We present BV(RI)C and JHKs photometry and low- and high-resolution spectroscopy of the 11th mag G-type star TYC 2627-638-1. Our investigation reveals that the target is separated into two young, ...early-G-type main-sequence (or late pre-main-sequence) stars, which are most probably bound and form a wide binary system. A substellar body orbits the brighter component as implied by radial velocity variations. The brighter component possibly also has a faint, later type stellar companion. Both components of the wide binary have clear emission cores in the Ca ii H&K lines and filled-in Hα absorption, indicating that both stars are chromospherically active. Our photometric time series reveals clear but only a few hundredths of a magnitude amplitude rotational modulation, which is most likely due to cool starspots. Two distinct periods, near 3.5 and 3.7 days, are found in the brightness variations. Photometry obtained separately of the two components of the wide binary show that these periodicities belong to the brighter star. The fainter component shows a much slower light variation of about 0.3 mag. amplitude. In addition, long-term changes in the brightness of both stars are seen. The spectral energy distribution shows a strong near-infrared excess in the fainter component of the wide binary.
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We carried out a spectroscopic survey of several ${\rm B}$, ${\rm Be}$, and shell stars in optical and near-infrared regions. Line profiles of the ${\rm H}\alpha$ line and of selected ...$\ion{Fe}{ii}$ and $\ion{O}{i}$ lines are presented.
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We examined the possibility of making a null measurement of optical absorbance by using pulse-width modulation to control the intensity of a light-emitting diode (LED). This type of measurement is ...intriguing because the instrumental sources of noise are different from those in the traditional absorbance measurement. Our experiment employed phototransistor detectors and a RC integrator to measure the amount of light being transmitted. However, instead of measuring the ratio of the detector voltages for a blank and sample, we measured the ratio of the LED duty cycles required to give the same detector voltage for a blank and a sample. Using this method, it is presumed that the same amount of light reaches the detector during measurement of the blank and sample.
ABSTRACT We assembled a catalogue of bright, hot subdwarf and white dwarf stars extracted from a joint ultraviolet, optical and infrared source list. The selection is secured using colour criteria ...that correlate well with effective temperatures Teff 12000 K. We built a NUV-V versus V-J diagram for 60000 bright sources using theGalaxy Evolution Explorer(GALEX)NUV magnitude (NUV < 14), the associated Guide Star Catalog (GSC2.3.2) photographic quick-Vmagnitude and the Two-Micron All-Sky SurveyJandHmagnitudes. This distillation process delivered a catalogue of asymptotically =700 sources with NUV-V< 0.5 comprising 160 known hot subdwarf stars and another 60 known white dwarf stars. A reduced proper-motion diagram built using the proper-motion measurements extracted from the Naval Observatory Merged Astrometric Dataset allowed us to identify an additional 120 new hot subdwarf candidates and 10 hot white dwarf candidates. We present a spectroscopic study of a subset of 52 subdwarfs, 48 of them analysed here for the first time, and with nine objects brighter than V 12. Our sample of spectroscopically confirmed hot subdwarfs comprises 10 sdO-type stars and 42 sdB-type stars suitable for pulsation and binary studies. We also present a study of 50 known white dwarfs selected in theGALEXsurvey and six new white dwarfs from our catalogue of subluminous candidates. Ultraviolet, optical and infrared synthetic magnitudes employed in the selection and analysis of white dwarf stars are listed in appendix. PUBLICATION ABSTRACT
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
We report the discovery of a bright (V ~ 13.7), extremely low mass white dwarf in a close double degenerate system. We originally selected GALEX J171708.5+675712 for spectroscopic follow-up among a ...group of white dwarf candidates in an ultraviolet-optical reduced proper-motion diagram. The new white dwarf has a mass of 0.18 M and is the primary component of a close double degenerate system (P = 0.246137 days, K 1 = 288 km s--1) comprising a fainter white dwarf secondary with M 2 0.9 M . Light curves phased with the orbital ephemeris show evidence of relativistic beaming and weaker ellipsoidal variations. The light curves also reveal secondary eclipses (depth 8 mmag) while the primary eclipses appear partially compensated by the secondary gravitational deflection and are below detection limits. Photospheric abundance measurements show a nearly solar composition of Si, Ca, and Fe (0.1-1 ), while the normal kinematics suggest a relatively recent formation history. Close binary evolutionary scenarios suggest that extremely low mass white dwarfs form via a common-envelope phase and possible Roche lobe overflow.
Body mass decomposition and hydration state imbalances affect patients on maintenance dialysis. We compared body composition, hydration and nutritional state of patients on peritoneal dialysis (PD) ...and hemodialysis (HD) based on dialysis vintage (DV).
Three hundred and fifty-nine prevalent patients on HD (
= 301) and PD (
= 58) were divided into 3 subgroups depending on DV: < 2 years HD (
= 41) and PD (
= 28), 2-4 years HD (
= 111) and PD (
= 17), > 4 years HD (
= 149) and PD (
= 13). Bioimpedance analysis delivered data including overhydration (OH), Lean (LTM) and adipose lipids mass (FAT). Other measurements included daily diuresis (DD), subjective global assessment (SGA) and serum albumin (alb), C-reactive protein (CRP) and total cholesterol (TChol), and hemoglobin (Hb).
Dialysis vintage < 2 years. Hemodialysis patients were older (65.5 ±18.5 vs. 50.9 ±17.1;
< 0.01) with a higher mortality (28 vs. 1;
< 0.01) and OH (8.0 ±4.3 vs. 1.6 ±3.1;
< 0.001). Hemoglobin (10.6 ±1.5 vs. 11.8 ±1.7;
< 0.05), TChol (180.2 ±47.0 vs. 211.7 ±46.3;
< 0.05), DD (871 ±729 vs. 1695 ±960;
< 0.001) and LTM (46.5 ±12.9 vs. 53.8 ±14.4;
< 0.05) were lower on HD. Dialysis vintage 2-4 years: when compared to PD, HD patients had higher OH (11.7 ±5.9 vs. 2.1 ±3.2;
< 0.001) and lower Hb (10.8 ±1.5 vs. 11.9 ±1.4;
< 0.01). Dialysis vintage > 4 years: compared to PD, HD patients had higher LTM (44.3 ±11.7 vs. 38.6 ±7.9;
< 0.05) and lower FAT (34.4 ±11.1 vs. 42.8 ±6.4;
< 0.01).
Dialysis patients' body composition depends on dialysis modality and DV. Dialysis vintage < 2 years is associated with better hydration, nutritional state, and survival in PD patients, but longer DV reduces these benefits. Dialysis vintage > 4 years associated with similar hydration and mortality in both PD and HD while body composition was better on HD.
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