Peculiar classified Wolf-Rayet stars, HD 90657 and HD 117688

Spectral observations of Wolf-Rayet stars HD 90657 and HD 117688 were made at the Cerro Tololo Interamerican Observatory, in Chile. These stars have been classified by earlier authors as intermediate objects between the two sequences of W-R stars, presenting in their spectra lines of both carbón and nitrogen. However, our observations do not confirm this classification, the observed spectra look like “normal” WN stars. In addition, HD 90657, earlier classified as WN4—C -J- OB, shows variations of radial velocity of the order of 130 km/s and variations of type V/R in the shape of the emission lines.Asociación Argentina de Astronomí

A short history and other stories of binary stars

A short history of binary stars from the first discoveries is presented. Examples of currently known binary Systems with components of highest temperature and mass are discussed.Se presenta una corta historia de estrellas binarias desde los primeros descubrimientos. Se discuten ejemplos actualmente conocidos de sistemas con componentes de temperatura y masas más altas.Facultad de Ciencias Astronómicas y Geofísica

Possible new binaries among the Wolf-Rayet stars

Spectra of Wolf-Rayet stars HD 92740 and HD 93131, obtained between May 16 - May 23, 1970, at Cerro Tololo Intermaerican Observatory, in Chile, confirm that these stars show the superior members of the Balmer series in absorption. The radial velocities of various emission lines measured indicate variations of the order of 140 km/s for HD 92740 and of the order of 180 km/s for HD 93131. These stars may be binaries with periods of the order of a month.Asociación Argentina de Astronomí

Possible new binaries among the Wolf-Rayet stars

Spectra of Wolf-Rayet stars HD 92740 and HD 93131, obtained between May 16 - May 23, 1970, at Cerro Tololo Intermaerican Observatory, in Chile, confirm that these stars show the superior members of the Balmer series in absorption. The radial velocities of various emission lines measured indicate variations of the order of 140 km/s for HD 92740 and of the order of 180 km/s for HD 93131. These stars may be binaries with periods of the order of a month.Asociación Argentina de Astronomí

Peculiar classified Wolf-Rayet stars, HD 90657 and HD 117688

Spectral observations of Wolf-Rayet stars HD 90657 and HD 117688 were made at the Cerro Tololo Interamerican Observatory, in Chile. These stars have been classified by earlier authors as intermediate objects between the two sequences of W-R stars, presenting in their spectra lines of both carbón and nitrogen. However, our observations do not confirm this classification, the observed spectra look like “normal” WN stars. In addition, HD 90657, earlier classified as WN4—C -J- OB, shows variations of radial velocity of the order of 130 km/s and variations of type V/R in the shape of the emission lines.Asociación Argentina de Astronomí

Possible new binaries among the Wolf-Rayet stars

Spectra of Wolf-Rayet stars HD 92740 and HD 93131, obtained between May 16 - May 23, 1970, at Cerro Tololo Intermaerican Observatory, in Chile, confirm that these stars show the superior members of the Balmer series in absorption. The radial velocities of various emission lines measured indicate variations of the order of 140 km/s for HD 92740 and of the order of 180 km/s for HD 93131. These stars may be binaries with periods of the order of a month.Asociación Argentina de Astronomí

Peculiar classified Wolf-Rayet stars, HD 90657 and HD 117688

Spectral observations of Wolf-Rayet stars HD 90657 and HD 117688 were made at the Cerro Tololo Interamerican Observatory, in Chile. These stars have been classified by earlier authors as intermediate objects between the two sequences of W-R stars, presenting in their spectra lines of both carbón and nitrogen. However, our observations do not confirm this classification, the observed spectra look like “normal” WN stars. In addition, HD 90657, earlier classified as WN4—C -J- OB, shows variations of radial velocity of the order of 130 km/s and variations of type V/R in the shape of the emission lines.Asociación Argentina de Astronomí

