Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

What might aquinas have said?: the outcome of an experiment involving an electrical generator and a capacitor

We present a comparison of two forms of analysis applied to a simple experiment in electrodynamics. One uses contemporary physics and the other metaphysics as espoused by the 13th century scholar Thomas Aquinas. The aim is to illustrate an example of scientific abstraction and prediction of experimental outcomes, and the pitfalls of applying simple intuition

Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

A Spectroscopic Study of Mass Outflows in the Interacting Binary RY Scuti

The massive interacting binary RY Scuti is an important representative of an active mass-transferring system that is changing before our eyes and which may be an example of the formation of a Wolf-Rayet star through tidal stripping. Utilizing new and previously published spectra, we present examples of how a number of illustrative absorption and emission features vary during the binary orbit. We identify spectral features associated with each component, calculate a new, double-lined spectroscopic binary orbit, and find masses of 7.1 +/- 1.2 M_sun for the bright supergiant and 30.0 +/- 2.1 M_sun for the hidden massive companion. Through tomographic reconstruction of the component spectra from the composite spectra, we confirm the O9.7 Ibpe spectral class of the bright supergiant and discover a B0.5 I spectrum associated with the hidden massive companion; however, we suggest that the latter is actually the spectrum of the photosphere of the accretion torus immediately surrounding the massive companion. We describe the complex nature of the mass loss flows from the system in the context of recent hydrodynamical models for beta Lyr, leading us to conclude RY Scuti has matter leaving the system in two ways: 1) a bipolar outflow from winds generated by the hidden massive companion, and 2) mass from the bright O9.7 Ibpe supergiant flowing from the region near the L2 point to fill out a large, dense circumbinary disk. This circumbinary disk (radius ~ 1 AU) may feed the surrounding double-toroidal nebula (radius ~ 2000 AU).Comment: 41 pages with 7 tables and 11 figures, accepted to Ap

Investigation of Non-Stable Processes in Close Binary Ry Scuti

We present results of reanalysis of old electrophotometric data of early type close binary system RY Scuti obtained at the Abastumani Astrophysical Observatory, Georgia, during 1972-1990 years and at the Maidanak Observatory, Uzbekistan, during 1979-1991 years. It is revealed non-stable processes in RY Sct from period to period, from month to month and from year to year. This variation consists from the hundredths up to the tenths of a magnitude. Furthermore, periodical changes in the system's light are displayed near the first maximum on timescales of a few years. That is of great interest with regard to some similar variations seen in luminous blue variable (LBV) stars. This also could be closely related to the question of why RY Sct ejected its nebula.Comment: 11 pages, 6 figures, 2 table

Four-colour photometry of eclipsing binaries. XL, uvby light curves for the B-type systems DW Carinae, BF Centauri, AC Velorum, and NSV 5783

Aims. In order to increase the limited number of B-stars with accurately known dimensions, and also the number of well studied eclipsing binaries in open clusters, we have undertaken observations and studies of four southern double-lined eclipsing B-type binaries; DWCar, BF Cen, ACVel, and NSV 5783. Methods. Complete uvby light curves were observed between January 1982 and April 1991 at the Danish 0.5 m telescope at ESO La Silla, since 1985 known as the Strömgren Automatic Telescope (SAT). Standard indices for the systems and the comparison stars,as well as additional minima observations for ACVel, have been obtained later at SAT. For DWCar and ACVel, high-resolution spectra for definitive spectroscopic orbits have also been obtained; they are presented as part of the detailed analyses of these systems. A few spectra of NSV 5783 are included in the present paper. Results. For all four systems, the first modern accurate light curves have been established. DWCar is a detached system consisting of two nearly identical components. It is member of the young open cluster Cr228. A detailed analysis, based on the new light curves and 29 high-resolution spectra, is published separately. BFCen is semidetached and is member of NGC 3766. Modern spectra are needed for a detailed study. ACVel is a detached system with at least one more star. A full analysis, based on the new light curves and 18 high-resolution spectra, is published separately. NSV 5783 is discovered to be an eclipsing binary consisting of two well-detached components in an 11-day period eccentric (e = 0.18) orbit. Secondary eclipse is practically total. From the light curves and a few high-resolution spectra, accurate photometric elements and preliminary absolute dimensions have been determined. The quite similar components have masses of about 5 M and radii of about 3.5 R, and they seem to have evolved just slightly off the ZAMS. The measured rotational velocities (≈150 km s−1) are about 6 times those corresponding to pseudosynchronization

Episodic mass loss in binary evolution to the Wolf-Rayet phase: Keck and HST proper motions of RY Scuti's nebula

Binary mass transfer via Roche-lobe overflow (RLOF) is a key channel for producing stripped-envelope Wolf-Rayet (WR) stars and may be critical to account for SN Ib/c progenitors. RY Scuti is an extremely rare example of a massive binary star caught in this brief but important phase. Its toroidal nebula indicates equatorial mass loss during RLOF, while the mass-gaining star is apparently embedded in an opaque accretion disk. RY Scuti's toroidal nebula has two components: an inner ionised double-ring system, and an outer dust torus that is twice the size of the ionised rings. We present two epochs of Lband Keck NGS-AO images of the dust torus, plus three epochs of HST images of the ionised gas rings. Proper motions show that the inner ionised rings and the outer dust torus came from two separate ejection events roughly 130 and 250 yr ago. This suggests that RLOF in massive contact binaries can be accompanied by eruptive and episodic burst of mass loss, reminiscent of LBVs. We speculate that the repeating outbursts may arise in the mass gainer from instabilities associated with a high accretion rate. If discrete mass-loss episodes in other RLOF binaries are accompanied by luminous outbursts, they might contribute to the population of extragalactic optical transients. When RLOF ends for RY Scuti, the overluminous mass gainer, currently surrounded by an accretion disk, will probably become a B[e] supergiant and may outshine the hotter mass-donor star that should die as a Type Ib/c supernova.Comment: 15 pages, 7 figures, submitted to MNRA