The LHS 1678 system : two earth-sized transiting planets and an astrometric companion orbiting an M dwarf near the convective boundary at 20 pc

Funding: The MEarth Team gratefully acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering (awarded to D.C.). This material is based upon work supported by the National Science Foundation under grants AST-0807690, AST-1109468, AST-1004488 (Alan T. Waterman Award), and AST-1616624, and upon work supported by the National Aeronautics and Space Administration under Grant No. 80NSSC18K0476 issued through the XRP Program. This work is made possible by a grant from the John Templeton Foundation. N. A.-D. acknowledges the support of FONDECYT project 3180063. TD acknowledges support from MIT’s Kavli Institute as a Kavli postdoctoral fellow. KH acknowledges support from STFC grant ST/R000824/1. E.A.G. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, the Brinson Foundation, and the Moore Foundation; The material is based upon work supported by NASA under award number 80GSFC21M0002. This work was supported by the lead author’s appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASAWe present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting a bright (VJ = 12.5, Ks = 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.70 ± 0.04 R⊕ and 0.98 ± 0.06 R⊕ in 0.86 day and 3.69 day orbits, respectively. Both planets are validated and characterized via ground-based follow-up observations. High Accuracy Radial Velocity Planet Searcher RV monitoring yields 97.7 percentile mass upper limits of 0.35 M⊕ and 1.4 M⊕ for planets b and c, respectively. The astrometric companion detected by the Cerro Tololo Inter-American Observatory/Small and Moderate Aperture Telescope System 0.9 m has an orbital period on the order of decades and is undetected by other means. Additional ground-based observations constrain the companion to being a high-mass brown dwarf or smaller. Each planet is of unique interest; the inner planet has an ultra-short period, and the outer planet is in the Venus zone. Both are promising targets for atmospheric characterization with the James Webb Space Telescope and mass measurements via extreme-precision radial velocity. A third planet candidate of radius 0.9 ± 0.1 R⊕ in a 4.97 day orbit is also identified in multicycle TESS data for validation in future work. The host star is associated with an observed gap in the lower main sequence of the Hertzsprung–Russell diagram. This gap is tied to the transition from partially to fully convective interiors in M dwarfs, and the effect of the associated stellar astrophysics on exoplanet evolution is currently unknown. The culmination of these system properties makes LHS 1678 a unique, compelling playground for comparative exoplanet science and understanding the formation and evolution of small, short-period exoplanets orbiting low-mass stars.Publisher PDFPeer reviewe

Complex Modulation of Rapidly Rotating Young M Dwarfs: Adding Pieces to the Puzzle

New sets of young M dwarfs with complex, sharp-peaked, and strictly periodic photometric modulations have recently been discovered with Kepler/K2 (scallop shells) and TESS (complex rotators). All are part of star-forming associations, are distinct from other variable stars, and likely belong to a unified class. Suggested hypotheses include starspots, accreting dust disks, corotating clouds of material, magnetically constrained material, spots and misaligned disks, and pulsations. Here, we provide a comprehensive overview and add new observational constraints with TESS and SPECULOOS Southern Observatory photometry. We scrutinize all hypotheses from three new angles: (1) We investigate each scenario's occurrence rates via young star catalogs, (2) we study the feature's longevity using over one year of combined data, and (3) we probe the expected color dependency with multicolor photometry. In this process, we also revisit the stellar parameters accounting for activity effects, study stellar flares as activity indicators over year-long timescales, and develop toy models to simulate typical morphologies. We rule out most hypotheses, and only (i) corotating material clouds and (ii) spots and misaligned disks remain feasible-with caveats. For (i), corotating dust might not be stable enough, while corotating gas alone likely cannot cause percentage-scale features and (ii) would require misaligned disks around most young M dwarfs. We thus suggest a unified hypothesis, a superposition of large-amplitude spot modulations and sharp transits of corotating gas clouds. While the complex rotators' mystery remains, these new observations add valuable pieces to the puzzle going forward