The spectrum of Gamma-2 Velorum : II

The study of the series of spectra of Gamma-2 Velorum taken by C. D. Perrine at the Córdoba Observatory in 1919 suggests that the variations in the radial velocities and in the intensities of the absorption lines that show the effect of diluted radiation are periodic with Vainu Bappu and Ganesh’s period of 78,5 days and permits to improve this figure to 78,5002 days. The same period is followed by V/R variations displayed by the emissions of H and He I. Thus the emission features of Gamma-2 Velorum can be separated into two groups, one of the broad H and He I emissions that show V/R variations, and a second one of the relatively narrow and stronger He II, C IV, O IV, etc. lines that do not show V/R variations. One obvious conclusion is that the Wolf - Rayet spectrum does actually show H in its spectrum, the behaviour of the H lines being different than the behaviour of He II. The examination of the spectra taken at Bosque Alegre by Sahade in the interval 1948-62 and that of the spectra taken by Perrine, suggest that no noticeable changes have occurred in the spectrum of Gamma-2 Velorum in the last fifty years. Furthermore, the V/R variations in the red part of the spectrum is also shown on the 1948-62 plates. Identifications of the spectral features are given in the wavelength range λ 3100 - 6800 A. Relative to H8, the distribution of the radial velocities of the absorption line of He I 3888 that show dilution effect and is violet displaced by about 1200 km /sec on the average, both on Perrine’s plates as well as on those taken with the Bosque Alegre reflector, apparently follow the trend of the radial velocities of the W - R component but with a much larger amplitude. This will be checked with the measurement of the Bosque Alegre spectra and may be explained in terms of form and density distribution of the envelope that surrounds the whole system. The paper will be published in full elsewhere.Asociación Argentina de Astronomí

The spectrum of Gamma-2 Velorum : II

The study of the series of spectra of Gamma-2 Velorum taken by C. D. Perrine at the Córdoba Observatory in 1919 suggests that the variations in the radial velocities and in the intensities of the absorption lines that show the effect of diluted radiation are periodic with Vainu Bappu and Ganesh’s period of 78,5 days and permits to improve this figure to 78,5002 days. The same period is followed by V/R variations displayed by the emissions of H and He I. Thus the emission features of Gamma-2 Velorum can be separated into two groups, one of the broad H and He I emissions that show V/R variations, and a second one of the relatively narrow and stronger He II, C IV, O IV, etc. lines that do not show V/R variations. One obvious conclusion is that the Wolf - Rayet spectrum does actually show H in its spectrum, the behaviour of the H lines being different than the behaviour of He II. The examination of the spectra taken at Bosque Alegre by Sahade in the interval 1948-62 and that of the spectra taken by Perrine, suggest that no noticeable changes have occurred in the spectrum of Gamma-2 Velorum in the last fifty years. Furthermore, the V/R variations in the red part of the spectrum is also shown on the 1948-62 plates. Identifications of the spectral features are given in the wavelength range λ 3100 - 6800 A. Relative to H8, the distribution of the radial velocities of the absorption line of He I 3888 that show dilution effect and is violet displaced by about 1200 km /sec on the average, both on Perrine’s plates as well as on those taken with the Bosque Alegre reflector, apparently follow the trend of the radial velocities of the W - R component but with a much larger amplitude. This will be checked with the measurement of the Bosque Alegre spectra and may be explained in terms of form and density distribution of the envelope that surrounds the whole system. The paper will be published in full elsewhere.Asociación Argentina de Astronomí

The spectrum of Gamma-2 Velorum : II

The study of the series of spectra of Gamma-2 Velorum taken by C. D. Perrine at the Córdoba Observatory in 1919 suggests that the variations in the radial velocities and in the intensities of the absorption lines that show the effect of diluted radiation are periodic with Vainu Bappu and Ganesh’s period of 78,5 days and permits to improve this figure to 78,5002 days. The same period is followed by V/R variations displayed by the emissions of H and He I. Thus the emission features of Gamma-2 Velorum can be separated into two groups, one of the broad H and He I emissions that show V/R variations, and a second one of the relatively narrow and stronger He II, C IV, O IV, etc. lines that do not show V/R variations. One obvious conclusion is that the Wolf - Rayet spectrum does actually show H in its spectrum, the behaviour of the H lines being different than the behaviour of He II. The examination of the spectra taken at Bosque Alegre by Sahade in the interval 1948-62 and that of the spectra taken by Perrine, suggest that no noticeable changes have occurred in the spectrum of Gamma-2 Velorum in the last fifty years. Furthermore, the V/R variations in the red part of the spectrum is also shown on the 1948-62 plates. Identifications of the spectral features are given in the wavelength range λ 3100 - 6800 A. Relative to H8, the distribution of the radial velocities of the absorption line of He I 3888 that show dilution effect and is violet displaced by about 1200 km /sec on the average, both on Perrine’s plates as well as on those taken with the Bosque Alegre reflector, apparently follow the trend of the radial velocities of the W - R component but with a much larger amplitude. This will be checked with the measurement of the Bosque Alegre spectra and may be explained in terms of form and density distribution of the envelope that surrounds the whole system. The paper will be published in full elsewhere.Asociación Argentina de Astronomí