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A photometric and radial velocity survey of the six coolest extreme helium (eHe) stars confirms that at least five, and probably all, of these objects are both photometric and radial velocity variables. The stars have photometric variations on time-scales ranging from 8 to perhaps 25 d, and radial velocity amplitudes of 6 to 20 km s −1 . In at least one case the variations appear to indicate that the star is pulsating in a radial mode. The pulsational characteristics of these objects appear to represent a direct extension of the cool, hydrogen-deficient carbon star sequence to higher temperatures. Known eHe stars range in effective temperature (T eff ) from 8400 to 55 000 K

We present 117 h of high-speed Johnson B observations of HD 84041, obtained during 1992 at the South African Astronomical Observatory and the Cerro Tololo Inter-American Observatory. We also present 14 h of previously unpublished B high-speed photometry acquired in 1991. These observations show that HD 84041 pulsates in several p-modes with periods near 15 min. The amplitude of the oscillations is modulated in such a complex way that the modulating frequencies cannot be identified with certainty. We present 26 nights of differential UBVRI photometry acquired at the SAAO witch we use to determine the rotation period of HD 84041, P rot , = 3.69 ± 0.01 d. The mean light variations have a double-wave nature, which indicates that both magnetic (pulsation) poles are seen, but from different aspects

The results of a four-year campaign to monitor the variations of 35 southern Seyfert galaxies, using UBV(RI) c multi-aperture photometry, are presented. Most of the galaxies are found to be variable. The light curves are displayed and some of their more interesting details are discussed. The relationships between the fluxes through different filters are well described by straight lines, which suggests that the spectral shape of the variable part of the optical continuum stays constant. The values of the slopes are used to derive the shapes of the continua, the extinctions and the luminosities of the Seyfert nuclei

The first detailed photometric observations of the WC11 star CPD −56°8032 is presented, showing the star to be variable on time-scales ranging from hours to months. These measurements suggest that the amplitude of the variation is nearly ΔV = 1 with associated colour variations. Possible causes for this variability are discussed, including binary and ejection hypotheses

We have acquired simultaneous high-precision space photometry and radial velocities of the bright hybrid Beta Cep/SPB pulsator Gamma Peg. Frequency analyses reveal the presence of six g modes of high radial order together with eight low-order Beta Cep oscillations in both data sets. Mode identification shows that all pulsations have spherical degrees l = 0 - 2. An 8.5 solar mass model reproduces the observed pulsation frequencies; all theoretically predicted modes are detected. We suggest, contrary to previous authors, that Gamma Peg is a single star; the claimed orbital variations are due to g-mode pulsation. Gamma Peg is the first hybrid pulsator for which a sufficiently large number of high-order g modes and low order p and mixed modes have been detected and identified to be usable for in-depth seismic modeling., Comment: 18 pages (4 pages in journal style), 4 figures, accepted for ApJ Letters

We study the short-term evolution of starspots on the ultrafast-rotating star HD197890 ("Speedy Mic" = BO Mic, K 0-2V, P_rot = 0.380 d) based on two Doppler images taken about 13 stellar rotations apart. Each image is based on spectra densely sampling a single stellar rotation. The images were reconstructed by our Doppler imaging code CLDI (Clean-like Doppler imaging) from line profiles extracted by spectrum deconvolution. Our Doppler images constructed from two independent wavelength ranges agree well on scales down to 10 degrees on the stellar surface. In conjunction with nearly parallel V-band photometry our observations reveal a significant evolution of the spot pattern during as little as two stellar rotations. We suggest that such a fast spot evolution demands care when constructing Doppler images of highly active stars based on spectral time series extending over several stellar rotations. The fast intrinsic spot evolution on BO Mic impedes the determination of a surface differential rotation; in agreement with earlier results by other authors we determine an upper limit of |alpha| < 0.004 +- 0.002.

BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (~ 1.1 M_sun) to theoretically crystallize while still inside the ZZ Ceti instability strip (T_eff ~ 12,000 K). As a consequence, this star represents our first opportunity to test crystallization theory directly. If the core is substantially crystallized, then the inner boundary for each pulsation mode will be located at the top of the solid core rather than at the center of the star, affecting mainly the average period spacing. This is distinct from the "mode trapping" caused by the stratified surface layers, which modifies the pulsation periods more selectively. In this paper we report on Whole Earth Telescope observations of BPM 37093 obtained in 1998 and 1999. Based on a simple analysis of the average period spacing we conclude that a large fraction of the total stellar mass is likely to be crystallized., Comment: 7 pages, 3 figures, 3 tables, accepted for Astronomy & Astrophysics

