MWC 656 has been reported as classical Be star with a black hole companion. Revisited spectral variability properties render this unlikely, with a hot subdwarf more probable.

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

Be stars (for an in-depth review see Rivinius, Carciofi & Martayan 2013) rotate at ⩾80% of the critical velocity and are multi-mode nonradial pulsators. Magnetic dipole fields are not detected, and binaries with periods less than 30 days are rare. The name-giving emission lines form in a Keplerian decretion disk, which is viscously re-accreted and also radiatively ablated unless replenished by outburts of unknown origin.

Months-long, high-cadence space photometry with the BRITE-Constellation nanosatellites (Pablo et al. 2016) of about 10 early-type Be stars reveals the following (cf. Baade et al. 2016a, Baade et al. 2016b):

• ○ Many Be stars exhibit 1 or 2 so-called Δ frequencies, which are differences between two nonradial-pulsation (NRP) frequencies and much lower (mostly less than 0.1 c/d) than the parent frequencies. The associated light curves are roughly sinusoidal. The amplitudes can exceed that of the sum of the parent amplitudes.

• ○ Conventional beat patterns also occur.

• ○ Amplitudes of both Δ and beat frequencies can temporarily be enhanced. Around phases of maximal amplitude the mean brightness is in- or decreased, and the scatter can be enhanced.

• ○ During high-activity phases (outbursts), broad and dense groups of numerous spikes arise in the power spectra. The two strongest groups often have a frequency ratio near 2. The phase coherence seems to be low.

• ○ Time coverage (less than half a year) is not yet sufficient to infer whether two Δ or beat frequencies can combine to cause long-lasting (years) superoutbursts (cf. Carciofi et al. 2012).

From these observations it is concluded:

• • The variable mean brightness and the increased Δ-frequency amplitude and scatter trace the amount of near-circumstellar matter.

• • Increase or decrease of mean brightness is aspect-angle dependent (pole-on vs. equator-on).

• • Increased amounts of near-circumstellar matter are due to rotation-assisted mass ejections caused by coupled NRP modes.

• • Observations do not constrain the location of the coupling (atmosphere or stellar interior).

• • Broad frequency groups do not represent stellar pulsation modes but circumstellar variability.

• • Be stars later than B5 are less active and may in some cases even behave differently.

The role of episodic mass loss in evolved massive stars is one of the outstanding questions in stellar evolution theory. Integral field spectroscopy of nebulae around massive stars provide information on their recent mass-loss history. η Car is one of the most massive evolved stars and is surrounded by a complex circumstellar environment. We have conducted a three-dimensional morpho-kinematic analysis of η Car’s ejecta outside its famous Homunculus nebula. SHAPE modelling of VLT MUSE data establish unequivocally the spatial cohesion of the outer ejecta and the correlation of ejecta with the soft X-ray emission.

For early type magnetic stars slow, at most moderate rotational velocities have been considered an observational fact. The detection of a multi-kilogauss magnetic field in the B2Vpn star with P ≈ 0.52 d and v sin i ≈ 300 km/s has brought down this narrative. We have obtained more than 100 high-resolution, high-S/N echelle spectra in 2009. These spectra provide the most detailed description of the variability of any He-strong star to date. The circumstellar environment is dominated by a rotationally locked magnetosphere out to several stellar radii, causing hydrogen emission. The photosphere is characterized by surface chemical abundance inhomogeneities, with much stronger amplitudes, at least for helium, than slower rotating stars like σ Ori E. The highly complex rotational line profile modulations of metal lines are probably a consequence the equatorial gravity darkening of HR 7355, and thus may offer an independent measurement of the von Zeipel parameter β.

Star clusters are privileged laboratories for studying the evolution of massive stars (OB stars). One particularly interesting question concerns the phases during which the classical Be stars occur, which—unlike HAe/Be stars—are not pre-main-sequence objects, nor supergiants. Rather, they are extremely rapidly rotating B-type stars with a circumstellar decretion disk formed by episodic ejections of matter from the central star. To study the impact of mass, metallicity, and age on the Be phase, we observed Small Magellanic Cloud (SMC) open clusters with two different techniques: (i) with the ESO–WFI in slitless mode, which allowed us to find the brighter Be and other emission-line stars in 84 SMC open clusters, and (ii) with the VLT–FLAMES multifiber spectrograph to determine accurately the evolutionary phases of Be stars in the Be-star-rich SMC open cluster NGC 330. Based on a comparison to the Milky Way, a model of Be stellar evolution, appearance as a function of metallicity and mass, and spectral type is developed, involving the fractional critical rotation rate as a key parameter.

