Quantitative classification of WC and WO stars

We present a quantitative classification scheme for carbon and oxygen sequence Wolf-Rayet stars. Our scheme uses new high-quality optical AAT and INT observations of 20 stars for which we provide narrow-band photometry and estimates of interstellar reddenings. In increasing order of excitation, our spectral classes range from WC11 to WC4 for Wolf-Rayet stars with a dominant carbon line visual spectrum, and subsequently from WO4 to WO1 for those with predominantly oxygen lines. We refine existing WC and WO schemes to incorporate stars with higher and lower excitation spectral features. Both massive stars and central stars of planetary nebulae (CSPNe) can be classified with the unified system. We have found no criterion that cleanly separates spectra of the two types of star, including elemental abundances (C/O or C/He). However, CSPNe show a wider range of line strength and width than massive stars in the same ionization subclass. Systematically lower FWHM(C IV λ5808) values are observed from WO-type CSPNe than from massive WO stars. For WC4-11 stars, our primary diagnostic is the equivalent width or line flux ratio C IV λλ5801-12/C III λ5696. We extend the use of this as the principal criterion throughout the WC sequence, with few reclassifications necessary relative to Smith, Shara & Moffat. For WO stars, C III is absent and our new criteria, using primarily oxygen lines, take over smoothly. We define subclasses WO4-1, using O VI λλ3811-34/O V λ5590 as our primary diagnostic. The continuation in spectral sequence from WC to WO is used to indicate that the sequence is a result primarily of excitation effects, rather than significant abundance differences. Our scheme allows us to confirm that massive stars and CSPNe are differently distributed over the subclasses. Around 3/5 of massive WC stars lie within the range WC5-8, while ≤1/5 of CSPNe are found within these spectral types. Stars within both the highest (WO1) and lowest (WC10-11) excitation spectral classes are unique to CSPNe. A WC classification for the hot R CrB star V348 Sgr is excluded (previously [WC 12]) since both C III λ5696 and C IV λ5808 are absent in its optical spectrum. Additional criteria allow us to distinguish between WC-type, 'weak emission line' CSPNe, and O stars, allowing us to reclassify the central star of IRAS 21282+5050 (previously [WC11] ) as an O star

Bone Density and Cross-sectional Geometry of the Proximal Femur Are Bilaterally Elevated in Elite Cricket Fast Bowlers

The skeleton of a cricket fast bowler is exposed to a unique combination of gravitational and torsional loading in the form of substantial ground reaction forces delivered through the front landing foot, and anterior-posterior shear forces mediated by regional muscle contractions across the lumbo-pelvic region. The objectives of this study were to compare the hip structural characteristics of elite fast bowlers with recreationally active age-matched controls, and to examine unilateral bone properties in fast bowlers. Dual-energy X-ray absorptiometry of the proximal femur was performed in 26 elite male fast bowlers and 26 normally active controls. Hip structural analysis (GE Lunar; enCORE version 15.0) determined areal bone mineral density (BMD) of the proximal femur, and cross-sectional area, section modulus (Z), cross-sectional moment of inertia, and femoral strength index at the narrow region of the femoral neck. Mean femoral neck and trochanter BMD were greater in fast bowlers than in controls (p  0.05). Elite fast bowlers have superior bone characteristics of the proximal femur, with results inferring enhanced resistance to axial compression (cross-sectional area), and bending (Z) forces, and enhanced strength to withstand a fall impact as indicated by their higher femoral strength index. No asymmetries in hip bone properties were identified, suggesting that both torsional and gravitational loading offer significant osteogenic potential

On the distance to M1-67

The interstellar Na I D2 absorption spectrum of 209 BAC, the WN 8 central star of M1 - 67, shows a total velocity extent of 60 km/s. This is consistent with the spread of gas velocities expected from galactic rotation, provided 209 BAC is at a distance of 4-5 kpc, implying that it is a massive population I WN 8 star surrounded by a stellar ejecta nebula. If M1 - 67 was a planetary nebula at a distance of only 0.5-1 kpc, the velocity extent of the Na I absorption line should be 5-6 times smaller than that observed. It is suggested that similar observations should be obtained of We 21, recently discovered by Duerbeck and Reipurth (1990) to be a WN 8 star in a ringlike nebula

Ultra-high-resolution measurements of the intrinsic line profiles of interstellar C2 towards ζ Ophiuchi and HD 169454

We have used the Ultra-High-Resolution Facility at the Anglo-Australian Telescope (AAT), operating at a resolution of 0.35 km s−1 (FWHM), to measure the intrinsic profiles of the Q(2) and Q(4) lines of the (2-0) Phillips band of interstellar C2 towards ζ Oph and HD 169454. The C2 lines were found to be very narrow, with intrinsic velocity dispersions (b-values) in the range 0.25−0.71 km s−1. In the case of ζ Oph, two velocity components (separation 1.10 ± 0.17 km s−1) have been resolved, and found to have rather different linewidths and rotational excitation temperatures. In the case of HD 169454, the data are consistent with a single velocity component, but the well-defined b-value (0.59 + 0.04 km s−1) and low kinetic temperature would then imply supersonic turbulent velocities. One way to avoid this conclusion is to postulate the existence of unresolved velocity structure (or a velocity gradient) within the cloud

