Wide binaries are rare in open clusters Deacon, N R; Kraus, A L
Monthly notices of the Royal Astronomical Society,
08/2020, Letnik:
496, Številka:
4
Journal Article
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ABSTRACT
The population statistics of binary stars are an important output of star formation models. However, populations of wide binaries evolve over time due to interactions within a system’s birth ...environment and the unfolding of wide, hierarchical triple systems. Hence, the wide binary populations observed in star-forming regions or OB associations may not accurately reflect the wide binary populations that will eventually reach the field. We use Gaia DR2 data to select members of three open clusters, Alpha Per, the Pleiades, and Praesepe and to flag cluster members that are likely unresolved binaries due to overluminosity or elevated astrometric noise. We then identify the resolved wide binary population in each cluster, separating it from coincident pairings of unrelated cluster members. We find that these clusters have an average wide binary fraction in the 300–3000 au projected separation range of 2.1$\pm ^{0.4}_{0.2}$ per cent increasing to 3.0$\pm ^{0.8}_{0.7}$ per cent for primaries with masses in the 0.5–1.5 M⊙ range. This is significantly below the observed field wide binary fraction, but shows some wide binaries survive in these dynamically highly processed environments. We compare our results with another open cluster (the Hyades) and two populations of young stars that likely originated in looser associations (young moving groups and the Pisces-Eridanus stream). We find that the Hyades also has a deficit of wide binaries while the products of looser associations have wide binary fractions at or above field level.
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’.
To update and expand upon prior Osteoarthritis Research Society International (OARSI) guidelines by developing patient-focused treatment recommendations for individuals with Knee, Hip, and ...Polyarticular osteoarthritis (OA) that are derived from expert consensus and based on objective review of high-quality meta-analytic data.
We sought evidence for 60 unique interventions. A systematic search of all relevant databases was conducted from inception through July 2018. After abstract and full-text screening by two independent reviewers, eligible studies were matched to PICO questions. Data were extracted and meta-analyses were conducted using RevMan software. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Evidence Profiles were compiled using the GRADEpro web application. Voting for Core Treatments took place first. Four subsequent voting sessions took place via anonymous online survey, during which Panel members were tasked with voting to produce recommendations for all joint locations and comorbidity classes. We designated non-Core treatments to Level 1A, 1B, 2, 3, 4A, 4B, or 5, based on the percentage of votes in favor, in addition to the strength of the recommendation.
Core Treatments for Knee OA included arthritis education and structured land-based exercise programs with or without dietary weight management. Core Treatments for Hip and Polyarticular OA included arthritis education and structured land-based exercise programs. Topical non-steroidal anti-inflammatory drugs (NSAIDs) were strongly recommended for individuals with Knee OA (Level 1A). For individuals with gastrointestinal comorbidities, COX-2 inhibitors were Level 1B and NSAIDs with proton pump inhibitors Level 2. For individuals with cardiovascular comorbidities or frailty, use of any oral NSAID was not recommended. Intra-articular (IA) corticosteroids, IA hyaluronic acid, and aquatic exercise were Level 1B/Level 2 treatments for Knee OA, dependent upon comorbidity status, but were not recommended for individuals with Hip or Polyarticular OA. The use of Acetaminophen/Paracetamol (APAP) was conditionally not recommended (Level 4A and 4B), and the use of oral and transdermal opioids was strongly not recommended (Level 5). A treatment algorithm was constructed in order to guide clinical decision-making for a variety of patient profiles, using recommended treatments as input for each decision node.
These guidelines offer comprehensive and patient-centered treatment profiles for individuals with Knee, Hip, and Polyarticular OA. The treatment algorithm will facilitate individualized treatment decisions regarding the management of OA.
