Coude Spectrograph Research Articles

Spectroscopic study of the supergiant star 6 Cassiopeiae

Twenty-five coude spectrograms (22 with dispersion 12 A mm−1 and three 7 A mm−1) of 6 Cassiopeiae (A3 Ia) have been studied. The observations were made at the Haute Provence Observatory. The results of the analysis suggest a correlation between the variations of the equivalent widths, the microturbulence and the radial velocity. The radial velocity and turbulent velocity present a rapid variation with time, even in intervals as short as about an hour. The hydrogen lines are slightly asymmetric but the strongest Feii lines are clearly asymmetric. We found that the amount of asymmetry of the strongest Feii lines (I>6) correlates with the loggf value, with the estimated laboratory intensityI, and with the equivalent widthWλ.

THE DOUBLE LINED SPECTROSCOPIC BINARY HD 214686.

ABSTRACT Orbital elements for the 6th-magnitude 21.7-day double-lined binary HD 214686 are determined from coude spectrograms. Photometric observations show the system to contain two F7 V stars, and minimum masses near 1.16 solar masses are found for both components. These results remove an apparent contradiction between the spectral types and the masses of the components obtained by Sanford in 1931, based upon neglect of an earlier revision of the type. The orbital inclination is near 90 deg, and a search for eclipses is urged.

New diffuse interstellar bands in the wavelength region 6500-8900 A

view Abstract Citations (59) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS New diffuse interstellar bands in the wavelength region 6500 - 8900 Å. Sanner, F. ; Snell, R. ; vanden Bout, P. Abstract The coude spectrograph of the 2.7-m telescope at McDonald Observatory has been used with a Reticon detector to search for diffuse interstellar features in the wavelength region 6500-8900 A. Low-resolution (0.92 A) spectra of 15 spectral-type O, B, and A stars with color excesses ranging from E(B - V) equals 0.00 to 1.28 were recorded. These spectra show the previously detected features in this wavelength region at 6613, 6661, and 8621 A; confirm the interstellar nature of a previously suspected feature at 6699 A; and show several new features: at 7562 A of definite, at 7570, 8650 A of probable, and at 8572, 8384 A of possible interstellar origin. Correlations between diffuse-feature equivalent widths and color excess are presented. As in the near-ultraviolet, the frequency of occurrence of diffuse features in the near-infrared per unit energy interval is much less than in the visual. Publication: The Astrophysical Journal Pub Date: December 1978 DOI: 10.1086/156628 Bibcode: 1978ApJ...226..460S Keywords: Astronomical Spectroscopy; Interstellar Matter; Interstellar Radiation; Spectral Bands; Ultraviolet Astronomy; Astronomical Catalogs; Early Stars; Stellar Spectra; Wavelengths; Astrophysics; Interstellar Lines full text sources ADS | data products SIMBAD (15)

Three southern hemisphere Of stars, HD 163758, HD 150958, and HD 152386. I - The lines in the blue region

view Abstract Citations (7) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Three southern hemisphere Of stars, HD 163758, HD 150958, and HD 152386. I. The lines in the blue region. Leep, E. M. Abstract At least seven coude spectrograms have been obtained for each of the three Of stars, HD 163758, HD 150958, and HD 152386. One of them, HD 150958, appears to be a single-lined spectroscopic binary with a period of around 5 days. Velocity gradients have been observed in the Balmer lines of all three stars. In each case, the narrow N III emission lines at 4634 and 4641 A and the broad He II emission lines at 4686 A were displaced redward with respect to the absorption features. Spectral types were calculated and found to be in general agreement with those of Walborn (1974). The strengths and shapes of the upper Balmer lines in these Of stars were found to be similar to those of WN 'transition' stars. Also compared were the profiles of He II 4686-A emission in these Of stars and in the 'transition' types. The anomalously strong carbon lines found in the case of HD 163758 make it a possible carbon-rich Of star. Publication: The Astrophysical Journal Pub Date: October 1978 DOI: 10.1086/156477 Bibcode: 1978ApJ...225..165L Keywords: Line Spectra; O Stars; Spectrum Analysis; Stellar Spectra; Balmer Series; Binary Stars; Carbon Stars; Chemical Composition; Data Reduction; Radial Velocity; Spectral Line Width; Stellar Evolution; Stellar Mass; Astronomy; Line Profiles:Of Stars; Of Stars:Radial Velocities; Of Stars:Wolf-Rayet Stars full text sources ADS | data products SIMBAD (12)