We present results from a multisite (‘Whole Earth Telescope’) photometric campaign on PG 1336−018, the close eclipsing binary system containing a pulsating subdwarf B (sdB) star. The main part of the campaign (1999 April) resulted in ~172 h of observations, representing a coverage of about 47 per cent, and additional data were obtained outside the core campaign. Periodogram analysis shows that the light variations are dominated by three frequencies near 5757, 5585 and 5369 μHz (~174, 179 and 186s, respectively), although many frequencies are present, particularly in the range 5000–6000 μHz (~200–170 s). We identify, with some confidence, 28 frequencies down to a semi-amplitude of 0.0005 in fractional intensity (equivalent to about 0.5 mmag). It is clear that the pulsation frequencies of PG 1336−018 have changed substantially since the 1996 discovery observations were made, and that amplitude changes occur, at least in the dominant three frequencies, on relatively short time-scales (of the order of a day). On the assumption that the pulsating star is phase-locked in the binary system, we have searched for rotational splitting of frequencies near the orbital and half of the orbital period, but the results are confused by aliasing at those frequencies (due to the data gaps caused by the eclipses). A preliminary model qualitatively matches the distribution of frequencies in PG 1336−018, with some good individual correspondences, but cannot be considered adequate because geometric cancellation should hide some of the modes which are apparently detected. Analysis of the pulsations during eclipse recovers three of the strongest modes, but the limited eclipse data – which can, at best, be only about 9 per cent of the total – do not allow mode identification at this stage. Simulations indicate that an overall coverage of about 80 per cent would be required for this to be viable. An attempt was made to determine phase shifts in the pulsation frequencies as a way of directly measuring the size of the binary orbit, but the uncertainties in the method are comparable to the light travel time across the orbit (probably less than a second).

We have identified 317 stars included in the Hipparcos astrometric catalogue which have parallaxes measured to a precision of better than 15%, and whose location in the (M_V, (B-V)_T) diagram implies a metallicity comparable to or less than that of the intermediate-abundance globular cluster, M5. We have undertaken an extensive literature search to locate Stromgren, Johnson/Cousins and Walraven photometry for over 120 stars. In addition, we present new UBVRI photometry of 201 of these candidate halo stars, together with similar data for a further 14 known metal-poor subdwarfs. Those observations provide the first extensive dataset of RI photometry of metal-poor, main-sequence stars with well-determined trigonometric parallaxes. Finally, we have obtained intermediate-resolution optical spectroscopy of 175 stars. We are able to estimate abundances for 270 stars. The overwhelming majority have near-solar abundance, with their inclusion in the present sample stemming from errors in the colours listed in the Hipparcos catalogue. Only 44 stars show consistent evidence of abundances below [Fe/H]= -1.0. Nine are additions to the small sample of metal-poor subdwarfs with accurate photometry. We consider briefly the implication of these results for cluster main-sequence fitting., Comment: to appear in Monthly Notices of the Royal Astronomical Society (some tables appear out of order in the text)

We examined the safety and utility of the combined assessment of aspiration cytology and mammography in 705 women who had clinically suspicious or malignant palpable breast masses. Histological assessment confirmed 176 benign and 529 malignant lesions. There were no incorrect (false positive) diagnoses made in the 176 benign masses when combined assessment was used (specificity 1.0; predictive value 0.86); in isolation, however, there was a false positive cytological diagnosis ('papillary carcinoma') and 3 false positive mammographic diagnoses. Benign disease (false negative) was incorrectly diagnosed by combined assessment in 4 of the 529 malignant masses (sensitivity 0.99; predictive value 0.98): cytological diagnoses were of fat necrosis (2) and benign cells on cytospin (1) and aspiration biopsy (1); mammographic diagnoses were of benign disease (2) and normality (2). Indeterminate ('atypical', 'suspicious') diagnoses were problematic and frequent (overall 223 (31.6%), malignant masses 137 (25.9%), benign masses 86 (48.9%); cytology 117 (16.6%), mammography 141 (20%). Thus, with the combined assessment of mammography and cytology in clinically suspicious breast masses, a decisive diagnosis was made in about two-thirds of cases allowing the safe commencement of therapy; the balance of patients required core or excision biopsy.

