Bispectrum phase, closure phase and their generalization to kernel phase are all independent of pupil-plane phase errors to first order. This property, when used with sparse aperture masking behind ...adaptive optics, has been used recently in high-contrast observations at or inside the formal diffraction limit of large telescopes. Finding the limitations to these techniques requires an understanding of spatial and temporal third-order phase effects, as well as effects such as time-variable dispersion when coupled with the non-zero bandwidths in real observations. In this paper, formulae describing many of these errors are developed, so that a comparison can be made to fundamental noise processes of photon noise and background noise.
I show that the current generation of aperture-masking observations of young solar-type stars, taken carefully in excellent observing conditions, are consistent with being limited by temporal phase noise and photon noise. This has relevance for plans to combine pupil remapping with spatial filtering.
Finally, I describe calibration strategies for kernel phase, including the optimized calibrator weighting as used for LkCa15, and the restricted kernel phase POISE (phase observationally independent of systematic errors) technique that avoids explicit dependence on calibrators.
We present 237 new spectroscopically confirmed pre-main-sequence K- and M-type stars in the young Upper Scorpius subgroup of the Sco–Cen association, the nearest region of recent massive star ...formation. Using the Wide-Field Spectrograph at the Australian National University 2.3 m telescope at Siding Spring, we observed 397 kinematically and photometrically selected candidate members of Upper Scorpius, and identified new members by the presence of lithium absorption. The HR-diagram of the new members shows a spread of ages, ranging from ∼3 to 20 Myr, which broadly agrees with the current age estimates of ∼5–10 Myr. We find a significant range of Li 6708 equivalent widths among the members, and a minor dependence of HR-diagram position on the measured equivalent width of the Li 6708 Å line, with members that appear younger having more lithium. This could indicate the presence of either populations of different age, or a spread of ages in Upper Scorpius. We also use Wide-Field Infrared Survey Explorer data to infer circumstellar disc presence in 25 of the members on the basis of infrared excesses, including two candidate transition discs. We find that 11.2 ± 3.4 per cent of the M0–M2 spectral type (0.4–0.8 M⊙) Upper Sco stars display an excess that indicates the presence of a gaseous disc.
Increasing attention is being paid to how adults on the autism spectrum perceive and interpret the interoceptive sense. This 20-item Interoception Sensory Questionnaire represents a single factor ...scale that can be interpreted as representing confusion about interoceptive bodily states unless these states are extreme (Alexisomia), and has been designed to discriminate across populations (total sample 511 participants). Findings showed that 74% of adults with autism reported interoceptive confusion. Another finding of the study was that as autistic traits increased, interoceptive confusion increased, with adults with diagnosed autism scoring highest on the construct. Implications for physiological self-regulation as well as physical health outcomes are discussed, as well as recommendations for future research.
We classified the reddest (r − J > 2.2) stars observed by the NASA Kepler mission into main-sequence dwarf or evolved giant stars and determined the properties of 4216 M dwarfs based on a comparison ...of available photometry with that of nearby calibrator stars, as well as available proper motions and spectra. We revised the properties of candidate transiting planets using the stellar parameters, high-resolution imaging to identify companion stars, and, in the case of binaries, fitting light curves to identify the likely planet host. In 49 of 54 systems, we validated the primary as the host star. We inferred the intrinsic distribution of M dwarf planets using the method of iterative Monte Carlo simulation. We compared several models of planet orbital geometry and clustering and found that one where planets are exponentially distributed and almost precisely coplanar best describes the distribution of multiplanet systems. We determined that Kepler M dwarfs host an average of 2.2 ± 0.3 planets with radii of 1–4 R⊕ and orbital periods of 1.5–180 d. The radius distribution peaks at ∼1.2 R⊕ and is essentially zero at 4 R⊕, although we identify three giant planet candidates other than the previously confirmed Kepler-45b. There is suggestive but not significant evidence that the radius distribution varies with orbital period. The distribution with logarithmic orbital period is flat except for a decline for orbits less than a few days. 12 candidate planets, including two Jupiter-size objects, experience an irradiance below the threshold level for a runaway greenhouse on an Earth-like planet and are thus in a ‘habitable zone’.
CoKu Tau/4 has been labeled as one of the very few known transition disk objects--disks around young stars that have their inner disks cleared of dust, arguably as a result of planetary formation. We ...report aperture-masking interferometry and adaptive optics imaging observations showing that CoKu Tau/4 is in fact a near-equal binary star of projected separation similar to 53 mas ( similar to 8 AU). The spectral energy distribution of the disk is then naturally explained by the inner truncation of the disk through gravitational interactions with the binary star system. We discuss the possibility that such "unseen" binary companions could cause other circumbinary disks to be labeled as transitional.
The GALAH survey: scientific motivation De Silva, G. M; Freeman, K. C; Bland-Hawthorn, J ...