The CA II V/R ratio and mass loss

High-dispersion coude spectrograms of 181 MK standards of types early F through late M, including luminosity classes Ia, Ib, II, and III, are analyzed. It is shown that the brightness ratio of the V and R self-reversed emission peaks (denoted V/R) in the center of the Ca II K line is correlated with spectral type as well as with certain other spectral-type and luminosity-sensitive parameters, including indicators of mass loss and the H-K wing emission lines. The observations indicate that V/R varies smoothly from less than unity in late K and M giants to greater than unity for G giants. This trend appears to be true for bright giants as well but not necessarily for supergiants and seems to hold for the average V/R for a given star, although short-term variations in V/R occur. It is suggested that the V/R values, which can be interpreted in terms of atmospheric motions, may indirectly relate to effects of evolutionary changes in stellar structure and that V/R among late-type stars could be useful as an indicator of both chromospheric activity and the state of stellar evolution.

Spectroscopic study of the eclipsing binary V 367 Cygni

Seventeen coude spectrograms (dispersion 20 A mm−1) of the β Lyrae-type eclipsing binary V 367 Cygni (P=18.6 d) have been studied. The observations were made at the Haute Provence Observatory during a period of almost two years (May 1973–March 1975). An anomalous behavior for the radial velocities of the spectrograms taken during one cycle (406) was observed; it is suggested that gas eruption under form of prominences may explain it. The spectrum is dominated by shell lines very similar to those present in the spectrum of the supergiant A9 Ia e Aurigae. The underlying stellar spectrum is classified as A5 I on the basis of the intensity of the sole clearly visible stellar line, λ4481 MgII, of the wings of the stellar Balmer lines, and an estimate of the intensity of the stellarK line. The radial velocity curves for the shell lines of CaII, HI, metallic ions and neutral iron, as well as the phase dependence of the microturbulence, indicate stratification in the shell.

The effects of stellar rotation on measurements from coude spectrograms

The effects of rotation on the measurement of line blocking and equivalent widths from tracings of coudé spectrograms have been studied by artificially ‘spinning-up’ the spectra of two sharp-lined stars. The anticipated decrease in the measured blocking coefficients with increase of υ sin i is confirmed for F stars, while abundances deduced from curve of growth analyses are increased owing to the apparent domination of line blending over depression of the continuum as factors affecting equivalent widths.

THE A2P STAR HD 3473.

ABSTRACT The Ap star HD 3473 is investigated on the basis of three coude spectrograms, two covering the blue region from 3500 to 4500 A and the other centered at H-alpha in the red. Many of the stronger features in the blue region are identified as being due to high-excitation lines of Si II and Mg II, an excitation temperature of 9750 K is determined by several separate means, and it is found that both Mg and Si are quite overabundant while Ca is probably slightly overabundant. The observed weakness of the neutral metal lines in the spectrum of HD 3473 is discussed, and weak emission is taken as a possible reason for this. The results indicate that HD 3473 is obviously an Ap-type star and is an extreme example of an Si star, that the low temperature and high abundance of rare-earth elements suggest a transition between Si and Eu-Cr-Sr stars, and that the star shows rare-earth enhancement despite its rapid rotation. The possible existence of a shell is considered.