The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc

We present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting a bright (V J = 12.5, K s = 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.70 ± 0.04 R ⊕ and 0.98 ± 0.06 R ⊕ in 0.86 day and 3.69 day orbits, respectively. Both planets are validated and characterized via ground-based follow-up observations. High Accuracy Radial Velocity Planet Searcher RV monitoring yields 97.7 percentile mass upper limits of 0.35 M ⊕ and 1.4 M ⊕ for planets b and c, respectively. The astrometric companion detected by the Cerro Tololo Inter-American Observatory/Small and Moderate Aperture Telescope System 0.9 m has an orbital period on the order of decades and is undetected by other means. Additional ground-based observations constrain the companion to being a high-mass brown dwarf or smaller. Each planet is of unique interest; the inner planet has an ultra-short period, and the outer planet is in the Venus zone. Both are promising targets for atmospheric characterization with the James Webb Space Telescope and mass measurements via extreme-precision radial velocity. A third planet candidate of radius 0.9 ± 0.1 R ⊕ in a 4.97 day orbit is also identified in multicycle TESS data for validation in future work. The host star is associated with an observed gap in the lower main sequence of the Hertzsprung-Russell diagram. This gap is tied to the transition from partially to fully convective interiors in M dwarfs, and the effect of the associated stellar astrophysics on exoplanet evolution is currently unknown. The culmination of these system properties makes LHS 1678 a unique, compelling playground for comparative exoplanet science and understanding the formation and evolution of small, short-period exoplanets orbiting low-mass stars

Habitat use by the serotine bat Eptesicus serotinus in Belgium

peer reviewedThe radiotracking of 10 serotine bats during a period of 73 nights shows that the animals hunt mainly at forest edges and above meadows. The mean distance between the main diurnal roost and hunting grounds is 2.1 +/- 1.2 km (n = 24). Secondary diurnal roosts are used within a radius of 250 m of the main diurnal quarters. Nocturnal resting places are situated in beech forests (Fagus sylvatica) near feeding areas. The activity area (minumum area method) of radiotracked serotine bats, all originating from the same colony, stretches to 15.8 km²

Human recombinant tissue factor, platelet-rich plasma, and tetracycilne induce a high-quality human bone graft: a 5-year survey.

PURPOSE: To increase human bone graft regeneration and quality by the use of a mixture containing autologous ground calvarial bone, human recombinant tissue factor (rhTF), platelet-rich plasma (PRP), and tetracycline. MATERIALS AND METHODS: Maxillary sinus floor augmentation was performed on 18 patients by grafting a "bone paste" made of PRP (1.8 x 10(6) platelets/mm3 plasma), about 1 microg rhTF, calvarial bone chips (2 to 5 mm in size), and tetracycline (10 to 30 microg/mL preparation). Five to 6 months after the surgical phase and grafting a bone core was extracted for implant fixation, and the osseous core samples were analyzed microscopically. RESULTS: Histology revealed vascularized connective tissue rich in lamellar bone spicules containing osteocytes and surrounded by osteoblasts. The success rate of grafting was 90.3%. In 6-month postoperative blood samples, no residual coagulating disturbances could be found. DISCUSSION: The combination of calvarial bone chips, rhTF, PRP, and tetracycline results in a paste that is easy to handle, safe for patients, and possesses high bone-regeneration capacity. CONCLUSION: The generalized use in implant dentistry, oral surgery, and orthopedics of such a protocol could facilitate the healing process as well as patient safety and surgeon comfort.Journal Articleinfo:eu-repo/semantics/publishe

Foraging and feeding ecology of the Serotine bat Eptesicus serotinus

peer reviewe

Human recombinant tissue factor, platelet-rich plasma, and tetracycline induce a high-quality human bone graft: a 5-year survey

PURPOSE: To increase human bone graft regeneration and quality by the use of a mixture containing autologous ground calvarial bone, human recombinant tissue factor (rhTF), platelet-rich plasma (PRP), and tetracycline. MATERIALS AND METHODS: Maxillary sinus floor augmentation was performed on 18 patients by grafting a "bone paste" made of PRP (1.8 x 10(6) platelets/mm3 plasma), about 1 microg rhTF, calvarial bone chips (2 to 5 mm in size), and tetracycline (10 to 30 microg/mL preparation). Five to 6 months after the surgical phase and grafting a bone core was extracted for implant fixation, and the osseous core samples were analyzed microscopically. RESULTS: Histology revealed vascularized connective tissue rich in lamellar bone spicules containing osteocytes and surrounded by osteoblasts. The success rate of grafting was 90.3%. In 6-month postoperative blood samples, no residual coagulating disturbances could be found. DISCUSSION: The combination of calvarial bone chips, rhTF, PRP, and tetracycline results in a paste that is easy to handle, safe for patients, and possesses high bone-regeneration capacity. CONCLUSION: The generalized use in implant dentistry, oral surgery, and orthopedics of such a protocol could facilitate the healing process as well as patient safety and surgeon comfort.info:eu-repo/semantics/publishe