Algol ( beta Per) is an extensively studied hierarchical triple system whose inner pair is a prototype semi-detached binary with mass transfer occurring from the sub-giant secondary to the ...main-sequence primary. We present here the results of our Algol observations made between 2006 and 2010 at the CHARA interferometer with the Michigan Infrared Combiner in the H-band. The use of four telescopes with long baselines allows us to achieve better than 0.5 mas resolution and to unambiguously resolve the three stars. The inner and outer orbital elements, as well as the angular sizes and mass ratios for the three components, are determined independently from previous studies. We report a significantly improved orbit for the inner stellar pair with the consequence of a 15% change in the primary mass compared with previous studies. We also determine the mutual inclination of the orbits to be much closer to perpendicularity than previously established. State-of-the-art image reconstruction algorithms are used to image the full triple system. In particular an image sequence of 55 distinct phases of the inner pair orbit is reconstructed, clearly showing the Roche-lobe-filling secondary revolving around the primary, with several epochs corresponding to the primary and secondary eclipses.
We present comprehensive models for the Herbig Ae stars MWC 275 and AB Aur that aim to explain their spectral energy distribution (from UV to millimeter) and long-baseline interferometry (from ...near-infrared to millimeter) simultaneously. Data from the literature, combined with new mid- infrared (MIR) interferometry from the Keck Segment Tilting Experiment, are modeled using an axisymmetric Monte Carlo radiative transfer code. Models in which most of the near-infrared (NIR) emission arises from a dust rim fail to fit the NIR spectral energy distribution (SED) and sub-milliarcsecond NIR CHARA interferometry. Following recent work, we include an additional gas emission component with similar size scale to the dust rim, inside the sublimation radius, to fit the NIR SED and long-baseline NIR interferometry on MWC 275 and AB Aur. In the absence of shielding of starlight by gas, we show that the gas-dust transition region in these YSOs will have to contain highly refractory dust, sublimating at similar to 1850 K. Despite having nearly identical structure in the thermal NIR, the outer disks of MWC 275 and AB Aur differ substantially. In contrast to the AB Aur disk, MWC 275 lacks small grains in the disk atmosphere capable of producing significant 10-20 mum emission beyond similar to 7 AU, forcing the outer regions into the "shadow" of the inner disk.
Context. The quest for hot dust in the central region of debris disks requires high resolution and high dynamic range imaging. Near-infrared interferometry is a powerful means to directly detect ...faint emission from hot grains. Aims. We probed the first 3 AU around \tau Ceti and \epsilon Eridani with the CHARA array (Mt Wilson, USA) in order to gauge the 2 \mum excess flux emanating from possible hot dust grains in the debris disks and to also resolve the stellar photospheres. Methods. High precision visibility amplitude measurements were performed with the FLUOR single mode fiber instrument and telescope pairs on baselines ranging from 22 to 241 m of projected length. The short baseline observations allow us to disentangle the contribution of an extended structure from the photospheric emission, while the long baselines constrain the stellar diameter. Results. We have detected a resolved emission around \tau Cet, corresponding to a spatially integrated, fractional excess flux of 0.98\pm0.21 \times 10 with respect to the photospheric flux in the K{\prime}-band. Around \epsilon Eri, our measurements can exclude a fractional excess of greater than 0.6\times 10 (3\sigma). We interpret the photometric excess around \tau Cet as a possible signature of hot grains in the inner debris disk and demonstrate that a faint, physical or background, companion can be safely excluded. In addition, we measured both stellar angular diameters with an unprecedented accuracy: \Theta_{\rm LD}(\tau\,{\rm Cet}) = 2.015 \pm 0.011 mas and \Theta_{\rm LD}(\epsilon\,{\rm Eri}) =2.126 \pm 0.014 mas.