Several components of the metabolic syndrome, particularly diabetes and CVD, are known to be oxidative stress-related conditions and there is research to suggest that antioxidant nutrients may play a protective role in these conditions. Carotenoids are compounds derived primarily from plants and several have been shown to be potent antioxidant nutrients. The aim of the present study was to examine the associations between metabolic syndrome status and major serum carotenoids in adult Australians. Data on the presence of the metabolic syndrome, based on International Diabetes Federation 2005 criteria, were collected from 1523 adults aged 25 years and over in six randomly selected urban centres in Queensland, Australia, using a cross-sectional study design. Weight, height, BMI, waist circumference, blood pressure, fasting and 2 h blood glucose and lipids were determined, as well as five serum carotenoids. Mean serum α-, β-carotenes and the sum of the five carotenoid concentrations were significantly lower (P < 0·05) in persons with the metabolic syndrome (after adjusting for age, sex, education, BMI status, alcohol intake, smoking, physical activity status and vitamin/mineral use) than persons without the syndrome. α-, β- and total carotenoids also decreased significantly (P < 0·05) with increased number of components of the metabolic syndrome, after adjusting for these confounders. These differences were significant among former smokers and non-smokers, but not in present smokers. Low concentrations of serum α-, β-carotenes and the sum of five carotenoids appear to be associated with metabolic syndrome status. Additional research, particularly longitudinal studies, may help to determine whether these associations are causally related to the metabolic syndrome, or are a result of the pathologies of the syndrome.

We discuss the possible connection between supernova explosions (SN) and gamma-ray bursters (GRB) from the perspective of our current understanding of SN physics. Core collapse supernovae (SN) are the final stages of stellar evolution in massive stars during which the central region collapses, forms a neutron star (NS) or black hole, and the outer layers are ejected. Recent explosion scenarios assumed that the ejection is due to energy deposition by neutrinos into the envelope but detailed models do not produce powerful explosions. There is new and mounting evidence for an asphericity and, in particular, for axial symmetry in several supernovae which may be hard to reconcile within the spherical picture. The 3-D signatures are a key to understand core collapse supernovae and the GRB/SN connection. In this paper we study the effects and observational consequences of asymmetric explosions.

66 Oph is a multiple system with a close binary orbiting the B2Ve primary Be star. The binary parameters were derived by two independent methods and spectra of components BA and BB were separated by Fourier disentangling.

Recently, the line profile variability (lpv) of two low-v sin i Be stars, μ Cen and ω (28) CMa was successfully modelled as nonradial pulsation (nrp) of rapidly rotating stars seen pole-on. In this work, it is shown that the lpv of low-v sin i early-type Be stars in general closely resembles these two cases, and is therefore explainable by the same mechanism. The lpv of intermediate to high-v sin i Be stars can be explained by the same model if the inclination angle of the model alone is increased. Consequently, early-type Be stars form a distinct, fairly homogeneous class of non-radial low-order g-mode pulsators.

Astero-oscillometry is presented as a new method for deriving stellar parameters on the basis of a physical modeling of line profile variability (lpv) caused by nonradial pulsation (nrp). First applications to rapidly rotating B-type stars show that the method is able to yield reasonable stellar parameters. The radii are systematically smaller compared to those derived by conventional methods. This could be attributed to possible effects of rapid rotation on stellar evolution. Since the method requires only one or a few pulsation modes to be excited, it is ideally suited to investigating early-type stars.

In spite of considerable progress in the investigation of rapid line-profile variations (lpv) of Be stars, at least two models still compete in the literature: the rotational modulation, assuming mostly corotating circumstellar structures (Balona, 2000), and nonradial pulsations (Maintz et al. and Rivinius et al., these proceedings). Attempts to explain the lpv of Be stars were often connected with the proto-typical star 28 (ω) CMa (HR 2749 = HD 56139, B2IV-Ve, v sin i = 80 km/s). Štefl et al. (1998) described variability in three line-profile components: in the narrow component of the line core, in the line core itself and in the wings. The Balmer emission of 28 CMa is variable and has always been observed to be at least moderate, mostly strong.