Spectroscopic studies of O-type stars. VIII - Radial velocities and the K-term

Radial velocities are measured on coude spectrograms of over 200 O-type stars in both hemispheres. The selection of effective wavelengths for the stellar lines to be measured is reviewed, and the measured velocities are compared with those available in a catalog of O stars. The Trumpler (1935) effect (a reported anomalous redshift in certain O stars) is inconclusively reinvestigated, atmospheric motions in Of stars are examined, and some kinematic properties of O stars are discussed statistically. It is found that 58% of all O stars and 41% of all the Of stars considered are certain or probable binaries. A K-term in the range from 1 to 2 km/s is derived for the O stars, but the Of stars are shown to have a highly significant negative K-term. It is suggested that the systematically negative peculiar velocities of the Of stars are due to outflow of material beginning at the photospheric level.

Spectrophotometry of the transient X-ray source A0620-00

Optical observations of the transient X-ray source A0620-00 over the wavelength range from about 3200 to 6600 A are analyzed which were made with the 5-m Hale telescope using a multichannel spectrometer, a digital spectrograph with a cooled integrating SIT vidicon, and an image photon-counting system attached to the camera of the coude spectrograph. Infrared observations at 1.65, 2.2, and 3.5 microns are also examined. Individual spectral lines of special interest are discussed, the E(B-V) color excess is estimated to be about 0.40, and a distance of 1200 pc is adopted. Analysis of the continuous spectrum yields several simple binary models. A specific model is proposed in which one of the continuum sources is an optically thick object characterized by a model atmosphere at a temperature of 25,000 to 30,000 K and the second source is either a cool black body at 4000 K or a partially optically thick source of bound-free plus free-free radiation from a hydrogen gas with an electron temperature of at least 100,000 K. Some possible parameters of these sources and of the accretion disk are considered.

Beryllium in main-sequence stars

Beryllium abundances are determined in 38 stars of spectral types F and G, including the Sun. New observations in the ultraviolet at 6.7 A mm/sup -1/ of 15 stars have been made with the coude spectrograph of the 224 cm telescope at Mauna Kea. These data supplement values found in the literature. A model atmosphere analysis with Carbon and Gingerich (1969) models and the equivalent widths of one of the Be II resonance lines, 3131.064 A, gives the Be abundance for each of the 38 stars. Effective temperatures were found from H..beta.. photometry; values of log g were estimated from the position of the star in the (c/sub 1/, b: y) diagram.The derived Be abundances show no dependence on stellar surface temperature or B: V, and the mean abundance is Be/H=1.31 x 10/sup -11/ +- 0.36 +- 10/sup -11/. The solar system abundances are similar. This value thus represents the cosmic or universal abundance, and the origin of Be can be explained by galactic cosmic-ray spallation reactions in the interstellar gas.One-third of the stars in the temperature range 6600--7400 K have only upper-limit Be abundances and are Be-deficient. These stars are also Li-deficient. A discussion of the light-element depletion inmore » terms of diffusion (including turbulent diffusion) and convective overshoot is given. Diffusion and rotational braking appear to offer the more promising explanation of the two. (AIP)« less

13.9-MINUTE PERIODICITY IN X PERSEI (=3U 0352+30?).

ABSTRACT Observations were made with a 1.2-m telescope coude spectrograph and an Image Isocon camera of the spectrum of X Per at 4686 A and H beta to look for 13.9-minute periodic changes, observed previously in the X-ray source 3U 0352 plus 30, in order to confirm the optical identification. From the data, it appears that over regions of 2 A or less, associated with these wavelengths, periodic changes modulo 13.9 minutes are not seen above the 2 percent level. Changes below this level are indicated in the power spectra, but are not of high statistical significance.