Context. The main sequence binary star 61 Cyg (K5V+K7V) is our nearest stellar neighbour in the northern hemisphere. This proximity makes it a particularly well suited system for very high accuracy ...interferometric radius measurements. Aims. Our goal is to constrain the poorly known evolutionary status and age of this bright binary star. Methods. We obtained high accuracy interferometric observations in the infrared K logical or prime band, using the CHARA/FLUOR instrument. We then computed evolutionary models of 61 Cyg A & B with the CESAM2k code. As model constraints, we used a combination of observational parameters from classical observation methods (photometry, spectroscopy) as well as our new interferometric radii. Results. The measured limb darkened disk angular diameters are theta_{\rm LD}({\rm A}) = 1.775 pm 0.013 mas and theta_{\rm LD}({\rm B}) = 1.581 pm 0.022 mas, respectively for 61 Cyg A and B. Considering the high accuracy parallaxes available, these values translate into photospheric radii of R({\rm A}) = 0.665 pm 0.005 R_{\odot} and R({\rm B}) = 0.595 pm 0.008 R_{\odot}. The new radii constrain efficiently the physical parameters adopted for the modeling of both stars, allowing us to predict asteroseismic frequencies based on our best-fit models. Conclusions. The CESAM2k evolutionary models indicate an age around 6 Gyr and are compatible with small values of the mixing length parameter. The measurement of asteroseismic oscillation frequencies in 61 Cyg A & B would be of great value to improve the modeling of this important fiducial stellar system, in particular to better constrain the masses.
NF-κB essential modulator (NEMO), encoded by IKBKG, is necessary for activation of the ubiquitous transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Animal ...studies suggest NEMO is required for NF-κB mediated bone homeostasis, but this has not been thoroughly studied in humans. IKBKG loss-of-function mutation causes incontinentia pigmenti (IP), a rare X-linked disease featuring linear hypopigmentation, alopecia, hypodontia, and immunodeficiency. Single case reports describe osteopetrosis (OPT) in boys carrying hypomorphic IKBKG mutations.
We studied the bone phenotype in women with IP with evaluation of radiographs of the spine and non-dominant arm and leg; lumbar spine and femoral neck aBMD using DXA; μ-CT and histomorphometry of trans-iliac crest biopsy specimens; bone turnover markers; and cellular phenotype in bone marrow skeletal (stromal) stem cells (BM-MSCs) in a cross-sectional, age-, sex-, and BMI-matched case-control study. X-chromosome inactivation was measured in blood leucocytes and BM-MSCs using a PCR method with methylation of HpaII sites. NF-κB activity was quantitated in BM-MSCs using a luciferase NF-κB reporter assay.
Seven Caucasian women with IP (age: 24–67 years and BMI: 20.0–35.2 kg/m2) and IKBKG mutation (del exon 4–10 (n = 4); c.460C>T (n = 3)) were compared to matched controls. The IKBKG mutation carriers had extremely skewed X-inactivation (>90:10%) in blood, but not in BM-MSCs. NF-κB activity was lower in BM-MSCs from IKBKG mutation carriers (n = 5) compared to controls (3094 ± 679 vs. 5422 ± 1038/μg protein, p < 0.01). However, no differences were identified on skeletal radiographics, aBMD, μ-architecture of the iliac crest, or bone turnover markers. The IKBKG mutation carriers had a 1.7–fold greater extent of eroded surfaces relative to osteoid surfaces (p < 0.01), and a 2.0–fold greater proportion of arrested reversal surface relative to active reversal surface (p < 0.01).
Unlike mutation-positive males, the IKBKG mutation-positive women did not manifest OPT.
•Opposite to boys, women with IKBKG (NEMO) mutations did not present an osteopetrosis bone phenotype.•IKBKG mutation-positive women had a greater extent of eroded bone surfaces relative to osteoid surfaces.•In IKBKG mutation carriers, X-inactivation was extremely skewed (>90:10%) in blood, but not in BM-MSCs.
Hypophosphatasia (HPP) is the inborn error of metabolism characterized by low serum alkaline phosphatase (ALP) activity caused by inactivating mutations within TNSALP, the gene that encodes the ...“tissue‐nonspecific” isoenzyme of ALP (TNSALP). In HPP, extracellular accumulation of inorganic pyrophosphate, a TNSALP substrate, inhibits hydroxyapatite crystal growth leading to rickets or osteomalacia. Chronic recurrent multifocal osteomyelitis (CRMO) is the pediatric syndrome of periarticular pain and radiographic changes resembling infectious osteomyelitis but without lesional pathogens. Some consider CRMO to be an autoinflammatory disease. An unrelated boy and girl with the childhood form of HPP suffered chronic, multifocal, periarticular pain, and soft tissue swelling. To investigate this unusual complication, we evaluated their cumulative clinical, biochemical, radiological, and histopathological findings and performed mutation analysis of their TNSALP alleles. The earliest radiographic disturbances were typical of childhood HPP. Subsequently, changes consistent with CRMO developed at sites where there was pain, including lucencies, osteosclerosis, and marked expansion of the underlying metaphyses. Bone marrow edema was shown by MRI. Biopsies of affected bone showed nonspecific histopathological findings and no pathogens. The boy was heterozygous (c.1133A>T, p.D378V) and the girl compound heterozygous (c.350A>G, p.Y117C, c.400_401AC>CA, p.T134H) for different TNSALP missense mutations. Nonsteroidal anti‐inflammatory drugs diminished their pain, which improved or resolved at maturity. HPP should be considered when CRMO is a diagnostic possibility. Metaphyseal radiographic changes and marrow edema associated with periarticular bone pain and soft tissue swelling suggestive of osteomyelitis can complicate childhood HPP.