HR 4074 (HD 89890, B3 III, v sin i = 70 km/s) has a different history of its emission activity. From a single spectrogram taken in 1893, Pickering (1898) reported an emission in Hβ. Subsequent observations never confirmed this. If it was not mis-identified by Pickering, HR 4074 would be in the probably longest B-star phase known of any Be star. HR 4074 is very probably not an SPB star - the spectral type is too early, the rotational velocity too high and light variations too low for this classification. Baade (1984) detected rapid lpv with a period P ≈ 2.25 d. Our time series analysis of radial velocity (RV) variations, measured as line modes, and that of full profiles give P = (2.3179 ± 0.0008) d.

Adopting non-radial pulsation (nrp) the line profile variability lpv of several absorption lines of different ions was modeled for ω (28) CMa. The parameters suggested by Baade (1982) to characterise the pulsation could be confirmed. The pulsation period in the inertial frame was found to be negative, i.e. an actually retrograde mode appears prograde due to the rapid stellar rotation. The line profiles could be reproduced in detail including structures like spikes and ramps. They were identified as velocity effect due to the latitudinal component of the nrp velocity field υϑ in combination with low inclination i. In spite of small photometric variations (Štefl et al. 1999) the lpv of the absorption lines can be explained by nrp entirely.

The wide range of periodic and cyclic variabilities commonly observed in Be stars and their circumstellar disks is reviewed. Many of them are related to the basic nonradial pulsation, the effects of which may range from the photosphere to the disk. Through pulsation-triggered outbursts, some stars may owe their Be characteristics largely to their intrinsic variability. However, because late-type Be stars do not normally show detectable short-periodic variability, this is probably not true of all Be stars. Comparisons are made with other variable early-type stars.

We re-discuss the reality of the four periods near 0.5 d and reject the claim (Balona et al., these proceedings) that μ Cen exhibits a single ∼0.66-d period caused by co-rotating clouds. The alleged 0.66-d period is not genuine but results from the simultaneous proximity of this value to the beat period between the true 0.28- and 0.5-d periods as well as to a 2-c/d alias of the 0.28-d period.

Spectra of the Be star 28 CMa obtained with the HEROS echelle spectrograph in 1996 and 1997 were used to check the presence of transient periods in commonly measured scalar parameters of absorption and emission lines. Transient periods can be convincingly detected in modes of higher absorption and single peak emission lines of the Balmer series as well as in the V/R ratio of Fell lines. Consequences for the frequency analyses of datasets containing radial velocities derived from different ions are discussed. The significant differences in amplitudes of radial velocities of different ions and in individual seasons were confirmed and a mean ephemeris derived.

Spectrophotometric observations of the Be star ηCen obtained in May, 1993 show smooth variations of both the stellar and circumstellar Balmer discontinuity (BD) on a time scale of hours. Simultaneous photometry and high-resolution spectroscopy suggest possible correlations with the large-amplitude brightness and line-profile variations.

We sketch a new method for the accurate flux calibration and normalization of stellar spectra. This is of particular importance for the analysis of rapidly rotating early–type stars. Some preliminary log g determinations by profile fitting of H γ are presented.

A large fraction of Be stars show periodic light and line profile variations with a timescale of about one day. The mechanism which causes these periodic variations has been attributed to nonradial pulsation (NRP) or rotational modulation (RM). The authors present arguments supporting the two opposing points of view with the purpose of stimulating subsequent discussion by the Symposium participants.

Slitless field Hα spectroscopy with a resolution of 0.2 nm has detected numerous Be stars in 3 young open star clusters in the LMC but only a few each in one Galactic and one LMC cluster. The line widths indicate rapid rotation as is typical of Galactic field Be stars. In NGC 2004 (LMC) their distribution seems inconsistent with the assumption of either very similar equatorial rotation velocities or random orientation of the rotation axes or both, which are believed to be valid for Galactic field Be stars.