The distance to the WN8 star We 21

A high-resolution spectrum of the interstellar Na D lines toward We 21 shows a total velocity extent of about 95 km/s, extending from -65 to +30 km/s in the LSR velocity frame. In this line-of-sight the positive velocities can arise only from beyond the solar circle, and this suggests that We 21 lies in the far part of the Carina spiral arm, at a distance of about 11.5 kpc. Contrary to the conclusions of Duerbeck and Reipurth (1990), We 21 appears to be a massive Population I WN8 star surrounded by a stellar ejecta bubble, and not a PN central star

Ultra-high-resolution observations of circumstellar K I and C2 around the post-AGB star HD 56126

We have used the Ultra-High-Resolution Facility (UHRF) at the AAT, operating at a resolution of 0.35 km s−1 (FWHM), to observe K I and C2 absorption lines arising in the circumstellar environment of the post-AGB star HD 56126. We find three narrow circumstellar absorption components in K I, two of which are also present in C2. We attribute this velocity structure to discrete shells resulting from multiple mass-loss events from the star. The very high spectral resolution has enabled us to resolve the intrinsic linewidths of these narrow lines for the first time, and we obtain velocity dispersions (b-values) of 0.2–0.3 km s−1 for the K I components, and 0.54 ± 0.03 km s−1 for the strongest (and best defined) C2 component. These correspond to rigorous kinetic temperature upper limits of 211 K for K I and 420 K for C2, although the b-value ratio implies that these two species do not co-exist spatially. The observed degree of rotational excitation of C2 implies low kinetic temperatures (Tk ≈10 K) and high densities (n ≈ 106 to 107 cm−3) within the shell responsible for the main C2 component. Given this low temperature, the line profiles then imply either mildly supersonic turbulence or an unresolved velocity gradient through the shell

First results of an Hα based search of classical Be stars in the Perseus Arm and beyond

We investigate a region of the Galactic plane, between 120° ≤ l ≤ 140° and-1° ≤ b≤+4°, and uncover a population of moderately reddened (E(B-V) ~ 1) classical Be stars within and beyond the Perseus and Outer Arms. 370 candidate emission-line stars (13≲r≲16) selected from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane have been followed up spectroscopically. A subset of these, 67 stars with properties consistent with those of classical Be stars, have been observed at sufficient spectral resolution (δλ ≈ 2-4 Å) at blue wavelengths to narrow down their spectral types. We determine these to a precision estimated to be ±1 subtype and then we measure reddenings via spectral energy distribution fitting with reference to appropriate model atmospheres. Corrections for contribution to colour excess from circumstellar discs are made using an established scaling to Ha emission equivalent width. Spectroscopic parallaxes are obtained after luminosity class has been constrained via estimates of distances to neighbouring A/F stars with similar reddenings. Overwhelmingly, the stars in the sample are confirmed as luminous classical Be stars at heliocentric distances ranging from 2 kpc up to ~12 kpc. However, the errors are presently too large to enable the cumulative distribution function with respect to distance to distinguish between models placing the stars exclusively in spiral arms, or in a smooth exponentially declining distribution.Peer reviewe

Detection of a variable interstellar absorption component towards δ Orionis A

Observations of δ Ori A made with the UHRF in its highest resolution mode (R≈900 000) have revealed the presence of a cool (Tk⩽350 K) variable absorption component at a heliocentric velocity of +21.3 km s−1. The component is detected in Na I D1, where clear hyperfine splitting is seen, and Ca II K. Comparison of our data with existing spectra suggests that the component has consistently increased in strength from 1966 to 1994, and subsequently reduced in intensity by 1999. Following a discussion of the possible origins of this component it is concluded that an interstellar, rather than circumstellar, origin is most likely. This is one of very few detections of variable interstellar absorption reported in the literature, and we suggest an origin within filamentary material associated with the expanding H I shell surrounding the Orion-Eridanus superbubble

High resolution observations of interstellar Na I and Ca II towards the Scorpius OB1 association

Observations of Na I and Ca II in absorption toward 22 stars in the Sco OB1 region, obtained at resolution R = 100,000 with a coude echelle spectrograph and 3.3-m camera on the 1.9-m telescope at Mt. Stromlo Observatory during 1986, are reported. The data are presented in extensive tables and graphs and analyzed in detail. Features discussed include (1) strong absorption at heliocentric velocities between 0 and -20 km/sec, (2) sharp discrete components with blueshifted velocities of up to -50 km/sec, and (3) some absorption at positive heliocentric velocities up to +20 km/sec. The (Na I)/(Ca II) ratios are found to be 4-200 for component (1), near 1 for component (2), and 0.4 or less for component (3

Six-year body composition change in male elite senior rugby league players

This study investigated the change in body composition and bone mineral content (BMC) of senior rugby league (RL) players between 2008 and 2014. Twelve male professional RL players (age, 24.6 ± 4.0 years; stature, 183.4 ± 8.4 cm) received a dual-energy X-ray absorptiometry scan during preseason in 2008 and 2014. Between 2008 and 2014, very likely increases in leg lean mass (LM), total trunk and leg BMC, and a likely increase in arm BMC and possible increases in body mass (BM), total and trunk fat mass (FM), and total, trunk and arm LM were observed. Unlikely decreases and unclear changes in leg and arm FM were also found. Large negative correlations were observed between age and BM (r = −0.72), LM (r = −0.70), FM (r = −0.61) and BMC (r = −0.84) change. Three participants (19.1 ± 1.6 years) increased LM by 7.0–9.3 kg. Younger players had the largest increases in LM during this period, although an older player (30-year old) still increased LM. Differences in body composition change were also observed for participants of the same age, thus contextual factors should be considered. This study demonstrates the individuality of body composition changes in senior professional rugby players, while considering the potential change in young athletes