HD 47129 - The most massive binary

view Abstract Citations (39) References (8) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS HD 47129: the most massive binary. Hutchings, J. B. ; Cowley, A. P. Abstract Thirty-two coude spectrograms of Plasketts's star have been obtained. These show that the primary star has a stellar wind which is stronger from the following side of the star. New orbital elements are presented for lines of different excitation. Lines of the secondary absorption spectrum are distinguished from shell features, and show an orbital velocity indicating a mass ratio near unity. The mass of each component exceeds 55 solar masses. Neither star fills its Roche limiting surface, but it appears that both lose mass to the system. The secondary is underluminous for its mass and may be smaller than the primary. He II emission at lambda 4686 is not strongly associated with either star, and arises in part between the two. Publication: The Astrophysical Journal Pub Date: June 1976 DOI: 10.1086/154404 Bibcode: 1976ApJ...206..490H Keywords: Binary Stars; Early Stars; Giant Stars; O Stars; Stellar Mass; Stellar Spectra; Absorption Spectra; Emission Spectra; Mass Ratios; Orbital Elements; Spectrograms; Stellar Evolution; Stellar Winds; Velocity Distribution; Astronomy full text sources ADS | data products SIMBAD (1)

Ultraviolet FeII emission in late-type stars.

view Abstract Citations (16) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet Fe II emission in late-type stars. Boesgaard, A. M. ; Boesgaard, H. Abstract Spectrograms of 44 K and M giants and supergiants have been taken with the Cassegrain and coude spectrographs of the Mauna Kea 224 cm telescope to determine the presence and intensity of the ultraviolet emission lines of Fe II from multiplets 1, 6, and 7. The emission is nearly universal in the M stars, but not found in any of the K stars; it thus appears to be a natural consequence of stellar surface temperature. The intensity of the emission is well correlated with the strengths of the circumstellar components of the K-line of Ca II and of Ha. It is suggested that the emission arises in the circumstellar gas shell and that its intensity is a primary indicator of the extent of the shell. There is no apparent relationship between the Fe II emission intensity and the amount of infrared excess at 11 and 20 , the indicators of a circumstellar dust shell. Subject headings: stars: circumstellar shells stars: emission-line - stars: late-type Publication: The Astrophysical Journal Pub Date: April 1976 DOI: 10.1086/154297 Bibcode: 1976ApJ...205..448B full text sources ADS | data products SIMBAD (47)

Velocity dispersions in galaxies. V - The nuclei of M31 and M32

view Abstract Citations (22) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Velocity dispersion in galaxies. V. The nuclei of M31 and M32. Morton, D. C. ; Elmergreen, Bruce G. Abstract Stigmatic spectra between 4160 and 4385 A of the central regions of M31 and M32 as well as the K0 III star 51 Ori are presented which were obtained using a SEC-vidicon integrating television tube and the coude spectrograph of the Hale telescope. Line-of-sight velocity dispersions of approximately 130 and 55 km/s are determined for the nuclei of M31 and M32, respectively, by directly comparing their spectra with Gaussian-broadened spectra of 51 Ori. The analytical techniques are outlined, and alternative methods for estimating velocity dispersions are evaluated, including least-squares fitting of intensities and division of Fourier transforms. It is noted that the broadened spectrum of 51 Ori fits the nucleus of M32 and the bulge of M31 much better than the nucleus of M31 in the region between 4180 and 4370 A. Publication: The Astrophysical Journal Pub Date: April 1976 DOI: 10.1086/154250 Bibcode: 1976ApJ...205...63M Keywords: Andromeda Galaxy; Galactic Nuclei; Stellar Motions; Stellar Spectra; Velocity Distribution; Fourier Transformation; Galactic Structure; Least Squares Method; Spectral Line Width; Astrophysics full text sources ADS | data products NED (2) Related Materials (4) Part 1: 1972ApJ...174..489M Part 2: 1973ApJ...179...55M Part 3: 1973ApJ...180..705M Part 4: 1977ApJ...212...13M

