128 research outputs found
Variability of Hot Supergiant IRAS 19336-0400 in the Early Phase of its Planetary Nebula Ionization
We present photoelectric and spectral observations of a hot candidate
proto-planetary nebula - early B-type supergiant with emission lines in
spectrum - IRAS 19336-0400. The light and color curves display fast irregular
brightness variations with maximum amplitudes Delta V=0.30 mag, Delta B=0.35
mag, Delta U=0.40 mag and color-brightness correlations. By the variability
characteristics IRAS 19336-0400 appears similar to other hot proto-planetary
nebulae. Based on low-resolution spectra in the range lambda 4000-7500 A we
have derived absolute intensities of the emission lines H_alpha, H_beta,
H_gamma, [SII], [NII], physical conditions in gaseous nebula: n_e=10^4 cm^{-3},
T_e=7000 \pm 1000 K. The emission line H_alpha, H_beta equivalent widths are
found to be considerably variable and related to light changes. By
UBV-photometry and spectroscopy the color excess has been estimated:
E_{B-V}=0.50-0.54. Joint photometric and spectral data analysis allows us to
assume that the star variability is caused by stellar wind variations.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Pis'ma
Astron. Zh. (Astronomy Letters
Gravity-mode period spacings as seismic diagnostic for a sample of gamma Doradus stars from Kepler space photometry and high-resolution ground-based spectroscopy
Gamma Doradus stars (hereafter gamma Dor stars) are gravity-mode pulsators of
spectral type A or F. Such modes probe the deep stellar interior, offering a
detailed fingerprint of their structure. Four-year high-precision space-based
Kepler photometry of gamma Dor stars has become available, allowing us to study
these stars with unprecedented detail. We selected, analysed, and characterized
a sample of 67 gamma Dor stars for which we have Kepler observations available.
For all the targets in the sample we assembled high-resolution spectroscopy to
confirm their F-type nature. We found fourteen binaries, among which four
single-lined binaries, five double-lined binaries, two triple systems and three
binaries with no detected radial velocity variations. We estimated the orbital
parameters whenever possible. For the single stars and the single-lined
binaries, fundamental parameter values were determined from spectroscopy. We
searched for period spacing patterns in the photometric data and identified
this diagnostic for 50 of the stars in the sample, 46 of which are single stars
or single-lined binaries. We found a strong correlation between the
spectroscopic vsini and the period spacing values, confirming the influence of
rotation on gamma Dor-type pulsations as predicted by theory. We also found
relations between the dominant g-mode frequency, the longest pulsation period
detected in series of prograde modes, vsini, and log Teff.Comment: 61 pages, 61 figures, 6 tables, accepted for publication in ApJ
Near-Infrared Photometric Survey of Proto-Planetary Nebula Candidates
We present JHK' photometric measurements of 78 objects mostly consisting of
proto-planetary nebula candidates. Photometric magnitudes are determined by
means of imaging and aperture photometry. Unlike the observations with a
photometer with a fixed-sized beam, the method of imaging photometry permits
accurate derivation of photometric values because the target sources can be
correctly identified and confusion with neighboring sources can be easily
avoided. Of the 78 sources observed, we report 10 cases in which the source
seems to have been misidentified or confused by nearby bright sources. We also
present nearly two dozen cases in which the source seems to have indicated a
variability which prompts a follow-up monitoring. There are also a few sources
that show previously unreported extendedness. In addition, we present H band
finding charts of the target sources.Comment: 3 tables, 1 figur
Evaluation of the ADOS Revised Algorithm: The Applicability in 558 Dutch Children and Adolescents
The revised ADOS algorithms, proposed by Gotham et al. (J Autism Dev Disord 37:613–627, 2007), were investigated in an independent sample of 558 Dutch children (modules 1, 2 and 3). The revised algorithms lead to better balanced sensitivity and specificity for modules 2 and 3, without losing efficiency of the classification. Including the restricted repetitive behaviour domain in the algorithm contributes to a clinical ASD classification in modules 2 and 3. For module 1, the results indicate less improvement, probably due to the low-functioning population. In most groups, the advantages of the revised algorithms are achieved without losing the strength of the original algorithm
Standardized ADOS Scores: Measuring Severity of Autism Spectrum Disorders in a Dutch Sample
The validity of the calibrated severity scores on the ADOS as reported by Gotham et al. (J Autism Dev Disord 39: 693–705, 2009), was investigated in an independent sample of 1248 Dutch children with 1455 ADOS administrations (modules 1, 2 and 3). The greater comparability between ADOS administrations at different times, ages and in different modules, as reached by Gotham et al. with the calibrated severity measures, seems to be corroborated by the current study for module 1 and to a lesser extent for module 3. For module 2, the calibrated severity scores need to be further investigated within a sample that resembles Gotham’s sample in age and level of verbal functioning
The Child and Adolescent Psychiatry: Study of Training in Europe (CAP-STATE)
