the narrow field mode (NFM) can provide observations at optical wavelengths with high spatial (∼75 mas) and medium spectral (R  ∼  2500) resolution. With the high-resolution spectral differential imaging technique, we can characterize the kinematic structures and physical conditions of jets down to 100 mas. Results. We detect multiple atomic lines in two new knots, B3 and A4, at distances of < 4 from the host star with MUSE. The derived M jet/M acc is about 0.08 and 0.06 for knots B3 and A4, respectively. The observed [Ca II]/[S II] ratios indicate that there is no sign of dust grains at distances of < 4. Assuming the A4 knot traced the streamline, we can estimate a jet radius at the origin by fitting the half width half maximum of the jet, which sets an upper limit of 2.2 au on the size of the launching region. Although MUSE has the ability to detect the velocity shifts caused by high- and low-velocity components, we found no significant evidence of velocity decrease transverse to the jet direction in our 500 s MUSE observation. Conclusions. Our work demonstrates the capability of using MUSE NFM observations for the detailed study of stellar jets in the optical down to 100 mas. The derived M jet/M acc, no dust grain, and jet radius at the star support the magneto-centrifugal models as a launching mechanism for the jet. © C. Xie et al. 2021.
    • A near-infrared interferometric survey of debris-disk stars: VII. The hot-to-warm dust connection

      Absil, O.; Marion, L.; Ertel, S.; Defrère, D.; Kennedy, G.M.; Romagnolo, A.; Le Bouquin, J.-B.; Christiaens, V.; Milli, J.; Bonsor, A.; et al. (EDP Sciences, 2021)
      Context. Hot exozodiacal dust has been shown to be present in the innermost regions of an increasing number of main sequence stars over the past 15 yr. However, the origin of hot exozodiacal dust and its connection with outer dust reservoirs remains unclear. Aims. We aim to explore the possible connection between hot exozodiacal dust and warm dust reservoirs (>100 K) in asteroid belts. Methods. We use precision near-infrared interferometry with VLTI/PIONIER to search for resolved emission at H-band around a selected sample of 62 nearby stars that show possible signs of warm dust populations. Results. Our observations reveal the presence of resolved near-infrared emission around 17 out of 52 stars with sufficient data quality. For four of these, the emission is shown to be due to a previously unknown stellar companion. The 13 other H-band excesses are thought to originate from the thermal emission of hot dust grains, close to their sublimation temperature. Taking into account earlier PIONIER observations, where some stars with warm dust were also observed, and after re-evaluating the warm dust content of all our PIONIER targets through spectral energy distribution modeling, we find a detection rate of 17:1+8:1-4:6% for H-band excess around main sequence stars hosting warm dust belts, which is statistically compatible with the occurrence rate of 14:6+4:3-2:8% found around stars showing no signs of warm dust. After correcting for the sensitivity loss due to partly unresolved hot disks, under the assumption that they are arranged in a thin ring around their sublimation radius, we find tentative evidence at the 3s level that H-band excesses around stars with outer dust reservoirs (warm or cold) could be statistically larger than H-band excesses around stars with no detectable outer dust. Conclusions. Our observations do not suggest a direct connection between warm and hot dust populations at the sensitivity level of the considered instruments, although they bring to light a possible correlation between the level of H-band excess and the presence of outer dust reservoirs in general. © 2021 ESO.
    • A New Crater Near InSight: Implications for Seismic Impact Detectability on Mars

      Daubar, I. J.; Lognonne, P.; Teanby, N. A.; Collins, G. S.; Clinton, J.; Staehler, S.; Spiga, A.; Karakostas, F.; Ceylan, S.; Malin, M.; et al. (AMER GEOPHYSICAL UNION, 2020-08)
      A new 1.5 m diameter impact crater was discovered on Mars only similar to 40 km from the InSight lander. Context camera images constrained its formation between 21 February and 6 April 2019; follow-up High Resolution Imaging Science Experiment images resolved the crater. During this time period, three seismic events were identified in InSight data. We derive expected seismic signal characteristics and use them to evaluate each of the seismic events. However, none of them can definitively be associated with this source. Atmospheric perturbations are generally expected to be generated during impacts; however, in this case, no signal could be identified as related to the known impact. Using scaling relationships based on the terrestrial and lunar analogs and numerical modeling, we predict the amplitude, peak frequency, and duration of the seismic signal that would have emanated from this impact. The predicted amplitude falls near the lowest levels of the measured seismometer noise for the predicted frequency. Hence, it is not surprising this impact event was not positively identified in the seismic data. Finding this crater was a lucky event as its formation this close to InSight has a probability of only similar to 0.2, and the odds of capturing it in before and after images are extremely low. We revisit impact-seismic discriminators in light of real experience with a seismometer on the Martian surface. Using measured noise of the instrument, we revise our previous prediction of seismic impact detections downward, from similar to a few to tens, to just similar to 2 per Earth year, still with an order of magnitude uncertainty.
    • A New Digital Terrain Model of the Huygens Landing Site on Saturn's Largest Moon, Titan

      Daudon, C.; Lucas, A.; Rodriguez, S.; Jacquemoud, S.; Escalante, López, A.; Grieger, B.; Howington-Kraus, E.; Karkoschka, E.; Kirk, R.L.; Perron, J.T.; et al. (Blackwell Publishing Ltd, 2020)
      River valleys have been observed on Titan at all latitudes by the Cassini-Huygens mission. Just like water on Earth, liquid methane carves into the substrate to form a complex network of rivers, particularly stunning in the images acquired near the equator by the Huygens probe. To better understand the processes at work that form these landscapes, one needs an accurate digital terrain model (DTM) of this region. The first and to date the only existing DTM of the Huygens landing site was produced by the U.S. Geological Survey (USGS) from high-resolution images acquired by the DISR (Descent Imager/Spectral Radiometer) cameras on board the Huygens probe and using the SOCET SET photogrammetric software. However, this DTM displays inconsistencies, primarily due to nonoptimal viewing geometries and to the poor quality of the original data, unsuitable for photogrammetric reconstruction. We investigate a new approach, benefiting from a recent reprocessing of the DISR images correcting both the radiometric and geometric distortions. For the DTM reconstruction, we use MicMac, a photogrammetry software based on automatic open-source shape-from-motion algorithms. To overcome challenges such as data quality and image complexity (unusual geometric configuration), we developed a specific pipeline that we detailed and documented in this article. In particular, we take advantage of geomorphic considerations to assess ambiguity on the internal calibration and the global orientation of the stereo model. Besides the novelty in this approach, the resulting DTM obtained offers the best spatial sampling of Titan's surface available and a significant improvement over the previous results. © 2020. The Authors.