Monthly Notices of the Royal Astronomical Society,
05/2015, Letnik:
449, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The Galactic Archaeology with HERMES (GALAH) survey is a large high-resolution spectroscopic survey using the newly commissioned High Efficiency and Resolution Multi-Element Spectrograph (HERMES) on ...the Anglo-Australian Telescope. The HERMES spectrograph provides high-resolution (R ∼ 28 000) spectra in four passbands for 392 stars simultaneously over a 2 deg field of view. The goal of the survey is to unravel the formation and evolutionary history of the Milky Way, using fossil remnants of ancient star formation events which have been disrupted and are now dispersed throughout the Galaxy. Chemical tagging seeks to identify such dispersed remnants solely from their common and unique chemical signatures; these groups are unidentifiable from their spatial, photometric or kinematic properties. To carry out chemical tagging, the GALAH survey will acquire spectra for a million stars down to V ∼ 14. The HERMES spectra of FGK stars contain absorption lines from 29 elements including light proton-capture elements, α-elements, odd-Z elements, iron-peak elements and n-capture elements from the light and heavy s-process and the r-process. This paper describes the motivation and planned execution of the GALAH survey, and presents some results on the first-light performance of HERMES.
We present a new high-mass membership of the nearby Sco OB2 association based on Hipparcos positions, proper motions and parallaxes, and radial velocities taken from the 2nd Catalogue of Radial ...Velocities with Astrometric Data (CRVAD-2). The Bayesian membership selection method developed makes no distinction between subgroups of Sco OB2 and utilizes linear models in calculation of membership probabilities. We select 436 members, 88 of which are new members not included in previous membership selections. We include the classical non-members α-Cru and β-Cru as new members as well as the pre-main-sequence stars HIP 79080 and 79081. We also show that the association is well mixed over distances of 8° on the sky, and hence no determination can be made as to the formation process of the entire association.
Context.
Interferometric observables are strongly correlated, yet it is common practice to ignore these correlations in the data analysis process.
Aims.
We develop an empirical model for the ...correlations present in Very Large Telescope Interferometer GRAVITY data and show that properly accounting for them yields fainter detection limits and increases the reliability of potential detections.
Methods.
We extracted the correlations of the (squared) visibility amplitudes and the closure phases directly from intermediate products of the GRAVITY data reduction pipeline and fitted our empirical models to them. Then, we performed model fitting and companion injection and recovery tests with both simulated and real GRAVITY data, which are affected by correlated noise, and compared the results when ignoring the correlations and when properly accounting for them with our empirical models.
Results.
When accounting for the correlations, the faint source detection limits improve by a factor of up to ∼2 at angular separations > 20 mas. For commonly used detection criteria based on
χ
2
statistics, this mostly results in claimed detections being more reliable.
Conclusions.
Ignoring the correlations present in interferometric data is a dangerous assumption which might lead to a large number of false detections. The commonly used detection criteria (e.g. in the model fitting pipeline CANDID) are only reliable when properly accounting for the correlations; furthermore, instrument teams should work on providing full covariance matrices instead of statistically independent error bars as part of the official data reduction pipelines.
Purpose
Many people do not participate in mail-out bowel cancer screening programs due to difficulties using the screening kit. The current study investigated the ways the screening kit could be ...modified to improve usability.
Methods
1,109 people evaluated 15 different screening kit modifications. Participants reported on how these kit modifications would affect their screening barriers, their future screening intentions, and how much they would recommend that the modification is made to the current screening kit used the program. All responses were given via an online survey conducted between April and December of 2021.
Results
Seventeen percent of previous NBCSP non-participators indicated that a
one-sample
test would increase their intention to participate. Recommendation ratings demonstrated higher levels of support for modifications that included providing a barcode naming label (
M
= 9.06, 95% CI 8.81, 9.31), having a larger diameter opening of the collection tube (
M
= 8.42, 95% CI 8.10, 8.74), and highlighting the expiry date on the kit packaging (
M
= 8.59, 95% CI 8.29, 8.89). There were lower levels of support for modifications that reduced the size of the packaging the kit is sent in (
M
= 6.47, 95% CI 6.09, 6.85), removed branding from kit packaging (
M
= 5.98, 95% CI 5.57, 6.39), and removed the information booklet that comes with the screening kit (
M
= 5.25, 95% CI 4.78, 5.72).
Conclusion
These findings highlight multiple ways in which bowel cancer screening kits can be changed to increase usability for invitees of national bowel cancer screening programs. Findings have implications for all screening programs that use immunochemical-based bowel cancer screening kits.
At wide separations, planetary-mass and brown dwarf companions to solar-type stars occupy a curious region of parameter space not obviously linked to binary star formation or solar system scale ...planet formation. These companions provide insight into the extreme case of companion formation (either binary or planetary), and due to their relative ease of observation when compared to close companions, they offer a useful template for our expectations of more typical planets. We present the results from an adaptive optics imaging survey for wide (~50-500 AU) companions to solar-type stars in Upper Scorpius. We report one new discovery of a ~14 M J companion around GSC 06214--00210and confirm that the candidate planetary-mass companion 1RXS J160929.1--210524 detected by Lafreniere et al. is in fact comoving with its primary star. In our survey, these two detections correspond to ~4% of solar-type stars having companions in the 6-20 M J mass and ~200-500 AU separation range. This figure is higher than would be expected if brown dwarfs and planetary-mass companions were drawn from an extrapolation of the binary mass function. Finally, we discuss implications for the formation of these objects.
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