There is great cultural diversity across Europe. This is reflected in the organisation of child and adolescent mental health (CAMH) services and the training of the respective professionals in different countries in Europe. Patients and their parents will want a high quality, knowledgeable, and skillful service from child and adolescent psychiatrists (CAPs) wherever they see them in Europe. A European comparison of training programs allows all stakeholders in different European countries to assess the diversity and to initiate discussions as to the introduction of improvements within national training programs. Major issues to be addressed in comparing child and adolescent psychiatric training programs across Europe include: (1) formal organisation and content of training programs and the relationship to adult psychiatry and paediatrics; (2) flexibility of training, given different trainee interests and that many trainees will have young families; (3) quality of governance of training systems; (4) access to research; and (5) networking. The Child and Adolescent Psychiatry-Study of Training in Europe (CAP-State) is a survey of training for child and adolescent psychiatrists (CAPs) across European countries. It aims to revisit and extend the survey carried out in 2006 by Karabekiroglu and colleagues. The current article is embedded in a special issue of European Child + Adolescent Psychiatry attempting to for the first time address training in CAP at the European and global levels. Structured information was sought from each of 38 European and neighboring countries (subsequently loosely referred to as Europe) and obtained from 31. The information was provided by a senior trainee or recently qualified specialist and their information was checked and supplemented by information from a senior child and adolescent psychiatry trainer. Results showed that there is a very wide range of provision of training in child and adolescent psychiatry in different countries in Europe. There remains very substantial diversity in training across Europe and in the degree to which it is subject to national oversight and governance. Some possible reasons for this variation are discussed and some recommendations made.info:eu-repo/semantics/publishedVersio
Trends in postoperative radiotherapy delay and the effect on survival in breast cancer patients treated with conservation surgery
The adequate timing of adjuvant radiotherapy (RT) in breast cancer has become a subject of increasing interest in recent years. A population-based study was undertaken to determine the influence of demographic and clinical factors on the postoperative RT delay in patients treated with breast-conserving surgery (BCS) and to assess the impact of delay on survival. In total, 7800 breast cancer patients treated with BCS and adjuvant RT between 1986 and 1998 in Yorkshire were included in the study. The median interval between surgery and the start of RT (S-RT interval) was 8 weeks (7 weeks for chemotherapy negative and 11 for chemotherapy positive patients). This interval increased substantially over time from 5 weeks during 1986-1988, irrespective of patients' chemotherapy status, to 10 and 17 weeks among chemotherapy negative and chemotherapy positive patients, respectively, in 1997-1998. The S-RT interval was also significantly influenced by travel time to RT centre, year and at which RT centre patient had the treatment (
Herschel images of NGC 6720: H-2 formation on dust grains
Herschel PACS and SPIRE images have been obtained of NGC 6720 (the Ring nebula). This is an evolved planetary nebula with a central star that is currently on the cooling track, due to which the outer parts of the nebula are recombining. From the PACS and SPIRE images we conclude that there is a striking resemblance between the dust distribution and the H2 emission, which appears to be observational evidence that H2 forms on grain surfaces. We have developed a photoionization model of the nebula with the Cloudy code which we used to determine the physical conditions of the dust and investigate possible formation scenarios for the H2. We conclude that the most plausible scenario is that the H2 resides in high density knots which were formed after the recombination of the gas started when the central star entered the cooling track. Hydrodynamical instabilities due to the unusually low temperature of the recombining gas are proposed as a mechanism for forming the knots. H2 formation in the knots is expected to be substantial after the central star underwent a strong drop in luminosity about one to two thousand years ago, and may still be ongoing at this moment, depending on the density of the knots and the properties of the grains in the knots
A stubbornly large mass of cold dust in the ejecta of Supernova 1987A
We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 mu m data and improved imaging quality at 100 and 160 mu m compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 mu m [O-I] line flux, eliminating the possibility that line contaminations distort the previously estimated dustmass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 mu m flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 +/- 0.1M(circle dot) of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3M(circle dot) of amorphous carbon and 0.5M(circle dot) of silicates, totalling 0.8M(circle dot) of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies
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