A Spectroscopic Orbit for Regulus Gies, D. R; Dieterich, S; Richardson, N. D ...
The Astrophysical journal,
08/2008, Volume:
682, Issue:
2
Journal Article
Peer reviewed
Open access
We present a radial velocity study of the rapidly rotating B star Regulus that indicates the star is a single-lined spectroscopic binary. The orbital period (40.11 days) and probable semimajor axis ...(0.35 AU) are large enough that the system is not Interacting at present. However, the mass function suggests that the secondary has a low mass (M sub(2) > 0.30 M), and we argue that the companion may be a white dwarf. Such a star would be the remnant of a former mass donor that was the source of the large spin angular momentum of Regulus itself.
We present the first K'-band, long-baseline interferometric observations of the northern Be stars g Cas, h Per, Tau, and Dra. The measurements were made with multiple telescope pairs of the CHARA ...Array interferometer and in every case the observations indicate that the circumstellar disks of the targets are resolved. We fit the interferometric visibilities with predictions from a simple disk model that assumes an isothermal gas in Keplerian rotation. We derive fits of the four model parameters (disk base density, radial density exponent, disk normal inclination, and position angle) for each of the targets. The resulting densities are in broad agreement with prior studies of the IR excess flux, and the resulting orientations generally agree with those from interferometric Ha and continuum polarimetric observations. We find that the angular size of the K' disk emission is smaller than that determined for the Ha emission, and we argue that the difference is the result of a larger Ha opacity and the relatively larger neutral hydrogen fraction with increasing disk radius. All the targets are known binaries with faint companions, and we find that companions appear to influence the interferometric visibilities in the cases of h Per and Dra. We also present contemporaneous observations of the Ha, Hg, and Brg emission lines. Synthetic model profiles of these lines that are based on the same disk inclination and radial density exponent as derived from the CHARA Array observations match the observed emission line strength if the disk base density is reduced by -1.7 dex.
ABSTRACT
Juvenile Paget's disease (JPD) is a rare heritable osteopathy characterized biochemically by markedly increased serum alkaline phosphatase (ALP) activity emanating from generalized ...acceleration of skeletal turnover. Affected infants and children typically suffer bone pain and fractures and deformities, become deaf, and have macrocranium. Some who survive to young adult life develop blindness from retinopathy engendered by vascular microcalcification. Most cases of JPD are caused by osteoprotegerin (OPG) deficiency due to homozygous loss‐of‐function mutations within the TNFRSF11B gene that encodes OPG. We report a 3‐year‐old Iranian girl with JPD and craniosynostosis who had vitamin D deficiency in infancy. She presented with fractures during the first year‐of‐life followed by bone deformities, delayed development, failure‐to‐thrive, and pneumonias. At 1 year‐of‐age, biochemical studies of serum revealed marked hyperphosphatasemia together with low‐normal calcium and low inorganic phosphate and 25‐hydroxyvitamin D levels. Several family members in previous generations of this consanguineous kindred may also have had JPD and vitamin D deficiency. Mutation analysis showed homozygosity for a unique missense change (c.130T>C, p.Cys44Arg) in TNFRSF11B that would compromise the cysteine‐rich domain of OPG that binds receptor activator of NF‐κB ligand (RANKL). Both parents were heterozygous for this mutation. The patient's serum OPG level was extremely low and RANKL level markedly elevated. She responded well to rapid oral vitamin D repletion followed by pamidronate treatment given intravenously. Our patient is the first Iranian reported with JPD. Her novel mutation in TNFRSF11B plus vitamin D deficiency in infancy was associated with severe JPD uniquely complicated by craniosynostosis. Pamidronate treatment with vitamin D sufficiency can be effective therapy for the skeletal disease caused by the OPG deficiency form of JPD.
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