Aims. We carried out high-resolution spectroscopy and BV(I)C photometric monitoring of the two fastest late-type rotators in the nearbyPictoris moving group, HD 199143 (F7V) and CD 64 ◦ 1208 (K7V). The motivation for this work is to investigate the rotation periods and photospheric spot patterns of these very young stars, with a longer term view to probing the evolution of rotation and magnetic activity during the early phases of main-sequence evolution. We also aim to derive information on key physical parameters, such as rotational velocity and rotation period. Methods. We applied maximum entropy (ME) and Tikhonov regularizing (TR) criteria to derive the surface spot map distributions of the optical modulation observed in HD 199143 (F7 V) and CD 64 ◦ 1208 (K7 V). We also used cross- correlation techniques to determine stellar parameters such as radial velocities and rotational velocities. Lomb-Scargle periodograms were used to obtain the rotational periods from differential magnitude time series. Results. We find periods and inclinations of 0.356 days and 21.5 deg for HD 199143, and 0.355 days and 50.1 deg for CD 64 ◦ 1208. The spot maps of HD 199143 obtained from the ME and TR methods are very similar, although the latter gives a smoother distribution of the filling factor. Maps obtained at two different epochs three weeks apart show a remarkable increase in spot coverage amounting to � 7% of the surface of the photosphere over a time period of only � 20 days. The spot maps of CD 64 ◦ 1208 from the two methods show good longitudinal agreement, whereas the latitude range of the spots is extended to cover the whole visible hemisphere in the TR map. The distributions obtained from the first light curve of HD 199143 show the presence of an extended and asymmetric active longitude with the maximum filling factor at longitude � 325 ◦ . A secondary active longitude is present at � 100 ◦ . The spotted area distributions on CD 64 ◦ 1208 show two active longitudes separated by about 180 ◦ , which is not unusual on such

A sample of 90 Galactic S stars observed by the Spitzer Space Telescope includes two sources with unusual low-contrast spectral structure between 7 and 14 μm. The most likely estimate of the spectral continuum leads to the identification of molecular emission features from SiS at 7 and 13-14 μm. The spectra also show what is best described as featureless excess emission, most likely from iron dust but possibly from amorphous carbon, as well as an emission feature from amorphous alumina dust peaking at 11-12 μm. The spectra show long-wavelength excesses from cool dust grains in an extended envelope and additional emission features of unknown origin.

We present simultaneous starspot photometry and high resolution Hα spectroscopy of II Peg which gives evidence of differential motions in the chromosphere.

The Seyfert 1 galaxy NGC 3783 was intensely monitored between 1991 December and 1992 August. We present the results from the ground-based observations in the optical and near-IR, which complement the data-set from the IUE, discussed elsewhere. Spectroscopic and photometric data from many observatories were combined in order to obtain well sampled light curves of the continuum and of H-Beta. During the campaign the source varied significantly. The light curves of the optical continuum and of H-Beta are similar to those obtained with the IUE. The near-IR flux did not vary significantly except for an increase at the end of the campaign. The optical continuum and the flux of H-Beta lag the UV continuum by 1 day or less and by 8 days respectively. These results confirm that the continuum variations are simultaneous or have a very small lag across the entire UV-optical range, and that the lines of NGC 3783 respond to ionizing continuum variations with less delay than those of NGC 5548. As in NGC 5548, the lag of H-Beta is greater than those of the high ionization lines.

Presentation des observations photometriques et spectroscopiques de SN 1987A effectuees a l'Observatoire Sutherland du SAAO entre 386 et 616 jours apres l'episode de neutrinos de Kamiokande-II

Les observations photometriques et spectroscopiques de SN1987A entre les jours 617 et 792 sont presentees. La luminosite bolometrique, la contribution IR-lointain, les courbes de lumiere et l'energie totale produite sont analysees

A 99mTc-DTPA radiorenographic study, supported by excretory urography, blood chemistry and eventually histology was performed on 8 chacma baboons (Papio ursinus) after surgical induction of unilateral renal vein hypertension. Frequent sequential repeat renograms during 6 post-operative months detected fluctuating renal behaviour but did not reveal typical course of the disease. Neither did any one of the radiorenographic parameters (TP, T1/2, FF, relative clearances and perfusion) prove to be more sensitive than the others in detecting abnormalities. Initial microscopic or macroscopic haematuria and proteinuria in general eventually cleared up. Light microscopy demonstrated only mild abnormalities. The effects of venous occlusion of the kidney and the prognosis seemed to be variable as was reflected by radiorenography.

Investigations conducted in this Laboratory into the dehydration of stockfish (Merluccius capensis) have indicated that the moisture content of the dried product has a great influence on its keeping quality.

[This corrects the article DOI: 10.1007/s41666-018-0040-y.]., (© Springer Nature Switzerland AG 2019.)