Abstract
Kepler 1627A is a G8V star previously known to host a 3.8
R
⊕
planet on a 7.2 day orbit. The star was observed by the Kepler space telescope because it is nearby (
d
= 329 pc) and it ...resembles the Sun. Here, we show using Gaia kinematics, TESS stellar rotation periods, and spectroscopic lithium abundances that Kepler 1627 is a member of the
38
−
5
+
6
Myr old
δ
Lyr cluster. To our knowledge, this makes Kepler 1627Ab the youngest planet with a precise age yet found by the prime Kepler mission. The Kepler photometry shows two peculiarities: the average transit profile is asymmetric, and the individual transit times might be correlated with the local light-curve slope. We discuss possible explanations for each anomaly. More importantly, the
δ
Lyr cluster is one of ∼10
3
coeval groups whose properties have been clarified by Gaia. Many other exoplanet hosts are candidate members of these clusters; their ages can be verified with the trifecta of Gaia, TESS, and ground-based spectroscopy.
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.
Abstract
Stellar positions and velocities from Gaia are yielding a new view of open cluster dispersal. Here we present an analysis of a group of stars spanning Cepheus (
l
= 100°) to Hercules (
l
= ...40°), hereafter the Cep-Her complex. The group includes four Kepler objects of interest: Kepler-1643 b (
R
p
= 2.32 ± 0.13
R
⊕
,
P
= 5.3 days), KOI-7368 b (
R
p
= 2.22 ± 0.12
R
⊕
,
P
= 6.8 days), KOI-7913 Ab (
R
p
= 2.34 ± 0.18
R
⊕
,
P
= 24.2 days), and Kepler-1627 Ab (
R
p
= 3.85 ± 0.11
R
⊕
,
P
= 7.2 days). The latter Neptune-sized planet is in part of the Cep-Her complex called the
δ
Lyr cluster. Here we focus on the former three systems, which are in other regions of the association. Based on kinematic evidence from Gaia, stellar rotation periods from TESS, and spectroscopy, these three objects are also ≈40 million years (Myr) old. More specifically, we find that Kepler-1643 is
46
−
7
+
9
Myr old, based on its membership in a dense subcluster of the complex called RSG-5. KOI-7368 and KOI-7913 are
36
−
8
+
10
Myr old, and are in a diffuse region that we call CH-2. Based on the transit shapes and high-resolution imaging, all three objects are most likely planets, with false-positive probabilities of 6 × 10
−9
, 4 × 10
−3
, and 1 × 10
−4
for Kepler-1643, KOI-7368, and KOI-7913, respectively. These planets demonstrate that mini-Neptunes with sizes of ≈2 Earth radii exist at ages of 40 Myr.
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.
Post-traumatic arthritis (PTA) is a rapidly progressive form of arthritis that develops due to joint injury, including articular fracture. Current treatments are limited to surgical restoration and ...stabilization of the joint; however, evidence suggests that PTA progression is mediated by the upregulation of pro-inflammatory cytokines, such as interleukin-1 (IL-1) or tumor necrosis factor-α (TNF-α). Although these cytokines provide potential therapeutic targets for PTA, intra-articular injections of anti-cytokine therapies have proven difficult due to rapid clearance from the joint space. In this study, we examined the ability of a cross-linked elastin-like polypeptide (xELP) drug depot to provide sustained intra-articular delivery of IL-1 and TNF-α inhibitors as a beneficial therapy. Mice sustained a closed intra-articular tibial plateau fracture; treatment groups received a single intra-articular injection of drug encapsulated in xELP. Arthritic changes were assessed 4 and 8 weeks after fracture. Inhibition of IL-1 significantly reduced the severity of cartilage degeneration and synovitis. Inhibition of TNF-α alone or with IL-1 led to deleterious effects in bone morphology, articular cartilage degeneration, and synovitis. These findings suggest that IL-1 plays a critical role in the pathogenesis of PTA following articular fracture, and sustained intra-articular cytokine inhibition may provide a therapeutic approach for reducing or preventing joint degeneration following trauma.
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