A system of standard stars for rotational velocity determinations

view Abstract Citations (360) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A system of standard stars for rotational velocity determinations. Slettebak, A. ; Collins, G. W., II ; Boyce, P. B. ; White, N. M. ; Parkinson, T. D. Abstract Profiles for the He I lambda 4471, Mg II lambda 4481, and Fe I lambda 4476 lines were measured in the spectra of 217 bright northern and southern stars of types O9-F9, using photoelectric scans and photographic coude spectrograms obtained at the Cerro Tololo Inter-American Observatory, Kitt Peak National Observatory, and Lowell Observatory. Half-intensity widths of the observed line profiles were compared with the corresponding quantities in a set of theoretical rotationally-broadened line profiles computed using the model-atmosphere approach. The resulting v sin i's are used to establish a system of standard rotational velocity stars, for use in estimating v sin i directly from visual inspection of spectrograms. An atlas of rotationally broadened spectra is presented, showing the effects of rotation on spectra of representative B-, A-, and F-type stars. Publication: The Astrophysical Journal Supplement Series Pub Date: May 1975 DOI: 10.1086/190338 Bibcode: 1975ApJS...29..137S Keywords: Angular Velocity; Line Spectra; Reference Stars; Stellar Rotation; Stellar Spectra; Astronomical Models; Atmospheric Models; F Stars; Radiant Flux Density; Rotational Spectra; Spectral Line Width; Standards; Astronomy full text sources ADS | data products SIMBAD (219)

THE EFFECT OF LINE BLOCKING ON THE LIGHT CURVES OF THE AP STAR HR 5355 (HD 125248).

ABSTRACT Line-blocking coefficients were measured from coude spectrograms covering the blue and green parts of the spectra, throughout the 9d3 cycle of HR 5355. The coefficient for the V band of the uvby photometry is found to vary through a range of 0" 06 of the continuum in a double wave, with maxima corresponding to the maxima of both the Eu ii and the Cr spectrum variation, which occur in antiphase. This line blocking cannot account for the strong single-wave light variation in the V band, which has a minimum at rare-earth maximum, but may be responsible, by redistribution of flux, for the double-wave character of the b- and y-band light variations. There is little variation of line blocking in the b and y bands. Line blocking varies significantly with wavelength and with phase in the vicinity of 5200 A, and is partially responsible for the minimum in the apparent continuum found by photometric observers. It does not appear to be possible to interpret the basic light variations of HR 5355 by the mechanisms recently proposed for this and other Ap stars. Key words: peculiar A stars - line blocking - spectrum variation - light variation

Outburst in U Cephei

A SYSTEMATIC survey of the profiles of the Hα line in binary stars, shell stars, Be stars and related peculiar objects is being conducted by us (and G. J. Peters) with the Varo image intensifier attached to the coude spectrograph of the 120-inch telescope and the 24-inch coude auxiliary telescope of the Lick Observatory. Emission at Hα is found to be a more common Phenomenon among the Algol-type eclipsing binaries than was thought before. Usually, but not always, the emission is best observed during the primary minimum when the light of the hotter and brighter component is either greatly reduced or completely occulted. This is in agreement with the models representing the Algol systems as evolved binaries in which mass is still being transferred from the late-type secondary component to the hotter primary star1,2. Although the general picture is fairly clear, the problem remains how the on-flowing material and its angular momentum are distributed among the primary star, the disk revolving around it and a possible envelope enclosing the whole system. The purpose of our survey is to furnish quantitative data on this process.

FURTHER OBSERVATIONS OF THE NUCLEAR ROTATION IN M31

ABSTRACT Radial-velocity observations of the nucleus of M31 obtained with the Lallemand electronic camera and 120-inch coude spectrograph and with the prime-focus nebular spectrograph are presented. These observations cover the radial distance range (r) from 0 to 24 sec of arc and show that the rotation curve, which has its maximum amplitude in P.A. equals 52 deg, increases linearly from zero at r equals 0 to 104 km per sec at r equals 1.9 sec of arc, beyond which it drops approximately as inversely to the square root of r. After making approximate correction for the effect of seeing and instrumental resolution, we find the radius of the nucleus r equals 1.55 sec of arc or 5.2 pc, a rotational period of 310,000 years, and a mass of 0.16 billion solar masses.

ON THE LOCATION OF THE EXTINCTION IN NGC 7027

ABSTRACT Coude spectrograms of NGC 7027 were obtained at sufficiently high dispersion to resolve the H alpha, H beta, and H gamma line profiles. Comparison of the blue and red sides shows no differences that can be attributed to internal extinction by dust within this planetary nebula.