22 research outputs found
Red-giant and main-sequence solar-like oscillators in binary systems revealed by ESA Gaia Data Release 3 -- Reconstructing stellar and orbital evolution from binary-star ensemble seismology
Binary systems constitute a valuable astrophysics tool for testing our
understanding of stellar structure and evolution. Systems containing a
oscillating component are interesting as asteroseismology offers independent
parameters for the oscillating component that aid the analysis. About 150 of
such systems are known in the literature. To enlarge the sample of these
benchmark objects, we crossmatch the Two-Body-Orbit Catalogue (TBO) of Gaia
DR3, with catalogs of confirmed solar-like oscillators on the main-sequence and
red-giant phase from NASA Kepler and TESS. We obtain 954 new binary system
candidates hosting solar-like oscillators, of which 45 and 909 stars are on the
main sequence and red-giant, resp., including 2 new red giants in eclipsing
systems. 918 oscillators in potentially long-periodic systems are reported. We
increase the sample size of known solar-like oscillators in binary systems by
an order of magnitude. We present the seismic properties of the full sample and
conclude that the grand majority of the orbital elements in the TBO is
physically reasonable. 82% of all TBO binary candidates with multiple times
with APOGEE are confirmed from radial-velocity measurement. However, we suggest
that due to instrumental noise of the TESS satellite the seismically inferred
masses and radii of stars with 30Hz could be
significantly overestimated. For 146 giants the seismically inferred
evolutionary state has been determined and shows clear differences in their
distribution in the orbital parameters, which are accounted the accumulative
effect of the equilibrium tide acting in these evolved binary systems. For
other 146 systems hosting oscillating stars values for the orbital inclination
were found in the TBO. From testing the TBO on the SB9 catalogue, we obtain a
completeness factor of 1/3.Comment: under review for publication in A&A (22 pages + 4 pages of appendix,
21 figures, 33 pages of tables in the Appendix
Horizons: nuclear astrophysics in the 2020s and beyond
Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities
Horizons: Nuclear Astrophysics in the 2020s and Beyond
Nuclear Astrophysics is a field at the intersection of nuclear physics and
astrophysics, which seeks to understand the nuclear engines of astronomical
objects and the origin of the chemical elements. This white paper summarizes
progress and status of the field, the new open questions that have emerged, and
the tremendous scientific opportunities that have opened up with major advances
in capabilities across an ever growing number of disciplines and subfields that
need to be integrated. We take a holistic view of the field discussing the
unique challenges and opportunities in nuclear astrophysics in regards to
science, diversity, education, and the interdisciplinarity and breadth of the
field. Clearly nuclear astrophysics is a dynamic field with a bright future
that is entering a new era of discovery opportunities.Comment: 96 pages. Submitted to Journal of Physics
Horizons: nuclear astrophysics in the 2020s and beyond
Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities
The Wide-field Spectroscopic Telescope (WST) Science White Paper
The Wide-field Spectroscopic Telescope (WST) is proposed as a new facility dedicated to the efficient delivery of spectroscopic surveys. This white paper summarises the initial concept as well as the corresponding science cases. WST will feature simultaneous operation of a large field-of-view (3 sq. degree), a high multiplex (20,000) multi-object spectrograph (MOS) and a giant 3x3 sq. arcmin integral field spectrograph (IFS). In scientific capability these requirements place WST far ahead of existing and planned facilities. Given the current investment in deep imaging surveys and noting the diagnostic power of
spectroscopy, WST will fill a crucial gap in astronomical capability and work synergistically with future ground and space-based facilities. This white paper shows that WST can address outstanding scientific questions in the areas of cosmology; galaxy assembly, evolution, and enrichment, including our own Milky Way; origin of stars and planets; time domain and multi-messenger astrophysics. WST's uniquely rich dataset will deliver unforeseen discoveries in many of these areas. The WST Science Team (already including more than 500 scientists worldwide) is open to the all astronomical community. To register in the WST Science Team please visit https://www.wstelescope.com/for-scientists/participat
Pull-out strength of patient-specific template-guided vs. free-hand fluoroscopically controlled thoracolumbar pedicle screws: a biomechanical analysis of a randomized cadaveric study
PURPOSE To assess the pull-out strength of thoracolumbar pedicle screws implanted via either a patient-specific template-guided or conventional free-hand fluoroscopically controlled technique in a randomized cadaveric study, and to evaluate the influence of local vertebral bone density, quantified by Hounsfield units (HU), on pedicle screw pull-out strength.
METHODS Thoracolumbar pedicles of three spine cadavers were instrumented using either a free-hand fluoroscopically controlled or a patient-specific template-guided technique. Preoperative bone density was quantified by HU measured on CT. Pedicle perforation was evaluated on postoperative CT scans by an independent and blinded radiologist. After dissected vertebrae were embedded in aluminum fixation devices, pull-out testing was initiated with a preload of 50 N and a constant displacement rate of 0.5 mm/s. Subgroup analyses were performed excluding pedicle screws with a pedicle breach (n = 47).
RESULTS Pull-out strength was significantly different with 549 ± 278 and 441 ± 289 N in the template-guided (n = 50) versus fluoroscopically controlled (n = 48) subgroups (p = 0.031), respectively. Subgroup analysis limited to screws with an intrapedicular trajectory revealed a tendency toward a higher pull-out strength in the template-guided (n = 30) versus fluoroscopically controlled screws (n = 21) with 587 ± 309 and 454 ± 269 N (p = 0.118), respectively. There was a trend toward a higher pull-out strength (709 ± 418 versus 420 ± 149 N) in vertebrae with a bone density of (>171 HU) versus (<133 HU), respectively (p = 0.061).
CONCLUSIONS There was a significantly higher pull-out strength of thoracolumbar pedicle screws when inserted via a patient-specific template-guided versus conventional free-hand fluoroscopically controlled technique, potentially associated with screw trajectory